Publisher：Proceedings of the International Congress on Sound and Vibration  

Pest management using insecticides is probably the most conventional option among various control methods; however, the overuse of insecticides often causes the acquisition of resistance, and also often negatively impacts the ecosystem. As an alternative, increasing attention has been paid to other procedures such as the physical management of insect pests. Utilizing substrate-borne vibrations is one of such methods, as this pest management tool has modest ecosystem impacts. This method exploits acoustic communications used by insects for mating and the perception of enemy attacks, provoking behavioral responses in an ingenious manner. We have examined whether substrate-borne vibrations are effective enough to mitigate the damage of tobacco whiteflies, Bemisia tabaci (Hemiptera: Aleyrodidae), which are known as serious agricultural pests. So far, we have attempted field and laboratory experiments to evaluate the effectiveness of vibrations especially for the reproductive behaviors of whiteflies. A substantial reduction in the average density of B. tabaci nymphs and adults was achieved by transmitting vibration stimuli on the plants. We would like to introduce the progress of ongoing project and discuss future perspective for the usage of vibrations in pest management and related subjects.

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Ecology and Evolution  

Global commerce and transportation facilitate the spread of invasive species. The African big-headed ant, Pheidole megacephala (Fabricius), has achieved worldwide distribution through globalization. Since the late 19th century, Taiwan has served as a major seaport because of its strategic location. The population genetic structure of P. megacephala in Taiwan is likely to be shaped by international trade and migration between neighboring islands. In this study, we investigated the population genetics of P. megacephala colonies sampled from four geographical regions in Taiwan and elucidated the population genetic structures of P. megacephala sampled from Taiwan, Okinawa, and Hawaii. We observed a low genetic diversity of P. megacephala across regions in Taiwan. Moreover, we noted low regional genetic differentiation and did not observe isolation by distance, implying that long-distance jump dispersal might have played a crucial role in the spread of P. megacephala. We sequenced the partial cytochrome oxidase I gene and observed three mitochondrial haplotypes (TW1-TW3). TW1 and TW3 most likely originated from populations within the species' known invasive range, suggesting that secondary introduction is the predominant mode of introduction for this invasive ant. TW2 represents a novel haplotype that was previously unreported in other regions. P. megacephala populations from Taiwan, Okinawa, and Hawaii exhibited remarkable genetic similarity, which may reflect their relative geographic proximity and the historical connectedness of the Asia-Pacific region.

DOI： 10.1002/ece3.9660

Web of Science

Scopus

PubMed

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

This paper provides descriptions of two new theridiosomatid species, Theridiosomanigrivirgatum sp. nov. and Sennintanikawai gen. nov., sp. nov. from the Ryukyu Islands, southwest Japan, with photographs and illustrations of both sexes. Sennin gen. nov. is a troglophilic genus composed of two species, S.tanikawai sp. nov. (Iriomote Island, Japan) and S.coddingtoni (Zhu, Zhang & Chen, 2001), comb. nov. (southern China). Zomadibaiyin Miller, Griswold & Yin, 2009, which recently joined the Japanese fauna, was morphologically reexamined based on specimens from the Ryukyus, and taxonomic features of Zoma males were reassessed. A distributional map of theridiosomatid spiders in the Ryukyus is also provided, including T.dissimulatum Suzuki, Serita & Hiramatsu, 2020, and T.alboannulatum Suzuki, Serita & Hiramatsu, 2020 with their habitat types, web morphology, and web-building behavior in detail.

DOI： 10.3897/zookeys.1109.83807

Web of Science

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PubMed

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Language：English   Publisher：Arachnological Society of Japan  

A new pill millipede species, <I>Hyleoglomeris magy</I> sp. nov., is described from Okinawa and adjacent islands, Ryukyu Archipelago, Japan. The new species is mainly characterized by its large body (maximum length: 12.1mm) and general light yellowish-brown coloration marked with pairs of blackish spots. The general appearance of the new species resembles that of <I>Hyleoglomeris hongkhraiensis</I> Golovatch & Panha 2015, but can be distinguished from this species by the number of striae on the thoracic shield (typically 8–10, with 3 or 4 crossing the dorsum, vs 7 or 8 in total with 4 or 5 crossing the dorsum) and the shape of the telopod (femur strongly bulged distally, vs not bulged). An identification key to all five species of <I>Hyleoglomeris</I> known to occur in the Ryukyu Archipelago is also provided.

DOI： 10.2476/asjaa.71.5

Scopus

CiNii Research

Language：Japanese  

Language：Japanese   Publisher：The Society of Instrument and Control Engineers  

Pest Control Using Vibration

DOI： 10.11499/sicejl.61.31

CiNii Books

CiNii Research

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Language：Japanese  

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

DOI： 10.1111/ens.12469

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

Sexual conflict can result in coercive mating. Because males bear low costs of heterospecific mating, coercive males may engage in misdirected mating attempts toward heterospecific females. In contrast, sexual selection through consensual mate choice can cause mate recognition cues among species to diverge, leading to more accurate species recognition. Some species show both coercive mating and mate choice-associated courtship behaviors as male alternative reproductive tactics. We hypothesized that if the selection pressures on each tactic differ, then the accuracy of species recognition would also change depending on the mating tactic adopted. We tested this hypothesis in the guppy (Poecilia reticulata) and mosquitofish (Gambusia affinis) by a series of choice experiments. Poecilia reticulata and G. affinis males both showed imperfect species recognition and directed all components of mating behavior toward heterospecific females. They tended to direct courtship displays more frequently toward conspecific than heterospecific females. With male P. reticulata, however, accurate species recognition disappeared when they attempted coercive copulation: they directed coercions more frequently toward heterospecific females. We also found that heterospecific sexual interaction had little effect on the fecundity of gravid females, which suggests that prepregnancy interactions likely underpin the exclusion of G. affinis by P. reticulata in our region.

DOI： 10.1002/ece3.7267

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

Batesian mimicry is a striking example of Darwinian evolution, in which a mimetic species resembles toxic or unpalatable model species, thereby receiving protection from predators. In some species exhibiting Batesian mimicry, nonmimetic individuals coexist as polymorphism in the same population despite the benefits of mimicry. In a previous study, we proposed that the abundance of mimics is limited by that of the models, leading to polymorphic Batesian mimicry in the swallowtail butterfly, Papilio polytes, on the Ryukyu Islands in Japan. We found that their mimic ratios (MRs), which varied among the Islands, were explained by the model abundance of each habitat, rather than isolation by distance or phylogenetic constraint based on the mitochondrial DNA (mtDNA) analysis. In the present study, this possibility was reexamined based on hundreds of nuclear single nucleotide polymorphisms (SNPs) of 93 P. polytes individuals from five Islands of the Ryukyus. We found that the population genetic and phylogenetic structures of P. polytes largely corresponded to the geographic arrangement of the habitat Islands, and the genetic distances among island populations show significant correlation with the geographic distances, which was not evident by the mtDNA-based analysis. A partial Mantel test controlling for the present SNP-based genetic distances revealed that the MRs of P. polytes were strongly correlated with the model abundance of each island, implying that negative frequency-dependent selection interacting with model species shaped and maintained the mimetic polymorphism. Taken together, our results support the possibility that predation pressure, not isolation by distance or other neutral factors, is a major driving force of evolution of the Batesian mimicry in P. polytes from the Ryukyus.

DOI： 10.1002/ece3.7092

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

Managing pests with insecticides is probably the most conventional available control method. However, insecticide overuse often results in resistance and subsequent pest resurgence, and often adversely affects the ecosystem. The physical management of insect pests by utilizing substrate-borne vibrations, sounds, or both is increasingly attracting attention as an alternative, as it has modest ecosystem impacts. This method exploits vibroacoustic insect communication used for mating and the perception of approaching enemies, provoking behavioral responses in an ingenious manner. We aimed to examine whether substrate-borne vibrations effectively drive away tobacco whiteflies [Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae)], which are serious agricultural pests. To do so, B. tabaci individuals were artificially introduced into greenhouses where tomato (Solanum lycopersicum L.) plants were reared. A substantial reduction in the average density of B. tabaci nymphs and adults was achieved by transmitting vibrational stimuli to the plants. At the same time, no obvious reduction was found in the number of tomato plant flowers. Although the performance of the vibrational device and transmission procedures requires further improvement, the present results shed light on the potential of substrate-borne vibrations as a promising alternative for pest management.

