Applied Entomology and Zoology最新文献

Insects with positive phototaxis fly to artificial light sources at night, stay there for a certain amount of time, and then fly away. Although many studies have been conducted on the arrival time of flying insects at artificial light sources, little is known about the time at which they fly away (departure time), duration of stay, and staying time zone. This information is important to protect phototactic insects from the fatal attraction to light that is known as a serious ecological light pollution. In this study, we aimed to identify the duration of stay and staying time zone for various insect species by marking them with light traps. Among the 63 species belonging to 11 orders observed at the study site, cluster analysis focused on 27 species for which 5 or more data points were obtained, highlighting three predominant stay patterns. Type 1 species arrived approximately 1.3 h and flew away approximately 4.1 h after sunset and stayed for a short period of approximately 2.6 h. Type 2 species arrived at approximately 1.2 h and flew away for approximately 9.6 h, with an 8.4 h stay. Type 3 species arrived later than Types 1 and 2, were attracted for 5.4 h, and flew away approximately 13.5 h with an 8.2 h stay. These results suggest that conservation biological countermeasures against light-attracted flying insects need to consider the stay patterns of insects that remain under outdoor lighting.

Reemergence and sister broods (second broods) are commonly observed in bark beetles (Coleoptera: Curculionidae: Scolytinae), particularly in species with male-initiated polygyny and female-initiated monogyny. Polygraphus proximus Blandford, a male-initiated monogynous bark beetle, is a quarantine species in the EU, which has been introduced from east Asia into both Siberia and central European Russia, causing mortality of trees across large areas of Abies sibirica forests. To clear whether P. proximus females reemerge to lay additional broods (sister broods), we observed the reproduction of reemerged females under laboratory conditions. We prepared 25 females reproducing in galleries collected by peeling the infested logs and 25 females reemerged from such logs. These females were put into the tubes vertically attached onto the surfaces of logs. Consequently, approximately 40% of both the reproducing females in galleries and the reemerged females bored into the logs and established sister broods without repeated mating. Moreover, 21% of these reproducing females established sister broods again using the same procedures, suggesting that the females can establish sister broods more than once. Our results indicated that the fecundity of P. proximus is higher than previously assumed, suggesting that its population levels can rapidly increase in weakened or dead trees, ultimately leading to the ability to attack healthy trees during the epidemic phase.

Invasive longhorn beetles are serious pests of tree stands worldwide. The rusty-spotted longhorn beetle, Apriona swainsoni (Hope) (Coleoptera: Cerambycidae: Lamiinae), is native to continental Asia, where it is a significant pest of legume trees. Its invasion into non-native ranges and damage to the local legume tree, Maackia amurensis, were first reported from Fukushima Prefecture, Japan, in 2021. This study investigated the biology of A. swainsoni in relation to adult emergence in Japan. Preliminary observations confirmed that A. swainsoni larvae create planned emergence holes on the host surface in late May. By exploiting these planned emergence holes, the adult emergence period was investigated in a field promenade of M. amurensis during the summer of 2022 and 2023. The researchers plugged the holes and recorded plug removal, resulting in the observation of 60 and 227 putative emergence events in respective years, with the majority occurring in early to mid-July. Further, during the summer of 2022, a periodic field survey of adult emergence was conducted, obtaining eight adults. Furthermore, a supplementary survey using infested logs maintained in a field cage demonstrated that the emergence period does not differ between sexes and the male-to-female ratio is one:one. Our results suggest that control efforts to suppress A. swainsoni adults in the field, such as insecticide spraying, should be prioritized in the relatively short, peak emergence period. This work indicates that the plug survey is useful for detecting the emergence period.

