Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

We examined the attraction of adults to six LEDs in the red flour beetles, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), which is widespread as a stored grain insect. In the experiment, bluish green and green were more attractive than the two UVs, blue, and red LEDs only in females. On the other hand, no difference was found in attraction among the six LEDs in males. Next, we investigated the relationship between light intensity and attractiveness. No sexual difference in attractiveness in different light intensities was found, but the strongest light intensity was more attractive than other light intensities. Finally, we investigated the relationship between light attraction and strains artificially selected for the duration of death feigning. Short-strain beetles were more attracted to UV lights than long-strain beetles.

File： s13355-023-00829-6.pdf

DOI： 10.1007/s13355-023-00829-6

researchmap

Other Link： https://link.springer.com/article/10.1007/s13355-023-00829-6/fulltext.html

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Royal Society  

Death-feigning behaviour is a phenomenon in which a prey is rendered motionless due to stimulation or threat from a predator. This anti-predator defence mechanism has been observed across numerous animal taxa and is considered adaptive in nature. However, longer durations of death feigning can result in decreased opportunities for feeding and reproduction, and therefore is often associated with fitness costs as compared to environments without predators. Differences have also been observed in the frequencies and durations of death feigning within populations, and these differences are thought to be influenced by the balance between survival and other fitness costs. Furthermore, this balance is predicted to vary in response to changes in environmental conditions. In this study, we examined the death feigning in 38 populations of the red flour beetle ( Tribolium castaneum ). Our results demonstrate that frequencies and durations of the death feigning in T. castaneum show geographical variations and a latitude cline, indicating that this behaviour is influenced by location as well as latitude. This study is the first to demonstrate the existence of a latitudinal cline in death feigning and suggests that death-feigning behaviour might have evolved in response to environmental factors that vary with latitude.

File： matsumura-miyatake-2023-latitudinal-cline-of-death-feigning-behaviour-in-a-beetle-(tribolium-castaneum).pdf

DOI： 10.1098/rsbl.2023.0028

researchmap

Other Link： https://royalsocietypublishing.org/doi/full-xml/10.1098/rsbl.2023.0028

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10709-022-00174-6

researchmap

Other Link： https://link.springer.com/article/10.1007/s10709-022-00174-6/fulltext.html

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10164-022-00757-y

researchmap

Other Link： https://link.springer.com/article/10.1007/s10164-022-00757-y/fulltext.html

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s10519-022-10108-9

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10164-022-00753-2

researchmap

Other Link： https://link.springer.com/article/10.1007/s10164-022-00753-2/fulltext.html

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/eth.13279

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/eth.13279

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/eth.13272

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/eth.13272

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/ece3.8533

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ece3.8533

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Since the variables inherent to various diseases cannot be controlled directly in humans, behavioral dysfunctions have been examined in model organisms, leading to better understanding their underlying mechanisms. However, because the spatial and temporal scales of animal locomotion vary widely among species, conventional statistical analyses cannot be used to discover knowledge from the locomotion data. We propose a procedure to automatically discover locomotion features shared among animal species by means of domain-adversarial deep neural networks. Our neural network is equipped with a function which explains the meaning of segments of locomotion where the cross-species features are hidden by incorporating an attention mechanism into the neural network, regarded as a black box. It enables us to formulate a human-interpretable rule about the cross-species locomotion feature and validate it using statistical tests. We demonstrate the versatility of this procedure by identifying locomotion features shared across different species with dopamine deficiency, namely humans, mice, and worms, despite their evolutionary differences.

DOI： 10.1038/s41467-021-25636-x

PubMed

researchmap

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10164-021-00709-y

researchmap

Other Link： https://link.springer.com/article/10.1007/s10164-021-00709-y/fulltext.html

Authorship：Lead author,　Last author,　Corresponding author   Language：English  

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JStage (Ornithological Society of Japan)  

DOI： 10.3838/jjo.70.53

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/ece3.7418

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ece3.7418

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Royal Society  

Tonic immobility and escape are adaptive anti-predator tactics used by many animals. Escape requires movement, whereas tonic immobility does not. If anti-predator tactics relate to weapon size, males with larger weapons may adopt tonic immobility, whereas males with smaller weapons may adopt escape. However, no study has investigated the relationship between weapon size and anti-predator tactics. In this study, we investigated the relationship between male weapon size and tonic immobility in the beetle
<italic>Gnathocerus cornutus</italic>
. The results showed that tonic immobility was more frequent in males with larger weapons. Although most studies of tonic immobility in beetles have focused on the duration, rather than the frequency, tonic immobility duration was not affected by weapon size in
<italic>G</italic>
.
<italic>cornutus</italic>
. Therefore, this study is the first, to our knowledge, to suggest that the male weapon trait affects anti-predator tactics.

DOI： 10.1098/rsbl.2020.0601

researchmap

Other Link： https://royalsocietypublishing.org/doi/full-xml/10.1098/rsbl.2020.0601

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Brill  

<title>Abstract</title>
Animal behaviours often dependent on age. In many insect species, walking shows an age-dependent decline, and food intake may also be dependent on age. However, few studies have investigated the relationship between age and walking or food intake. In the present study, we compared walking traits and food intake among individuals of different ages in the assassin bug <italic>Amphibolus venator</italic> (Hemiptera, Reduviidae). The present results showed an age-dependent decline in walking, similar to findings in many animal species. On the other hand, food intake showed a positive correlation with age. Therefore, the decline in walking did not lead to a decline in feeding. The positive relationship between food intake and age may be related to the type of predation, sit-and-wait, used by <italic>A. venator</italic> via alterations in investment in reproductive traits with age.

DOI： 10.1163/1568539x-bja10060

researchmap

Other Link： https://brill.com/downloadpdf/journals/beh/aop/article-10.1163-1568539X-bja10060/article-10.1163-1568539X-bja10060.xml

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Public Library of Science (PLoS)  

Many species show rhythmicity in activity, from the timing of flowering in plants to that of foraging behavior in animals. The free-running periods and amplitude (sometimes called strength or power) of circadian rhythms are often used as indicators of biological clocks. Many reports have shown that these traits are highly geographically variable, and interestingly, they often show latitudinal or longitudinal clines. In many cases, the higher the latitude is, the longer the free-running circadian period (i.e., period of rhythm) in insects and plants. However, reports of positive correlations between latitude or longitude and circadian rhythm traits, including free-running periods, the power of the rhythm and locomotor activity, are limited to certain taxonomic groups. Therefore, we collected a cosmopolitan stored-product pest species, the red flour beetle <italic>Tribolium castaneum</italic>, in various parts of Japan and examined its rhythm traits, including the power and period of the rhythm, which were calculated from locomotor activity. The analysis revealed that the power was significantly lower for beetles collected in northern areas than southern areas in Japan. However, it is worth noting that the period of circadian rhythm did not show any clines; specifically, it did not vary among the sampling sites, despite the very large sample size (n = 1585). We discuss why these cline trends were observed in <italic>T</italic>. <italic>castaneum</italic>.

DOI： 10.1371/journal.pone.0245115

researchmap

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Part of collection (book)  

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.aspen.2021.01.012

researchmap

Publishing type：Research paper (scientific journal)  

researchmap

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s10164-020-00680-0

researchmap

Other Link： http://link.springer.com/article/10.1007/s10164-020-00680-0/fulltext.html

Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/eth.13094

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/eth.13094

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Multiple mating by females increases both the risk and intensity of sperm competition for males. The ability to temporarily or permanently inhibit female receptivity to further mating represents a highly adaptive strategy to reduce the risk of sperm competition. Males of the West Indian sweet potato weevilEuscepes postfasciatus(Fairmaire) (Coleoptera: Curculionidae) and the seed bugTogo hemipterus(Scott) (Heteroptera: Lygaeidae) use accessory gland substances to inhibit remating in females. It is known that there is variance in the length of the female refractory period (i.e., the effectiveness of male ejaculate substances that inhibit female remating) within a species. However, it is unclear what types of male traits affect the length of the female refractory period. The mechanism of the female refractory period is not sufficiently revealed. We focused on male body size, which is often a target of sexual selection, and investigated the relationship between male body size and both the refractory period of females and mating duration. Contrary to our thought, male body size did not significantly influence the refractory period of females or mating duration in either species. Smaller male body size was not particularly favored by post-copulatory sexual selection in either species.

DOI： 10.1007/s10164-020-00669-9

Web of Science

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

<title>Abstract</title>
Circadian rhythms, their free-running periods and the power of the rhythms are often used as indicators of biological clocks, and there is evidence that the free-running periods of circadian rhythms are not affected by environmental factors, such as temperature. However, there are few studies of environmental effects on the power of the rhythms, and it is not clear whether temperature compensation is universal. Additionally, genetic variation and phenotypic plasticity in biological clocks are important for understanding the evolution of biological rhythms, but genetic and plastic effects are rarely investigated. Here, we used 18 isofemale lines (genotypes) of Gnatocerus cornutus to assess rhythms of locomotor activity, while also testing for temperature effects. We found that total activity and the power of the circadian rhythm were affected by interactions between sex and genotype or between sex, genotype and temperature. The males tended to be more active and showed greater increases in activity, but this effect varied across both genotypes and temperatures. The period of activity varied only by genotype and was thus independent of temperature. The complicated genotype–sex–environment interactions we recorded stress the importance of investigating circadian activity in more integrated ways.

File： Gnatocerus rhythm paper 20200109.docx

DOI： 10.1093/biolinnean/blaa016

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/jeb.13641

researchmap

Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jeb.13641

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Brill  

<title>Abstract</title>
Tonic immobility is an adaptive anti-predator behaviour observed in many species. This anti-predator behaviour is often correlated with a species’ movement motivation, so a relationship between the duration of tonic immobility and morphological traits supporting movement would be expected. Using the red flour beetle, <italic>Tribolium castaneum</italic>, we carried out two-way artificial selection for the duration of tonic immobility over more than 43 generations, establishing populations with longer (L) and shorter (S) tonic immobility durations compared to those of a non-selected control (C) population. Here, we investigated differences in walking motivation and leg length between the selected populations. Walking motivation was significantly higher in beetles from the S population than that in those from the L population. Moreover, S-population beetles of both sexes had significantly longer legs than those from L and C populations. The present results suggest the evolution of longer legs in response to selection pressure for a shorter duration of tonic immobility in <italic>T. castaneum</italic>.

DOI： 10.1163/1568539X-00003579

researchmap

Other Link： https://brill.com/downloadpdf/journals/beh/157/1/article-p17_2.xml

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s13355-019-00643-z

researchmap

Other Link： http://link.springer.com/article/10.1007/s13355-019-00643-z/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)  

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Tonic immobility (TI) is an effective anti-predator strategy. However, long immobility status on the ground increases the risk of being eaten by predators, and thus insects must rouse themselves when appropriate stimulation is provided. Here, the strength of vibration causing arousal from the state of TI was examined in strains artificially selected for longer duration of TI (L-strains: long sleeper) in a beetle. We provided different strengths of vibration stimuli to the long sleepers in Tribolium castaneum. Although immobilized beetles were never awakened by the stimuli from 0.01 to 0.12 mm in amplitude, almost of the beetles were aroused from immobilized status by the stimulus at 0.21 mm. There was a difference in sensitivity of individuals when the stimuli of 0.14 mm and 0.18 mm were provided. F2 individuals were also bred by crossing experiments of the strains selected for shorter and longer duration of TI. The arousal sensitivity to vibration was well separated in the F2 individuals. A positive relationship was observed between the duration of TI and the vibration amplitude, suggesting that immobilized beetles are difficult to arouse from a deep sleep, while light sleepers are easily aroused by even small vibrations. The results indicate a genetic basis for sensitivity to arousal from TI.

DOI： 10.1007/s10519-019-09962-x

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>
The molecular basis of death feigning, an antipredator behavior that has received much attention recently, was analyzed. We compared the gene expression profiles of strains with different behaviors, i.e., different durations of death feigning, in the beetle <italic>Tribolium castaneum</italic>. Beetles artificially selected for short (S) and long (L) durations of death feigning for many generations were compared thoroughly by RNA sequencing. We identified 518 differentially expressed genes (DEGs) between the strains. The strains also showed divergence in unexpected gene expression regions. As expected from previous physiological studies, genes associated with the metabolic pathways of tyrosine, a precursor of dopamine, were differentially expressed between the S and L strains; these enzyme-encoding genes were expressed at higher levels in the L strain than in the S strain. We also found that several genes associated with insulin signaling were expressed at higher levels in the S strain than in the L strain. Quantitative real-time PCR analysis showed that the relative expression levels of <italic>Tchpd</italic> (encoding 4-hydroxyphenylpyruvate dioxygenase, <italic>Hpd</italic>) and <italic>Tcnat</italic> (encoding N<italic>-acetyltransferase</italic>, <italic>Nat</italic>) were significantly higher in the L strain than in the S strain, suggesting the influence of these enzymes on the supply of dopamine and duration of death feigning.

DOI： 10.1038/s41598-019-50440-5

researchmap

Other Link： http://www.nature.com/articles/s41598-019-50440-5

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/beheco/arz110/5528034

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1007/s1016

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/PERCOMW.2019.8730647

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.5338/hsj.38.14

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/eth.12831

researchmap

Other Link： http://onlinelibrary.wiley.com/wol1/doi/10.1111/eth.12831/fullpdf

Language：English   Publishing type：Research paper (scientific journal)  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1111/jeb.13356

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Academic Press  

Three-way interactions consisting of a female and her current and previous mates have been studied intensively in the context of sperm competition involving male manipulation of female remating rate but have rarely been documented in a broader context involving classical premating male display and stimulatory traits such as courtship behaviour. This is surprising because premating traits influence the intensity of postmating competition, which occurs only when a mated female consecutively accepts another male. In Drosophila fruit flies, the subsequent male has an advantage over the previous male in sperm competition. However, the ejaculate of the previous male changes the female's behaviour to refuse remating for several days (remating suppression), reducing the potential advantage of the subsequent male. Under such conditions, the evolution of any means that counteract remating suppression is thought to be adaptive for the subsequent male. Males of the fruit fly Drosophila prolongata perform a unique courtship behaviour called ‘leg vibration’. Although leg vibration increases female receptivity, it is not always required for mating with virgin females, raising a question of why it evolved in the first place. In this study, the role of leg vibration in remating was examined, using leg amputation to manipulate the efficiency of leg vibration and an eye colour mutation to detect remating events. Leg vibration had a profound effect on mated females: the remating rate was extremely low with leg-amputated males, indicating that leg vibration was almost indispensable for remating of recently mated females. Our results demonstrated that single courtship behaviour has different levels of importance or necessity for the first male and the subsequent males, providing an example of the evolution of courtship behaviour that was possibly driven by postmating competition.

DOI： 10.1016/j.anbehav.2018.04.002

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Tokyo  

Divergent lines selected artificially for many generations make it possible to answer two questions: (1) whether genetic variation still exists within the selected population
and (2) whether the selection itself is costly for the selected strain. In previous studies, the red flour beetle Tribolium castaneum was divergently selected artificially for duration of death-feigning, and strains selected for longer (L-strain) and shorter (S-strain) durations of death-feigning have been established (Miyatake et al. 2004, 2008). Because the selection experiments have been conducted for more than 27 generations, genetic variation may be eroded. Furthermore, because another previous study reported physiological costs to L-strains, the L-strains selected artificially for longer duration of death-feigning may have suffered more costs than the S-strains. In the present study, therefore, we relaxed the selection pressure after the 27th or 30th generation of S- and L-strains. We also carried out reverse selection during the most recent eight generations of S- and L-strains. The results showed that each strain clearly responded to relaxation of selection and reverse selection, suggesting that (1) additive genetic variation still existed in both strains after long-term selection, and (2) selection for shorter and longer duration of death-feigning was costly. These results suggest that anti-predator behavior is controlled by many loci, and longer or shorter duration of death-feigning is costly in a laboratory without predators.

DOI： 10.1007/s10164-018-0548-x

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier B.V.  

