Applied Entomology and Zoology最新文献

Some maternally inherited endosymbionts are known to cause Cytoplasmic incompatibility (CI), in which uninfected females cannot or seldom produce offspring by mating with infected males. Mortality by CI may vary depending on the bacterial strain, the host’s genotype, or the host’s age. Mesenetia is an alphaproteobacterial endosymbiont infecting the coconut hispine beetle Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), a serious pest of the coconut palm. This bacterium was discovered in the Pacific clade B. longissima, which causes 100% CI mortality. The Mesenetia infection in the other Asian clade, which is considered more invasive than the Pacific clade, was then discovered; however, the CI was unknown. We investigated the CI ability of Mesenetia infecting the Asian clade using different ages of hosts originally collected in Japan. The effects of the host’s age on bacterial density were also investigated with qPCR. The results of crossing tests showed that infected males caused CI with approximately 70% mortality with uninfected females in all age groups: 21–30, 30–40, 60–70, or 90–100-day-old males. CI mortality did not differ among the males’ ages. Infected females rescued CI caused by infected males in all age groups: 15–20, 30–40, 60–70, or 90–100-day-old females. Results of qPCR showed that, in males, bacterial density did not diverge according to age in the testis, hindleg, foregut, midgut, and hindgut. In females, aged insects tended to have higher bacterial density than younger ones in the ovary and, to a lesser extent, in the hindgut.

Mirid bugs include polyphagous predators, which are used for augmentative biological control in the greenhouses to manage whiteflies, thrips and lepidopteran pests around the world. Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), which is indigenous to Japan, has recently been commercialised to control whiteflies and thrips. This predator species is expected to control both Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and Thrips palmi Karny (Thysanoptera: Thripidae) on greenhouse-grown cucumbers in Japan. To examine the suppressive effects of N. tenuis against these two pest species, occurring in cucumbers, it is essential to clarify the prey selection between them. In this study, we examined the preference of N. tenuis between B. tabaci and T. palmi on cucumber leaf discs under controlled conditions. Nesidiocoris tenuis female adults preferred T. palmi larvae over B. tabaci nymphs. Preference for T. palmi larvae was weakest when the density ratio of B. tabaci to T. palmi presented to the N. tenuis female was highest. Neither the nymphal developmental stage of B. tabaci, nor predation experience in either prey species prior to the experiment, significantly affected prey selection. Nesidiocoris tenuis has excellent predatory characteristics for the control of T. palmi when it co-occurs with B. tabaci on cucumbers in greenhouses.

Male solitary bees visit flowers and forage for floral resources (pollen and/or nectar), similar to females. However, little is known about the use of floral resources during this activity. In the present study, we focused on the solitary bee species Eucera spurcatipes Pérez, 1905 (Hymenoptera: Apidae), and investigated whether male individuals of any age continuously feed on floral resources throughout their lives. We collected males visiting red clover flowers from April to May. Wing-wear was used as an indicator of age, and the collected specimens were dissected to differentiate between feeding conditions. Wing-wear stages were positively related to the sampling period. Most individuals fed on nectar, and more than half fed on pollen. The proportion of pollen feeders was not related to age, whereas that of nectar feeders was significantly related to age. Our results suggest that males use pollen and nectar throughout most of their lifetimes.

Our earlier study revealed that pesticide use considering the preservation of phytoseiid mites is crucially important for the effective utilization of commercialized Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) release materials for spider mite control in Japanese pear orchards. Pesticide use alteration corresponding to commercialized N. californicus release material installation might change phytoseiid mite species composition and affect the efficacy of commercialized N. californicus in spider mite control. This study evaluated the effect of pesticide use alteration on phytoseiid mite species composition and subsequent spider mite control using commercialized N. californicus at Japanese pear orchards. We examined the population dynamics of spider mites and phytoseiid mites in Japanese pear orchards during 2019–2023. In 2022 and 2023, commercialized N. californicus release materials were installed at a Japanese pear orchard under conditions limiting the use of pesticides with adverse effects on phytoseiid mites. The results demonstrated that the most dominant species was shifted from N. californicus to Amblyseius eharai Amitai et Swirski (Acari: Phytoseiidae) with no significant suppression effects of commercialized N. californicus in spider mite control. The results also demonstrated a decline in the distribution of commercialized N. californicus to pear leaves. Amblyseius eharai and indigenous N. californicus dominantly existed in that order before commercialized N. californicus distribution to pear leaves. These results suggest that intraguild predation by A. eharai and competition with indigenous N. californicus might be involved in the less efficient distribution of commercialized individuals as major and minor factors, respectively.

