Entomological Science最新文献

Polybia is a common wasp genus found in most of South America. Polybia (gr. occidentalis) encompasses several species that are difficult to identify because of their similar morphologies. Our goal was to cytogenetically characterize three species belonging to Polybia (gr. occidentalis) and discuss the importance of cytogenetic data for integrative taxonomy. Polybia colonies were sampled from different regions of Brazil to perform classical and molecular cytogenetic analyses. Polybia paulista and Polybia sp. 1 showed 2n = 34 and 18S rDNA loci on two chromosomes, whereas Polybia sp. 2 showed 2n = 40 and 18S rDNA clusters on four chromosomes. The microsatellites GA₍₁₅₎, GAG₍₁₀₎, CAA₍₁₀₎, TTAGG₍₆₎, and TCAGG₍₆₎ showed similar distributions among the species, forming blocks in the euchromatic regions of the chromosomes, whereas CGG₍₁₀₎ did not yield any positive markings. In contrast, TAT₍₁₀₎ hybridized on the centromeric heterochromatin, showing differences in the number of marked chromosomes among the species. Therefore, it may potentially be a species-specific cytotaxonomic marker in this group of wasps, but this feature needs further investigation. Fluorochromes evidenced that AT-rich DAPI⁺ sequence distribution was coincident with heterochromatin, while the distribution of CG-rich CMA₃⁺ sequences was coincident with the 18S rDNA region. The present study revealed differences in diploid number, heterochromatin content, 18S rDNA sites, and microsatellite patterns between morphologically similar species, demonstrating the usefulness of cytotaxonomy in studying species complexes.

Among several methods of active and passive sampling bees (Hymenoptera: Apoidea), pan traps, also known as bee bowls, are commonly utilized for their efficiency and as a means of avoiding collector bias. When comparing pan-trap samples using traditional statistical methods, the assumption of independence among samples needs to be met. To determine the necessary distance between pan traps to obtain independent samples, we investigated spatial dependence in bee catches using pan traps at four sites. At each site, a regular grid of pan traps was laid out, with each sample having two colors of fluorescent trap (i.e. blue and yellow). These trap pairs were separated by 10 m, with 100–109 points in the grid. In addition, five points within the grid were chosen randomly, and an additional 40 traps were placed at 2 m and 4 m from the five sample points to sample bees at a minimum 2 m trap distance. Traps collected bees for five consecutive days and bees were counted for each point and each trap color. Bee count data were analyzed using geostatistics to determine the spatial dependency in trap catches for yellow traps, blue traps, and both colors combined. The highest value of the range parameter of the semivariogram found across the four sites and pan trap colors was 17 m for blue traps. From this, we recommend a conservative minimum distance of 17 m between adjacent pan traps to obtain spatially independent samples for optimizing sampling plans when independent samples are necessary.

The Japanese species of the family Stephanidae Leach, 1815 are revised. A total of nine extant species are recognized from Japan, including two new species, Megischus pretiosus sp. nov. and Parastephanellus ryukyuensis sp. nov., and one species, Foenatopus ruficollis (Enderlein, 1913), is newly recorded from Japan. The female of Foenatopus cervinus Townes, 1958 and the male of Megischus baogong Ge & Tan, 2022 are newly described. A key to the Japanese genera and species of this family is proposed. The biogeographic pattern and the origin of Japanese stephanids, the role of Kuroshio Current, and the conservation importance of endemic species to the Ogasawara (Bonin) Islands are also discussed.

Terrestrial isopods are known to play significant roles in litter decomposition and seed predation. The present study examines the function of terrestrial isopods, particularly Armadillidium vulgare and Armadillidium nasatum, in the seed dispersal of a nonphotosynthetic plant, Phacellanthus tubiflorus. These isopods were observed ingesting seeds in the natural habitat of P. tubiflorus in Hyogo Prefecture, Japan. Contrary to the prevailing belief that invertebrates do not serve as effective internal seed dispersers, our analysis demonstrated that some seeds ingested by A. vulgare and A. nasatum were excreted whole, with viability rates comparable to those of seeds directly sourced from fruits. This indicates that these isopods could act not only as seed predators but also as seed dispersers. The research highlights the importance of further exploration into the ecological contributions of isopods and other invertebrates as seed dispersers.

As temperatures in the Japanese Archipelago vary, species widely distributed in Japan should have different active periods, ecologies, and life histories. Information on developmental zero and effective accumulated temperature is necessary to estimate life history. The giant water bug, Appasus japonicus, found in rice paddies, ponds, and other lentic waters, is distributed throughout Japan except for the Ryukyu Islands, and is a representative taxon in which the male cares for the eggs. In this study, we investigated the life history, including the length of the breeding season, of different A. japonicus populations from Hokkaido, Ibaraki, Hyogo, and Nagasaki. The developmental period, developmental zero, and effective accumulated temperature of the eggs and nymphs showed no significant differences among the populations. The life history for each population was estimated based on climate data. This showed that the Hokkaido population had a shorter and more extremely limited breeding season than the other populations. The estimated number of generations during one breeding season was approximately one in Hokkaido, two in Ibaraki and Hyogo, and three in Nagasaki. The estimated number of times males cared for eggs during the breeding season was less than one in Hokkaido, eight in Ibaraki and Hyogo, and twelve in Nagasaki. Although Belostomatidae may carry multiple egg masses during the breeding season, this study shows that the male of the Hokkaido population does not care for multiple egg masses.