DOI： 10.1007/s13355-020-00711-9

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

Batesian mimicry, in which harmless organisms resemble unpalatable or harmful species, is a well-studied adaptation for predation avoidance. The females of some Batesian mimic species comprise mimetic and nonmimetic individuals. Mimetic females of such polymorphic species clearly have a selective advantage due to decreased predation pressure, but the selective forces that maintain nonmimetic females in a population remain unclear. In the swallowtail butterfly, Papilio polytes, female polymorphism is controlled by the H (mimetic) and h (nonmimetic) alleles at a single autosomal locus. Here, we examined whether the dominant H allele has a deleterious effect on the pre-adult survival rate (egg-to-adult emergence rate). We repeated an assortative mating-like treatment-that is breeding of males and females whose mothers had the same phenotype (mimetic or nonmimetic)-for three consecutive generations, while avoiding inbreeding. Results showed that pre-adult survival rate decreased over generations only in lines derived from mothers with the mimetic phenotype (hereafter, mimetic-assorted lines). This lowered survival was due to an increased mortality at the final instar larval stage and the pupal stages. Interestingly, the pre-adult mortality in the mimetic-assorted lines seemed to be associated with a male-biased sex ratio at adult emergence. These results suggest that the dominant H allele displays a mildly deleterious effect that is expressed more strongly in females and homozygous individuals than in heterozygous individuals. We propose that this cost of mimicry in larval and pupal stages contributes to the maintenance of female-limited polymorphism in P. polytes.

DOI： 10.1111/jeb.13686

Language：Japanese  

DOI： 10.11257/jjeez.30.151

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

Temperature-dependent toxicity of acetaminophen in Japanese medaka larvae

DOI： 10.1016/j.envpol.2019.113092

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

The cytogenetic characteristics of the grasshopper Podisma sapporensis (two races 2n = 23♂ X0/XX and 2n = 22♂ neo-XY/neo-XX) were analysed through fluorescence in situ hybridization with rDNA and telomeric DNA probes, C-banding, fluorochrome and silver staining. For the first time, samples from the neighbourhood of a hybrid population (i.e., Mikuni Pass population) were studied. Our results indicated a significant degree of chromosomal differentiation between P. sapporensis races when comparing the number and position of the rDNA sites, as well as the heterochromatin composition and distribution obtained by C-banding and DAPI/CMA3 staining. Telomeric signals were usually detected at the distal and/or subdistal position of the autosomes; however, some chromosome ends lacked signals, probably due to a low number of telomeric repeats. On the other hand, telomeric DNA sequences were found as interstitial telomeric repeats in some autosomes, which can trigger a variety of genome instability. B chromosomes were found in specimens belonging to both main races from nine out of 22 localities. Four types of X chromosomes in the X0/XX race were identified. It was concluded that the physical mapping of rDNA sequences and heterochromatin are useful as additional markers for understanding the phylogeographic patterns of cytogenetic differentiation in P. sapporensis populations.

DOI： 10.1038/s41598-019-53416-7

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

Batesian mimicry is a well-studied adaptation for predation avoidance, in which a mimetic species resembles an unpalatable model species. Batesian mimicry can be under positive selection because of the protection gained against predators, due to resemblance to unpalatable model species. However, in some mimetic species, nonmimetic individuals are present in populations, despite the benefits of mimicry. The mechanism for evolution of such mimetic polymorphism remains an open question. Here, we address the hypothesis that the abundance of mimics is limited by that of the models, leading to mimetic polymorphism. In addition, other forces such as the effects of common ancestry and/or isolation by distance may explain this phenomenon. To investigate this question, we focused on the butterfly, Papilio polytes, that exhibits mimetic polymorphism on multiple islands of the Ryukyus, Japan, and performed field surveys and genetic analysis. We found that the mimic ratio of P. polytes was strongly correlated with the model abundance observed on each of the five islands, suggesting negative frequency-dependent selection is driving the evolution of polymorphism in P. polytes populations. Molecular phylogenetic analysis indicated that the southern island populations are the major source of genetic diversity, and the middle and northern island populations arose by relatively recent migration. This view was also supported by mismatch distribution and Tajima's D analyses, suggesting a recent population expansion on the middle and northern islands, and stable population persistence on the southern islands. The frequency of the mimetic forms within P. polytes populations is thus explained by variations in the model abundance rather than by population structure. Thus, we propose that predation pressure, rather than neutral forces, have shaped the Batesian mimicry polymorphism in P. polytes observed in the Ryukyus.

DOI： 10.1002/ece3.5182

Language：Others  

Reproductive interference in live-bearing fish: the male guppy is a potential biological agent for eradicating invasive mosquitofish

DOI： 10.1038/s41598-019-41858-y

Language：Others  

Latitudinal variation and coevolutionary diversification of sexually dimorphic traits in the false blister beetle Oedemera sexualis

DOI： 10.1002/ece3.5101

Language：Others  

When a male perceives a female: the effect of waxy components on the body surface on decision-making in the invasive pest weevil

DOI： 10.1098/rsos.181542

Language：Others  

Interspecific variation in life history traits of Elasmostethus (Hemiptera: Acanthosomatidae)

DOI： 10.4039/tce.2018.56

Language：Others  

Interspecific variation in life history traits of Elasmostethus (Hemiptera: Acanthosomatidae) (vol 151, 2018)

DOI： 10.4039/tce.2018.65

Language：English  

Many groups of insects utilize substrate-borne vibrations for communication. They display various behaviors in response to vibrations in sexual and social communication and in predator-prey interactions. Although the number of reports on communication and behaviors using vibrations has continued to increase across various insect orders, there are several studies of the exploitation of vibrations for pest management in Hemiptera and Coleoptera. Here, we review the studies of behaviors and communication using vibrations in hemipteran and coleopteran insects. For instance, pentatomid bugs display species- and sex-specific vibrational signals during courtship, whereas cerambycid beetles show startle responses to vibrations in the context of predator-prey interactions. Concepts and case studies in pest management using vibrationsespecially regarding the disruption of communication and behaviorare also presented.

DOI： 10.1007/s13355-018-00603-z

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

Wing polymorphism of butterflies provides a good system in which to study adaptation. The Asian Batesian mimic butterfly Papilio polytes has unmelanized, putative mimetic red spots on its black hind wings. The size of those red spots is non-heritable but it is highly polymorphic, the adaptive significance of which is unknown. We hypothesized that under strong ultraviolet (UV) irradiation, butterflies develop a wider melanized black area to protect the wings from UV damage, and as a result express smaller mimetic red spots. Our field survey on Okinawa Island revealed a negative relationship between the sizes of the red spot and the black area in the wings. The size varied seasonally and was negatively correlated with the intensity of solar UV radiation at the time of capture. Laboratory experiments revealed that the size was reduced by strong UV irradiation not only of the eggs and larvae, but also of their mothers through a putative epigenetic mechanism. The flexible phenotypic expression of the red spots in P. polytes suggests a trade-off between protection against UV damage and predation avoidance, and provides a new insight into the evolution of Batesian mimicry.

DOI： 10.1038/s41598-018-31732-8

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

Sandy beach ecosystems are decreasing worldwide and organisms living there are becoming threatened. The burrowing wolf spider Lycosa ishikariana is one such example. To establish effective conservation strategies under habitat fragmentation, we examined population genetic structure of L. ishikariana from mitochondrial cytochrome oxidase I gene and 6 microsatellite loci. Mitochondrial sequence data revealed 6 population subgroups with very high fixation indices, indicating that L. ishikariana has a clear phylogeographic structure and that the level of differentiation among regions is considerable. In particular, one subgroup in the western Honshu mainland (clade G) has a highly distinct genetic structure, despite having no clear geographic barriers from its parapatric population. Moreover, the distribution ranges of the other two subgroups (clades D and E) were highly restricted, suggesting their vulnerability to local human impacts and highlighting their high conservation priorities. Microsatellite data revealed 10 subgroups that were compatible with the clades identified from the mitochondrial data. Fixation indices among these groups were very high, indicating a limited gene flow induced by male spiders. Based on these results, we proposed six conservation units of L. ishikariana and effective conservation/restoration strategies in the face of ongoing coastal armoring.

DOI： 10.1007/s10592-017-0996-9

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

In the present paper, karyotypes of 7 Japanese Podismini species, Anapodisma beybienkoi, Fruhstorferiola okinawaensis, Parapodisma caelestis, P. mikado, P. setouchiensis, P. tenryuensis, and Sinopodisma punctata (2n♂ = 21, all acrocentric), are described and compared on the basis of conventional (C-banding, DAPI/CMA3-staining, Ag-NOR) and molecular (FISH with 18S rDNA and telomeric probes) cytogenetic staining methods. This is the first study to report karyotypes of A. beybienkoi and P. caelestis. Differential staining techniques showed karyotypic diversity in these species. The number of 18S rDNA signals ranged from 2 to 6, and the signals were located on the autosomes or sex chromosomes. In all species, clusters of rDNA coincided with Ag-NORs. Telomeric signals occurred at the chromosome ends at the pachytene stage and seldom at other stages of meiosis. Paracentromeric and some distal and interstitial blocks of constitutive heterochromatin were detected in the chromosomes of Anapodisma, Fruhstorferiola, and Parapodisma species. Staining with DAPI and CMA3 revealed 2 groups of heterochromatin composition. In addition, intraspecific differences in the number of rDNA clusters and C-bands were observed within Parapodisma species. Based on the evidence of cytogenetic characteristics, the monophyly of Tonkinacridina cannot be supported.