The spillover and spillback of pathogens caused by invasive alien species represent a cryptic and significant risk. Honey bees, vital ecological and economic pollinators, face threats from numerous pathogens. Recently, honey bee pathogenic viruses have been identified in various arthropods, including ants, which are phylogenetically close to honey bees, raising concerns about non-honey bee insects transmitting these viruses. Argentine ants Linepithema humile Mayr (Hymenoptera: Formicidae), a globally invasive species, have been expanding their range in Japan since their first detection in 1993. This study attempted to detect four pathogenic viruses frequently detected in and may cause serious damage to the western honey bees Apis mellifera Linnaeus (Hymenoptera: Apidae) in Japan from Argentine ants invading managed hives of the honey bees. Quantitative PCR targeting four honey bee pathogenic DNA and RNA viruses detected Apis mellifera filamentous virus (AmFV) and black queen cell virus (BQCV) in Argentine ants attacking hives, with copy numbers ranging from 10¹–10² and 10³–10⁴, respectively. The copy number of deformed wing virus and sacbrood virus was below the detection limit. Homology searches of capsid protein-encoding genes and phylogenetic analysis revealed that all BQCV sequences from this study were most homologous to those previously identified in managed honey bees in Japan. However, AmFV sequences could not be obtained, likely due to the low copy number. These findings suggest that Argentine ants may act as a vector of AmFV and BQCV, raising concerns about their potential impact on the beekeeping industry.

The onion fly, Delia antiqua Meigen, 1826 (Diptera: Anthomyiidae), pupates underground and emerges as an adult in the early morning. This dipteran insect actively avoids adult eclosion in the middle of the day using the temperature amplitude as modulator of the circadian timing system. Daytime emergence is likely disadvantageous for newly eclosed D. antiqua adults. Therefore, in this study, we investigated whether high sand temperatures during the day prevented adult emergence from the sand. First, the upper thermal limit of the activity of newly eclosed adults was determined to be approximately 42 °C. Next, the newly eclosed adults were buried in heated sand in the laboratory to examine whether high sand temperatures inhibited their emergence to the sand surface. The flies failed to emerge to the sand surface when the temperature of the sand reached 43 °C. Finally, the newly eclosed adults were buried in sand in the field at different times of the day. All flies buried in the morning hours, when the sand temperature at a depth of 5 mm remained below 42 °C, successfully emerged from the sand. However, those buried at noon, when the sand temperature exceeded 42 °C, did not emerge to the sand surface. These results suggested that the temperature of sun-heated sand during the hottest times of the day is a limiting factor determining adult eclosion timing in D. antiqua.

Many insects use their sensory systems in various ways to detect substrate-borne vibrations for survival. This sensitivity can be utilized for pest management using vibrations as a sustainable non-chemical method. Recently, increases in ambient noise associated with human activity—known as anthropogenic noise—can also produce vibrations that may lead to unexpected reactions in insects. However, little is known about the impact of vibrations on individual development in insects. Furthermore, previous studies of anthropogenic noise have been dominated by airborne sound, and studies of substrate-borne vibration are limited. Here, we investigated the effects of vibrations on egg hatching and larval development in the dark-winged fungus gnat, Lycoriella ingenua (Dufour, 1839) (Diptera: Sciaridae), which is a major pest of commercial mushrooms worldwide. Vibration at a frequency of 3000, 1000, 800, or 100 Hz with low- or high-acceleration treatment suppressed the emergence rate to almost zero. Emergence rate suppression was caused by increased early and late larval mortality at 3000 Hz vibration, whereas it was caused by increased early larval mortality at 100 Hz vibration, suggesting that the impact varied with the frequency. Hatch rate was suppressed only at 3000 Hz and with low acceleration, indicating that the impact of vibration was much higher on emergence rate than on hatch rate. Our findings will help to develop vibrational pest management and mushroom cultivation, and to estimate the previously unexplored impacts of anthropogenic-noise-related vibration on insects.