Wolbachia are ubiquitous endosymbionts that infect many invertebrates and often manipulate their hosts' reproduction. Although a bias in the sex ratio of the host species due to infection with Wolbachia has been reported in the field, few studies have investigated the seasonal change in rates of infection by Wolbachia. Examining seasonal changes in Wolbachia infection is important because many parasitic infection agents, such as bacteria or viruses, usually show seasonal dynamics. In the present study, we examined the seasonal abundance and sex ratio of two closely related pill bug species that sympatrically inhabit Okayama, Japan. Phylogenetic and morphological analyses identified the two closely related species as Spherillo sp. sensu Karasawa et al. 2014 and Spherillo sp. shi-1 sensu Karasawa and Kawano 2014
they cohabit in fallen leaves, i.e., litter, on a mountain in Okayama City. An obvious peak in emergence of the two pill bug species was not observed. Both sympatric species were infected by Wolbachia, but no seasonal trends were found in the infection rate of Wolbachia. In Spherillo sp., females had higher infection rates than males, while the rates were almost 100% in both sexes in Spherillo sp. shi-1. The results suggest that the two pill bug species are infected by different Wolbachia strains with dissimilar manipulations of the sex ratio.

DOI： 10.1016/j.aspen.2017.08.009

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS INC  

Two species, the cigarette beetle Lasioderma serricorne (F.) and the drugstore beetle Stegobium paniceum (L.), are particularly important stored-product pests because they damage dry food. A previous study showed that L. serricorne adults are attracted more to ultraviolet (UV) and blue light wave ranges more than others such as turquoise, green, yellow, red, and warm white. However, the previous study did not equalize the amounts of light. The study also evaluated the attractiveness by the numbers of L. serricorne individuals that were lured to LED lights in a small box in the laboratory. In some storehouses, damage by S. paniceum is more serious and establishment of an effective monitoring tool is required. Therefore, in the present study, attractions of these beetles to UV and blue light traps were compared to develop a tool to monitor the beetle pests. First, adult L. serricorne and S. paniceum beetles were provided with UV-and blue-LED panels whose light intensities were equalized in the laboratory, and the walking and flying paths of each adult were recorded and measured. As a result, adults were clearly attracted to the side of UV-LED panel by walking compared to the blue one. Second, we compared the numbers of cigarette beetles collected by sticky sheets that were set in the back of UV or bluelight LED traps in a real storehouse. The results showed that these beetles were significantly more attracted to UV than blue-light LED traps, indicating the UV-LED trap is a powerful tool to monitor these two pest species.

DOI： 10.1093/jee/tox127

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Many animal behaviors have a genetic base, and behavioral traits often correlate with one another. In this study, we tested for a behavioral correlation between tonic immobility and walking distance in the larval and adult stages independently of two holometabolous insects. We confirmed a negative correlation of traits between strains in adults of both the species; however, we did not find it in larvae of either species. This suggests that the negative correlation between tonic immobility and walking is decoupled across life stages from larva to adult. In contrast, previous studies have reported that phenotypic correlations between behavioral traits are maintained from larvae to adults in hemimetabolous insects. In addition, our present results differ from previous results with holometabolous insects. Therefore, our results suggest that metamorphosis can change trade-offs between behavioral traits.

DOI： 10.1007/s10519-017-9847-1

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

Previous studies showed that the survival rate of Wolbachia decreases under high temperature in incubators. It is also known that a high density of Wolbachia in the host body reduces the host emergence rate, while low densities fail to change reproduction rates. However, few studies have examined the density of Wolbachia in hosts in the field. Here, we focus on Wolbachia infection of the pale grass blue butterfly, Zizeeria maha (Lepidoptera: Lycaenidae), which is distributed throughout the Japanese islands. We examined the rate and density of Wolbachia infection in the bodies of butterflies at thirteen locations in Japan. At seven of these places, we collected butterflies in different seasons to determine seasonal differences in the infection rate and density and found that Wolbachia density has seasonal differences within the same population. Moreover, to determine whether Wolbachia density has a geographical cline, we compared the infection density of Wolbachia amongst all geographical populations. In addition, we determined the sequences of Wolbachia wsp and host mtDNA CO1 haplotypes of all populations. The results showed that Wolbachia density increased in early summer and decreased in autumn. Further, the density of Wolbachia infecting the same strain of Z. maha varied amongst populations, although no tendency in geographical cline was observed.

DOI： 10.1371/journal.pone.0175373

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

A clock controlling circadian rhythm may relate to another clock controlling development time. The relationship between the two clocks remains open to discussion. Genetic correlation between developmental and circadian periods is observed in two Dipteran species (Bactrocera cucurbitae and Drosophila melanogaster), whereas it is not observed in a Coleopteran species (Callosobruchus chinensis). No studies, however, are available that report on the phenotypic correlation between the two traits. In the present study, free-running circadian periods are compared between individuals that develop fastest and slowest within a population of B. cucurbitae. The measurement of circadian periods is replicated using five populations of B. cucurbitae with different geographical and rearing histories. The results demonstrate that the flies developing more slowly have significantly longer circadian periods compared with the flies developing more quickly in two of five populations examined in B. cucurbitae, and thus the phenotypic correlation is dependent on population.

DOI： 10.1111/phen.12182

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS INC  

The cigarette beetle, Lasioderma serricorne (F.), is an important stored-product pest worldwide because it damages dry foods. Detection and removal of the female L. serricorne will help to facilitate the control of the insect by removal of the egg-laying populations. In this manuscript, we examined the responses by L. serricorne to direct and reflected light in transparent cube (50 m(3)) set in a chamber (200 m(3)) and a stored facility with both direct and reflected UV-LED lights. The study also examined the responses by the beetles to light in the presence or absence of pheromone in traps that are placed at different heights. Reflected light attracted more beetles than the direct light in the experimental chamber, but the direct light traps attracted more beetles than the reflected light traps in the storehouse. Pheromone traps attracted only males; UV-LED traps attracted both sexes. The UV-LED traps with a pheromone, i.e., combined trap, attracted more males than UV-LED light traps without a pheromone, whereas the attraction of UV-LED traps with and without the pheromone was similar in females. The results suggest that UV-LED light trap combined with a sex pheromone is the best solution for monitoring and controlling L. serricorne.

DOI： 10.1093/jee/tow225

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Various types of weapon traits found in insect order Coleoptera are known as outstanding examples of sexually selected exaggerated characters. It is known that the sex determination gene doublesex (dsx) plays a significant role in sex-specific expression of weapon traits in various beetles belonging to the superfamily Scarabaeoidea. Although sex-specific weapon traits have evolved independently in various Coleopteran groups, developmental mechanisms of sex-specific expression have not been studied outside of the Scarabaeoidea. In order to test the hypothesis that dsx-dependent sex-specific expression of weapon traits is a general mechanism among the Coleoptera, we have characterized the dsx in the sexually dimorphic broad-horned beetle Gnatocerus cornutus (Tenebrionidea, Tenebirionidae). By using molecular cloning, we identified five splicing variants of Gnatocerus cornutus dsx (Gcdsx), which are predicted to code four different isoforms. We found one male-specific variant (GcDsx-M), two female-specific variants (GcDsx-FL and GcDsx-FS) and two non-sex-specific variants (correspond to a single isoform, GcDsx-C). Knockdown of all Dsx isoforms resulted in intersex phenotype both in male and female. Also, knockdown of all female-specific isoforms transformed females to intersex phenotype, while did not affect male phenotype. Our results clearly illustrate the important function of Gcdsx in determining sex-specific trait expression in both sexes.

DOI： 10.1038/srep29337

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Dispersal ability may influence antipredator and mating strategies. A previous study showed a trade-off between predation avoidance and mating success in strains of the red flour beetle Tribolium castaneum selected for walking distance . Specifically, beetles derived from strains selected for longer walking distance suffered higher predation pressure and had higher male mating success than their counterparts derived from strains selected for shorter walking distance. In the study reported here, we compared the locomotor activity, biogenic amine expression in the brain, and death-feigning behavior of the red flour beetle strains selected for walking distance. The results indicated that individuals genetically predisposed to longer walking distance had higher locomotor activity and lower intensity of death-feigning behavior than those genetically predisposed to shorter walking distance. However, no significant differences were found in the expression of biogenic amines in the brain among strains selected for walking distance, although the level of dopamine in the brain differed from that of the strains divergently selected for duration of death-feigning behavior. The relationships between walking speed, activity, death-feigning behavior, and brain biogenic amines in T. castaneum are discussed.

DOI： 10.1007/s10164-015-0452-6

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PESTICIDE SCI SOC JAPAN  

Cypermethrin resistance and reproductive types were examined for T. tabaci strains. Some arrhenotokous and thelytokous strains encoded the sodium channel mutation (T929I) involved in cypermethrin resistance. However, the resistance levels varied to some degree among the strains. A cytochrome P450 inhibitor, piperonyl butoxide, showed different synergistic effects on the strains examined. These results suggest that fundamental and additional levels of cypermethrin resistance in T. tabaci are conferred respectively by reduced sensitivity of the sodium channel and by cytochrome P450-mediated detoxification. (C) Pesticide Science Society of Japan

DOI： 10.1584/jpestics.D16-049

Web of Science

researchmap

Language：English   Publisher：SPRINGER JAPAN KK  

DOI： 10.1007/s10144-015-0514-1

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

Individuals of both dispersal and non-dispersal types (disperser and non-disperser) are found in a population, suggesting that each type has both costs and benefits for fitness. However, few studies have examined the trade-off between the costs and benefits for the types. Here, we artificially selected for walking distance, i.e., an indicator of dispersal ability, in the red flour beetle Tribolium castaneum and established strains with longer (L-strains) or shorter (S-strains) walking distances. We then compared the frequency of predation by the assassin bug Amphibolus venator and the mating frequency of the selected strains. L-strain beetles suffered higher predation risk, than did S-strain beetles. L-strain males had significantly increased mating success compared to S-strain males, but females did not show a significant difference between the strains. The current results showed the existence of a trade-off between predation avoidance and mating success associated with dispersal types at a genetic level only in males. This finding can help to explain the maintenance of variation in dispersal ability within a population.

DOI： 10.1371/journal.pone.0127042

Web of Science

researchmap

Language：English   Publisher：WILEY  

Current concepts of sexual selection suggest that male reproductive success is determined by multiple sexual traits. As expression and production of multiple sexual traits are frequently associated with each other, positive or negative correlations among multiple sexual traits ensue. These relationships among traits associated with male reproductive success may be crucial in the evolution of male reproductive strategies. Here, we investigate phenotypic relationships among sexually selected traits in the armed bean bug Riptortus pedestris. In this insect, males with a larger body and weapon are more likely to win male-male competitions, and males with a larger weapon or higher courtship rate are more attractive to females. There was a significant positive correlation between body size and weapon size, whereas the courtship rate had significant negative correlations with body size and weapon size. Our results suggested that there was a phenotypic trade-off between courtship rate and male morphology. In this insect, smaller males may make more effort in courtship behavior as an alternative mating tactic.

DOI： 10.1111/ens.12114

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Social insects provide an intriguing model system in chronobiology. Typically, an egg-laying queen exhibits arrhythmicity in activity while foraging worker has clear rhythmicity. In the queenless ant, Diacamma sp., from Japan, colony members lack morphological caste, and reproductive differentiation occurs as a consequence of dominance hierarchy formation. Their specialized dominance interaction "gemmae mutilation", provide us a fascinating model system to investigate the effect of social dominance on rhythmic ontogeny. Measurement of individual rhythms revealed that they have clear circadian rhythm at eclosion but it is diminished by social mutilation of gemmae. Moreover, unlike highly eusocial species, mated egg-layer (i.e., gamergate) possessed a circadian rhythm even after mating in Diacamma. Measurement of colony-level rhythms revealed that gemmae mutilations are performed in the limited time of the day, but foraging occurs around-the-clock. The above finding is a novel form of temporal organization in social insects, providing a new insight in morphologically casteless species. We discuss the causes and consequences of rhythmic variability in social organization.

DOI： 10.1007/s00265-014-1793-9

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

In many insects, mating is affected by the day-night cycle, i.e., diurnal rhythm. Although there are many reports that mating and other reproductive behaviors are controlled by daily rhythms in various taxonomic insect species, little attention has been paid to the effect of daily rhythms on male fighting behavior. Here, we investigate whether the frequency and escalation of male-male aggressive interaction exhibit diurnal rhythms under a long-day condition in the bean bug Riptortus pedestris. Despite the fact that male aggressive behaviors were most often observed in the middle of the later half of light periods, no interaction was found between escalation of fighting and the time period. The results, at least, suggest that male aggressive behaviors are influenced by diurnal rhythms like other reproductive behaviors in R. pedestris.

DOI： 10.1111/ens.12066

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Tonic immobility (death-feigning) behavior of the red flour beetle, Tribolium castaneum, is a predator defense mechanism; it is a reflex elicited when a beetle is jarred with the substrate, often a result of the activities of a predator. We previously demonstrated that the frequency of predation by a jumping spider, Hasarius adansoni, was significantly lower among beetles with higher frequencies and longer durations of tonic immobility (L-type) than those with lower frequencies and shorter durations of tonic immobility (S-type). However, we found that the population of L-type beetles is much smaller than that of S-type beetles in their natural habitat. Here we demonstrated that L-type beetles are significantly more sensitive to environmental stressors such as mechanical vibration and high or low temperatures. We measured expression levels of stress-responsive genes such as heat shock proteins (Hsps) and antioxidant enzymes in both types of beetles. Among the genes we investigated, only catalase gene expression levels were significantly higher in S-type than in L-type beetles. Furthermore, a similar difference in the gene expression was observed in the T. castaneum ortholog of the insect cytokine growth-blocking peptide (GBP) gene. These results indicate the possibility that high expression of catalase and GBP in S-type beetles contributes to augmentation of their anti-stress capacity and expansion of their population in their natural habitat. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2013.11.008

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

Females prefer male traits that are associated with direct and/or indirect benefits to themselves. Male-male competition also drives evolution of male traits that represent competitive ability. Because female choice and male-male competition rarely act independently, exploring how these two mechanisms interact is necessary for integrative understanding of the evolution of sexually selected traits. Here, we focused on direct and indirect benefits to females from male attractiveness, courtship, and weapon characters in the armed bug Riptortus pedestris. The males use their hind legs to fight other males over territory and perform courtship displays for successful copulation. Females of R. pedestris receive no direct benefit from mating with attractive males. On the other hand, we found that male attractiveness, courtship rate, and weapon size were significantly heritable and that male attractiveness had positive genetic covariances with both courtship rate and weapon traits. Thus, females obtain indirect benefits from mating with attractive males by producing sons with high courtship success rates and high competitive ability. Moreover, it is evident that courtship rate and hind leg length act as evaluative cues of female choice. Therefore, female mate choice and male-male competition may facilitate each other in R. pedestris. This is consistent with current basic concepts of sexual selection.

DOI： 10.1371/journal.pone.0083278

Web of Science

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The cigarette beetle, Lasioderma serricorne (Fabricius), is an important pest insect that consumes a variety of dry foods. It is known that UV light traps attract this species. However, less attention has been paid to its preferred wavelength. First, we investigated the spectral sensitivity of the compound eye. Next, we compared the attraction efficiency of LEDs of different colors (wavelengths). Our results showed that ultraviolet (UV, 375 nm) and blue (470 nm) LEDs attracted the most cigarette beetles of both sexes, irrespective of mating or oviposition status, although the UV LED consistently tended to attract the most beetles. Although the primary sensitivity peak of the compound eye was 520 nm, the green LED (520 nm) scarcely attracted beetles. Although the reason for the difference between the peaks in spectral sensitivity and attraction of beetles awaits further studies, whether UV and/or blue LEDs is more effective as a practical light trap for controlling L. serricorne beetle is discussed in this study. © 2013 The Japanese Society of Applied Entomology and Zoology.

DOI： 10.1007/s13355-013-0205-3

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

The seed beetle Callosobruchus maculatus larvae exhibit two types of resource competition: scramble, in which a resource is shared, and contest, in which the resource is monopolized. This difference in larval behavior results in different adult densities. Under contest competition, adult density remains constant regardless of larval density, but under scramble competition, adult density increases with larval density. This in turn affects mating frequency during adulthood, and thus, the intensity of sexual selection operating on males. In this study, we examined the relationship between larval competition types and male reproductive investment in mating. We assessed the male ejaculate expenditure per mating across geographic strains of C. maculatus. The male investment (ejaculate expenditure) increased with the degree of scramble competition and decreased with the degree of contest competition. We therefore suggest that males experience different selective pressures depending on the type of larval competition: scramble type males are selected for increased reproductive investment.