DOI： 10.1159/000487063

Language：Japanese  

Language：Japanese  

Language：English  

The recent expansion of a variety of morphometric tools has brought about a revolution in the comparison of morphology in the context of the size and shape in various fields including entomology. First, an overview of the theoretical issues of geometric morphometrics is presented with a caution about the usage of traditional morphometric measurements. Second, focus is then placed on two broad approaches as tools for geometric morphometrics
that is, the landmark-based and the outline-based approaches. A brief outline of the two methodologies is provided with some important cautions. The increasing trend of entomological studies in using the procedures of geometric morphometrics is then summarized. Finally, information is provided on useful toolkits such as computer software as well as codes and packages of the R statistical software that could be used in geometric morphometrics.

DOI： 10.1111/ens.12293

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

Euscepes postfasciatus (Fairmaire) is an invasive pest of the sweet potato (Ipomoea batatas) and is also parasitic to other wild host plants of the Ipomoea genus. The population density of E. postfasciatus is sometimes greater in Ipomoea pes-caprae L. than in Ipomoea indica (Burm. f.). We investigated the desirability of I. pes-caprae as a host plant for E. postfasciatus in terms of reproductive and developmental potential. Females laid fewer eggs on I. pes-caprae, and the eclosion of their larvae was delayed compared with on I. indica. Furthermore, the larval growth rate was slower on I. pes-caprae than on I. indica. These results suggest that I. pes-caprae is not always the preferred host for egg laying and growth rate in the early developmental stages. However, the larval survival rate after the initial period of development was markedly better on I. pes-caprae than on I. indica. The present simulation study demonstrated that the population density of E. postfasciatus on I. pes-caprae overwhelmed that on I. indica over generations. Comparing the two wild host plant species, I. pes-caprae outweighs I. indica with respect to total population growth, but reproduction on I. indica may be advantageous for the colonization of the new habitat.

DOI： 10.1007/s13355-017-0535-7

Language：English  

Fish embryo toxicology is important because embryos are more susceptible than adults to toxicants. In addition, the aquatic toxicity of chemicals depends on water quality. We examined the toxicities to medaka embryos of three types of silver-AgNO3, silver nanocolloids (SNCs), and silver ions from silver nanoparticle plates (SNPPs)-under three pH conditions (4.0, 7.0, and 9.0) in embryo-rearing medium (ERM) or ultrapure water. Furthermore, we tested the later-life-stage effects of SNCs on medaka and their population growth. "Later-life-stage effects" were defined here as delayed toxic effects that occurred during the adult stage of organisms that had been exposed to toxicant during their early life stage only. AgNO3, SNCs, and silver ions were less toxic in ERM than in ultrapure water. Release of silver ions from the SNPPs was pH dependent: in ERM, silver toxicity was decreased owing to the formation of silver chloro-complexes. SNC toxicity was higher at pH 4.0 than at 7.0 or 9.0. AgNO3 was more toxic than SNCs. To observe later-life effects of SNCs, larvae hatched from embryos exposed to 0.01 mg/L SNCs in ultrapure water were incubated to maturity under clean conditions. The mature medaka were then allowed to reproduce for 21 days. Calculations using survival ratios and reproduction data indicated that the intrinsic population growth rate decreased after exposure of embryos to SNC. SNC exposure reduced the extinction time as a function of the medaka population-carrying capacity.

DOI： 10.1016/j.envpol.2017.10.028

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

Batesian mimicry, a phenomenon in which harmless organisms resemble harmful or unpalatable species, has been extensively studied in evolutionary biology. Model species may differ from population to population of a single mimetic species, so different predation pressures might have driven microevolution towards better mimicry among regions. However, there is scant direct evidence of microevolutionary change over time in mimicry traits. Papilio polytes shows female-limited Batesian mimicry. On Okinawa, one mimicry model is Pachliopta aristolochiae, which was not present on the island until 1993. In P. polytes, the size of the hind-wing white spot, a mimetic trait, is maternally heritable. Among specimens collected between 1961 and 2016, the average white spot size was unchanged before the model's arrival but has rapidly increased since then. However, white spot size showed greater variance after the model's establishment than before. This suggests that before 1993, white spot size in this population was not selectively neutral but was an adaptive trait for mimicking an unpalatable native, Byasa alcinous, which looks like P. aristolochiae apart from the latter's hind-wing white spot. Thus, some females switched their model to the new one after its arrival.

DOI： 10.1038/s41598-017-06376-9

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

Members of the tribe Podismini (Orthoptera: Acrididae: Melanoplinae) are distributed mainly in Eurasia and the western and eastern regions of North America. The primary aim of this study is to explore the phylogenetic relationship of Japanese Podismini grasshoppers by comparing partial sequences of cytochrome c oxidase subunit I (COI) mitochondrial gene. Forty podismine species (including nineteen Japanese species) and thirty-seven species from other tribes of the Melanoplinae (Dactylotini, Dichroplini, Melanoplini, and Jivarini) were used in the analyses. All the Japanese Podismini, except Anapodisma, were placed in a well-supported subclade. However, our results did not correspond with the classification on the basis of morphological similarity for the status of Tonkinacridina. This group of Japanese species constituted a single clade with other species of Miramellina and Podismina, while Eurasian continental species of Tonkinacridina were placed in other separate clades. This incongruence might have resulted from historical migratory events between continent and ancient islands and subsequent convergent/parallel evolution in morphology. Some remarks on phylogenetic positions in Podismini and other tribes were also made in terms of reconstructed phylogeny.

DOI： 10.3897/jor.26.14547

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

The brachypterous grasshopper Podisma sapporensis (Orthoptera: Acrididae) is distributed throughout the Sakhalin, Kunashir and Hokkaido Islands. Karyotypes of this species consist of two major chromosomal races with different sex chromosome systems, XO/XX and XY/XX. Molecular phylogeographic analysis of the chromosome races and subraces confirms the genetic divergence of the races and subraces in P.sapporensis. Here we first report that P.sapporensis is infected with Wolbachia consisting of three variants on wsp locus, while gatB locus was monomorphic. Furthermore, observation of cell tissue of P.sapporensis using electron microscopy confirmed the infection of Wolbachia that was inferred from polymerase chain reaction and revealed the distribution of the bacteria in the head, thorax and abdomen of P.sapporensis embryos. Our finding may shed new light on Wolbachia as a possible agent causing hybrid dysfunction resulting from experimental crosses between chromosome races or subraces of P.sapporensis.

DOI： 10.1111/ens.12187

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

Raptorial characteristics may evolve in predators because of their importance in obtaining food. The giant water bug, Kirkaldyia deyrolli, possesses a claw on the terminal segment of the raptorial foreleg that is crucial for capturing prey. Claw curvature has been previously shown to change during growth in this species, but the adaptive significance of this change has not yet been explored. Predation experiments have demonstrated that young nymphs with highly curved claws caught proportionally larger prey than older nymphs with less-curved claws. Catching behaviours for a certain prey size differed significantly between young and older nymphs. The observation that nymphal growth affects prey-catching behaviour in the giant water bug supports the hypothesis that predators can change catching behaviours based on changes in raptorial characteristics in order to maximize prey resources acquired at each developmental stage.

DOI： 10.1111/bij.12693

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

The sex pheromone of Herpetogramma submarginale (Swinhoe) was studied by gas chromatography (GC) with electroantennographic detection and GC coupled with mass spectrometry. Two pheromone candidates detected in the gland extracts of females were identified as (Z)-13-hexadecenyl acetate (Z13-16:OAc) and (E)-13-hexadecenyl acetate (E13-16:OAc) in a ratio of 87:13 by mass spectral analysis of the natural pheromone components and their dimethyldisulfide adducts. In field tests, Z13-16:OAc alone attracted H. submarginale males and caught significantly more males than live virgin females. Addition of E13-16:OAc did not enhance the attractiveness of Z13-16:OAc. Derivatives of Z13-16:OAc also were tested as potential pheromone components. Addition of (Z)-13-hexadecen-1-ol significantly reduced the number of males captured, and (Z)-13-hexadecenal had no effect on the attractiveness of the lure. These results suggest that the female-produced sex pheromone of H. submarginale is Z13-16:OAc. This hexadecenyl acetate is a novel moth sex pheromone component.