Anopheles species are vectors for malaria. To date, insecticide application has been the primary method for controlling mosquito disease vectors. Chemical interventions to control vectors may occasionally prove ineffective, due to the development of insecticide resistance. Target-site insensitivity is one of the primary mechanisms that contribute to resistance. This study aims to determine the G119S (mutation of glycine to serine) and L1014S (mutation of leucine to phenylalanine) mutation rates of Anopheles superpictus Grassi, 1899 (Culicidae: Anophelinae) and Anopheles sacharovi Favre, 1903 (Culicidae: Anophelinae) populations and their seasonal variations in the Aegean Region. For both A. superpictus and A. sacharovi, the G119S mutation was observed at a low frequency during all three periods. The mean L1014S frequency for A. sacharovi populations in the spring 2018, fall 2018, and spring 2019 periods was 0.063, 0.156, and 0.196, respectively. For A. superpictus populations, the frequencies were 0.025, 0.013, and 0.024, respectively. Pyrethroids, the most widely utilized insecticide in recent years, which are presumed to be effective, will ultimately exhibit reduced efficacy in some of these populations.

The photoperiodic regulation of pupariation and pupal diapause was investigated in the flesh fly, Sarcophaga similis (Diptera: Sarcophagidae), focusing on the roles of short neuropeptide F (sNPF) and prothoracicotropic hormone (PTTH). Under long-day conditions, pupariation occurred earlier than under short-day conditions, corresponding to an earlier peak in hemolymph ecdysteroid titer. The molecular elements regulating the transient ecdysteroid surge for pupariation remain unknown. After pupation, the ecdysteroid titer remained higher in long-day individuals, preventing diapause. Notably, sNPF and Ptth were simultaneously upregulated before the increase in ecdysteroids under long days, followed by upregulation of an ecdysteroidogenesis gene neverland (nvd). These results suggest that the downregulation of sNPF and Ptth under short days is involved in the downregulation of nvd and ecdysteroids, initiating diapause. This study provides insights into the photoperiodic regulation of diapause, highlighting the potential involvement of sNPF and PTTH, but further research using data-driven multi-omics approaches is necessary to elucidate the molecular mechanisms underlying these photoperiodic responses.

Many plant-sucking stinkbugs develop a symbiotic organ in a posterior region of the midgut, wherein specific symbiotic bacteria exist and contribute to survival and reproduction of their hosts. The symbiotic bacteria range from uncultivable ones that have lost the capability of proliferation without their hosts to cultivable ones that retain the ability to proliferate not only within their hosts but also in the external environment. Such diverse host–symbiont relationships seem to represent different evolutionary stages from free-living through facultative symbiosis to obligatory mutualism. However, our understanding of such evolutionary processes toward symbiosis is still limited. Here we investigated the gut symbiotic bacteria of the invasive jewel stinkbugs Scutellera amethystina (Germar) (Hemiptera: Scutelleridae) collected from different subtropical island populations in Japan. While most insects were associated with a specific Pantoea-allied uncultivable bacterial symbiont in the midgut symbiotic organ, we found an insect associated with a phylogenetically distinct Pantoea symbiont, which was cultivable and closely related to cultivable gut symbiotic bacteria previously reported from other stinkbug species. These results uncover intraspecific coexistence of uncultivable and cultivable gut symbiotic bacteria in S. amethystina, which provides insights into the evolutionary processes toward obligatory mutualism and symbiont uncultivability.