Entomological Science最新文献

This study examined the effects of diet mixing during the nymphal stage on the performance of the brachypterous grasshopper Podisma sapporensis during both the nymphal and adult stages. This species mainly feed on the leaves of Japanese butterbur, Petasites japonicus var. giganteus (Pjg), and also feed on the leaves of giant knotweed, Reynoutria sachalinensis (Rs), wormwood leaves, Artemisia montana, and angular Solomon's seal, Polygonatum odoratum var. maximowiczii. We investigated whether diet mixing with Pjg during the nymphal stage enhances the survival or fecundity of this grasshopper. It was revealed that feeding nutritionally inferior Rs to nymphs extended the adult lifespan. The reproductive speed per lifespan was reduced in females fed the mixed diet, as there was no significant difference in the number of eggs laid per lifespan regardless of the Rs ingested. These results indicate that diet mixing, or the additional Rs intake, had an opposite effect on the life history in the form of higher nymphal mortality and longer adult lifespan of P. sapporensis, altering the reproduction schedule.

The Dermaptera (earwigs) are widely known to the public but have been much less documented in the literature as a taxon of anthophilous insects. Here, we report on the floral utilization of two sympatric earwig species, Forficula mikado and Anechura harmandi, from summer to autumn on Rebun Island, Hokkaido, Japan. Both the nymphs and adults utilized diverse plant taxa (36 species from 15 families) as either foraging or resting sites. They often utilized flowers of the Asteraceae (15 species) and/or Apiaceae (5 species) as foraging sites, probably because of their easily accessible, exposed pollen. In A. harmandi, both nymphs and adults primarily foraged on asteraceous flowers. However, in F. mikado, nymphs frequently utilized apiaceous flowers, whereas adults primarily exploited asteraceous flowers. This ontogenetic dietary shift may be explained by an innate preference of F. mikado nymphs for apiaceous flowers rather than competition for floral resources between F. mikado and A. harmandi nymphs, because flower-visiting earwigs were not so abundant on the island.

Thickness of woody tissue of host plants may affect behaviors of wood-using insects that excavate the woody tissue during oviposition. To determine whether females of the bamboo-using lizard beetle, Doubledaya bucculenta (Coleoptera: Erotylidae: Languriinae) choose thin-walled areas of Pleioblastus simonii bamboo internodes to penetrate the wall for oviposition, we investigated the diameter and wall thickness at each of the relative heights (0 to 10 from basal node) within internodes and the distribution pattern of oviposition marks of D. bucculenta within each internode. Internodes of P. simonii were tapered and the wall was thinnest around the relative heights 7 and 8. Most oviposition marks were made where the wall was thinnest. Therefore, it is suggested that D. bucculenta females prefer thin-walled areas of P. simonii internodes for oviposition.

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.