DOI： 10.1007/s10886-015-0576-8

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

We investigated the interspecific variation of silver nanoparticle (SNP) sensitivity in common cladocerans (Daphnia magna, D. galeata, and Bosmina longirostris) and the exact cause of both acute and chronic toxicity focusing on the form of silver (NPs and ions). Materials tested were non-surface-coated silver nanocolloids (SNCs) and AgNO3. The results of the acute toxicity tests support the theory that the effects of SNPs on aquatic organisms is mainly due to Ag+ released from SNPs. Among the three cladocerans, D. galeata was more sensitive to silver (as Ag+) than both D. magna and B. longirostris. Moreover, the chronic toxicity of SNCs was also derived from dissolved silver (especially Ag+). SNCs (as total silver concentration) showed far lower chronic compared with acute toxicity to daphnids because the amount of dissolved silver decreased in the presence of prey algae. The chronic end-point values (EC10 values for net reproductive rate and the probability of survival to maturation) did not differ largely from acute ones (48-h EC50 obtained from acute toxicity tests and 48-h LC50 estimated by the biotic ligand model) when the values were calculated based on Ag+ concentration. The alpha value (concentration at which intrinsic population growth rate is decreased to zero) estimated by a power function model was a reliable parameter for assessing the chronic toxicity of silver.

DOI： 10.1007/s00244-014-0091-x

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

While 11 species in the family Saturniidae are found in Japan, no sex pheromones of the native species had been investigated previously. We collected larvae of Rhodinia fugax in Nagano and Tottori Prefecture, and of Loepa sakaei in Okinawa Prefecture, and extracted sex pheromones of these two species from virgin female moths. In gas chromatography-electroantennogram detection (GC-EAD) analyses, male antennae of each species responded to one component in the respective pheromone extracts of conspecific females. Chemical analyses of the extracts by GC/mass spectrometry revealed that the EAD-active compounds of R. fugax and L. sakaei were a hexadecadienal and a tetradecadienyl acetate, respectively. The two species belong to the subfamily Saturniinae, and the mass spectra of both were similar to that of the 6,11-hexadecadienyl acetate identified from Antheraea polyphemus, classified in the same subfamily, suggesting the same 6,11-dienyl structure for the C-16 aldehyde and a 4,9-dienyl structure for the C-14 acetate. Based on this assumption, four geometrical isomers of each dienyl compound were stereoselectively synthesized via acetylene intermediates, compared to the natural products, and tested in the field. Male catches confirmed the pheromone structures of the two Japanese saturniid species as (6E,11Z)-6,11-hexadecadienal for R. fugax and (4E,9Z)-4,9-tetradecadienyl acetate for L. sakaei. The compounds have a characteristic 1,6-dienyl motif common to the pheromones of Saturniinae species.

DOI： 10.1007/s10886-014-0538-6

Language：Japanese  

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

We present a novel framework for estimating site-specific effects of pollutants on natural populations. Our method is based on fitness optimization and uses observed differences in tolerance (sensitivity) to a particular pollutant between populations at contaminated and uncontaminated sites (i.e., target and reference populations). In addition, the method uses laboratory estimates of the fitness cost of tolerance, that is, the reduction of population growth rate (fitness) of a target population compared to that of a reference population when both are maintained in uncontaminated conditions. As a case study, we applied this framework to analyze observed genetic differentiation in tolerance to the pyrethroid insecticide fenvalerate between Daphnia galeata populations in Lake Kasumigaura and an adjacent agricultural pond. The estimated exposure level at the contaminated site was about 0.015 mu g/L, and the population-level risk corresponded to about a 24 &#37; reduction of the intrinsic rate of natural increase.

DOI： 10.1007/s10646-013-1081-x

Language：Japanese  

Evaluation of the effect of genetic divergence on variability in susceptibility to a chemical toxicant in zooplankton populations
Although many ecological risk assessments of hazardous chemicals have beenconducted with test organisms, such procedures may be insufficient for establishingreliable hazard assessments in wild organisms. The genetic variation within a species israrely considered in such assessments. Here, the relationship between variability insusceptibility to fenvalerate, an agrochemical toxicant, and the degree of divergence inallele frequencies at six microsatellite loci were assessed in Daphnia galeatapopulations in Lake Kasumigaura and an adjacent local pond. The acute EC50, basedon changes in neonate immobility, in isofemale lines from three populations in LakeKasumigaura was 5–10 times that observed in lines from the local pond population;however, the degree of divergence in allele frequencies was much larger among the LakeKasumigaura populations than between the lake and local pond populations. Theseresults suggest that the level of resistance to the toxicant was determined primarily bythe gradient of pollutants resulting from water flow and did not reflect the geneticdivergence of local populations. I also discuss a possible causal link betweensusceptibility against toxicant and genetic variation for future perspectives of ecologicalrisk assessments.

DOI： 10.11403/jset.16.29

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

Cyclosa spiders attach prey carcasses as decorations to their webs, but the functions of the carcasses are unclear and controversial. We investigated distinctive features of these webs in the field and conducted prey-capture experiments in the lab using the orb-web spider Cyclosa mulmeinensis. Webs with attached decoration had a significantly narrower mesh width than those without decoration and a higher degree of vertical asymmetry in the web's shape. In the laboratory, webs without decorations trapped significantly more prey, even though other features of the webs were nearly identical. These results suggest that web decorations do not attract prey in this species, but might play other roles such as blinding predators to the spider's presence.

DOI： 10.1007/s10905-012-9319-7

Language：Japanese  

Variation in Disturbance Songs in the West Indian Sweet Potato Weevil Euscepes postfasciatus and a Future Perspective of its Control

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

Understanding why some hybrid zones are bimodal and others unimodal can aid in identifying barriers to gene exchange following secondary contact. The hybrid zone between the grasshoppers Chorthippus brunneus and C. jacobsi contains a mix of allopatric parental populations and inter-mingled bimodal and unimodal sympatric populations, and provides an ideal system to examine the roles of local selection and gene flow between populations in maintaining bimodality. However, it is first necessary to confirm, over a larger spatial scale, previously identified associations between population composition and season and habitat. Here we use cline-fitting of one morphological and one song trait along two valley transects, and intervening mountains, to confirm previously identified habitat associations (mountain versus valley) and seasonal changes in population composition. As expected from previous findings of studies on a smaller spatial scale, C. jacobsi dominated mountain habitats and mixed populations dominated valleys, and C. brunneus became more prevalent in August. Controlling for habitat and incorporating into the analysis seasonal changes in cline parameters and the standard errors of parental trait values revealed wider clines than previous studies (best estimates of 6.4 to 24.5 km in our study versus 2.8 to 4.7 km in previous studies) and increased percentage of trait variance explained (52.7&#37; and 61.5&#37; for transects 1 and 2 respectively, versus 17.6&#37;). Revealing such strong and consistent patterns within a complex hybrid zone will allow more focused examination of the causes of variation in bimodality in mixed populations, in particular the roles of local selection versus habitat heterogeneity and gene flow between differentiated populations.

DOI： 10.1371/journal.pone.0037684

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

A statistical genetics method is presented for estimating the genetic variance (heritability) of tolerance to pollutants on the basis of a standard acute toxicity test conducted on several isofemale lines of cladoceran species. To analyze the genetic variance of tolerance in the case when the response is measured as a few discrete states (quantal endpoints), the authors attempted to apply the threshold character model in quantitative genetics to the threshold model separately developed in ecotoxicology. The integrated threshold model (toxicant threshold model) assumes that the response of a particular individual occurs at a threshold toxicant concentration and that the individual tolerance characterized by the individual's threshold value is determined by genetic and environmental factors. As a case study, the heritability of tolerance to p-nonylphenol in the cladoceran species Daphnia galeata was estimated by using the maximum likelihood method and nested analysis of variance (ANOVA). Broad-sense heritability was estimated to be 0.199?+/-?0.112 by the maximum likelihood method and 0.184?+/-?0.089 by ANOVA; both results implied that the species examined had the potential to acquire tolerance to this substance by evolutionary change. Environ. Toxicol. Chem. 2012;31:813818. (c) 2012 SETAC

DOI： 10.1002/etc.1753

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

Invasive exotic ants often have a mutualistic relationship with other insects excreting honeydew, and this is considered to play a key role in their invasion success. We investigated the multispecies association patterns between ants and hemipteran insects in the Yanbaru forests, Okinawa, Japan, an Asian biodiversity hotspot. We especially focused on roadside environments, which are the frontlines of invasion for exotic ants. We found that only a small number of herbaceous and pioneer plants were predominant on the roadsides. Four honeydew producers, Melanaphis formosana, Dysmicoccus sp. A, Heteropsylla cubana, and Sogata hakonensis, living on these roadside plants accounted for 94.9&#37; of the total honeydew-producer aggregations observed. Only a few exotic ants, such as Technomyrmex brunneus and Anoplolepis gracilipes, were observed with these honeydew-producer aggregations, and densities of these ants and honeydew producers were often positively correlated. An ant exclusion experiment showed that exotic ant occurrence improved the survival of some of the hemipteran colonies. Interestingly, the abundance of native ants was not correlated with the abundance of honeydew producers, and the local density of Pheidole noda was negatively correlated with that of M. formosana. These findings, i.e., only a few ants, all exotic, tended to hemipteran honeydew producers despite the existence of many native ants, and the abundances of those exotic ants and those hemipteran insects had positive correlations, provide some insights into the mechanism of biological invasion and provide information for the management of exotic ants.