DOI： 10.1007/s10144-013-0380-7

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

A flightless strain of the lady beetle, Harmonia axyridis Pallas, has been established, by artificial selection, for effective biological control of aphids. However, this biological control technique is costly because of the high cost of production of the adults. It is, therefore, important to consider the utility of the larvae in biological control. This study examined the potential for larvae of the flightless strain to be used as biological control agents compared with those of the wild-type, in terms of how they behave on aphid-infested plants. We found no differences between the strains with regard to residence time and aphid consumption on the plant for the first, second, and fourth instars, and at low and high aphid densities. In contrast, however, aphid consumption by third-instar larvae of the flightless strain tended to be lower, although they remained on the plant longer than third-instar larvae of the wild-type. Consequently, our results suggest the flightless strain does not differ from the wild-type in its ability to control aphids across all larval stages, except for the third instars. On the basis of these results, and in conjunction with the results from previous studies, we discuss the appropriateness of different larval instars for release.

DOI： 10.1007/s13355-013-0163-9

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Biological clocks regulate various behavioural and physiological traits
slower circadian clocks are expected to slow down the development, suggesting a potential genetic correlation between the developmental period and circadian rhythm. However, a correlation between natural genetic variations in the developmental period and circadian rhythm has only been found in Bactrocera cucurbitae. The number of genetic factors that contribute to this genetic correlation is largely unclear. In this study, to examine whether natural genetic variations in the developmental period and circadian rhythm are correlated in Drosophila melanogaster, we performed an artificial disruptive selection on the developmental periods using wild-type strains and evaluated the circadian rhythms of the selected lines. To investigate whether multiple genetic factors mediate the genetic correlation, we reanalyzed previously published genome-wide deficiency screening data based on DrosDel isogenic deficiency strains and evaluated the effect of 438 genomic deficiencies on the developmental periods. We then randomly selected 32 genomic deficiencies with significant effects on the developmental periods and tested their effects on circadian rhythms. As a result, we found a significant response to selection for longer developmental periods and their correlated effects on circadian rhythms of the selected lines. We also found that 18 genomic regions had significant effects on the developmental periods and circadian rhythms, indicating their potential for mediating the genetic correlation between the developmental period and circadian rhythm. The novel findings of our study might lead to a better understanding of how this correlation is regulated genetically in broader taxonomic groups. © 2013 Macmillan Publishers Limited All rights reserved.

DOI： 10.1038/hdy.2012.88

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Wolbachia are Gram-negative bacteria that cause intracellular inherited infections in many invertebrates. They are extremely common, with 20-75 % of all insects being infected. Wolbachia belong to taxa of the Anaplasmataceae family, alpha proteobacteria. Because previous studies have shown that Wolbachia generally disappear from the host insect's body under high-temperature conditions in laboratories, we investigated seasonal changes in infection of the pale grass blue butterfly, Zizeeria maha (Kollar, 1848) by Wolbachia, for 7 months of the year. Total annual infection was 86. 7 % (n = 15) of females and 96. 3 % (n = 81) of males. Statistical analysis showed that monthly infection was not significantly different among months. In addition, no significant difference was found between Wolbachia densities in cells of summer and winter butterfly samples by use of real-time PCR during the months examined. The results suggest that Wolbachia infection is not affected by seasonal factors, at least for Z. maha. © 2012 The Japanese Society of Applied Entomology and Zoology.

DOI： 10.1007/s13355-012-0152-4

Scopus

researchmap

Language：English   Publisher：SPRINGER JAPAN KK  

DOI： 10.1007/s13355-012-0140-8

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Daily activity rhythms are widespread characteristics among many organisms and are usually related to one or more physical environmental variables, such as light and temperature. Even organisms that are not obviously exposed to wide fluctuations in environmental variables, such as troglodytic and endogeic species, exhibit some daily activity patterns. Termites inhabit underground areas or tree trunks where little or no fluctuation in light occurs. In the present study, the activity rhythms of field colonies of the subterranean termite Reticulitermes speratus Kolbe (Blattodea: Termitidae) are examined, during all four seasons, by monitoring their acoustic emissions using a newly-modified method. Nest temperature affects termite activity significantly during all four seasons. By contrast, no significant effect of time is observed during the different seasons, with the exception of autumn. Activity and nest temperature are negatively correlated in summer and autumn, although thay are are positively correlated during winter and spring. The greatest activity occurs at 2325 degrees C. The experimental observations suggest that the activity of R. speratus termite colonies is affected mainly by ambient temperature, in a manner that is based on optimum temperature.

DOI： 10.1111/j.1365-3032.2012.00841.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

The body sizes of individuals of the choosing and chosen sexes in a mate choice may affect sequential mating of females. We examined the effects of the body sizes of females and their mates on attributes of female first mating, and the effects of body sizes of females and their previous and potential future mates on female remating in the adzuki bean beetle, Callosobruchus chinensis. Large- and small-sized adults were derived from larvae reared under conditions of low and high density in a bean, respectively. The speed of first mating of large females was not affected by the size of courting males, whereas small females initiated mating more rapidly when courted by small males. The remating probability of large females was not affected by first male size, whereas small females that mated first with smaller males were more likely to remate. These data suggest that pre- and post-copulatory female choices for male size depend on the female's size, and the small females might be more willing to copulate with smaller males but prefer larger males to sire their offspring after copulation. A possible explanation for this preference is that small females may suffer greater harm from copulating with larger males.

DOI： 10.1007/s10164-012-0331-3

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

The West Indian sweet potato weevil Euscepes postfasciatus (Fairmaire) is a troublesome pest insect of sweet potato that originally came from the Caribbean, but is now expanding its distribution into the Pacific Islands. Although sterile insect techniques have been used against this pest in a demonstration experiment on Kume Island [Ohno et al. (2006) Kontyu to Shizen 41:25-30], effective methods of monitoring E. postfasciatus are scarce. It is necessary to detect the weevils at an early stage of invasion in uninvaded areas, and an attractant trap can be used to achieve this. Thus, we developed an ultraviolet (UV) light-emitting diode trap, invented a method for diffusing the light to attract more insects, and investigated the attractiveness of the light trap to E. postfasciatus under laboratory conditions. Our results indicate that diffused UV light has a higher potential to attract E. postfasciatus than direct UV light. Furthermore, sweet potato is an effective bait to use to capture the weevils attracted by UV light. Thus, E. postfasciatus can be trapped using diffused UV light and sweet potato bait.

DOI： 10.1007/s13355-012-0113-y

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS INC  

An evolutionary correlation between the effects of male seminal substances that reduce female sexual receptivity and female remating frequency was found among strains of the adzuki bean beetle, Callosobruchus chinensis. Variation in female remating frequency had been also previously documented in this species, together with the identification in males of low- and high-molecular weight substances that exhibited quick- and slow-acting effects on female sexual receptivity. Here, we examined the differences in the effects of both substances on female sexual receptivity between strains with high and low remating frequencies. We found that the female response to the quick-acting substances differed. Moreover, not only female response to the slow-acting substances but also the male effect of these substances differed between strains. In remating experiments, a difference in female response to mating was found, but no difference was found in the effect of males between strains. Thus, male sexual receptivity-inhibiting substances are one of the reasons for the difference in female remating frequency between the 2 strains. Next, the relationship between the effect of male substances on female sexual receptivity and female remating frequency was examined among multiple strains. Correlations between the effect of mating and male substances were found for both molecular weight classes of male substances. These results suggest that both female response to male substances and the effect of male receptivity-inhibiting substances reflect variations in female remating frequency among strains.

DOI： 10.1093/beheco/ars017

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Sexually selected exaggerated traits are often coupled with modifications in other nontarget traits. In insects with weapons, enlargements of nontarget characters that functionally support the weapon often occur (i.e. supportive traits). The support of sexual traits requires developmental coordination among functionally related multiple traitsan explicit example of morphological integration. The genetic theory predicts that developmental integration among different body modules, for which development is regulated via different sets of genes, is likely to be coordinated by pleiotropic factors. However, the developmental backgrounds of morphological integrations are largely unknown. We tested the hypothesis that the juvenile hormone (JH), as a pleiotropic factor, mediates the integration between exaggerated and supportive traits in an armed beetle Gnatocerus cornutus. During combat, males of this beetle use exaggerated mandibles to lift up their opponents with the supportive traits, that is, the head and prothoracic body parts. Application of methoprene, a JH analog (JHA), during the larval to prepupal period, induced the formation of large mandibles relative to the body sizes in males. Morphometric examination of nontarget traits elucidated an increase in the relative sizes of supportive traits, including the head and prothoracic body parts. In addition, reductions in the hind wing area and elytra length, which correspond to flight and reproductive abilities, were detected. Our findings are consistent with the genetic theory and support the idea that JH is a key pleiotropic factor that coordinates the developmental integration of exaggerated traits and supportive characters, as well as resource allocation trade-offs.

DOI： 10.1111/j.1525-142X.2012.00554.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Adults of the cigarette beetle, Lasioderma serricorne (Fabricius), usually have brownish-red bodies. In this study, we selected for black body color and established a black body strain as a genetic marker. Subsequently, we conducted experimental crosses and discovered that the black body color was characterized by recessive inheritance. Moreover, we observed no difference between the mating behavior and life history of the black strain and normal beetles. On the basis of these results, our black strain could be a mutant in which only adult body color is genetically changed. Thus, our strain is thought to be a useful genetic marker to improve pest control methods for L. serricorne.

DOI： 10.1007/s13355-012-0103-0

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Individuals in many animal species exhibit 'personality,' consistent differences in behaviour across time, situations and/or contexts. Previous work has revealed a negative genetic correlation between intensity of tonic immobility and walking activity levels in the confused flour beetle, Tribolium confusum, thus suggesting these beetles exhibit personality in activity-related traits. The present study investigated the mechanism underlying this correlation. We used individuals derived from two strains established via artificial divergent selection for duration of tonic immobility. "Long" (L) strains exhibited higher frequencies and longer durations of tonic immobility, and lower activity levels, while "Short" (S) strains exhibited lower frequencies and shorter durations of tonic immobility and higher activity levels. We found that the duration of tonic immobility, and activity level, could be altered by caffeine administration; L strains fed with caffeine exhibited decreased durations of tonic immobility and increased activity levels. We also found that brain dopamine levels were lower in L strains than in S strains. Consequently, this study demonstrates that the dopaminergic system plays an important part in controlling the genetic correlation between tonic immobility and activity levels in this species. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2012.02.011

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

Male fighting frequently results in the evolution of traits used as weapons. These are often coupled with correlated modifications in other somatic traits (hereafter referred to as supportive traits), which are thought to support the weapon functionally. No previous studies have investigated whether supportive traits themselves affect fighting success. We evaluated this possibility in two armed insects, the beetle Gnatocerus cornutus and the bug Riptortus pedestris. Using a principal components analysis, we identified a subset of supportive traits that were associated with weapons in both species. The patterns of supportive structures differed between the two species, probably reflecting differences in the use of weapons during fights. In both species, fighting success was higher in males with enhanced supportive traits. It appears that weapon-supportive structures develop as the result of selection that favours coordination among multiple traits associated with fighting behaviour. Thus, our results provide rare evidence of the benefit of a supportive trait that is a clear example of phenotypic integration. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.anbehav.2012.01.021

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Males and females frequently have different fitness optima for shared traits, and as a result, genotypes that are high fitness as males are low fitness as females, and vice versa. When this occurs, biasing of offspring sex-ratio to reduce the production of the lower-fitness sex would be advantageous, so that for example, broods produced by high-fitness females should contain fewer sons. We tested for offspring sex-ratio biasing consistent with these predictions in broad-horned flour beetles. We found that in both wild-type beetles and populations subject to artificial selection for high- and low-fitness males, offspring sex ratios were biased in the predicted direction: low-fitness females produced an excess of sons, whereas high-fitness females produced an excess of daughters. Thus, these beetles are able to adaptively bias sex ratio and recoup indirect fitness benefits of mate choice.

DOI： 10.1111/j.1461-0248.2011.01725.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The effectiveness of hybrid vigor, which can counteract deleterious effects of inbreeding in flightless Harmonia axyridis Pallas (Coleoptera: Coccinellidae), was investigated. First, we performed the reciprocal cross between two isofemale lines and compared survival and reproductive characteristics between isofemale and hybrid lines under laboratory conditions. The survival of one of the hybrid lines was significantly higher than that of the two isofemale lines. Early fecundity tended to be higher in the two hybrid lines than in the two isofemale lines. Second, we compared the effectiveness of control of Aphis gossypii Glover (Homoptera: Aphididae) between isofemale and hybrid lines by release experiments in greenhouses. The number of A. gossypii was suppressed in treatments in which two hybrid lines were released compared with those in which two isofemale lines were released. These results suggest that hybrid vigor is effective as a method for assuring the quality of flightless H. axyridis.

DOI： 10.1007/s10526-011-9407-1

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

The scarab beetle Anthracophora rusticola Burmeister breeds in the nests of carnivorous birds including the honey buzzard Pernis apivorus (Linnaeus), Chinese goshawk Accipiter soloensis (Horsfield), oriental stork Ciconia boyciana Swinhoe and great cormorant Phalacrocorax carbo (Linnaeus). Although larvae of the beetle probably feed on animal matter (e.g. remnants of birds' food) in the nests of these birds, the effect of eating flesh on the growth of larvae has not been investigated. Laboratory experiments clearly showed that the development was faster, survival rate higher and body heavier just before pupation in larvae fed dried chicken meat with humus soil than in those fed only humus soil. We also investigated feeding behaviors of larvae of the beetle. A piece of chicken meat placed on the surface of humus soil was pulled under the soil by the larva, mostly at night. Video recordings made during the night showed that larvae came to the humus soil surface and ate the dried chicken meat or tried to take the meat under the soil. Our laboratory observations suggest that larvae in nature stay under the humus accumulated in bird nests during the daytime, and then come up to the surface mostly at night to actively seek and eat remnants of the birds' food.

DOI： 10.1111/j.1479-8298.2011.00470.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

For successful sterile insect technique (SIT), synchronized copulation between invaded females and sterilized males is required. Understanding the mating time of the invaded strain is an aid in synchronizing and thus improving the effectiveness of SIT. We previously demonstrated a relationship between variation at two sites of a circadian clock gene cryptochrome (cry) (cry1212 and cry1865) and circadian behavior in the melon fly Bactrocera cucurbitae (Coquillett). Here we investigated the relationship in two other populations, Taiwan1 (T1) and Taiwan2 (T2), which may re-invade Okinawa. The results showed that T1 exhibited a lower frequency of the S-type allele, which was observed in early mating flies in the strains in Okinawa, than T2 at the site of cry1212. In addition, T1 showed a longer circadian period than T2. We also noted that the cry1212 site showed higher amino acid sequence conservation than cry1865 by comparing CRY1 among five insect species. These results suggest that genotyping of only the cry1212 site of trapped flies enables an immediate estimate of the mating time of the B. cucurbitae population from Taiwan and that cry1212 would be more likely to be involved in determining the mating time than cry1865.

DOI： 10.1007/s13355-011-0075-5

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

Sexual selection leads to the evolution of various traits that increase male fitness under male-male competition including sperm competition. In many taxa, bimodal distributions of copulation and/or intromission duration are known to be the result of adaptation to sperm competition risk avoidance. However, the stalk-eyed seed bug, Chauliops fallax Scott (Heteroptera: Malcidae), exhibits completely different mating behaviour to other known examples. The male mounts the female and then inserts his aedeagus repeatedly and intermittently until the termination of copulation. Insertion duration exhibited a bimodal distribution with two peaks: a short insertion within 6 min which occurred one to three times without insemination, followed by long insertions of approximately 30 min with repeated insemination. To examine the adaptive significance of the two types of genital insertion, we investigated whether the amount of sperm transferred, female remating receptivity, number of eggs laid, hatchability and female longevity differed between the two insertion types. Sperm transfer mainly occurred during long insertions but very little occurred during short insertions. Similarly, long insertions induced mated females to resist subsequent mating attempts of other males but short insertions did not. Short insertions did not affect the number of eggs laid, hatchability or female longevity. Although our results showed that C. fallax males transferred sperm to females and inhibited female remating with long insertions, we currently cannot explain the adaptive function of short insertions without insemination. (C) 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.anbehav.2011.08.004

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ZOOLOGICAL SOC JAPAN  

Males of the bean bug species Riptortus pedestris possess larger hindlegs than females. Observations of male-male interactions showed that the enlarged hindlegs are used as weapons in male fights, and that males with larger hindlegs win fights more frequently. Morphological analysis based on the positive allometry test showed that the femora of larger males are relatively bigger than those of smaller males, but femora of larger females are not relatively larger than those of smaller females. These results suggest that sexual selection in R. pedestris favors larger hindlegs for male fighting. In addition, the thorax and abdomen lengths were larger in the male than in the female. The males often lift their abdomen with their back to the opponent for displays against an opponent. As a result, abdominal size may be under stronger selection in the male than in the female, as for the exaggerated hindlegs.