Water striders (Hemiptera: Gerridae) are sucking predators that inhabit freshwater and marine environments. They prey mainly on insects that fall on the water surface, but they are also known to feed on amphibian eggs. Here, we report on the predation of egg sacs of Hynobius nigrescens (Caudata: Hynobiidae) by Gerris (Macrogerris) insularis. We observed predation on egg sacs of H. nigrescens by G. insularis at a pond in a mountainous area of Nagano City, Nagano Prefecture, Japan. We also found egg sacs with predation marks probably made by water striders at a pond in the mountainous area of Nishimeya Village, Aomori Prefecture, Japan. Five water striders collected around the preyed egg sacs were identified as G. insularis. We filled three tanks with water and an egg sac, and three water striders that were collected at the site in Nishimeya Village were placed together in each tank. In two tanks, the jelly layer of the egg sac was partially cut in a horizontal manner, while in another tank, the jelly layer was removed on the part of the egg sac exposed on the water surface. Notably, the water striders exhibited predatory behavior only when the jelly layers were removed. Considering the results of the rearing experiment and the predation marks observed in the field, G. insularis is also likely to prey on egg sacs at the site in Nishimeya Village. Our study suggested that predation by G. insularis occurs when eggs are accidentally exposed due to disturbance of the jelly layer.

It is widely recognized that heterogeneous environments promote biodiversity. Consequently, we investigated whether heterogeneous environments influence the diversity of ground-dwelling beetles within a well-managed conifer plantation forest. We collected carabid beetles, and necrophagous silphid and dung beetles (necrophagous beetles) using pitfall traps at 37 sites with or without fish meat bait. The result of a two-dimensional principal component analysis (PCA) utilizing environmental indices measured at each site suggested that the environmental heterogeneity depended on the survival density of planted conifers, serving as an indicator of historical gap formation levels. Gaps populated by invading broadleaved trees exhibited low canopy opening percentages and understory cover degrees, while those filled by the growth of planted conifers displayed the opposite conditions. The presence of bait had a negligible impact on carabid beetles but significantly influenced necrophagous beetles. No significant relationships were found between the scores of PCA components and the beetle species richness, suggesting that a heterogeneous environment does not increase the beetle species diversities. However, significant relationships were observed with the scores on nonmetric multidimensional scaling axes, indicating that a heterogeneous environment contributes to the complexity of beetle assemblages. The most dominant carabid, Synuchus cycloderus, was abundant in areas where historical gap formation was thought to be more prevalent. Among necrophagous beetles, Pherotrupes laevistriatus and Panelus parvulus preferred habitats with darker environments, in contrast to Onthophagus fodiens and O. nitidus. This study will aid in developing forestry practices aimed at conserving specific ground-dwelling beetle species within conifer plantations.

There are approximately 850 species of Ficus (Moraceae). However, few species of gall midges (Diptera: Cecidomyiidae) inhabiting syconia and leaves of fig trees are known. In field surveys, gall midges were found in syconia of Ficus caulocarpa and Ficus subpisocarpa. Here, we examined adults, pupae and larvae of the gall midge species, describe the morphology, and provide information on distribution, behavior and genetic data. A new genus, Ficidiplosis Yukawa and Arimoto, gen. nov., is established in the supertribe Cecidomyiidi for two new species, Ficidiplosis subpisocarpae Yukawa and Arimoto, sp. nov. and Ficidiplosis caulocarpae Yukawa and Arimoto, sp. nov., which emerged from syconia of Ficus subpisocarpa and Ficus caulocarpa, respectively, in Japan and Taiwan. The larvae of Ficidiplosis species feed on the parenchyma of the fig wall and pupate there without making galls. The mitochondrial cytochrome c oxidase subunit I (COI)-based neighbor-joining tree using samples from Japan and Taiwan supported the existence of two separate species.

Mushrooms produce a great variety of defense chemical compounds to protect themselves from fungivores. Alpha-amanitin is one of such compounds found in some Amanita mushrooms. The present study focuses on the effect of α-amanitin on adult survival in 17 drosophilid species including mycophagous ones from the subgenus Drosophila and the genus Hirtodrosophila and nonmycophagous ones of the subgenera Drosophila, Siphlodora and Sophophora. The results showed that all the essential fungivores and some partially mycophagous species from different lineages are tolerant to this lethal toxin at a concentration of 50 μg/mL, suggesting that the α-amanitin tolerance may have been acquired more or less independently of the evolution of mycophagy in the family Drosophilidae.

Drosophila subobscura is an excellent model species for testing genetic variation in thermal adaptation due to its rich inversion chromosomal polymorphism. In Palearctic populations, the inversions of this species can be classified as “cold”, “warm” or “nonthermal” adapted. Based on this classification the Chromosomal Thermal Index (CTI) was developed, which allows measuring the thermal adaptation of populations and monitoring changes over time. Here, we aim to use this index in American colonizing populations of D. subobscura for the first time to obtain new information on the species thermal adaptation. Thus, thermal adapted inversions (“cold” and “warm”) were defined for the American continent and CTI was computed in South American (1981 and 1999 samples) and North American (1985 and 2004 samples) populations of D. subobscura. In general, both American populations showed an inverse relationship between CTI values and latitude, with CTI values decreasing when latitude increases. When comparing populations sampled in different years, an increase in CTI values was detected in four out of six temporal comparisons (only one was significant) of South America (1981 and 1999) and in six out of seven populations of North America (1985 and 2004). A global analysis using a one-way repeated measures anova of CTI values in both American hemispheres showed a trend of increase for “warm” adapted inversions in Chile and North America, but this increase was only significant for the latter. Overall, these results are in agreement with global warming expectations, although natural selection acted differently in the colonized hemispheres.