DOI： 10.1007/s11284-011-0851-2

Language：Japanese  

What can biological morphometrics be used for? : Empirical examples in entomology
Recent developments in geometric morphometrics enable us to precisely examine morphological variations in the shape and size of organisms, including insect species. We review modern well-established morphometric approaches frequently used in entomology. Three non-mutually exclusive technical morphometrics methods are briefly explained: 1) multivariate morphometrics, 2) superimposition and thin-plate spline analysis, and 3) outline analysis. The latter two approaches are generally referred to as geometric morphometrics. We then review recent literature relevant to geometric morphometrics and consider the application of these approaches in the context of systematic and evolutionary studies of insects.

DOI： 10.20848/kontyu.14.3_194

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

Moths use ultrasounds as well as pheromones for sexual communication. In closely related moth species, variations in ultrasounds and pheromones are likely to profoundly affect mate recognition, reproductive isolation, and speciation. The European corn borer, Ostrinia nubilalis, and its Asian congeners, Ostrinia furnacalis and Ostrinia scapulalis, exhibit within-species and between-species variation in their pheromone communication. Recently, we reported ultrasound communication in O. furnacalis; however, variations in ultrasounds in the three congeners have not been addressed to date. Here we investigated features of ultrasound production and hearing in O. nubilalis and O. scapulalis, and compared them with those of O. furnacalis. As in O. furnacalis, males of O. nubilalis and O. scapulalis produced ultrasounds during courtship by rubbing specialized scales on the wings against scales on the thorax. The covering of these scales with nail polish muffled the sounds and significantly reduced mating success in O. nubilalis, showing the importance of ultrasound signaling in mating. The ultrasounds produced by O. nubilalis and O. scapulalis were similar, consisting of long trains of pairs of pulses with a main energy at 40 kHz, but distinctly different from the ultrasound produced by O. furnacalis, consisting of groups of pulses peaking at 50 kHz and with substantially more energy up to 80 kHz. Despite overall similarities, temporal features and patterns of amplitude modulation differed significantly among the geographic populations of O. nubilalis and O. scapulalis, which differed in pheromone type. In contrast, no significant difference in hearing was found among the three species with regard to the most sensitive frequencies and hearing threshold levels. The patterns of variations in the songs and pheromones well reflected those of the phylogenetic relationships, implying that ultrasound and pheromone communications have diverged concordantly. Our results suggest that concordant evolution in sexual signals such as courtship ultrasounds and sex pheromones occurs in moths.

DOI： 10.1371/journal.pone.0013144

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

Divergence in genital traits between closely related species is occasionally greater in sympatry than in allopatry, possibly because directional selection facilitates differentiation so as to prevent unfit hybridization. Here, we report for the first time that the shape of a functional genital structure, cercus, differs markedly between sympatrically and allopatrically occurring individuals in two brachypterous grasshopper species, Parapodisma setouchiensis Inoue 1979 and Parapodisma subastris Huang 1983 (Orthoptera: Podisminae). Although in areas of allopatry the cerci were straight in both species, in areas of sympatry the cerci of P. setouchiensis had an almost orthogonal bend. Furthermore, the angles of curvature of the cerci of P. setouchiensis varied continuously along a transect through sympatric and allopatric areas. We also observed copulation behavior in pairs and found that the apical part of the cerci was inserted into the space between the posterior edges of the seventh abdominal sternite and the seventh abdominal tergite of the female. We suggest that the orthogonally bent cerci allows the male to obtain a firm grip on the female's abdomen and propose that the conspicuous variation in the cerci of P. setouchiensis contributes to the strength of reinforcement of a premating isolation system.

DOI： 10.1603/AN09074

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

Drosophila simulans strains originating from Madagascar and nearby islands in the Indian Ocean often differ from those elsewhere in the number of sex comb teeth and the degree of morphological anomaly in hybrids with D. melanogaster. Here, we report a strong segregation distortion in the F1 intercross between two D. simulans strains originating from Madagascar and the US, possibly at both the gametic and zygotic levels. Strong bias against alleles of the Madagascar strain was observed for all ten marker loci distributed over the entire second chromosome in the F1 intercross, but only a few showed a weak distortion in the isogenic backgrounds of either strains. Significant deviations of genotype frequencies from Hardy-Weinberg proportions were consistently observed for the second chromosome. By contrast, the X and third chromosomes did not show any strong segregation distortion. Crossover frequency on the second chromosome was uniformly reduced in isogenic backgrounds whereas the map lengths in the F1 intercross were comparable to or larger than that of the standard D. melanogaster map. We discuss these findings in relation to previous studies on other traits and interspecific differences between D. mauritiana, which is endemic to Mauritius Island, and D. simulans.

DOI： 10.1007/s10709-009-9381-z

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

We isolated eight polymorphic microsatellite loci from the zooplankton Moina macrocopa (Straus), which is sensitive to pollutants such as insecticides and heavy metals. The isolated loci were polymorphic, with three to seven alleles among 23 individuals. Expected heterozygosities ranged from 0.167 to 0.787. These loci can be used to examine cryptic genetic structure and to infer the connectivity among metapopulations.

DOI： 10.1111/j.1755-0998.2008.02410.x

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

The genetic structure of populations is not necessarily reflected in the geographical proximity of individuals, because environmental gradients such as those of vegetation or climate can function as cryptic barriers to gene flow. We examined polymorphisms at nine microsatellite loci to determine and discuss whether a distinctive genetic structure was detectable in a spatially continuous population of the sika deer (Cervus nippon) on the Boso Peninsula of central Japan. Spatially explicit Bayesian analysis revealed that two genetically distinctive clusters exist in the Boso population. The spatial boundary of the two clusters approximately conformed to the border defined previously from a mitochondrial DNA dataset. By combining information on the geomorphic features surrounding the boundary and that on the lineage of 1970s population, we propose a schematic scenario for characterizing the population genetic structure to the present. The current population consists of genetically different lineages, and spatially discontinuous clusters have come into contact in the vicinity of a local road running along a steep-walled ravine that could act as principal barrier to gene flow. Biological factors such as distribution of vegetation and philopatric behavior might also have helped strengthen the cryptic genetic structure of the Boso population.

DOI： 10.2108/zsj.26.48

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

Fish embryo toxicology is important because embryos are considered more susceptible than adult fish to the effects of toxic chemicals. Recently, fish embryo bioassay was proposed to replace the conventional fish acute toxicity chemical test of the Organization for Economic Cooperation and Development guidelines because it offers the advantages of fewer reagents, easy handling, and efficient data production. To accelerate the establishment of a chemical toxicity database for the protection of environmental and human health, we need to determine whether the conventional toxicity test can safely be replaced by such fish embryo toxicity tests. For instance, it is unclear how the presence of the chorion moderates the toxic effects of some chemicals. If such chemical toxicities do differ between embryos and, for example, the larval stage, then different toxic effects should appear in later life. We tested the later-life effects of the neurotoxic insecticide carbaryl at sublethal concentrations (0 [ control] and 5 and 10 mg/L) in embryos and posthatch larvae of the freshwater fish medaka, Oryzias latipes. Although embryos exposed until hatching showed multiple developmental malformations and reductions in subsequent survival rates over three months, no significant reduction was observed in tolerance to starvation for 7 d and in intrinsic population growth rate (r). Exposure of larvae for 96 h resulted in dose-responsive vertebral fracture, significant reduction in tolerance to starvation for 7 d, and reduced three-month survival rate; r was reduced significantly and consistently. These results suggested that posthatch larvae were more susceptible than embryos to carbaryl exposure and that the toxic cascades may differ between larvae and embryos. The influences of carbaryl exposure on population growth rate differed significantly with developmental stage.

DOI： 10.1897/08-073.1

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

When giant water bugs (Heteroptera: Belostomatidae) encounter prey animals that are larger than they are themselves, they first hook the claw of their raptorial legs onto the animal, and then use all their legs to pin it. The claws of the raptorial legs in giant water bugs play an important role in catching larger prey, but the relationship between the claws, body lengths of predators, and prey size has not been fully investigated. To elucidate the functioning of claws in catching prey, we investigated prey body size relative to predator size in nymphs of two sympatric belostomatid giant water bug species, the vertebrate eater Kirkaldyia (=Lethocerus) deyrolli Vuillefroy and the invertebrate eater Appasus japonicus Vuillefroy, captured in rice fields. The younger nymphs of K. deyrolli caught preys that were larger than themselves, whereas those of A. japonicus caught preys that were smaller. Younger nymphs of K. deyrolli had claws that were curved more sharply than those of A. japonicus. The more curved claws of younger nymphs of K. deyrolli probably hook more easily onto larger vertebrates and thus this shape represents an adaptation for acquiring such prey.