DOI： 10.2108/zsj.28.659

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

We investigated the seasonal abundance and seasonal dynamics of reproduction in the stalk-eyed bug Chauliops fallax Scott, which is described as a minor pest of bean plants such as soybean and a minor cause of pecky rice. We counted the number of adult males and females, mating pairs, and nymphs of C. fallax on kudzu plants, Pueraria lobata (Willd.), in the southern part of Okayama City, Japan, from 2005 to 2007 and in 2009. Two peaks in abundance for mating pairs were found in late May and August. Both male and female solitary adults appeared from late April, and two peaks of solitary adults were found in May and September. Two clearly separate peaks of nymphs were found in late June and late August. Therefore, it seems that C. fallax produces two generations a year in the southern Okayama area. These data may provide essential information for pest control, and therefore, we discuss them from an applied entomological standpoint to predict invasions by C. fallax into agriculture fields from weeds that grow around and/or in fields.

DOI： 10.1007/s13355-011-0057-7

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Exaggerated traits can be costly and are often trade-off against other characters, such as life-history traits. Thus, the evolution of an exaggerated trait is predicted to affect male life-history strategies. However, there has been very little experimental evidence of the impact of the evolution of sexually selected traits on life-history traits. This study investigated whether increased investment in exaggerated traits can generate evolutionary changes in the life-history strategy for armed males. Male flour beetles, Gnatocerus cornutus, have enlarged mandibles that are used in male-male competition, but females lack this character exaggeration completely. We subjected these weapons to 11 generations of bidirectional selection and found a correlated response in pupal survival but not in larval survival or adult longevity in the male. That is, selecting for male mandibles negatively impacted survival during the production of mandibles. There is no correlated response in the life-history traits of the female.

DOI： 10.1111/j.1420-9101.2011.02303.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

A positive genetic correlation between periods of circadian rhythm and developmental time supports the hypothesis that circadian clocks are implicated in the timing of development. Empirical evidence for this genetic correlation in insects has been documented in two fly species. In contrast, here we show that there is no evidence of genetic correlation between circadian rhythm and development time in the adzuki bean beetle, Callosobruchus chinensis. This species has variation that is explained by a major gene in the expression and period length of circadian rhythm between strains. In this study, we found genetic variation in development time between the strains. The development time was not covaried with either the incidence or the period length of circadian rhythm among the strains. Crosses between strains suggest that development time is controlled by a polygene. In the F(2) individuals from the crosses, the circadian rhythm is attributable to allelic variation in the major gene. Across the F(2) individuals, development time was not correlated with either the expression or the period length of circadian rhythm. Thus, we found no effects of major genes responsible for variation in the circadian rhythm on development time in C chinensis. Our findings collectively give no support to the hypothesis that the circadian clock is involved in the regulation of development time in this species. (C) 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2010.12.012

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

Theory predicts trade-offs between investment in various life history traits, and it is also now generally accepted that reproduction is costly for males. Males must therefore optimize resource allocation across several episodes of reproduction, and this includes investment in both pre- and postcopulatory fitness components. We investigated this in the sperm-polymorphic Indian meal moth, Plodia interpunctella. Resource-limited males were smaller, and had decreased precopulatory mating success, measured as lifetime number of matings. However, they transferred similar numbers of fertile sperm as males reared under high-quality larval conditions, and more nonfertile sperm. By mating less frequently, resource-limited males may allocate sufficient resources to the matings they achieve to ensure fertilization success under sperm competition. (C) 2010 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.anbehav.2010.12.001

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

The sterile insect technique (SIT) is a method of eradicating insects by releasing mass-reared sterilized males into fields to reduce the hatchability of eggs laid by wild females that have mated with the sterile males. SIT requires mass-production of the target insect, and maintenance of the quality of the mass-reared insects. The most important factor is successful mating between wild females and sterile males because SIT depends on their synchronized copulation. Therefore, understanding the mating systems and fertilization processes of target insects is prerequisite. Insect behavior often has circadian rhythms that are controlled by a biological clock. However, very few studies of relationships between sterile insect quality and circadian rhythm have been performed compared with the amount of research on the mating ability of target insects. The timing of male copulation attempts with receptivity of females is key to successful mating between released males and wild females. Therefore, we should focus on the mechanisms controlling the timing of mating in target insects. On the other hand, in biological control projects, precise timing of the release of natural enemies to attack pest species is required because behavior of pests and control agents are affected by their circadian rhythms. Involving both chronobiologists and applied entomologists might produce novel ideas for sterile insect quality control by synchronized sex between mass-reared and wild flies, and for biological control agent quality by matching timing in activity between predator activity and prey behavior. Control of the biological clocks in sterile insects or biological control agents is required for advanced quality control of rearing insects.

DOI： 10.1007/s13355-010-0017-7

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

In some insect species certain substances in the seminal fluid of males induce egg production and laying in females We determined the effects of male-derived substances on female oviposition behaviour in two Callosobruchus species C chinensis and C maculatus Aqueous extracts of the accessory gland testis and seminal vesicle including the ejaculatory duct were prepared The injection of these extracts into abdomen of females induced oviposinon in both species Oviposition was induced by the testis and seminal vesicle extracts in C chinensis and by the accessory gland extracts in C maculatus The extracts were separated into three fractions by ultrafiltration fractions I molecular weight (MW) &lt;3 kDa fraction II 3-14 kDa and fraction III &gt;14 kDa Fraction III Induced oviposition in both species These results suggest that in these two species the substances that induce oviposition have similar MW but are present in different organs Oviposition was Induced by high-MW (&gt;14 kDa) substances in the testis and seminal vesicle in C chinensis and by high-MW substances in accessory gland in C maculatus Here we have discussed the relationship between oviposition and the abovementioned male-derived substances (C) 2010 Elsevier Ltd All rights reserved

DOI： 10.1016/j.jinsphys.2010.07.008

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Male-male competition frequently results in the evolution of sexually selected traits used as weapons and ornaments. The expression of these traits often depends on male condition, i.e., condition dependence. Although males often have multiple sexually selected traits, to date many studies have focused on the morphological analysis of one sexual trait whilst ignoring the others. We here report phenotypic plasticity for multiple sexual traits, by manipulating larval diet quality and density, in the broad-horned flour beetle Gnatocerus cornutus. The male beetles possess enlarged mandibles, developed genae and a pair of small horns, but females lack these completely. Larval density significantly affected overall body size but not relative investment in each sexual trait. In contrast, diet quality had no effect on body size but had a significant effect on relative investment in the mandibles and genae. These results indicate that the allometric intercepts of the mandible and genae alter in response to diet quality, i.e., allometric plasticity. However, diet quality had no effect on the growth of the horn. Thus, multiple sexual traits exhibited differences in plasticity as a result of larval nutrient condition in G. cornutus males.

DOI： 10.1007/s10682-010-9370-9

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：CELL PRESS  

Sexually antagonistic selection generates intralocus sexual conflict, an evolutionary tug of war between males and females over optimal trait values [1-4] Although the potential for this conflict is universal, the evolutionary importance of intralocus conflict is controversial because conflicts are typically thought to be resolvable through the evolution of sex specific trait development [1-8] However, whether sex specific trait expression always resolves intralocus conflict has not been established We assessed this with beetle populations subjected to bidirectional selection on an exaggerated sexually selected trait, the mandible Mandibles are only ever developed in males for use in male male combat, and larger mandibles increase male fitness (fighting [9, 10] and mating success, as we show here) We find that females from populations selected for larger male mandibles have lower fitness, whereas females in small mandible populations have highest fitness, even though females never develop exaggerated mandibles This is because mandible development changes genetically correlated characters, resulting in a negative intersexual fitness correlation across these populations, which is the unmistakable signature of intralocus sexual conflict [1] Our results show that sex limited trait development need not resolve intralocus sexual conflict, because traits are rarely, if ever, genetically uncle pendent of other characters [11] Hence, intralocus conflict resolution is not as easy as currently thought

DOI： 10.1016/j.cub.2010.10.023

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

We investigated the effects of injecting male-derived extracts on congeneric female receptivity in two species of Callosobruchus beetle, C. chinensis and C. maculatus. We also examined the influence of interspecific mating on female remating behaviour in these two species. Male-derived extracts reduced congeneric female receptivity in both species. As quick-acting components, extracts of C. chinensis male seminal vesicles reduced the receptivity of C. maculatus females, whereas extracts of C. maculatus male testes reduced the receptivity of C chinensis females. As slow-acting components, extracts of male accessory glands of other species reduced the receptivity of both C. maculatus and chinensis females. After interspecific mating, the sperm of C. maculatus males were transferred to the reproductive organs of C. chinensis females, thereby reducing their receptivity. In contrast, no C chinensis sperm were transferred to the reproductive organs of C. maculatus females; accordingly, the latter&apos;s receptivity was not reduced. Furthermore, the survival rate of C. chinensis females decreased markedly after interspecific mating. These results raise the possibility that under circumstances where populations of these two species share the same habitat, reproductive interference would occur only in the interactions between C. maculatus males and C chinensis females. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2010.05.014

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOLOGICAL SOC AMER  

The use of flightless strains of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), established via artificial selection, can be highly effective as a biological control agent for aphids. However, flightless H. axyridis must depend on walking for dispersion. Therefore, data on the walking activity levels in flightless strains are important for the development of effective methods when releasing these agents in the field. Results of measurement of walking activity levels using an infrared actograph showed that walking activity levels during the daytime (but not nighttime) in both sexes of pure flightless strains tended to be lower than those of control strains. We also found that walking activity levels during the daytime for the F1 generation of hybrid strains, produced by reciprocal crossing between two pure flightless strains, were approximately equal to those of pure strains; the reduction in walking activity levels was not recovered by hybrid vigor. Our results indicate that the reduction in walking activity levels in the pure flightless strains was not caused merely by inbreeding depression stemming from the artificial selection process. Instead, potentially flight ability and walking activity levels in this species may be controlled by the pleiotropic effect of a gene.

DOI： 10.1603/EC09420

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC  

Modulation of behaviours as a result of fighting experience has been observed in many animals and can influence pre-copulatory sexual selection. This study investigated how fighting experience affects ejaculatory strategies. In male flour beetles, Gnatocerus cornutus, experience of losing a fight decreases a male&apos;s aggressiveness for up to 4 days. We found that males losing a fight show increased ejaculatory investment, but there was no ejaculatory modulation owing to winning. However, the increase in ejaculate investment following a loss was no longer observed after 5 days. These results indicate that males adjust their investment in sperm competition according to their experience, and that fighting experience can significantly influence pre- and post-copulatory reproductive tactics.

DOI： 10.1098/rsbl.2010.0225

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Circadian rhythms are ubiquitous in a wide variety of organisms, although their genetic variation has been analyzed in only a few species. We found genetic differences in the circadian rhythm of adult locomotor activity among strains of the adzuki bean beetle, Callosobruchus chinensis, which differed in origin and have been maintained in isolation. All beetles in some strains clearly had free-running rhythms in constant darkness whereas most beetles in other strains were arrhythmic. The period of free-running rhythm varied from approximately 19 to 23 h between the strains. F(1) males from reciprocal crosses among strains with different periods of circadian rhythms had circadian periods that were intermediate between their parental strains. Segregation of the circadian rhythm appeared in the F(2) generation. These findings are consistent with the hypothesis that variation in the period length of circadian rhythm is explained by a major autosomal gene with additive effects and no dominance. This hypothesis was supported by the joint scaling test for the free-running period in the F(1) and F(2) generations. We discuss possible causes for genetic variation in circadian rhythm in the C. chinensis strains in terms of random factors and selection. Heredity (2010) 105, 268-273; doi:10.1038/hdy.2010.4; published online 10 February 2010

DOI： 10.1038/hdy.2010.4

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC  

Weapons used in male fighting can be costly to males and are often reported to trade off with other characters such as wings or spermatogenic investment. This study investigated whether increased investment into weapons can generate evolutionary changes in mating strategy for armed males. Male flour beetles, Gnatocerus cornutus, have enlarged mandibles that are used in male-male competition. We subjected these weapons to 12 generations of bidirectional selection and found trade-offs between weapons and two other male characters: wing and testis size. In addition, probably as a consequence of the observed changes in investment, dispersal ability and ejaculatory volume differ significantly between the lines. This indicates that the exaggeration of a weapon can be associated with dispersal and ejaculatory strategies. Thus, altered investment into weapons can lead to correlated changes in life-history traits.

DOI： 10.1098/rspb.2009.2017

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Biogenic amines are physiologically neuroactive substances that affect behavioural and physiological traits in invertebrates. In the present study, the effects of dopamine, octopamine, tyramine and serotonin on tonic immobility, or death-feigning, were investigated in Tribolium castaneum. These amines were injected into the abdomens of beetles artificially selected for long or short duration of tonic immobility. In beetles of the long strains, the durations of tonic immobility were shortened by injection of dopamine, octopamine and tyramine, and the effects of these amines were dose-dependent. On the other hand, serotonin injection did not affect the duration of tonic immobility. In the short-strain beetles that rarely feign death, no significant effects of the amines were found on the duration of tonic immobility. Brain expression levels of octopamine, tyramine and serotonin did not differ between long- and short-strain beetles, in contrast to the higher dopamine levels in short strains previously reported. Caffeine decreased the duration of death-feigning in both oral absorption and injection experiments. It is known that caffeine activates dopamine. Therefore, the present results suggest that the duration of tonic immobility is affected by dopamine via the dopamine receptor in T. castaneum. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2010.01.002

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

In male broad-horned flour beetles, Gnatocerus cornutus, losers of conflicts avoid fighting at subsequent encounters. The loser effect lasts for 4 days. It is considered that the memory of losing remains for 4 days. The duration of the memory is expected to affect the fitness, and the duration, 4 days, is expected to be optimal.We consider the fitness of a mutant in an homogeneous population to obtain the optimal duration. Here we carry out simulations using an individual-based model. The results suggest that the trade-off of getting mating chances and avoiding damage can cause the optimal duration of the memory, and that the decay in time of the female population is an important factor. © 2010 Taylor &amp
Francis.

DOI： 10.1080/17513750903161036

Scopus

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

Insects sometimes invade different habitats in new territory compared to their original habitat. In the present study, the seasonal abundance of an exotic leaf beetle, Ophraella communa Le Sage (Coleoptera: Chrysomelidae), which invaded Japan from North America in 1996, was investigated from April to October 2003 on two host plants, the common ragweed Ambrosia artemisiifolia L., and the giant ragweed A. trifida L., in Okayama City, Japan. Two peaks of population abundance were found on both plants within the year. Many O. communa were found on A. trifida growing on a hill area (land), whereas no insects were found on A. trifida growing on the bank of a riverbed (river), where the plants occasionally suffered water inundation. More pupae were found on the underside of plant leaves than on the surface of leaves, stems, and flowers; however, the pupation sites of the plants differed in September. No parasitoid or fungus was found in the laboratory and field, but predators were observed in the field in 2003, the fifth year after O. communa invaded Okayama. The results showed that the beetles fed on A. artemisiifolia as well as A. trifida in Japan, which is not reported as a host plant at their origin.