Three Japanese conifer-infesting gall midges (Diptera: Cecidomyiidae), Aschistonyx eppoi Inouye on Juniperus chinensis var. globosa, Dasineura nipponica Inouye on Larix kaempferi, and Janetiella kimurai Inouye on Pinus parviflora are redescribed based on specimens kept in the collection of Naturalis Biodiversity Center, The Netherlands, in the collection of Kyushu University, Japan, and those newly obtained in 2021 and 2022 from their type localities in Japan. In the redescriptions, we refer mainly to morphological features not sufficiently given in the original descriptions. For A. eppoi, a genus Byakushincecis is created. We provide genetic data of the three species for future taxonomic and phylogenetic studies. In addition, we identified Byakushincecis eppoi infesting bonsai of Juniperus chinensis var. sargentii at a nursery garden in Saitama, Japan. These trees were intended for export to the EU.

To optimize operating conditions and the selection of pesticides suitable for spraying from UAVs, we evaluated the coverage of sprayed droplets in the range of 0.001–100% coverage by constructing an indoor spraying device. With the device, the coverage rate decreased with the horizontal distance from the nozzle, and the complementary log–log transformed value of the coverage was approximated by a quadratic function of the distance. The natural logarithm of the deposited pesticide amount could be linearly expressed by the complementary log–log transformed value of the coverage. Different probit regression equations were obtained between the coverage rate of sprayed droplets and egg mortality of Panonychus citri due to four acaricides: spiromesifen, etoxazole, milbemectin, and acynonapyr. From the probit regressions, conventional spraying achieved 90% egg mortality with 150 mg/L spiromesifen (19–23% coverage rate), 50 mg/L etoxazole (14%), 10 mg/L milbemectin (98%), and 67 mg/L acynonapyr (92%). Ultra-low-volume concentrate spraying for UAVs achieved the same with 15,000 mg/L spiromesifen (0.017%), 5000 mg/L etoxazole (1.116%), 1000 mg/L milbemectin (1.339%), and 6667 mg/L acynonapyr (8.868%).

The Mexican soybean weevil, Rhyssomatus nigerrimus Fahraeus (Coleoptera: Curculionidae), is a pest of soybeans. In this study we evaluate the volatiles of the soybean flower of the varieties FT-Cristalina-RCH and Flores as possible attractants for R. nigerrimus. Behavioral bioassays using an “Y” tube olfactometer and Electroantennography tests were performed to evaluate the responses of R. nigerrimus to the soybean flowers and their volatile extracts, in addition the volatiles were collected by dynamic aeration and identified using gas chromatography coupled with mass spectrometry (GC–MS). Bioassays showed that females and males were attracted by the flowers and volatile extracts of flowers of both varieties. However, females exhibited stronger antennal response than males to the volatile extracts of flowers of both varieties and their synthetic blends. The volatile extracts analysis showed the presence of 1-octen-3-one, 2-ethyl-1-hexanol, limonene, α-copaene, α-pinene, undecane, nonanal, octyl hexanoate, trans-α-bergamotene and calamanene. Quantitative differences in 1-octen-3-one, 2-ethyl-1-hexanol, α-pinene and limonene between the varieties were observed. In bioassays, males and females were attracted by α-copaene, 1-octen-3-ol α-pinene, and both synthetic blends. Females exhibited stronger antennal response than males to the synthetic compounds α-pinene, α-copaene, 1-octen-3-ol, nonanal and limonene.

Trunk injection with imidacloprid is used to reduce the infestation rate of trees by pests. However, further research is needed to determine the insecticide persistence in trees. Here, we present a case study in which we evaluated horse chestnut trees for imidacloprid residues and the invasive leaf miner Cameraria ohridella (Lepidoptera: Gracillariidae) infestation 14 years after a single injection (5 mL of pesticide per tree). We detected residues of imidacloprid (on average 0.648 μg/kg in leaves) and its metabolites: imidacloprid-guanidine in leaves and inflorescences and imidacloprid-urea in the leaves of treated trees. In addition, imidacloprid residues in inflorescences were at much lower concentrations (on average 0.07 μg/kg) compared to those found in leaves. Tree infestation by leaf miners was significantly lower in injected trees (0.035 mines/cm²) than in control trees (0.091 mines/cm²). Our research thus indicates for the first time that, once applied, imidacloprid may affect the target and non-target species for a long time owing to its persistence in plant tissues.