DOI： 10.1111/j.1570-7458.2008.00772.x

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

Podisma sapporensis Shiraki, 1910 (Orthoptera: Acrididae) is distributed on the islands of northern Japan and Far East Russia (Hokkaido, Sakhalin,and Kunashiri), and it exhibits a unique diversity of chromosomal races (X0 and neo-XY) oil the island of Hokkaido. To infer the history of geographical isolation and chromosome rearrangements (main races and subraces), we Used mitochondrial DNA (mtDNA) sequence variation in two regions, NADH dehydrogenase subunit 2 (ND2) and cytochrome oxidase subunit II (COII), among 55 individuals representing eight X0/XX and three neo-XY/XX populations. The molecular phylogenetic tree revealed a high level of overall mitochondrial diversity,, hot the clustering of the examined population is ill most cases closely related to their geographic distribution and associated with chromosomal races and subraces. Together with cytogenetic observations, we discuss the origin of the polymorphism within the X0 and XY races as well aces.,is differences between both northern and eastern races.

DOI： 10.1603/0013-8746(2008)101[837:RBCSIT]2.0.CO;2

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

The distribution patterns of the X0/XX and neo-XY/neo-XX chromosome races, subraces, and "hybrids" between subraces of the grasshopper P. sapporensis were analyzed. The origin of the observed variation is Robertsonian translocations between a sex chromosome and an autosome, and chromosome rearrangements. The fixation levels of inversions varied depending on geographic regions. No hybrid population is known implying that a strong reproductive isolation system exists in hybrids between the different chromosomal races. The probable reasons for the purity of X0 and neo-XY chromosome races and high chromosome polymorphism in contact zones between chromosomal subraces are discussed. The presence of isolating barriers between chromosome races indicates a review of the taxonomic structure of P. sapporensis is required. It is proposed to divide P. sapporensis into two sibling species, which differ in the chromosome mechanisms of the sex determination system. The analysis of the distribution of chromosomal races and subraces of P. sapporensis allows a reconstruction of the history of this species in the Okhotsk sea region.

DOI： 10.14411/eje.2008.027

Language：Others  

Spatially heterogeneous distribution of mtDNA haplotypes in a sika deer (Cervus nippon) population on the Boso Peninsula, central Japan
We used variation in the mitochondrial DNA (mtDNA) control region (D-loop) to examine the genetic structure of the sika deer (Cervus nippon) population on the Boso Peninsula, central Japan. A total of four haplotypes was found. In order to examine whether or not artificial barriers such as roads, dams, and golf courses affect the spatial heterogeneity of mtDNA haplotypes, we implemented two exclusive spatial analyses (SAMOVA and network analysis based on Monmonier&#039;s algorithm) for searching genetic discontinuities between artificial barriers. Prior to the analyses, the whole distribution area was divided into meaningful eight blocks. Analysis of molecular variance (AMOVA) detected significant spatial heterogeneity in the constitution of the haplotypes among the blocks. The subsequent spatial analyses detected some significant spatial discontinuities on borders of the blocks. In particular, the largest discontinuity was observed in the area including motorway Line 81, but the traffic density of Line 81 is generally not very heavy compared to other major roads. These findings suggest that roads could be one of major barriers to hamper migration of sika deer to some extent, but other potential factors such as the location of food resources andor the history of bottleneck event are also likely to more or less contribute to configure the present patterns of haplotype distribution. © the Mammalogical Society of Japan.

DOI： 10.3106/1348-6160(2008)33[59:SHDOMH]2.0.CO;2

Language：Japanese  

Detection of genetic discontinuity in wildlife animals based on landscape genetic tools

Language：Japanese  

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

Sexual selection is generally caused by female choice and male-male competition. In female choice process, female preference is favored indirectly and/or directly by sexual selection. In indirect selection, females expressing the preference might gain indirect genetic benefits. In direct selection, females expressing the preference might gain direct benefits or avoid male-imposed costs. The white-tailed zygaenid moth Elcysma westwoodii is monandrous, and males often gather around a female to mate with her, suggesting a high opportunity for sexual selection on male traits. We quantified phenotypic selection on male morphology in this species in the field. The morphological characters analyzed included body weight, antenna length, forewing length, hind wing length, hind wing tail length, genital clasper length, and the fluctuating asymmetry (FA) of these bilateral traits. In E. westwoodii, selection favored males with more symmetric genital claspers, as well as longer and more symmetrical hind wings and antennae. Negative correlations between FA and size were also detected in the clasper and the antenna. Our results suggest that FAs of male traits, in particular the genital clasper, may have indirect and direct influences on mating success. During a copulatory attempt, an E. westwoodii male will try to grasp the female's abdominal tip with his claspers but often fail to do so because of the female's reluctance to mate. The female abdominal tips are smooth and strongly sclerotized and could thus be difficult for males to grasp. We hypothesize that more symmetrical male claspers are more efficient in overcoming female reluctance.

DOI： 10.1093/beheco/arm017

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

A DNA library derived from the B chromosome of Podisma kanoi was obtained by chromosome microdissection. A total of 153 DNA clones were isolated from the microdissected DNA library. Twenty of them were sequenced. A comparison of B chromosome DNA sequences with sequences of other species from the DDBJ/GenBank/EMBL database (http://www.ddbj.nig.ac.jp/) was performed. Different patterns of signals were observed after FISH with labeled cloned DNA fragments. FISH signals with cloned DNA fragments painted either whole Bs or their different regions. Some clones also gave signals in pericentromeric regions of A chromosomes. Other cloned DNA fragments gave only background-like signals on A and B chromosomes. Comparative FISH analysis of B chromosomes in Podisma kanoi and P. sapporensis with DNA probes derived from the Bs of these species revealed homologous DNA that was confined within pericentromeric and telometric regions of the B chromosome in P. kanoi. In contrast to the B chromosomes in P. sapporensis containing large regions enriched with rDNA, only a small cluster of rDNA was detected in one of the examined B chromosomes in P. kanoi. The data strongly suggest an independent origin of B chromosomes in two closely related Podisma species.

DOI： 10.1007/s10577-007-1128-z

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

Recent comparative studies have revealed that the rapid diversity of genitalia is closely related to sexual selection and that genital development interacts with the development of different body parts. Hypotheses about developmental stability due to selection to genital parts were tested by estimating allometric relations in a sexually dimorphic stag beetle Prosopocoilus inclinatus. All genital parts of males scaled to body size with a slope of less than 1 and all but the median lobe (male intromittent organ) showed smaller variability than other body parts. This supported the 'one-size-fits-all' hypothesis, which suggests broad copulation opportunity by males of any size with females within a population. Nevertheless, we found large variation among different genital parts in coefficients of variation and in values of the switch point where the allometric relations varied significantly. These results strongly support the view that developmental trajectories of genital traits are not necessarily integrated. Among the genitalic traits, male intromittent organ and female genitalia exhibited large variability, suggesting a high responsiveness to the selective regimes and physical interaction during copulation. This may account for rapid diversification of genital morphology, even in closely-related populations in beetle species. (c) 2007 The Linnean Society of London.

DOI： 10.1111/j.1095-8312.2007.00744.x

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

We examined cytochrome P450 production and activity and circulating hormone concentrations in male medaka exposed to 17 beta-estradiol (E2) or 17 alpha-ethinylestradiol (EE2). Intraperitoneal injection of E2 at 1, 10, or 100 mu g/g-fish completely suppressed CYNA38 protein production and suppressed CYP3A40 protein levels by 89&#37;, 52&#37;, or 47&#37;, respectively. CYP3A38 and CYP3A40 mRNA expression was unaltered, and CYP3A enzymatic activity initially increased and then decreased with increasing E2 dose. Males co-cultured with females were exposed to a markedly high concentration (43 ng/L) of E2 secreted by females. CYP3A protein levels in co-cultured males were suppressed. Serum testosterone (TE) and 11keto-testosterone levels in co-cultured males were downregulated to 40&#37; of pre-exposure levels. Serum E2 levels increased in co-cultured males or males exposed to EE2. Testicular CYP19, which converts TE to E2, increased by 9.5 times in males exposed to 50 ng/L EE2 and by 21.5 times in those exposed to 100 ng/L EE2. Male medaka exposed to EE2 showed increased serum Vtg levels. Estrogenic exposure induced Vtg production, suppressed CYP3A protein production, downregulated TE metabolism, and enhanced CYP19 activity. Serum E2 endogenously induced by CYP19 could contribute to Vtg induction in male medaka. (c) 2007 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.cbpc.2007.01.009

Language：Japanese  

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

Using the magnetic particles method, we isolated six polymorphic microsatellite loci from an apterous grasshopper, Podisma kanoi Strozhenko, which shows conspicuous structural variation in chromosomes. The isolated loci were polymorphic, with three to 10 alleles among 20 individuals. Expected heterozygosities ranged from 0.23 to 0.90. These loci can be used to examine the history of population fragmentation and the establishment of chromosomal variation.