DOI： 10.1303/aez.2010.283

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Differences in mating time between populations can give rise to premating reproductive isolation. Tephritid fruit flies exhibit large variation in mating time among intra-or inter-specific populations. We previously cloned the clock gene period from two strains of melon fly, Bactrocera cucurbitae; in one the individuals mate early during the day, whereas in the other the individuals mate later. These strains were originally established by divergent artificial selection for developmental time, 'short' and 'long', with early and late mating times, respectively. The deduced amino acid sequences of PERIOD proteins for these two strains were reported to be identical. Here we cloned another clock gene cryptochrome (cry) from the two strains, and found two stable amino acid substitutions in the strains. In addition, the allele frequency at the two polymorphic sites of cry gene correlated with the circadian locomotor period (tau) across strains, whereas the expression pattern of cry mRNA in the heads of flies taken from the short strain significantly differed from that from the long strain. These findings suggest that variation in the cry gene is related to differences in the circadian behaviour in the two strains, thus implying that the cry gene may have an important role in reproductive isolation. Heredity (2010) 104, 387-392; doi: 10.1038/hdy.2009.167; published online 16 December 2009

DOI： 10.1038/hdy.2009.167

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

Individuals frequently behave in a consistent manner across time or in different situations. We examined the repeatability of duration of death-feigning anti-predator behaviour when attacked, and then carried out artificial selection for duration to calculate its heritability and examine correlated responses to selection in activity levels, in the confused flour beetle, Tribolium confusum. Three replicates of two strains were established by artificial selection for more than 17 generations: S strains exhibited shorter duration and lower frequency of death feigning while L strains exhibited longer duration and higher frequency of death feigning. Duration of death feigning clearly responded to selection, and significant value of realized heritability was detected in all replicates of the two strains. Examination of locomotor activity levels over a constant period showed that S strains had higher locomotor activity levels than L strains. No significant differences between the sexes were observed. Our study thus demonstrates heritability of death feigning and the existence of a negative genetic correlation between intensity of death feigning and activity level.

DOI： 10.1007/s10144-009-0188-7

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Analyses of proximate mechanisms that control mating and oviposition behaviours in insects are important because they link behavioural ecology and physiology. Recently, seed beetles have been used as models to study evolution of female multiple mating and cost of reproduction including mating. In the present study, we investigated the effects of biogenic amines into the abdomens of females of two Callosobruchus species, Callosobruchus chinensis and Callosobruchus maculatus, on mating receptivity and oviposition behaviour. In C. chinensis, injection of octopamine and tyramine reduced receptivity to mating and tyramine and serotonin increased the number of eggs laid. Similarly, injection of tyramine reduced the receptivity of females and increased the number of eggs laid by females of C maculatus. These results show the possibility that biogenic amines control mating receptivity and oviposition behaviour in females of two Callosobruchus species. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2009.10.011

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Males of the giant water bug Appasus (= Diplonychus) japonicus Vuillefroy (Belostomatidae: Heteroptera) carry egg masses on their back, but little is known about the relationship between seasonal abundance and breeding ecology of the species. In the present study, therefore, a field survey based on a mark-and-recapture census was carried out at three survey points within a rice paddy area (0.3 km2) where A. japonicus forms a meta-population in northern Okayama, Japan. We investigated the body size, seasonal abundance, dispersion, egg mass size (number of eggs within one egg mass), number of egg masses and the total eggs carried on the back of each male as fundamental parameters of the population and breeding. Significant differences in egg mass size, number of egg masses, and total number of eggs that males carried was found among the survey points. The present results suggested the possibility that the differences in breeding parameters of A. japonicus were influenced by differences in environmental factors among the microhabitats. These results are discussed in conjunction with previous reports on seasonal abundance and breeding systems in Belostomatidae bugs.

DOI： 10.1111/j.1479-8298.2009.00358.x

Web of Science

Scopus

CiNii Article

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL PUBLISHING, INC  

When studying animal behavior, it is often necessary to examine traits as a package, rather than as isolated units. Evidence suggests that individuals behave in a consistent manner across different contexts or over time; that is, behavioral syndromes. We compared locomotor activity levels and mating success between beetles derived from two regimes artificially selected for the duration of death-feigning behavior in the adzuki bean beetle, Callosobruchus chinensis. The two selection regimes comprised strains with higher (L) and lower (S) intensity (frequency and duration) of death-feigning behavior, respectively. We found that S strains had higher activity levels than L strains for both sexes, i.e., there is a negative genetic correlation between death feigning and activity. In addition, we found that S strains had higher mating success than L strains, presumably due to higher activity, in males but not in females. We thus demonstrate that death feigning is genetically correlated to mating behavior in males but not females in this species, suggesting that behavioral correlations may not always reflect in the same way in both sexes.

DOI： 10.1111/j.1439-0310.2009.01721.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC  

Consistent individual differences in correlated behaviours across contexts or situations, that is, behavioural syndromes, have recently been identified as an important factor shaping the evolution of behavioural traits, because of their potential for explaining trade-offs in behavioural responses. We examined a genetic link between abilities to mate and to avoid predation from the viewpoint of two genetically correlated behavioural traits; tonic immobility (TI), which is considered to be an antipredator behaviour, and activity levels in the red flour beetle, Tribolium castaneum. Males derived from two strains artificially selected for divergent durations of TI were used in the present study: the L strain (with longer duration and higher frequency of TI) and the S strain (shorter duration and lower frequency of TI). We found that males of the L strain had higher survival rates in predatory environments than those of the S strain, and lower mating success even in predator-free environments. To our knowledge, this is the first empirical study showing a genetic trade-off between abilities to mate and to avoid predation in relation to behavioural syndromes, using individuals exhibiting different behavioural strategies.

DOI： 10.1098/rsbl.2009.0494

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Experience-dependent tactics of males trying to gain access to females were examined in the beetle Gnatocerus cornutus, which engages in male-male fighting for mates. In male fights, subsequent behavior is modified by winning and losing experiences. Males, therefore, may choose between several behavioral tactics to obtain a mate, based on his previous fighting experience. In G. cornutus, we examined for how long aggressive behaviors were modified by experiences of winning or losing, i.e., the duration of the prior experience effect. Losing decreased a male&apos;s frequency of fighting for 4 days, and few defeated males fought any male regardless of the opponent&apos;s size. By the fifth day, this effect disappeared. No modulation of male behavior due to winning was observed. Furthermore, the experience of losing not only decreased a male&apos;s aggressiveness but also switched the male behavior from fighting to dispersal from the fight site to another site. In future, it is necessary to clarify why the optimal term of the losing experience is 4 days in this beetle.

DOI： 10.1007/s00265-009-0852-0

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Usually, several traits in organisms are genetically linked with each other; thus, correlated responses to selection are generally observed. Anti-predator behaviors may be genetically correlated with other traits such as life-history. We compared the life-history traits of individuals derived from two regimes artificially selected for the duration of death feigning in the adzuki bean beetle, Callosobruchus chinensis. The two-way selected regimes include the L-lines with stronger intensity (longer duration and higher frequency) and the S-lines with weaker intensity (shorter duration and lower frequency) of death feigning. L-lines exhibited greater longevity, higher rates of emergence, laid bigger eggs and greater reproductive effort, and also had a tendency of faster development. Fecundity was not significantly different between L- and S-lines. These results provide the novel possibility that death feigning is a potentially advantageous anti-predator behavior that, through a positive genetic correlation with some life-history traits, can bring a higher fitness to an individual adopting this behavior. This novel aspect might explain why death-feigning behavior is prevalent in various taxonomic animal groups.

DOI： 10.1007/s10682-008-9266-0

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC  

Death-feigning, also called tonic immobility, is found in a number of animal species across vertebrate and invertebrate taxa. To date, five hypotheses have been proposed for the adaptive significance of tonic immobility. These are that tonic immobility is effective for prey because (i) avoiding dead prey is safer for predators, (ii) immobility plays a role in physical defence, (iii) immobility plays a role in concealment and/or background matching, (iv) predators lose interest in unmoving prey, and (v) the characteristic immobilization posture signals a bad taste to predators. The fourth and fifth hypotheses have been considered suitable explanations for tonic immobility of the red flour beetle against its predator, the jumping spider. In the present study, we used chemical analyses of secretions by the red flour beetles under attack by the jumping spider to reject the fifth hypothesis for this system. More importantly, we tested a selfish-prey hypothesis for the adaptive significance of death-feigning as an anti-predator strategy, in which individuals adopting tonic immobility survive by sacrificing neighbours. Findings showed that survival rates of feigners were higher when in the presence of non-feigners or prey of a different species, compared to when alone, thus confirming our selfish-prey hypothesis. In summary, our results suggest that immobility following a spider attack is selfish; death-feigning prey increase their probability of survival at the expense of more mobile neighbours.

DOI： 10.1098/rspb.2009.0558

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

Male fighting frequently results in the evolution of traits used as weapons. Additionally, males with well-developed weapons typically differ behaviourally and morphologically from weaponless males. However, the genetic basis to these phenotypic correlations has not been investigated. The broad-horned. our beetle, Gnatocerus cornutus, is a species in which males engage in fights using their enlarged mandibles. We conducted bidirectional selection on beetle mandible length to investigate the correlated responses in male behaviour and body shape. Mandible size diverged significantly after 10 generations of selection. We also found that the microevolutionary enlargement of mandibles affected male morphology and behaviour. Compensatory or supportive traits of the mandibles (head, prothorax, genae and forelegs) also became enlarged, but eye area, antenna, head horn and elytra length were all reduced. These correlated responses in morphology may be the result of developmental integration of these traits and mandibles, but the reduction in size of some traits could also be caused by trade-offs generated by resource competition between characters. In any case, the enlargement of the weapon (mandibles) altered male body shape into a suitable form for fighting. Fighting endurance also evolved as a correlated response to selection on mandible size, with lines selected for larger mandibles able to fight for longer. It therefore appears that morphology and fighting are genetically correlated with each other. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.anbehav.2009.01.008

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Insect body temperature is usually determined by ambient temperature. Therefore, most biochemical and physiological processes underlying behavioural patterns are temperature dependent. Mating duration is also dependent on temperature, and therefore temperature should influence on sperm transfer and female remating frequency. In the adzuki bean beetle, Callosobruchus chinensis, we found negative relationships between ambient temperature and mating duration, sperm transfer and sperm transfer duration. Female remating frequency at lower temperature (17 degrees C) was lower than at other temperatures (25 degrees C and 33 degrees C). The physiological and behavioural significance of these results is discussed. The number of ejaculated sperm was significantly lower at 33 degrees C than at 17 degrees C; the effect of temperature on sperm transfer is discussed in relation to the intensity of female refusal behaviour directed against males. (c) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2008.10.012

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

The evolution of female multiple mating, or polyandry, is difficult to comprehend and thus has been the subject of a large number of studies. However, there is only a little evidence for genetic variation in polyandry, although the evolution of a trait via selection requires genetic variation that enables the trait to respond to selection. We carried out artificial selection for increased and decreased female propensity to remate as a measure of polyandry to investigate whether this trait has a genetic component that can respond to selection in the adzuki bean beetle, Callosobruchus chinensis. Artificial selection produced responses in both directions and divergence between the selection lines in the female propensity to remate. Although the experimental design adopted in this study selected jointly for female receptivity to remating, which is a trait of females, and male ability to inhibit female remating-both of which are associated with female propensity to remate-the observed response to selection was attributable only to the female receptivity to remating. This study indicates that the female receptivity to remating has significant additive genetic variation and can evolve according to whether remating is advantageous or disadvantageous to females in C. chinensis.

DOI： 10.1007/s10144-008-0112-6

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The effects of male-derived extracts on female receptivity were investigated in Callosobruchus maculatus (Coleoptera: Bruchidae). Injection of aqueous extracts of the male reproductive tract into the abdomen of females reduced receptivity. Aqueous extracts of male reproductive tracts were divided to three molecular weight (MW) fractions by ultrafiltration: Fractions: (I) MW &lt; 3 kDa. (II) 3-14 kDa, and (III) &gt; 14 kDa. Fraction II reduced female receptivity from 3 h after injection, and Fraction III reduced female receptivity from 2 days after injection. On the other hand, no effect on receptivity was found for Fraction I. Furthermore, male reproductive tract organs were divided into accessory gland, testis, and seminal vesicle including the ejaculatory duct. Aqueous extracts of the seminal vesicle reduced receptivity of females immediately following injection, while aqueous extracts of the accessory gland reduced receptivity at the second day. The results suggest that the components of Fraction 11 existed in the seminal vesicle, and those of Fraction III in the accessory gland. The results of the present and the previous studies in Callosobruchus chinensis, a species closely related to C. maculatus, were compared and are discussed from the viewpoint of the significance of ejaculation in the two species. (c) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2008.09.001

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOLOGICAL SOC AMER  

The efficacy of sterile insect technique (SIT) depends on successful mating of released males with wild females. If the time of mating in a day of mass-reared and released males differs from those of wild females, the efficiency of SIT decreases. Therefore, understanding the molecular mechanisms controlling mating time of the target pests is particularly important for SIT. The period (per) gene, which has been considered as a key clock gene controlling the mating time of the melon fly. Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), was cloned from two strains having different times of mating during the day. DNA sites varied in the 5' and 3' untranslated regions and at synonymous sies, although protein sequences were identical. We also provide phylogenetic relationships among PER protein sequences of dipteran species including several tephritid pest species. The functional domains of PER in the melon fly are very similar to those in other tephritid species. A luciferase reporter assay showed that the melon fly PER can functionally complement that of Drosophila melanogaster (Meigen). The results implicate that the major genetic cause of the difference in circadian periods, and thus in reproductive isolation, is probably one or more other clock gene(s). Thus, the series of studies may provide a novel factor concerning genetic quality control of mass-reared insect pests for SIT, which depends on successful mating of released males and wild females.

DOI： 10.1603/0013-8746-101.6.1121

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

Variation in the level of polyandry of females produces a difference in the risk of sperm competition among males. As a consequence, investment in ejaculate expenditure by males should vary. We compared the number of sperm ejaculated by males into the female reproductive organ of six strains of the adzuki bean beetle, Callosobruchus chinensis (Coleoptera: Bruchidae), when males were reared at different larval densities in a bean. A significant positive correlation was found between the remating frequency of females and the ratio of the ejaculate sizes of high-density and low-density males as a measure of the response to the risk of sperm competition among males. The measure was estimated by dividing the number of sperm ejaculated by males reared at high larval density in a bean with the number of sperm ejaculated by males reared alone. The number of sperm transferred by a male to a female was not correlated with the duration of copulation. The results suggest an evolutionary relationship between ejaculatory expenditure and the level of polyandry in C. chinensis.

DOI： 10.1007/s10164-007-0051-2

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

1. Scaling relations between weapons and body size depart from linearity in many male beetles. In many previous studies, these males have been divided into major and minor males with a switch point, that is male dimorphism. Major and minor males adopt strikingly different reproductive tactics.
2. We found three size-dependent behaviours, i.e. fighting, dispersing, and sneaking, however, among Librodor japonicus males with dimorphic mandibles. We statistically classified males into large, medium, and small (L-, M-, and S-males) sizes and then compared the dispersal of males from a foraging site, behaviours to gain access to females, and sizes of mandibles, wings, and testes.
3. M-males dispersed earlier than L- and S-males from a territory in a field, but no difference in the frequency of dispersal was observed between L- and S-males. Observations of male-male interactions in the laboratory showed that L-males frequently fought with other males in a fighting arena, while S-males often showed sneaking behaviour without fighting.
4. On the basis of the morphological analysis, we concluded that S-males invested their available resources more in sperm (= testes), M-males more in wings, and L-males more in mandibles in L. japonicus.
5. Even though a morphological male dimorphism was detected, it might be possible to classify the males of the armed beetles into more than two behavioural tactics if we examine their behaviours.

DOI： 10.1111/j.1365-2311.2007.00965.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING  

Although the effects of temperature on insect behaviours are studied frequently, few studies report on the relationship between temperature and anti-predator behaviours. A negative relationship between ambient temperature and the intensity of death-feigning is found in adults of two seed beetle species, Callosobruchus maculatus (F.) and C. chinensis (L.) (Coleoptera: Bruchidae). Two traits representing the intensity of immobility, the frequency and the duration of death-feigning, are measured at different temperatures. Almost all adults feign death at 15 degrees C, but the frequency of death-feigning decreases at higher temperatures in C. maculatus, whereas all C. chinensis adults show this behaviour at 15 and 20 degrees C and almost all show it at 25 degrees C, but the frequency of death-feigning decreases at 30 and 35 degrees C. The difference between the two species might be due to the specific strain of each species used in the experiment. The duration of death-feigning is correlated negatively with the increase in ambient temperature in both species. The frequency at which adults feigned death is higher in females than in males in both species, but the duration of death-feigning is higher in females than in males only in C. maculatus. The relationships between temperature and death-feigning behaviours are discussed from physiological and ecological viewpoints.

