Fibers

AbstractHere, we report the bimodal adult emergence in a synergine gall‐inducing wasp. On December 29, 2019, 150 Quercus glauca acorns containing Synergus itoensis galls were obtained from the Ito Campus of Kyushu University, Fukuoka, Japan. The galls were kept in a test tube for each acorn in the shade under field conditions until October 24, 2022. The emergence of adult wasps from the galls was recorded. More adults emerged in 2020 (151 females and 181 males) than in 2021 (120 females and 93 males); however, no emergence occurred in 2022. The sex ratio was not significantly different from 1:1 in either 2020 or 2021. The 50% emergence date was early September in both years. Acorn production in Q. glauca fluctuates greatly from year to year. Hence, oviposition resources for adult female S. itoensis are abundant in years with high acorn production, but scarce in years with low acorn production. The bimodal emergence of adult S. itoensis wasps may have evolved to adapt to the fluctuations in acorn production in Q. glauca.

AbstractThe genus Leptopa Zetterstedt, 1838, which was recently regarded as a senior synonym of the genus Parallelomma Becker in Strobl, 1894 by Ozerov and Krivosheina (2023), is reviewed from Japan. Four species were identified, of which two new species, Leptopa kanmiyai sp. nov. and L. yezonica sp. nov., are described. The distributional records of all four species in Japan are given, and Leptopa hostae (Hering) is also recorded from the Republic of Korea for the first time. Leptopa yezonica sp. nov. was reared from the leaves of Polygonatum odoratum (Mill.) Druce var. pluriflorum (Miq.) Ohwi in Hokkaido, and its puparium is described. A key to the Japanese species of Leptopa is also provided.

AbstractWasps from the Polysphincta genus group (Hymenoptera: Ichneumonidae: Pimplinae) are currently the only parasitoid wasps that are ectoparasitoids of spiders. The species of the group exhibit several morphological and behavioral adaptations, which allow exploiting their host spiders. Here, we describe the external morphology, behavior and natural history of the immature stages of a Darwin wasp Eruga unilabiana Pádua & Sobczak, 2018, a parasitoid of sheet‐weaving spiders, Sphecozone sp. and Eurymorion sp. (Linyphiidae). The egg of E. unilabiana is a white mass that is deposited in the anterior region of the spider's abdomen. First stage larvae partially emerge from the egg's chorion. Second stage larvae have a body divided into 13 segments and induce spiders to build a modified web. The third stage larvae have eight pairs of retractable dorsal tubercles with tiny little hooks that help the larvae hang and move on the web threads after the spider dies. These results indicate that the immature stages of E. unilabiana present the same basic morphological and behavioral characteristics already known for the species of the group. However, the last stage larva's strategy of moving first to hang on the web threads before killing the spider is the first record in the group and more studies are needed to assess whether this behavior is adaptive for the wasp.

AbstractIn recent years, it has been suggested that Cybister tripunctatus lateralis is increasing in abundance and expanding its distribution, and there is concern about the effects of interspecific competition with another congeneric species, Cybister brevis. Although the two species appear to have overlapping niches, they are often observed sympatrically. Larval habitat use by the two species was investigated in a paddy field water system. The results display that C. brevis was more abundant in ditches and C. tripunctatus lateralis was more abundant in paddy fields. It is thought that C. tripunctatus lateralis, which has an ecology suited to high temperatures, has selected paddy fields, where water temperatures tend to rise, as its reproductive habitat. In contrast, phenology was generally synchronized, and no differences in underwater position in the rice paddies were observed. Thus, niches overlap in paddy fields and interspecific competition may occur.

ABSTRACTAnt nests accommodate a diverse group of strictly associated arthropods. Most of these arthropods are seldom observed outside their host nest, emphasizing significant gaps in our knowledge regarding their biology. We recorded a series of field observations of lepismatid silverfish (Zygentoma: Lepismatidae) moving outside their usual Messor nest habitat in southern Spain and France. We illustrate how they move between different nests and locate nests by closely tracking the foraging trails of their hosts. Additionally, we confirm a prior observation that they can follow their host ants when they migrate to a new nest site. Our observations offer new insights into the hidden biology and the intricate interactions of specialized arthropod symbionts with their hosts within a spatial context.

AbstractTo monitor insect diversity and community changes, it is necessary to select traps with a high sampling efficiency. We examined the effects of a flight interception window on a small yellow pan trap (flight interception pan; FIP). Our results showed that fewer Hymenoptera individuals were captured by the FIP than by the non‐FIP (NFIP) traps. Fewer Aculeata, Diptera and Hemiptera individuals were captured by the FIP than by the NFIP traps, whereas more Coleoptera individuals were captured by the FIP than by the NFIP traps. The flight interception window did not affect the Aculeata species composition. Considering the labor involved in attaching windows and the reduced ease of trap transport and setting, the NFIP traps are better for sampling Hymenoptera, Diptera and Hemiptera, whereas the FIP traps are better for sampling Coleoptera.

AbstractPolybia 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.

AbstractAmong 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.

AbstractThe 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.

AbstractTerrestrial 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.

AbstractWater 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.

AbstractAs 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.

AbstractIt 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.

AbstractThere 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.