DOI： 10.1111/j.1471-8286.2006.01436.x

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

The brachypterous grasshopper Podisma sapporensis Shiraki (Orthoptera: Acrididae) consists of two major chromosomal races with different sex chromosome systems. In the X0/XX race, the diploid number of chromosomes is 2n = 23 (X0) in males and 2n = 24 (XX) in females. In the XY/XX race, the diploid number is 2n = 22 (XY) in males and 2n = 22 (XX) in females, owing to Robertsonian fusion between an autosome and the X chromosome. The X0/XX and XY/XX races are allopatrically distributed, and each race contains geographical populations characterized by different chromosomal inversions. A previous hypothesis suggested that the XY/XX race was derived from the X0/XX race. To test this hypothesis, we examined mitochondrial DNA (mtDNA) sequence variation in two regions (cytochrome oxidase subunit II and 16S ribosomal DNA) among 29 P. sapporensis individuals representing five X0/XX and 12 XY/XX populations. The maximum parsimony tree of mtDNA indicated that neither of the two chromosomal races was monophyletic. Northern populations of XY/XX race did not join a clade consisting of more southern XY/XX populations but were included in a clade consisting of X0/XX populations. On the basis of these results, we propose two hypotheses for the differentiation between the northern and southern XY/XX populations. First, the XY/XX karyotype may have occurred more than once. Second, introgression of mtDNA may have occurred across adjacent populations possessing different karyotypes.

DOI： 10.1603/0013-8746(2006)99[457:OOCRPR]2.0.CO;2

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

The sex comb on the forelegs of Drosophila males is a secondary sexual trait, and the number of teeth on these combs varies greatly within and between species. To understand the relationship between the intra- and interspecific variation, we performed quantitative trait locus (QTL) analyses of the intraspecific variation in sex-comb tooth number. We used five mapping populations derived from two inbred Drosophila simulans strains that were divergent in the number of sex-comb teeth. Although no QTLs were detected on the X chromosome, we identified four QTLs on the second chromosome and three QTLs on the third chromosome. While identification and estimated effects of the second-chromosome QTLs depend on genetic backgrounds, significant and consistent effects of the two third-chromosome QTLs were found in two genetic backgrounds. There were significant epistatic interactions between a second-chromosome QTL and a third-chromosome QTL, as well as between two second-chromosome QTLs. The third-chromosome QTLs are concordant with the locations of the QTLs responsible for the previously observed differences in sex-comb tooth number between D. simulans and D. mauritiana.

DOI： 10.1017/S0016672306008111

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

Previous studies have suggested that the developmental pattern of insect body parts is influenced by food conditions during the nymphal stages. In this study, we compared the developmental patterns of five body parts (body length, fore-femur length, mid-femur length, hind-femur length, and angle of claw) in the predatory insect Lethocerus deyrolli Vuillefroy fed three diets (tadpoles, Odonata nymphs, and tadpole-Odonata nymph mixture) during the nymphal stages. Significant age by sex interactions were detected in body length, fore-femur length, mid-femur length, and bind-femur length, indicating developmental patterns of these traits varied between sexes. Significant age by food interactions were detected in body length and hind-femur length and were marginally significant in mid-femur length, showing developmental patterns of these traits varied among food types. None of the interactions were significant in angle of the claw. A predation experiment was performed using double-claw nymphs as a control and one-claw nymphs (adult type) as a treatment. Double-claw nymphs successfully caught both large and small tadpoles, whereas one-claw nymphs caught small tadpoles more frequently than large tadpoles. Our results suggest that the claw development, which is very likely related to predatory function, may be less affected by nutritional conditions, and that double claws during nymphal stages may be indispensable to increased predation success.

DOI： 10.1603/0013-8746(2006)099[0151:RLACAN]2.0.CO;2

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

Relationships between the ommatidial structure and photoperiodic behavior of several mosquito species were investigated. Host-seeking behavioral patterns of mosquitoes were classified into four main groups based on previously compiled reports on field or laboratory biting activity. These groups were pattern I and F (nocturnal), pattern 11 (crepuscular and nocturnal), pattern III (crepuscular and diurnal), and pattern IV (diurnal). Eye parameters (product of facet diameter and interommatidial angle) of mosquitoes that belong to the pattern I and I' group were higher (2.7-4.2) than those of mosquitoes that belong to the pattern IV group (0.8-2.3). Eye parameters of the mosquitoes categorized in the pattern 11 and III groups were intermediate (2.3-2.6). These results suggest that the crepuscular behavior of mosquitoes undergoes a transition in the course of evolution from nocturnal behavior to diurnal behavior. Large variations in the eye parameters were observed even within the same genus depending on their photoperiodic behavior. Therefore, the ommatidial structure of mosquitoes appears to be determined, not taxonomically, but evolutionarily by the photoenvironment in which the mosquitoes are most active. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jinsphys.2005.09.004

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

Knowledge of the genetic basis of divergence in mating signal characters that contribute to reproductive isolation is critical to understanding speciation. Here, we describe a semi-automated system for characterizing grasshopper acoustic signals. We used this system to study the genetic basis of divergence in three male calling song components [echeme (EL), syllable (SL) and phrase (PL) lengths] between Chorthippus brunneus and C. jacobsi, two species of grasshoppers that hybridize in northern Spain. We also studied the number of pegs in the stridulatory file. For all characters, additive effects accounted for most of the genetic differentiation between species. However, the three song components also showed small but significant epistatic effects. No sex linkage was detected. Wright-Castle-Lande estimates of the minimum numbers of genetic factors underlying song and peg number divergence were low: peg number (n(e) = 5.87 +/- 5.84), SL (n(e) = 2.37 +/- 4.79) and PL (n(e) = 0.87 +/- 0.86). On the other hand, EL appeared to be controlled by many genes. These results suggest that divergence in SL and PL might be driven by sexual selection whereas EL might not be under selection. This is consistent with experimental results on female song preference in related species. However, the fact that few factors appear to underlie the differences in peg number is surprising. Peg number is not closely related to song characteristics. It often varies between closely related grasshopper species and it has been assumed to be a neutral character. The biometrical approaches used here tend to underestimate the number of factors influencing a trait but provide valuable background for subsequent quantitative trait loci analyses.

DOI： 10.1111/j.1420-9101.2004.00838.x

Language：Japanese  

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

Studies of prezygotic and postzygotic isolation in Drosophila have shown in general that species in sympatry tend to evolve prezygotic barriers earlier than do species in allopatry. However, postzygotic barriers tend to evolve at the same evolutionary rate in both sympatric and allopatric species. In contrast to these observations, the grasshoppers Chorthippus parallelus parallelus and C. p. erythropus show complete hybrid male sterility but only limited prezygotic isolation after an estimated 0.5 millions years of divergence. Like their congeners, C. brunneus and C. jacobsi form a hybrid zone where their ranges meet in northern Spain. However, the hybrid zone is mosaic and bimodal and, in contrast to the high levels of postzygotic isolation between C. parallelus subspecies, these two species showed no significant reduction in hybrid fitness in F, or backcross generations relative to the parental generations. The level of prezygotic isolation in laboratory tests was comparable to that between C. parallelus subspecies. These results suggest that endogenous postzygotic isolation does not play an important role in the reproductive isolation between C. brunneus and C. jacobsi, or in determining the structure of the hybrid zone. Exogenous postzygotic isolation may be present and should be tested in future studies. (C) 2005 The Linnean Society of London.

DOI： 10.1111/j.1095-8312.2005.000424.x

Language：Japanese  

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

Male characters that are used for male-male combat are often developed and exaggerated, whereas female equivalent characters are vestigial or vanished. In order to assess whether the characters common to both sexes share the same phenotypic variability due to common genetic architecture, we compared males and females of the stag beetle Prosopocoilus inclinatus using recently developed geometric morphometric methods. Elliptic Fourier analysis was used to compare shape variation between male characters (including exaggerated mandibles) and developmentally homologous female characters. A significant positive correlation was found between the size or between the weight of different body parts in both sexes, but a conspicuous difference was detected in the frequency distribution of the weight of all the body parts. Elliptic Fourier analysis demonstrated that there was marked discontinuous variation in mandibles in males, whereas such a discontinuity was not clear in females. The shape of a character in males exhibited some similarity with that of other characters, but this was not found in females. In a character, growth trajectory of shape was significantly affected by both size and weight in males, whereas size and shape tended to vary independently in female characters. These results support the hypothesis that a large sexual dimorphism in variation in shape is due to alleles accumulating in tight linkage with a sex-determining gene. (C) 2004 The Linnean Society of London.