DOI： 10.1111/j.1365-3032.2007.00607.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The effects of male-derived extracts on female receptivity to remating were investigated in Callosobruchus chinensis (Coleoptera: Bruchidae). Injection of aqueous extracts of male reproductive tracts into the abdomen of females reduced receptivity. When aqueous extracts of male reproductive tracts were divided to three molecular weight (MW) fractions by ultrafiltration: &lt; 3, 3-14, and &gt; 14 kDa, the filtrate containing MW substances &lt; 3 kDa reduced female receptivity 3 h and I day after injection, whereas the fraction containing MW substances &gt; 14 kDa inhibited receptivity 2 and 4 days after injection. Finally, male reproductive tract organs were divided into accessory gland, seminal vesicle, and testis. Aqueous extracts of testis reduced receptivity of females on the second day and at 3 h, and aqueous extracts of accessory gland reduced receptivity of females on the second day after injection. On the other hand, aqueous extracts of seminal vesicle did not reduce female receptivity. The results indicate that more than one mechanism may be involved in producing the effects of male-derived substances on female receptivity; low MW male-derived substances, which possibly exist in testis, cause short-term inhibition, while high MW substances, which possibly exist in the accessory gland, inhibit female mating later than low MW substances in C chinensis. (c) 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2007.11.009

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

P(2), the proportion of offspring sired by the second male to mate, is an indicator of the outcome of postcopulatory sexual selection, which occurs through sperm competition and/or cryptic female choice. We determined the appropriate dose of gamma radiation for sterilization of adult males and, using the sterile male technique, measured P(2) in the adzuki bean beetle, Callosobruchus chinensis. Adult males of C. chinensis were almost completely sterilized when irradiated at 80 Gy. Thus, we obtained sterile males through irradiation at this dose. Neither the probability of female first mating nor the probability of female remating was affected by whether females were paired with normal or sterile males. The P(2) calculated from the hatching success of eggs laid by females that mated both with normal and sterile males did not differ between reciprocal mating sequences, indicating that the sterilization has no effect on sperm fertilizing ability. The P(2) was estimated at 0.25. This study shows that female remating in C. chinensis means the coexistence of sperm from two males and thus the occurrence of postcopulatory sexual selection within the female reproductive tract, resulting in first-male sperm precedence.

DOI： 10.1007/s10164-007-0067-7

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

A prey animal has the alternative of fleeing or feigning death to survive when it encounters predators. We found that fleeing by an artificial threat, locomotion and feigning death are pleiotropically correlated with a genetic factor related to a biogenic amine in the red. our beetle, Tribolium castaneum. Walking distance of adults was significantly lower in strains artificially selected for longer ( L strains) than shorter duration ( S strains) of death-feigning. Crosses showed that S-strain adults were dominant in the frequency and duration of death-feigning and locomotor activity compared to those of L strains, suggesting that death-feigning and activity have the same genetic basis. S-strain adults fled, but L-strain adults feigned death, when they encounter artificial threat. Not only adults that were directly selected for the duration of death-feigning, but also the larvae of L strains frequently showed tonic immobility, when they were dropped onto the ground: the larvae of S strains showed this behaviour less often. This suggests that chemical modulators of behaviour present in these insects before and after metamorphosis control both general locomotor activity and death-feigning. Brain levels of the candidate neuromodulator dopamine were, in fact, found to be significantly higher in S strains compared to L strains in the two selection replications. Thus, we suggest that two alternative behaviours related to antipredator strategies, fleeing or feigning death, are associated with the pleiotropic effects of a neuroactive substance in T. castaneum. (C) 2007 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.anbehav.2007.04.019

Web of Science

researchmap

Language：English   Publisher：ELSEVIER SCIENCE INC  

DOI： 10.1016/j.cbpb.2007.07.030

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

Status-dependent tactics of males trying to gain access to females were examined in relation to morphology, male-male interactions and dispersal in a sap beetle, Librodor japonicus. Males of this species have sexually dimorphic enlarged mandibles which they use in fights for mates on a sap site. Morphological analyses revealed a switchpoint at which the linear slopes of mandible and hindwing width to body length increased and decreased, respectively. Larger males frequently fought with other males in an experimental arena, whereas smaller males often showed sneaking behaviour without fighting. Mark-release-recapture experiments showed a size-dependent difference in dispersal ability of males in the field. The longest dispersal distance was seen in intermediate-sized males, and the shortest dispersal distances were observed in the largest and smallest males. In females, no relation was found between body size and dispersal distance. The largest males thus remain on sap sites and fought with other males, the smallest males also remain on sap sites and try to sneak access to females, and intermediate-sized males move among sap sites and settle on one without a larger male. The results suggest a nondichotomous difference in optimal behavioural tactics of males even though male dimorphism has been detected in armed beetles.

DOI： 10.1016/j.anbehav.2006.09.020

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Female multiple mating, which is common in animals, may have evolved not in response to fitness advantages to females but as a genetic corollary to selection on males to mate frequently. This nonadaptive hypothesis assumes a genetic correlation between females and males in mating frequency, which has received a few empirical investigations. We tested this hypothesis by observing the correlated response in male mating frequency in the adzuki bean beetle, Callosobruchus chinensis to artificial selection on female propensity to remate. Compared to control females, females from lines selected for increased or decreased female propensity to remate had, respectively, higher or lower mating frequency measured by the number of mating within a given period. This indicates that female receptivity to remating is genetically correlated with female mating frequency, and thus the artificial selection for female propensity to remate influenced female mating frequency. In contrast, males from the selected lines that diverged in female mating frequency did not vary significantly in their mating frequency. These results indicate that there is no genetic correlation between the sexes in mating frequency in C. chinensis. This study shows that the reason why females in C. chinensis remate despite suffering fitness costs cannot be explained by indirect selection resulting from selection on males to mate multiple times.

DOI： 10.1038/sj.hdy.6800996

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

Intra-sexual dimorphism is found in the weapons of many male beetles. Different behavioral tactics to access females between major and minor males, which adopt fighting and alternative tactics, respectively, are thought to maintain the male dimorphism. In these species major males have enlarged weapons that they use in fights with rival males. Minor males also have small weapons in some of these species, and it is unclear why these males possess weapons. We examined the hypothesis that minor males might adopt a fighting tactic when their status was relatively high in comparison with that of other males (e.g., ownership of a territory). We observed the behavioral tactics of major and minor males of the beetle Librodor japonicus, whose males have a dimorphism of their mandibles. Major males fought for resources, whereas minor males adopted two status-dependent tactics, fighting and sneaking, to access females, depending on their ownership of a sap site. We suggest that ownership status-dependent mating tactics in minor males may maintain the intra-sexual dimorphism in this beetle.

DOI： 10.1007/s10164-006-0021-0

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

Librodor japonicus (Motschulsky) is distributed throughout the satoyama forests in Japan, and inhabits the saps of oak trees all its life. Although the beetle is a potential indicator of bio-resource abundance in the satoyama forests, the life history traits and seasonal abundance have not been studied. In this study, first, the seasonal abundance of L. japonicus was investigated using banana bait traps in Okayama City in 2002. Two peaks of abundance were found: a large peak from April to June and a small peak from August to September. The beetles oviposited on banana slices, and a successful artificial rearing method was established using only banana slices and leaf mold. The effect of temperature on the survival rate, adult size and developmental period was examined at different temperatures. The survival rate and the adult size tended to be greater at 25 degrees C than at other temperatures. The thermal thresholds and thermal constants calculated from egg to adult development were 5.6 and 5.9 degrees C and 1,010.9 and 1,022.0 degree-days for females and males, respectively. On the basis of these developmental parameters and the seasonal abundance of L. japonicus, the number of generations per year in Okayama, Japan, was estimated to be one.

DOI： 10.1303/aez.2007.411

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOCIETY  

A prey animal may have the alternative of flying away or feigning death when it encounters predators. These alternatives have a genetic base as anti-predator strategies in the adzuki bean beetle, Callosobruchus chinensis. A negative genetic correlation between death-feigning intensity and flying ability was found in C. chinensis, i.e. lower flying ability is genetically connected to escaping by dropping from a perch and then feigning death, whereas higher flying ability does not correspond to death-feigning behaviour. Two bidirectional artificial selections for death-feigning duration and flying ability were conducted independently in C. chinensis. The strains selected for shorter (longer) duration of death-feigning had higher (lower) flying ability, while the strains selected for lower (higher) flying ability showed longer (shorter) duration of death-feigning. When the two traits were compared in 21 populations of C. chinensis derived from different geographical regions, a significant negative correlation was found between death-feigning intensity and flying ability. Based on these results, the choice between alternative escaping behaviours in animals is discussed from two points of view: phenotypic plasticity, an individual with two tactics; and pleiotropic genetic correlation, different individuals with opposite strategies.

DOI： 10.1098/rspb.2006.3750

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

The evolution of female multiple mating is best understood by consideration of male and female reproductive perspectives. Females should usually be selected to remate at their optimum frequencies whereas males should be selected to manipulate female remating to their advantage. Female remating behavior may therefore be changed by variation of male and female traits. In this study, our objective was to separate the effects of female and male strains on female remating for the adzuki bean beetle, Callosobruchus chinensis, for which there is interstrain variation in female remating frequency. We found that interstrain variation in female remating is primarily attributable to female traits, suggesting genetic variation in female receptivity to remating in C. chinensis. Some interstrain variation in female remating propensity was attributable to an interaction between female and male strains, however, with the males of some strains being good at inducing nonreceptivity in females from one high-remating strain whereas others were good at inducing copulation in nonvirgin females from the high-remating strain. There is, therefore, interstrain variation in male ability to deter females from remating and in male ability to mate successfully with nonvirgin females. These results suggest that mating traits have evolved along different trajectories in different strains of C. chinensis.

DOI： 10.1007/s10164-006-0204-8

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

We investigated the effect of the presence of an oviposition substrate on female remating behavior in three strains of the adzuki bean beetle, Callosobruchus chinensis. In the two strains with low levels of female remating, females maintained with an oviposition substrate, and thus allowed to lay eggs, had a greater tendency to remate than females maintained without an oviposition substrate to prevent them from laying eggs. The oviposition substrate had no significant effect on female remating in the strain with a high level of female remating. The results indicate that female remating is influenced by the presence of an oviposition substrate, an environmental factor, in C chinensis. This suggests that females adaptively change their receptivity to remate in response to environmental factors affecting the costs and benefits of remating in C chinensis.

DOI： 10.1303/aez.2006.569

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

In the stored-product beetle, the broad-horned flour beetle, Gnatocerus cornutus (Fabricius), all males possess enlarged mandibles, widened gena, and a pair of small horns on the vertex, but females lack these completely. Observations of male-male interactions of G. cornutus showed that larger individuals won male-male fights, and that the mandibles were used as weapons. Morphological analysis based on the non-linearity test of Eberhard and Gutierrez's model (1991) showed that intra-sexual dimorphism in males was only found in the mandibles used in male-male combat, but not in the gena and horns. This beetle can be an ideal model for evolutionary studies of exaggerated weapons for male combat, because rearing successive generations and observing male fighting are easy.

DOI： 10.1007/s10905-006-9038-z

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Genetic and environmental sources of egg size, fecundity and body size (forewing length) were examined in the butterfly, Parnara guttata guttata. Phenotypic and genetic correlation and heritability were estimated for these traits under different day-length and temperature conditions. Egg size and fecundity had relatively high heritabilities, and body sizes in males and females had moderate and high heritability, respectively. Negative phenotypic and genetic correlations between egg size and fecundity were estimated in treatments corresponding to the natural conditions during larval development of the first and second generations. Phenotypic and genetic correlations between body size and egg size differed considerably between insects reared under long and short day-lengths. Next, genotype-environment interactions were estimated by comparing reaction norms to day-length or temperature of these traits among families. ANOVA analysis revealed significant genotype-environment interactions in egg size and forewing length in both sexes for day-length and temperature. These results suggested that a large additive genetic variance for egg size might have been maintained by a genetic trade-off and/or by genotype-environment interactions in P. g. guttata.

DOI： 10.1007/s10144-006-0266-z

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOLOGICAL SOCIETY AMERICA  

Theoretical and empirical studies of life history assume that egg size and number cannot be maximized simultaneously because of a trade-off between them. In many empirical studies, however, only egg size or egg number was examined as a fitness component of the mother. We estimated phenotypic and genetic correlations between egg size and number, and heritabilities of each trait by half-sib analysis in Callosobruchus chinensis (L.) (Coleoptera: Bruchidae). The signs of all genetic correlations between egg size and egg number were negative, but near zero and not significantly different from zero. The result means that no trade-off was found between egg size and egg number, at least in this beetle population. We discuss three reasons (i.e., laboratory adaptation, mutation, and resource acquisition ability) why we did not detect a significant negative genetic correlation between egg size and egg number even when genetic trade-off existed.

DOI： 10.1603/0013-8746(2006)099[0364:HAGCEF]2.0.CO;2

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD  

In many insect species with high levels of polyandry, females benefit directly from remating. The effects of remating on female fitness have generally been examined by comparing the fitness of females in multiple-mating and single-mating treatments. In this standard approach, females in the multiple-mating group that refuse to remate are often excluded from the analysis. We investigated the effects of remating in the adzuki bean beetle, Callosobruchus chinensis, a species with low levels of polyandry. Females that refused to remate when given an opportunity to do so were less fecund and shorter lived than females that accepted remating. In this case, excluding females that refuse to remate from the multiple-mating treatment biases the composition of the two treatment populations, and is thus problematic. When we included such females, we found no difference in fecundity fertility and longevity between females given an opportunity to remate and those that were not. In addition, when we compared females that were allowed to complete remating naturally and those whose remating was interrupted before sperm transfer we found significantly negative effects of female remating on fecundity, suggesting that remating reduces the fitness of polyandrous females in C. chinensis, which is inconsistent with many studies on polyandrous species. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All fights reserved.

DOI： 10.1016/j.anbehav.2005.05.017

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Optimal sperm allocation should differ according to the level of polyandry within a population, because the risk of sperm competition depends on the remating frequency of females. We compared the number of sperm ejaculated by males into the female reproductive organ between strains with different levels of polyandry in the adzuki bean beetle, Callosobruchus chinensis (Coleoptera: Bruchidae) when males were reared in different larval densities in a bean. The results showed that males derived from a Population with a higher level of polyandry increased cjaculatory expenditure when they were reared under higher larval densities. We discuss the evolutionary correlation of ejaculatory expenditure to the level of polyandry. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2005.07.001

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD  

The evolution of polyandry remains controversial. Various hypotheses that account for its evolution assume heritable variation in polyandry. We compared the frequency of female remating in 10 strains of the adzuki bean beetle, Callosobruchus chinensis, then made crosses between populations of high and low remating frequencies to investigate the mode of inheritance of polyandry. We found significant heritable variation in polyandry between the strains. Lower levels of polyandry were found in populations derived from long-term laboratory cultures than in those from recently established ones, suggesting that a selection pressure favoured monandry in the laboratory cultures. F, offspring from reciprocal crosses between strains with high and low frequencies of female remating had frequencies similar to that of the strain with a high remating frequency, suggesting that polyandry is inherited with dominance in C. chinensis, unlike any other species reported to date. This study indicates that polyandry can evolve in response to selection in C. chinensis.

DOI： 10.1016/j.anbehav.2004.10.023

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER/PLENUM PUBLISHERS  

Size-dependent differences in death-feigning behavior, an anti-predator defense, was examined in the adult adzuki bean beetle, Callosobruchus chinensis (Coleoptera: Bruchidae). A positive correlation was observed between the duration of death-feigning and adult body weight in two replicated experiments. Moreover, under starved condition, beetles reared under high (= lighter beetles) larval density showed significantly shorter longevity and a shorter duration of death-feigning than those reared under low (= heavier beetles) larval density. The body-size-dependent difference in the duration of death-feigning is discussed from the viewpoint of the difference in survival strategies between small and large beetles. Because small beetles don't live as long, they have less time in which to reproduce and so any loss of that short time might be a greater proportion of their fitness lost. This is the first report on the body-size-dependent difference in death-feigning behavior in the adult holometabolic beetle.

DOI： 10.1007/s10905-005-5612-z

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC  

The adaptation of death-feigning (thanatosis), a subject that has been overlooked in evolutionary biology, was inferred in a model prey-and-predator system. We studied phenotypic variation among individuals, fitness differences, and the inheritance of death-feigning behaviour in the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). Two-way artificial selections for the duration of death-feigning, over 10 generations, showed a clear direct response in the trait and a correlated response in the frequency of death-feigning, thus indicating variation and inheritance of death-feigning behaviour. A comparison of the two selected strains with divergent frequencies of death-feigning showed a significant difference in the fitness for survival when a model predator, a female Adanson jumper spider, Hasarius adansoni Audouin (Araneomophae: Salticidae), was presented to the beetles. The frequency of predation was lower among beetles from strains selected for long-duration than among those for short-duration death-feigning. The results indicate the possibility of the evolution of death-feigning under natural selection.