Population models provide a logical knowledge base before conducting laborious and expensive field experiments. Historically, two types of population models have been developed: highly realistic simulations and simple analytical models. Highly realistic simulations comprise a complicated systems model, whereas simple analytical models comprise various analytical models that focus only on the fundamental structure of the target pest population. Although both approaches have contributed to pest management science, each has limitations, poor predictability, and lacks substantial connections to reality. Assimilation by state-space modeling, in which observation and process models are jointly incorporated, is a good compromise between a simple model and reality in nature. In the big data era, artificial intelligence (AI), specifically aimed at high predictability, has recently become popular. If vital physical and biological records are automatically censored in the field with high precision, AI will produce the most plausible predictions, providing the best practical solution given our current knowledge. AI can be a powerful tool in the contemporary world; however, deductive modeling approaches are still important when considering the behavior of AIs and may also provide important insights to detect deficient information in the data.

Among the hemocytes of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), oenocytoids are lysed very quickly after hemolymph collection. We clarified that the lysis of oenocytoids can be greatly inhibited by collecting hemolymph under the introduction of carbon dioxide (CO₂) gas. Since nitrogen and helium gasses were ineffective in inhibiting oenocytoid lysis, it was concluded that CO₂ itself was necessary to inhibit lysis. Insect anesthetization with CO₂ gas before bleeding was not necessary to prevent oenocytoid lysis, but CO₂ gas was required at and after the time of bleeding. When the hemolymph was collected in a Petri dish under CO₂ gas and sealed, oenocytoids remained present without lysis even after an hour at 25 °C. Oenocytoids were not irreversibly fixed since lysis occurred when this hemolymph was exposed to air. When the hemolymph was collected in air, granulocytes adhered to the bottom surface of the Petri dish, and plasmatocytes spread out on the bottom surface. However, when collected under CO₂ gas, both types of hemocytes remained spherical, and few cells were observed to spread out on the bottom surface. Thus, it was suggested that oenocytoid lysis inhibition by CO₂ gas is associated with the suppression of defensive reactions to foreign materials by hemocytes. This hemolymph collection method can be easily performed without special pretreatment of the hemolymph. Accordingly, this method is considered to be advantageous for studying the possible role of oenocytoids associated with host defense mechanisms in insects.

Diapause is a programmed stage-specific arrest or delay in reproduction or development and is commonly used to circumvent an adverse season. Some insect species exhibit maternal regulation of diapause, wherein environmental cues are perceived by the mother and subsequently determine the developmental fate of the offspring. Although maternal regulation of diapause is widespread, its endocrinological mechanisms remain largely unknown. In the band-legged ground cricket Dianemobius nigrofasciatus (Orthoptera: Trigonidiidae), embryonic diapause is maternally determined. Adult females under long-day conditions lay eggs that develop into nymphs without interruption, whereas those under short-day conditions lay diapause-destined eggs that arrest their development and enter diapause at a very early embryonic stage, the cellular blastoderm. How development is arrested at an early stage is a key area of interest. We hypothesized that juvenile hormone III (JH III) and 20-hydroxyecdysone (20E), the major insect hormones that regulate a wide variety of physiological processes, are involved not only in maternal decisions, but also in diapause entry in D. nigrofasciatus. The results showed that the hemolymph concentrations of JH III and 20E in adult females were lower under short-day conditions; however, the application of JH III and 20E to the mothers did not affect the diapause incidence of offspring. No differences were observed in the amounts of 20E between non-diapause and diapause-destined eggs, and JH III was not detected in these eggs. Thus, we found no evidence for the involvement of JH III and 20E in maternal decisions for embryonic diapause and diapause entry in D. nigrofasciatus.