DOI： 10.1111/j.1095-8312.2003.00279.x

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

This study aims to infer the proportion of queens and workers of the hornet Vespa analis parasitized by the strepsipterous parasite Xenos moutoni in overwintered females from morphological data collected for three years. It is known that both worker and queen hornets parasitized by strepsipterous insects overwinter. The parasitized queens cannot reproduce in the next season and thus the level of parasitism potentially affects the number of colonies to be established in the population. Thus, estimation of the ratio of parasitized queens to the total of parasitized females would be useful for understanding the population dynamics of the hornet. K-means cluster analysis demonstrated that 50 to 85&#37; of individuals were workers in the total of parasitized females during the period. From 8 to 15&#37; of total queens were thought to be sterilized by X. moutoni, a level that would not be expected to have a serious effect on the population dynamics of V analis. Forced hibernation of workers might be considered to be a result of manipulation of the diapause system of the host by the parasite to increase its reproductive success.

DOI： 10.1603/0046-225X-32.1.175

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

A new host record of Blaesoxipha grisea Meigen

Language：English  

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

The grasshopper Podisma sapporensis consists of two main chromosome races in Hokkaido. The western group of populations of P. sapporensis, belonging to the XO race, has a diploid number of chromosomes 2n=23 in the male and 2n=24 in the female (sex determination XO male/XX female). The eastern group of populations of this species, belonging to the XY race, differs from the western one as a result of Robertsonian translocation between the originally acrocentric X chromosome and M-5 autosome in homozygous state, having resulted in the forming of chromosome sex determination neo-XY male/neo-XX female (2n=22). These races are geographically isolated by the mountainous system consisting of the Mts Daisetsu and Hidaka range, occupying the central part of the island. The hybrid zones between the races have not so far been discovered. Various levels of polymorphism for the pericentric inversions and C-banding variation exist in different chromosomes throughout populations in both chromosome races. In some solitary populations (the population at the summit of Mt Yotei, populations in the vicinity of Naganuma, Oketo, and Tanno) pericentric inversions are fixed in some pairs of chromosomes, which enables marking of the discrete karyomorphes. In the Mt Daisengen population all chromosomes are two-armed as a result of fixing the pericentric inversions. These facts contradict karyotypical conservatism of the tribe Podismini. The level of diversity of P. sapporensis karyotypes could provide a new perspective on the evolutionary process of different karyotype in Orthoptera. The considerable occurrence of polymorphism in chromosomes suggests that karyotypic diversification is undergoing in P. sapporensis. The authors also proposed that P, sapporensis would be divided into four chromosome subraces in the XO chromosome race and two chromosome subraces in the XY race, on the basis of karyotypic features. These races may have been established by fundamental climatic changes during the glacial epoch.

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

Males of Lucanus maculifemoratus Motschulsky are markedly variable in size of body and heads. In this study, we investigated the possible causes that affect the development of the male heads and genitalia by comparing variability of weight among body parts and allometry in each part to bed, size. Genitalia varied least in weight among males, and the frequency, distribution of their weight was approximately normal. In contrast, the frequency distribution of head weight exhibited a conspicuous skew. Significant positive allometry was found for heads, whereas genitalia showed significant negative allometry. Heads that are used for fighting are allometrically highly variable, whereas genitalia are highly stable, suggesting variable strategies for obtaining mates M while maintaining equally sexually functional genitalia. The low variability and low allometric coefficient with body size for genitalia may indicate that the development mechanism for genitalia is separated from that for other body parts, as a result of sexual selection.

DOI： 10.1603/0013-8746(2001)094[0462:APOHAG]2.0.CO;2

Language：Japanese  

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

Seven categories of B chromosomes found in the brachypterus grasshopper Podisma sapporensis from Hokkaido populations differ in structure, size, and C-band content. The interchange between B and one autosome from M-3 and sporadically M-7 was observed in most of the populations examined. Such an interaction between standard and non-standard chromosomal set provides an insight into the integration of supernumerary chromosome. In addition, C-hrterochromatin polymorphism was also identified in male karyotypes in some populations. These facts indicate P. sapporensis is a highly polymorphic species from the cytogenetic point of view.

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

Distribution pattern of the XO/XX and neo-XY/neo-XX chromosomal races of the brachypterous grasshopper Podisma sapporensis (Orthoptera: Acrididae) in Hokkaido, northern Japan

Language：Japanese  

Language：Japanese  

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

We examined morphological variation in Kunashiri populations of P. sapporensis Shiraki and P. tyatiensis Bugrov using multivariate morphometrics to clarify their taxonomic status in comparison with Hokkaido populations of P. sapporensis. Although P. sapporensis in Kunashiri Island has a unique karyotypic characteristic, the neo-X and neo-Y system, cluster analysis indicated that the morphology is included in the range of variation seen in Hokkaido populations with the XO-male determination system. P. tyatiensis is characterized by having short-armed chromosomes compared with other Podisma species, but the morphology of this species did not differed much from P. sapporensis in Hokkaido, either. These results suggest that chromosomal changes do not contribute to phenotypic diversification. P. sapporensis in Kunashiri Island is probably reproductively isolated from P. tyatiensis on the same island because of conspicuous differences in the karyotype, whereas it is highly probable that P. tyatiensis in Kunashiri Island and P. sapporensis in Hokkaido constitute the same biological species.

DOI： 10.1303/aez.2000.1

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

Differences in the geographic patterns of genitalic and nongenitalic morphological characters in Podisma sapporensis (Podisminae) were examined using the hierarchical testing procedure in common principal component analysis. This analysis was used to evaluate the extent to which the covarience structure among characters varies geographically in both sexes. Males exhibited consistency in the covariance structure among populations both in genitalic and nongenitalic characters, whereas the covariance structures of female genitalic and nongenitalic characters were trot stable geographically. We suggest that the conspicuous sexual difference in covariance structure results from different selective pressures acting on genitalia: stabilizing selection is responsible for the stability of male genitalia, whereas variability in female is the result of directional sexual selection varying among populations.

DOI： 10.1603/0013-8746(2000)093[0127:VIPCSO]2.0.CO;2

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

We examined sexual dimorphism and its geographical pattern in 10 morphological characters, including the genitalia, in the brachypterous grasshopper Podisma sapporensis. Conspicuous sexual dimorphism was observed in all characters. Zn nine characters, variance in females was significantly greater than in males. Sexual differences among populations varied more in the genitalia than in other characters. Spatial autocorrelation analysis demonstrated that there was no geographical trend in the female genitalia, whereas significant autocorrelation existed in the male genitalia. These results suggest that cryptic female choice is responsible for the autocorrelation pattern of the male genitalia, while random genetic drift or a larger effect of environment has created the geographical pattern of the female genitalia.

DOI： 10.1139/cjz-76-8-1450

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

DOI： 10.1303/aez.32.527

Language：Japanese  

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Language：Japanese  

Language：Japanese  

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

Analyses of Morphological Variation in the Brachypterous Grasshopper, Podisma sapporensis (Orthoptera, Podisminae)

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

Geographic Variation in the Shape and Allometry of the Brachypterous Grasshopper Podisma sapporensis

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Oxya hyla and O. intricata (Smaller rice grasshopper)

Language：Japanese   Book type：General book, introductory book for general audience

Responsible for pages：総ページ数：xii, 320p   Language：Japanese  

Language：Japanese   Book type：Scholarly book

Responsible for pages：総ページ数：viii, 313p   Language：Japanese  

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Proceedings of the 4th International Symposium of the Biological Shape Analysis

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Proceedings of the 3rd International Symposium of the Biological Shape Analysis

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Proceedings of the 3rd International Symposium of the Biological Shape Analysis

Responsible for pages：総ページ数：637   Language：Japanese  

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Proceedings of the 2nd International Symposium of the Biological Shape Analysis

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Biological Shape Analysis: Proceedings of the 2nd International Symposium of the Biological Shape Analysis

Responsible for pages：総ページ数：xiii, 302p, 図版 [4] p   Language：Japanese  

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Biological Shape Analysis: The 1st International Symposium of the Biological Shape Analysis

Responsible for pages：総ページ数：186   Language：Japanese  

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ミジンコを用いた銀ナノ粒子毒性の評価

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急性毒性試験はミジンコへの銀毒性を過大評価する

Language：Japanese  

Relative abundance and its seasonal variation of Zygopteran larvae on Okinawajima Island
Members of the order Odonata are prevalent in both terrestrial and aquatic environments. Although morphological traits are well described in most of the species in Japan, there is little information on larval ecology of these species especially in Ryukyu Islands. We investigated the larval assemblage of damselflies (Suborder Zygoptera) in two ponds on Okinawajima Island, Japan, for 13 months. In total, four species were found in one of the ponds (Ogimi) and three in the other (Kunigami). Among these, Paracercion melanotum (Selys) dominated the assemblages, accounting for up to 71&#37; of the total abundance in both ponds. Based on the best model selected by AIC, we found that the relative frequency of the larvae varied among damselfly species, seasons, and macrophyte species of habitats. Moreover, patterns of seasonal changes and habitat selection in respect to macrophyte species also varied among damselfly species.

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Entomological Laboratory, Faculty of Agriculture, University of the Ryukyus

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：Japanese