DOI： 10.1098/rspb.2004.2858

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOLOGICAL SOC AMER  

Sexual dimorphism was found in the mandibles and other supportive structures used in male-male combat over females in Librodor japonicus. Observation of the behavior of male-male interactions of L. japonicus elucidated the influence of contestant size and resource ownership status on the outcome of male-male fighting. Interactions escalated in the presence of females, indicating the influence of resource value on the intensity of male fighting. At escalated fighting, the outcome of combat was influenced by size and ownership status. This study is the first on sexual dimorphism and male fighting in the Nitidulidae.

DOI： 10.1603/0013-8746(2004)097[1342:SDIMAM]2.0.CO;2

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The effects of mating duration on female remating (exp. 1) and under different male densities (exp. 2) were examined in two strains of the adzuki bean beetle, Callosobruchus chinensis and in one strain of the bruchid beetle, C maculatus. In experiment 1, the frequency of female remating was markedly different between the two strains of C chinensis. Females of the jC strain, reared long-term in the laboratory, did not remate after being allowed to mate freely (=monogamy), whereas females of the isC strain, recently established from the field, showed high remating frequencies (=polyandry). In both strains, the frequency of female remating increased after the duration of the first mating was deliberately shortened. The relation between mating duration and remating frequency was significantly different, however, between the two strains. In a closely related species, C maculatus, which manifests polyandry, this relation was more similar to that of the field-derived (=isC) than to that of the laboratory-derived (=jC) strain of C chinensis. The reasons for the inter-strain variation observed in the remating frequencies of C chinensis are also discussed. In experiment 2, the mating duration of the three strains was compared under different male densities. Only the lab-derived strain demonstrated a significantly shorter mating duration when one female was placed together with five males than when paired with one male. The shorter mating duration (approximately 26 s) was similar to that of females allowed to remate in the monogamous strain in experiment 1. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2004.02.007

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Pulse train intervals (PTI) of courtship song were differentiated between circadian clock mutants of the melon fly, Bactrocera cucurbitae (Coquillett) (Tephritidae: Diptera). We analysed the male mating song of B. cucurbitae flies of two mutant strains that differed in circadian locomotor rhythm by a LabVIEW programming system. Flies with a short cireadian rhythm (S-strain) had shorter PTI than those with a long circadian rhythm (L-strain) in the two age groups tested, young and old. Young flies showed longer PTI than old flies, but no interaction between strain and age was found in PTI. There was a significant interaction between strain and age for pulse train duration (PTD), whereas no stable difference was found in PTD between S- and L-strains. These results suggest a positive correlation between the length of the circadian locomotor rhythm and PTI of courtship song sounds in R cucurbitae. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2003.10.002

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ANNUAL REVIEWS  

The melon fly, Bactrocera cucurbitae, is a destructive insect of cucurbit and other fruits. It invaded the Southwestern Islands of Japan from 1919 to 1974. The sterile insect technique (SIT) was successfully applied rom 1972 to 1993 to eradicate the melon fly. Technical research into SIT function,, such as suppression of density, mass-rearing, sterilization, shipment, release, evaluation of efficacy, and quality control of mass-reared insects, was conducted for this eradication project. Fundamental research into the dispersion, mating and oviposition behavior, population dynamics and estimation of density, eradication models, spatia distribution, genetics, and evolution of the melon fly was also undertaken and supported the success of the eradication project.

DOI： 10.1146/annurev.ento.49.061802.123224

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOL SOC AMER  

We investigated ovipositional preference of Helicoverpa armigera (Lepidoptera: Noctuidae) for a range of host plants, larval performance on a range of host plants, dispersion rate of a concentrated population of fifth instar larvae, the fitness consequences of cannibalism at two levels of food availability, and the frequencies of cannibalism between larvae of different instars. Eggs laid by adult females were concentrated on some specific plants, despite the wide range of host plants of H. armigera. However, the larvae dispersed when they reached high larval density and eventually exhibited a uniform spatial distribution. Cannibalism frequently occurred under poorer nutritional conditions or greater larval rearing density. The effect of cannibalism on development and pupal weight differed between rich and poor nutritional rearing conditions. The cannibals' fitness was decreased under suitable food conditions, whereas larvae with a low frequency of cannibalism increased their pupal weight, a potential fitness trait, in unsuitable conditions. These results suggest that cannibalism is a behavior of larval H. armigera that has evolved to remove potential intraspecific competitors and thus to avoid unsuitable conditions.

DOI： 10.1603/0013-8746(2003)096[0793:ELPLDA]2.0.CO;2

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Costs of reproduction include the costs of mating and egg production. Specific techniques such as irradiation or genetic mutation have been used to divide the expense into costs of mating and egg production in previous studies. We tried to divide the costs in the adzuki bean beetle, Callosobruchus chinensis (Coleoptera: Bruchidae), which needs some kinds of bean as an oviposition substrate. Mated females that were not allowed to lay eggs had a shorter life span than virgin females, but they had a longer life span than mated females that were allowed to lay eggs. The results showed two independent significant costs. mating and egg production. on the life span in C. chinensis. Costs of mating. however, include the costs of sexual harassment by males and copulation itself, and we need further studies to divide the costs. The present method for dividing the cost of reproduction into costs of mating and egg production can be applied to a broad taxonomic range of insect species, and thus it will be a Useful model system for inter-specific comparisons of costs of mating and egg production. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/S0022-1910(03)00119-7

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER-VERLAG TOKYO  

The mechanism by which a clock gene pleiotropically controlling life history and behavioral traits causes reproductive isolation is explained using a model species, the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae). Melon flies mate once a day, at dusk. The population selected for life history traits exhibits correlated responses in the time of mating during the day. For example, the fly populations selected for faster (slower) development have an earlier (later) time of mating. A circathan rhythm controls the time of mating. The circadian periods in constant darkness were about 22h in lines selected for a short developmental period and about 31 h in lines selected for a long developmental period. The data on crosses between the selected lines indicated that the developmental period is controlled by a polygene, whereas the circadian period may be controlled by a single clock gene. These results suggest a clock gene pleiotropically controls developmental and circadian periods in the melon fly. Reproductive isolation may often evolve as an indirect (pleiotropic) consequence of adaptation to different environments or habitats. For example, niches that are temporally or seasonally offset can select organisms with different developmental characteristics. These developmennt differences can inadvertently cause reproductive isolation by a variety of means including shifts in mating activity patterns. The difference in time of mating between populations selected for developmental period translated into significant prezygotic isolation, as measured by mate choice tests. If the mating time between populations differed more than 1 h, the isolation index was significantly higher than zero. These findings indicate that premating isolation can be established by a pleiotropic effect of a clock gene. There are many examples in which the difference in timing of reproduction prevents gene flow between populations, such as the egg spawning time in marine organisms, the flowering time in angiosperms, and the time of mating in insects. In, such, organisms; if genetic correlations between circadian rhythm and reproductive traits exist, multifarious divergent selection for life history traits would often accelerate the evolution of reproductive isolation through clock genes. Natural populations may diverge in reproduction time through drift, direct natural selection for time of reproduction, or as a by-product effect of genetic correlations. In any case, clock genes are keys in reproductive isolation.

DOI： 10.1007/s101440200023

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL PUBLISHING LTD  

In many insect species, the size and number of eggs decrease with maternal age. Thus, both the size and number of eggs must be considered to know the exact cost of reproduction with maternal age. The resource depletion hypothesis was examined in the bruchid beetle Callosobruchus chinensis . The hypothesis explains why the egg size decreases with maternal age based on the decline of the female's reproductive capacity. A decrease was found in reproductive effort (= egg size x the number of eggs) and the fitness component of offspring with maternal age. The effects of the female's nutritional status on the relationship between maternal age and the reproductive effort of females with and without food and water were also examined. The results indicate that the decrease in size and number of eggs with maternal age can be explained by the resource depletion hypothesis in C. chinensis .

DOI： 10.1046/j.1365-3032.2002.00294.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC  

Clock genes that pleiotropically control circadian rhythm and the time of mating may cause allochronic reproductive isolation in the melon fly Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae). Flies with a shorter circadian period (ca. 22 h of locomotor activity rhythm) mated 5 h earlier in the day than those with a longer circadian period (ca. 30 h). Mate-choice tests demonstrated significant pre-mating isolation between populations with short and long circadian periods. Pre-mating isolation did not occur when the mating time was synchronized between the two populations by photoperiodic controls, indicating that reproductive isolation is due to variations in the time of mating and not any unidentified ethological difference between the two populations. We cloned the period (per) gene of B. cucurbitae that is homologous to the per gene in Drosophila. The relative level of per mRNA in the melon fly exhibited a robust daily fluctuation under light : dark conditions. The fluctuation of per expression under dark : dark conditions is closely correlated to the locomotor rhythm in B. cucurbitae. These results suggest that clock genes can cause reproductive isolation via the pleiotropic effect as a change of mating time.

DOI： 10.1098/rspb.2002.2152

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Entomological Society of America  

An eradication project has been initiated in the southwestern island of Japan to contain the West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) using the sterile insect technique (SIT). We report here about rearing this insect for &gt
14 successive generations on an artificial diet, an element required for successful use of SIT. The fecundity of reared weevils increased with each generation. Egg hatch (85-95%) and adult yield (30-60%) were consistenetly high throughout the test period. Comparisons of fecundity and preoviposition periods indicated that females from the artificially reared strain at generation 14 oviposited more and earlier in life than those from the base stock. These differences resulted from an increase in frequency (100%) of females that laid eggs without standard oviposition substrates in the artificially reared strain. Adaptation to an artificial diet is discussed in relation to the oviposition behavior of E. postfasciatus and the success of SIT against this weevil.

DOI： 10.1603/0013-8746(2002)095[0735:ATARDS]2.0.CO;2

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Blackwell Publishing Ltd.  

Chrono-biological traits were changed by selecting for life-history traits via a genetic linkage controlling both time-related behavioural and life-history traits. Behavioural traits were compared between lines selected for young (Y-lines) and old (O-lines) age at reproduction in the melon fly, Bactrocera cucurbitae (Coquillett). Adults from O-lines, which survive longer than flies from Y-lines, mated later in the day and had a longer period of circadian rhythm in the locomotor activity than those from Y-lines. Flies from F1 reciprocal crosses had an intermediate time of mating and periods of circadian rhythm between that of the parents, indicating a genetic basis to these traits. The presence of these behavioural differences across the selection lines indicates that chrono-biological traits exhibit correlated responses to selection on age at reproduction. The correlated responses in the behavioural traits to selection for life-history traits are discussed from two points of view: pleiotropy and inadvertent selection.

DOI： 10.1038/sj.hdy.6800044

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Entomological Society of America  

The bamboo bug Notobitus meleagris F. shows two types of mating aggregation: harem including a male and one or more females, and multi-male including some males and females. Both types of mating aggregations were formed only on young bamboo shoots. The mean body size of males was significantly smaller in multi-male aggregations than in harem aggregations, but female size was independent of aggregation type. There was a significant positive correlation between the body size of males and the number of females in harem aggregations that formed in association with male-male aggressive contests. More females were attracted to thicker than thinner bamboo shoots, where larger aggregations formed. Multi-male aggregations were observed more on thicker than thinner shoots. Multi-male mating aggregations may occur when females cannot be economically defended.

DOI： 10.1603/0013-8746(2002)095[0340:MMMAIN]2.0.CO;2

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC/PLENUM PUBL  

Diurnal periodicity of death-feigning behavior, or thanatosis, was found in adults of the sweet potato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae). The proportion of death-feigned weevils was significantly lower at night than in the daytime only in males. The duration of death-feint was shorter at night than in the daytime in both sexes. The influences of a weevil's behavior prior to being startled (prestimulus behavior) on the proportion of adults feigning death and on the duration of the death-feint were examined. Resting weevils feigned death more frequently and took a longer duration to recover compared to walking ones. The results suggest that, in general, death-feigning is less frequent in active weevils compared to inactive ones. A cost-benefit relationship of death-feigning behavior is discussed in relation to survival and reproduction of C. formicarius.

DOI： 10.1023/A:1011196420147

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Entomological Society of America  

Effects of starvation on death-feigning behavior, or thanatosis, were observed in adults of the sweetpotato weevil, Cylas formicarius (F.). A significantly lower proportion of death-feigned adults was observed in starved weevils compared with unstarved controls in both sexes. However, females needed a longer starvation period than males to show the decreased proportion of death-feigning. This contrast between males and females was caused by a differential tolerance of the sexes for starvation, because males died earlier than females without food. Starved male weevils had a shorter duration to recover from the death-feigning. There may be situations where C. formicarius gives priority to assuring food consumption compared with escaping from predators. © 2001 Entomological Society of America.

DOI： 10.1603/0013-8746(2001)094[0612:EOSODF]2.0.CO;2

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan International Research Center for Agricultural Sciences  

Eradication programs are being implemented for 2 sweetpotato weevil pests, Cylas formicarius and Euscepes postfasciatus, in the Ryukyu Islands located in the southernmost part of Japan by the application of the sterile insect technique (SIT). As it is essential for the implementation of the programs to assess the dispersal ability of the weevils, recent studies were reviewed. Both the flight and walking ability of C. formicarius was much higher in males than in females when determined in the laboratory. Synthesized sex pheromone of C. formicarius has been used as a strong lure to capture the males in the field. Results of the mark-recapture experiments suggest that a distance of at least 2 km is needed for the range of the buffer zone to separate the SIT target area from others. Since E. postfasciatus is unable to fly, only the walking ability was evaluated in the laboratory, indicating that the females exhibited a fairly higher locomotion activity compared with the males. Since no effective attractant for E. postfasciatus has been identified yet, information on the dispersal activity in the field is limited. Fundamental studies should be conducted to determine the dispersal ability of both weevil pests to implement successfully the eradication programs.

DOI： 10.6090/jarq.35.227

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

Dispersal of reared adult male sweetpotato weevils, Cylas formicarius (F.), was examined in different seasons using a mark-release-capture method in Okinawa, Japan, where a sterile insect release project has been conducted to eradicate the weevil. Release and capture were replicated 7 times in different seasons in the same locality consisting mainly of sweet potato and sugarcane fields. About 8,000 males were marked each time, thus 54,444 males in total were released, and 14,746 of them were captured by pheromone traps (27.1%). Population parameters, including dispersal, capture and survival rates of released males, and population density of wild adult males were estimated. Percentage captured and dispersal distance were positively correlated with mean temperature during each experiment. The highest estimated population density of wild males was found in the summer. The results offer strategical parameters for a successful eradication project against the weevil using the sterile insect technique.

DOI： 10.1303/aez.2000.441

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Entomological Society of America  

We found Bactrocera scutellata (Hendel) emerging from stem galls produced by a gall midge. Lasioptera sp., on three wild gourd species. Diplocyclos palmatus (L.) C. Jeffrey, Trichosanthes ovigera Blume, and Zehneria liukiuensis (Nakai) Jeffrey ex Walker, on Okinawa, Japan, a subtropical island. Because B. scutellata preferably attack galls to ungalled parts of gourds, we regard the fruit fly to be a cecidophagous species. Seasonal occurrences of the midge galls on the gourds, the number of galls fed on by B. scutellata, and the fruit fly males captured by cue-lure traps were studied in the northern part of the Island. Midge galls were observed during the period from May to December and fed on by B. scutellata most abundantly in June. Trap data showed that the abundance of male B. scutellata had two peaks
the first in March and the second in June. The second peak was consistent with the occurrence of cecidophagy, whereas the first was not. Host exploitation by B scutellata is discussed based on the relationship among the gourds. Lasioptera sp., and B. scutellata.

