Entomological Science最新文献

The analysis of 18S ribosomal DNA (rDNA) localization was undertaken in two subgenera of the genus Aedes (subgenus Aedes and subgenus Ochlerotatus). Seven species of the subgenus Ochlerotatus belonging to the cantans group (Ae. excrucians, Ae. behningi, Ae. euedes) and to the communis group (Ae. communis, Ae. punctor, Ae. intrudens, Ae. cataphylla) were studied. The subgenus Aedes was presented by the species Ae. rossicus. We revealed the difference in 18S rDNA localization in chromosomes between the studied subgenera. The study also indicated that the distribution of 18S rDNA in the groups of the subgenus Ochlerotatus correlates with their morphological division into groups, with the exception of one species, Ae. cataphylla. The obtained data can be used for chromosome mapping and evolutionary and taxonomic studies.

Here, 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.

The 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.

Wasps 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.

In 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.

To 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.

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.