Entomological Science最新文献

Female fritillary butterflies (Lepidoptera: Nymphalidae: Argynnini) are known to have diversified genital structures, especially at the entrance of the bursa copulatrix. However, the origin and function of such elaborated structures are poorly known to date. We examined the male and female genital structures of six Japanese species selected from five genera/subgenera [Argynnis (Argynnis), Argynnis (Damora), Argynnis (Argyronome), Fabriciana, and Speyeria] of the Argynnini tribe and found that traumatic copulation is widespread in Argynnini. Various male genital structures, such as the uncus, valva, and phallus, can cause wounds to the female genitalia. The eighth venter of the female, where the highest morphological diversity in female genitalia was detected, is hooked and held by the male uncus during copulation. It is very likely that the diversified female genital structure coevolved with the male uncus as a counterpart for traumatic coupling.

As differences in sex pheromones usually act as a barrier against interspecific mating, the fact that the closely related moths Xylena fumosa (Butler) and X. formosa (Butler) (Lepidoptera: Noctuidae: Xyleninae) are commonly attracted to the sex pheromone lure for Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae: Heliothinae) seems unlikely, suggesting that some mechanisms exist between them to mitigate a potential reproductive interference in pheromone communications. Thus, we examined the overlaps in ecological niches of the two species, and their attractiveness to commercial pheromone lures for other moths, through pheromone trap surveys and published reports. Long-term field surveys using traps baited with five to six types of artificial sex pheromone lures including those designed for H. armigera, and information in published works revealed that there was a nonnegligible overlap between the two species in terms of seasonal timing of captures, geographic habitats and host plants. These factors, therefore, did not appear to provide conclusive evidence mitigating reproductive interference. However, there was a slight but significant difference between them in the trends of attraction to different artificial pheromone lures; X. formosa was attracted albeit in a small number to the lures for Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), whereas X. fumosa was only attracted to those for H. armigera. This suggests that differences in pheromone composition, rather than differences in temporal and spatial distributions, between the two species could play a more significant role in premating reproductive isolations.

Invasive insect species threaten the productivity of ecosystems worldwide, and ecological niche models can be used to predict distributions of invaders and guide management efforts. Ecological niche models can also aid monitoring for invasive species that are globally distributed. One such species is the yellow spotted stink bug (Erthesina fullo Thunberg), a polyphagous pest native to Asia that has established in Europe and South America and threatens specialty crops. Here, we used ecological niche models to predict the potential distribution of E. fullo, and created a website to display predictions. We show that E. fullo has peak occurrence probability in areas with annual mean temperatures around 20°C, and that the occurrence probability increases as maximum monthly temperature reaches up to 38°C. The likelihood of occurrence decreased as annual precipitation increased, but increased with greater precipitation in the wettest and driest months. This suggests E. fullo is most suited to regions that are warm and dry and where most precipitation occurs across only a few months, such as southern North America, central and southern South America, southern Europe, southern Africa, and central and eastern Australia. Given that E. fullo is a highly mobile hitchhiking insect that travels through cargo and other containers to new areas, the potential spread of this species into new regions should be carefully monitored.

The giant water bug Kirkaldyia deyrolli is one of the most well-known endangered aquatic insects in Japan. The population of this species in Kyushu, one of the four major islands of the Japanese Archipelago, is extremely limited. In the present study, we identified a new population of K. deyrolli and undertook population genetic structure analyses based on genome-wide nuclear DNA single nucleotide polymorphisms (SNPs). We collected samples using a nonlethal sampling method and obtained 59,279 SNPs. The results of our study confirm that sufficient SNP data for population genetic structure analysis can be obtained through nonlethal sampling. We determined that the newly identified population is genetically differentiated from a previously identified population on Kyushu. Therefore, this population is considered highly important for the conservation of K. deyrolli in Kyushu.

The ontogeny of an organism provides fundamental insights into its life history and evolutionary background. Among insects, especially ants, relatively few observations have been formalized about the morphology of immature stages. Using light and scanning electron microscopy, this study presents the first description of the different larval instars of Aphaenogaster cristata (Forel, 1902) and Aphaenogaster pachei (Forel, 1906), species endemic to the Himalayas that predominate in areas where cold temperature stress and disturbances limit the presence of other ants. The existence of four larval instars was estimated based on the frequency distribution of their measured maximum head widths. We observed discrete alterations in the body constitution and parts among the different instars, suggesting they must follow similar habits until pupation. The two species, however, present noticeable particularities in their mandibles and hair types, suggesting intrinsic life adaptations. Observed traits complementary with previous descriptions with larvae of the genus and related taxa are suggestive of considerable evolutionary distance from Messor, considered the sister clade, which merits further taxonomic investigation in future studies.

Spatiotemporal characteristics of terrestrial foraging were studied in two ant species, Manica yessensis and Formica lemani, in a volcanic desert on the southeast slope of Mount Fuji, Gotenba, Japan. Both ants are common in this habitat, and they construct underground nests in this dry area with sparse vegetation. Nests of M. yessensis have multiple nest-openings on the surface, whereas nests of F. lemani have very few openings, but their nesting and foraging areas overlap completely. A “mark-and-observe” method applied to M. yessensis demonstrated that worker ants of this species move between openings more than 3 m away. A study plot (6 m × 12 m quadrat) was set up, in which all nest-openings of both species were mapped. Day-long observations on numbers of foragers in this plot revealed that foraging M. yessensis are active in morning and evening, while F. lemani continues foraging all day, but both species cease activity at night. Associations between locations of foragers and nest-openings differed significantly between the two species, that is, surface foraging of M. yessensis workers was largely confined to the vicinity of their nest-openings, whereas foragers of F. lemani travelled far from their nest-openings. The function of multiple nest-openings in M. yessensis is discussed.