DOI： 10.1603/0013-8746(2000)093[1274:SOOBSD]2.0.CO;2

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

A quantitative genetic analysis of rapid evolution of a life history trait has been conducted on the first 24 generations of mass-rearing in the melon fly Bactrocera cucurbitac (Coquillett) (Diptera: Tephritidae). The phenotypic variance of larval development time in each generation was divided into genetic and residual components. Mean and phenotypic coefficients of variation of larval development time decreased gradually as generations proceeded as a result of artificial selection for shorter larval period in the mass-rearing procedure. There was a trend that additive genetic coefficients of variation in larval development time decreased with generations. These changes are entirely attributed to genetic responses to laboratory selection under the mass-rearing environment because the population was maintained at a very large size so as to exclude random genetic drift and inbreeding depression, which would be other factors responsible for the observed genetic changes. The residual coefficients of variation in larval development time did not change with generations. Realized heritability of larval development time was low. The heritabilities for larval development time estimated from parent-offspring regression at generations 60 and 70, when the evolutionary plateau was asymptotically reached, were not significantly larger than 0.

DOI： 10.1007/s101440050034

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Mechanisms producing inhibition of remating in mated female Mediterranean fruit flies Ceratitis capitata, were investigated by matings with surgically altered males. Comparison of remating by females mated with either intact control males or males with a shortened penis, showed that ejaculate or a physical stimulus of penis insertion caused remating inhibition for at least 10 days after first mating. Remating frequency at two days after mating was significantly higher in females mated to castrated (spermless) males than in females mated to sham-operated control males. This difference disappeared by day four after mating, indicating that sperm cause a shorter-term inhibition of remating than does a normal first mating. Other factors in addition to sperm must therefore play a role in inhibition of remating. (C) 1999 Elsevier Science Ltd. All rights reserved.

DOI： 10.1016/S0022-1910(99)00083-9

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC STUDY EVOLUTION  

Reproductive isolation may often evolve as an indirect (pleiotropic) consequence of populations adapting to different environments or habitats. For example, niches that are temporally or seasonally offset can select for organisms with different developmental characteristics. These developmental differences can inadvertently cause reproductive isolation by a variety of means including shifts in mating activity patterns. Here, we show a genetic correlation between a life-history trait (developmental period) and a behavioral trait (time of mating) that causes significant premating isolation in the melon fly, Bactrocera cucurbitae (Diptera: Tephritidae). Fly lines selected for short and long developmental periods differ in their preferred times of mating during the evening. This difference translates into significant prezygotic isolation, as measured by mate choice tests. If the time of mating between two populations differed more than one hour, the isolation index was significantly higher than zero. These indicate that premating isolation can be established if the developmental period in divergently selected for. If such genetic correrlations are ubiquitous in many organisms, multifarious divergent selection for life-history traits would often accelerate the evolution of reproductive isolation. We speculate that reproductive isolation may have been evolved via genetic correlations among time-related traits, for example, developmental period and time of mating, as in other organisms.

DOI： 10.1111/j.1558-5646.1999.tb05345.x

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

Costs of reproduction include costs of producing eggs and of mating itself. In the present study, we made an experimental investigation of costs of reproduction in the Mediterranean fruit fly (medfly, Ceratitis capitata). We demonstrated that virgins live longer than non–virgin females. However, in strong contrast to most findings within the Diptera, non–virginity had no detectable effect on egg production. Therefore the increased longevity of the virgin females cannot be attributed to an increase in egg production in non–virgin females, and instead indicates a cost of mating. A comparison of the life spans of normal females and those sterilized by low doses of X–irradiation, revealed an additional cost of egg production. There were no significant differences in remating levels between females that did and did not lay eggs, showing that the cost of producing eggs is independent of mating frequency. Medfly females therefore suffer a decrease in survival as a result of egg production and of mating, and these costs are independent of one another. To put our results into context, we reviewed the existing literature on the effects of mating on longevity, egg production and sexual receptivity for 64 species of Diptera, and examined the pattern of mating effects that emerged.

DOI： 10.1098/rspb.1998.0516

CiNii Article

CiNii Books

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

Genetic variability of the pre-mating period in the mass-reared melon fly was evaluated by a quantitative genetic method for each sex. Males had heritable variation in pre-mating period, whereas in females no significant heritability was found. The long-term mass-reared melon flies had a shorter pre-mating period than the short-term reared flies. Possible selection pressure on flies during the mass-rearing of the Okinawa Prefecture is discussed.

DOI： 10.1303/aez.33.29

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Japan  

Quantitative genetic studies for life history and behavioral traits are important in quality control for insect mass-rearing programs. Firstly, a brief history of quality control in mass-reared insects is described. Next, the differentiation of many traits of wild and mass-reared melon flies, Bactrocera cucurbitae, in Okinawa is reviewed, and the factors which have caused variation in these traits are considered. As artificial selection pressures are thought to be more important than inbreeding depression and genetic drift in the mass-reared strain of the Okinawan melon fly, two artificial selection experiments were conducted to evaluate genetic variations and genetic correlations among life history and behavioral traits. These are divergent selections for age at reproduction and for developmental period. The genetic relationship among 5 traits, i.e. longevity, age at reproduction, developmental period, circadian period, and time of mating was clarified and discussed in relation to genetic changes of traits during the mass-rearing. The results suggest that the genetic trade-off relationships between traits should be taken into account in mass-rearing programs.

DOI： 10.1007/BF02763462

Scopus

researchmap

CiNii Article

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL SCIENCE LTD  

A gene causing an 8 h variation in the period of circadian rhythm in the adult locomotor activity was found in the melon fly Bactrocera cucurbitae by artificial selection for development time from egg to adult eclosion at 25 +/- 2 degrees C. The periods of free-running rhythm (mean +/- SD) in constant darkness were 22.6 +/- 0.6 and 22.5 +/- 0.4 h, respectively, in two replicate lines selected for short development time, and 30.9 +/- 0.9 and 26.5 +/- 3.6 h, respectively, in two replicate lines selected for long development time. Thus, the development time and the period of circadian clock were correlated. The period locus was autosomal.

DOI： 10.1038/hdy.1997.205

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PLENUM PUBL CORP  

Comparisons of ''time of mating'' (the time copulation begins) between lines selected for short and long developmental periods have been made in the melon fly, Bactrocera cucurbitae. These comparisons showed that longer developmental periods were associated with later initiation of mating. Crosses were also made between selected lines to ascertain the genetic basis of developmental period and time of mating. Comparisons of daily activity rhythms for four types of behavior (locomotion, preening, feeding, and wing vibration) between the selected lines showed the following; (1) locomotion and preening occurred in daytime for the short developmental period lines, versus mainly at night for the long developmental period lines; (2) feeding behavior occurred in daytime for both the short and the long developmental period lines; and (3) wing vibration, a component of courtship behavior of males, occurred at dusk for the short developmental period lines and at night for the long developmental period lines.

DOI： 10.1023/A:1025682618895

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PLENUM PUBL CORP  

Functional morphology of the hind legs as weapons in male contests was analyzed in the leaf-footed plant bog, Leptoglossus australis Fabricius. Measurement of some metrical tratis of the hind femur and tibia indicated that the weapon was the hind femur. Sexual dimorphism in the femoral length and width, and in the number of spines on the lower side of the femur, indicated that these parts play a significant role in male contests. It was also suggested that the length front the base to the widest part of the femur had a functional significance for male-male combat behaviors of L. australis.

DOI： 10.1007/BF02765389

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOL SOC AMER  

To determine the size needed for buffer zones in an eradication program, dispersal ability of male Cylas formicarius (F.) was evaluated by the mark-release-capture method in the central part of Okinawa island, Japan. Approximately 36,700 marked males were released from 2 islets. Forty-five pheromone trap were placed on 6 islets near Okinawa Island and 24 on the eastern seashore of Okinawa Island. Two traps were put at the 2 release points on the last day of the experiment. Of 71 recaptured males, 34 were caught by 3 traps on the Sea Road (a 5-km bank connecting Okinawa island and an islet) located 2 km north-west of a release point. Sixty-two traps did not capture marked males. This result suggests that for C. formicarius eradication projects, a buffer zone with a minimum radius of 2-4 km should surround the area targeted for control.

DOI： 10.1093/ee/26.2.272

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL SCIENCE LTD  

The response to selection on age at reproduction was measured to test for a genetic trade-off between early fecundity and longevity in the melon fly Bactrocera cucurbitae (Coquillett). Three replicate lines were selected for propagation by breeding from young (Y-lines) and old (O-lines) adults, respectively. Selection was continued for 24 and 9 generations for Y- and O-lines, respectively. Females from O-lines lived longer than Y-line females as an indirect response to selection, indicating that longevity is a trait under genetic control. Females from Y-lines had higher fecundity early in the lifespan, a shorter preoviposition period, and a shorter prepeak fecundity period than females from O-lines. However, total fecundity did not differ between lines from the two selection regimes. These results suggest the existence of a genetic trade-off between early fecundity and longevity in the population examined, which may be controlled by pleiotropy. The larval period of the O-lines was longer than that of the Y-lines, whereas there were no significant effects of selection regime on egg hatchability or preadult survival rate. The trade-off relationship between early fecundity and longevity is discussed in relation to mass production of the melon fly for the sterile insect technique programme.

DOI： 10.1038/hdy.1997.11

Web of Science

researchmap

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

Eight life history traits of adults were compared between lines selected for long and short larval and pupal developmental periods in the melon fly, Bactrocera cucurbitae (Diptera: Tephritidae). The traits compared were: (1) preoviposition period (days); (2) female age at peak fecundity (days); (3) number of eggs at peak fecundity; (4) total fecundity; (5) longevity of males; (6) longevity of females; (7) age at first mating and (8) number of lifetime matings. There were no consistent differences among the eight traits between long and short lines, except for the preoviposition period that was measured at generation 5 and 6 for long and short lines, respectively. These results are discussed in relation to quality control using mass-reared melon flies in Okinawa.

DOI： 10.1303/aez.31.335

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOL SOC AMER  

The mating success of mass-reared and individually marked melon flies, Bactrocera cucurbitae (Coquillett), was observed during 7 d under 1 different densities in the laboratory. Frequency distribution of mating success of individual males under the low density was clumpy, but that of males under the high density was random. This difference seemed to result from disturbance among individuals under high density, where males could not make their territories. As mating frequency of females showed random or repulsed distributions in the 2 densities, all females seemed to mate at similar frequencies. Adult size was not related to mating success in either sex under the 2 densities. The characteristics of mating success in mass-reared melon flies for sterile insect techniques were considered to be related to extremely high adult rearing density.

DOI： 10.1093/aesa/89.2.284

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ST LUCIE PRESS  

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN ETHOL SOC  

DOI： 10.1007/BF02350111

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOL SOC AMER  

Two replicate lines of the melon fly Bactrocera cucurbitae, were selected for short or long developmental periods. The lines selected for long developmental periods responded positively to the selection, and selection for short developmental periods sl;owed only a slight response. The responses to selection for long developmental periods were caused mainly by change in the larval period rather than in the pupal period. The comparisons of adult body sizes and survival rate before emergence showed that longer developmental periods were associated with larger adults, but also with lower survival rates during larval and pupal stages. These results are discussed in relation to the sterile insect technique in the melon fly.

DOI： 10.1093/aesa/88.6.848

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENTOMOL SOC AMER  

Dispersal distance of the male sweetpotato weevil, Cylas formicarius elegantulus (Summers), was estimated in the held. Two experiments were conducted. In experiment 1, release and capture were replicated 3 times from September to October in the same locality consisting mainly of sweet potato fields. Approximately 8,000 marked males were released and approximate to 30% of released males were captured by pheromone traps each time. Median dispersal distances per 2 d were 325.7 m in September, 119.8 m in early October, and &lt;50 m in late October. The maximum dispersal distance in September was 500 m, whereas it was 200 m in October. In experiment 2, the dispersal distances were compared in the fields with and without sweet potato plants. The dispersal distance in the held without sweet potato plants was longer than that obtained in the sweet potato cultivated area. The maximum dispersal distance in the fields with sweet potatoes was 500 m, whereas it was 1,000 m in the fields without sweet potatoes.

DOI： 10.1093/ee/24.5.1167

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

File： 1994 Miyatake AEZ.pdf

DOI： 10.1303/aez.29.601

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

File： 1994 Miyatake&Iwahashi BMO.pdf

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

File： 1993 Miyatake AEZ.pdf

DOI： 10.1303/aez.28.577

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN ETHOL SOC  

File： 1993 Miyatake JET.pdf

DOI： 10.1007/BF02350007

Web of Science

researchmap

researchmap

Authorship：Lead author,　Corresponding author  

File： 1993 MANEGEMENT OF INSECT PESTS　NUCLEAR AND RELATED MOLECULAR AND GENETIC TECHNIQUES_ Miyatake 1993.pdf

CiNii Article

researchmap

Language：Japanese   Publisher：The Association for Plant Protection of Kyushu  

File： 1993 KawasakiEtAl1993 Kyushu.pdf

DOI： 10.4241/kyubyochu.39.106

CiNii Article

researchmap

Language：Japanese   Publisher：The Association for Plant Protection of Kyushu  

The characteristics of oviposition punctures caused by sterile females of the melon fly, Bactrocera cucurbitae, and an evaluation of its economic damage were investigated in Okinawa, Japan. It was confirmed in a field-cage experiment that sterile females make oviposition punctures (sterile stings) on cucurbit fruits. The features of sterile stings were different depending on the species of fruits and were classified into five types. The punctures on cucurbit fruits collected in fields were checked and identified as sterile stings or not, using the criterion obtained from the field-cage experiment. The rates of damaged fruits by sterile females were estimated to be lower than 1% in cucumber, sponge gourd and bitter gourd.

DOI： 10.4241/kyubyochu.39.102

CiNii Article

researchmap

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Association for Plant Protection of Kyushu  

The overwintering aggregations of the leaf-footed plant bug, Leptoglossus australis, were observed on Okinawa Island during February through March, 1985. The aggrega-tions were formed on the withered leaves of the host plant, Luffa cylindrica, and the nonhost plants, Capsicum annuum, Lacluca longifolia, Curia papaya, and Rumex japonicus. Aggregated plant bugs gradually dispersed to fresh host plants from early March.

File： 1992 Miyatake Kyushu.pdf

DOI： 10.4241/kyubyochu.38.118

CiNii Article

researchmap

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

File： 1990 MiyatakeEtAl_OKIAGR.pdf

CiNii Article

researchmap

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Oviposition behavior in non-irradiated and irradiated melon fly, Dacus cucurbitae Coquillett, was studiedunder laboratory conditions. A few irradiated female melon flies inserted their ovipositors into slices of host fruits (melon and watermelon) and artificial oviposition devices. The quantity and frequency of ovipositional “acts” for irradiated flies was much lower than that of the non-irradiated ones. “Number” indicates the quantity of females which engaged in oviposition behavior per 1, 000 females per 15 min. “Frequency” indicates the total number of acts in varying behavioral modes per 1, 000 females per 15 min. © 1989, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.

File： 宮竹ほか(1993)応動昆和文.pdf

DOI： 10.1303/jjaez.33.94

Scopus

researchmap

Total pages：217  

ASIN

researchmap

Total pages：192  

ASIN

researchmap

researchmap

Total pages：190  

ASIN

researchmap

researchmap

Total pages：xiii, 327p   Language：Japanese

CiNii Books

researchmap

researchmap

researchmap

researchmap

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：JAPAN SOC APPL ENTOMOL ZOOL  

The cigarette beetle, Lasioderma serricorne (Fabricius), is an important pest insect, that feeds on various dry foods, including wheat, forage crops, snacks, dried noodles, and chili. In this study, we investigated the difference in their attraction to direct and reflected lights in a chamber. Reflected lights are attractive to insects, but direct lights do not attract them, which is a new finding.

DOI： 10.1303/jjaez.2014.133

Web of Science

researchmap

Language：Japanese   Publisher：Pesticide Science Society of Japan  

CiNii Article

CiNii Books

researchmap

Language：Japanese  

J-GLOBAL

researchmap

researchmap

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：京都大学  

CiNii Article

CiNii Books

researchmap

Other Link： http://hdl.handle.net/2433/171131

Language：Japanese  

J-GLOBAL

researchmap

Language：Japanese   Publisher：The Ecological Society of Japan  

CiNii Article

CiNii Books

researchmap

Language：Japanese  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

researchmap

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

DOI： 10.18960/seitai.56.1_10

researchmap

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本生態学会  

DOI： 10.14848/esj.ESJ50.0.251.1

CiNii Article

researchmap

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本植物防疫協会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

Language：Japanese   Publisher：日本応用動物昆虫学会  

CiNii Article

CiNii Books

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap

researchmap