Entomological Science最新文献

A marine rove beetle, Cafius pectoralis (Boheman, 1858), inhabits the coast and is found in seaweed washed ashore on sandy beaches. This species also inhabits Lake Shinji, a brackish lake with low-salinity, but there is no seaweed or kelp flies in this lake. Cafius pectoralis prefers to prey on beach hoppers, and many hoppers live in Lake Shinji. One rove beetle and one beach hopper were placed together in a container for 24 h. As a control, beach hoppers were placed in similar containers alone for 24 h. While the beach hoppers that were alone all survived, those with rove beetles were all dead after 24 h. Consequently, it is speculated that the beetles feed on beach hoppers and that they have become habituated to the brackish lake.

Research of the diversity and evolutionary history of Japanese soil invertebrates is scarce. Molecular data analysis can help to elucidate species classifications and evolutionary processes. We analyzed the mitochondrial cytochrome oxidase subunit I (COI) and nuclear 28S rDNA genes and the morphology of the male pleopod 2 endopod of Ligidium japonicum and its allied species from 67 sites in Hokkaido, Honshu and Shikoku, where only L. japonicum is thought to occur. We found males of the L. japonicum complex with a pleopod 2 endopod morphology matching that of the L. japonicum syntype specimens, except for the number of denticles at the inner margin. There were also more than five species that differed morphologically from the L. japonicum complex, and most of these species had allopatric distributions despite the absence of obvious barriers. A time-calibrated molecular phylogeny implied that the L. japonicum complex of the Kanto region first differentiated allopatrically in the mountains; this was followed by independent dispersal of three lineages to the Kanto Plain and Boso Peninsula, where secondary contact occurred. Two of the three sympatrically distributed L. japonicum complex lineages had a significant difference in the number of denticles at the inner margin of male pleopod 2 endopods. This variation implies the presence of cryptic species within the L. japonicum complex.

Thatched roofs are artificial environments that serve as nesting sites for a variety of insects, including tube-nesting wasps, but they have been declining drastically in recent years. In this study, we investigated the nesting habits of a eumenine wasp, Symmorphus apiciornatus, nesting in a group at thatched roofs in a northern part of Ibaraki Prefecture, central Japan. Genetic diversity and genetic structure in the area were also investigated. Sex ratios at most study sites were not biased. Males emerged first and waited for females to mate around the natal nests, suggesting a high possibility of breeding between the wasps having emerged at a given thatched roof under the recent situation where there has been a drastic reduction in the number of houses with a thatched roof. Nevertheless, the genetic diversity in a given local population or a thatched roof was relatively high and significant genetic differentiation among thatched roofs was not detected.

Although most aphid species living on leaves have a green body color, little is known regarding the biosynthetic pathways of green pigments. We found that a clone of the pea aphid, Acyrthosiphon pisum (Harris) produced both green- and yellow-colored males. The females of this clone were green in color, while 8.4% of the males produced were yellow. To date, yellow body color has been reported only in a single mutant clone in A. pisum. To explore the genetic pattern of yellow body color, green or yellow males were mated with green females of the same clone. The hatchability of the eggs sired by yellow males (26.2%) was less than half that of the eggs sired by green males (79.0%). The hatched foundresses of both groups were all green, with no yellow foundresses. Because aphids have an XX-XO sex determination system, color polymorphism in males suggests that male body color may be governed by an X-linked locus. If females possess heterozygosity at the putative locus, they can produce alternative phenotypes in males. The small proportion of yellow males and absence of yellow foundresses imply that the allele responsible for yellow body color has a deleterious effect. The present study suggests that this clone could be used to elucidate the biosynthetic pathways and underlying genetics of green pigments in aphids.

Lethocerinae water bugs are vertebrate predators that include in their diet large prey such as fish, turtles, snakes and frogs. Although frog consumption is common among the members of the genus Lethocerus, similar reports are unknown from Europe. Here we report a predation event by an adult Lethocerus patruelis (Stål, 1854) on a subadult Balkan water frog Pelophylax kurtmuelleri (Gayda, 1940), the first description of its kind in Europe.

The aquatic larvae of the family Hydrochidae (Coleoptera) have been considered ‘mystery larvae’, because ecological knowledge about them is lacking. We discovered that Hydrochidae larvae (Hydrochus japonicus Sharp) are benthic via laboratory rearing. The larvae have a terminal spiracular atrium, but we did not observe them breathing at the water surface. The larvae fed on Naididae worms that were collected from the same habitat.

Numerous delphacid planthopper species are major pests of economically important and widely cultivated crops (i.e. rice, corn, and sugarcane). These insects have the potential to become serious crop pests in areas where they have either naturally migrated or been newly introduced. The white-bellied planthopper, Stenocranus pacificus Kirkaldy, 1907, originally known from tropical South Pacific islands, appeared in tropical and subtropical Asia in the early years of the 21st century. Since then, S. pacificus has become a serious pest of corn in some Southeast Asian countries, although it also feeds on rice, sugarcane, sorghum, and other grasses. Here, we report the presence of S. pacificus in mainland Japan, representing the first record of this species in temperate Asia. Seven male and 17 female adult individuals collected in Kumamoto Prefecture in 2019 and 2020 were identified as S. pacificus based on their morphological characteristics and mitochondrial COI sequences. In addition, molecular phylogenetic analysis showed that S. pacificus formed a distinct clade from other Stenocranus species, indicating uncertainty in its generic assignment. Although crop damage by S. pacificus has not yet been reported from temperate regions, given its wide range of plant hosts and the potential for future range expansions, damaged crops in Asia, including in temperate regions, should be monitored for the presence of this species.

Various insect species lay tiny, thin- and soft-shelled eggs in a connected “egg mass”. Especially in several lepidopteran species, the structure of such clustered eggs is covered with complicated scale-like secretion, which has so far prevented analysis of individual embryos. However, few studies on methods to disperse egg clusters of such insects and to compare different methods have been carried out. To overcome these problems, we developed methods to separate egg masses into individual eggs, using two Tortricidae pests, Homona magnanima Diakonoff and Adoxophyes honmai Yasuda (Lepidoptera: Tortricidae). The eggs were successfully separated from each other using potassium hydroxide and sodium hypochlorite. Although the separated eggs no longer continued their embryogenesis, fixation with heptane–paraformaldehyde, permeabilization with heptane–methanol, and staining with several dyes enabled easy observation of embryogenesis. This protocol is expected to be applicable to other insect taxa and will facilitate further morphological and genetic studies in insects that lay egg masses.

Plant decomposition is an essential component of forest ecosystems. Wood-feeding cockroaches are responsible for the decomposition of rotten logs. However, the ecology of wood-feeding cockroaches is not well understood. To understand how they decompose rotten logs in the gallery inside the logs, it is necessary to observe them in laboratories. Here, I present an observable and cost-effective for rearing these log decomposers using a culture dish and an artificial fungal meal. The culture dish is traditionally used to cultivate fungi or bacteria with the lid on. The artificial fungal meal is a commercial product for stage beetle larvae, which are a kind of log decomposers. These let researchers easy to deal with wood-feeding cockroaches. In the course of keeping over 1,000 individuals of the wood-feeding cockroaches, I have developed effective techniques to rear them under the observable system for several years. I present these techniques along with several tips to keep the wood-feeding cockroaches healthy and observe them using video cameras. These techniques remove many of the limitations for study on the plant decomposers. When researchers use this observable rearing system, we can conduct rearing experiments easily and well understand the ecology of wood-feeding cockroaches and insects associating with them.