Applied Entomology and Zoology最新文献

Differences in life-history traits, such as fertility, resource consumption, and developmental parameters, can determine the advantage among competing species. A previous study of three leaf beetles with overlapping host ranges and active season—Laccoptera nepalensis Boheman (Coleoptera: Chrysomelidae: Cassidinae), Aspidimorpha difformis (Motschulsky) (Coleoptera: Chrysomelidae: Cassidinae), and Aspidimorpha transparipennis (Motschulsky) (Coleoptera: Chrysomelidae: Cassidinae)—revealed that L. nepalensis competitively excluded A. difformis due to resource competition under rearing conditions, but A. difformis still habited in the fields. Conversely, reared A. transparipennis and L. nepalensis did not compete, but A. transparipennis was rare in the field. Thus, this study aimed to clarify whether differences in life-history traits among the three phylogenetically-related leaf beetles influence the outcome of competition and competitiveness. Specifically, resource consumption, fertility, and developmental parameters of three leaf beetle species were measured experimentally, and their seasonal occurrence was predicted. Resource consumption and fecundity were the lowest in A. transparipennis and A. difformis, respectively; they were the highest in L. nepalensis. Additionally, predicted seasonal occurrence was mismatched between the two Aspidimorpha species and the coexisting L. nepalensis. These results suggest that the two Aspidimorpha species can avoid co-occurrence with L. nepalensis, which carries the risk of resource depletion through temporal niche partitioning. However, because the annual generation of L. nepalensis and A. transparipennis was more than one, any shift in their seasonal occurrence could lead to resource depletion for A. transparipennis. This study underscores the importance of discussing the processes and results of interspecific competition based on differences in life-history traits.

Aromia bungii is an invasive wood-boring beetle that creates planned adult emergence holes (PAEHs) prior to reaching the pupal stage, likely due to the limited boring ability of adults. Targeting PAEHs has been proposed as a physical control method, but its effectiveness under field conditions remains untested. We conducted laboratory and manipulation experiments to evaluate the ability of adhesive materials to seal PAEHs, ultimately selecting an epoxy-based adhesive with high blocking performance. A field trial on infested cherry trees showed that sealing visually identifiable PAEHs significantly reduced adult emergence compared to unsealed controls. These findings provide the first empirical support for sealing PAEHs as a non-chemical method to suppress A. bungii adult emergence. This technique represents a promising strategy for integrated pest management strategies. However, emergence from previously undetected PAEHs indicated that relying solely on visual detection is insufficient. Future research should focus on improving the accuracy of PAEH detection, refining adhesive application protocols, and integrating this method with other complementary control tools for more effective and sustainable management of this invasive pest.

Understanding the molecular mechanisms and evolutionary dynamics underlying pesticide resistance in arthropod pests is essential for developing effective control strategies. The two-spotted spider mite Tetranychus urticae Koch (Trombidiformes: Tetranychidae) has acquired resistance to most acaricides, leading to the emergence of multi-acaricide-resistant populations worldwide. This species has the smallest genome size among arthropods (~ 90 Mb) and the haploid chromosome number of n = 3. This review shows that there is a strong linear correlation between physical and genetic distances among loci in this spider mite, which allows direct estimation of recombination rates between loci. Notably, T. urticae showed the highest recombination rate (average 9.4 cM/Mb) among eukaryotes, excluding fungi and unicellular organisms. Next, the distribution of target sites and detoxification enzyme loci associated with acaricide resistance is summarized. Of the 14 target site loci, eight are located on chromosome 1 (CRM1), and three each are located on CRM2 and CRM3; the recombination rates between them exceeded 30% with only a few exceptions. The recombination rates of target sites and detoxification enzyme loci involved in resistance to major acaricides used worldwide were then analyzed. The results showed that these resistance genes have an uneven distribution across the genome. Three peak regions related to resistance to 6–9 acaricides per 10% recombination rate were detected on CRM1, and one on CRM3. The findings suggest that application of a certain acaricide selects individuals and associated genomic regions harboring target site mutations that disrupt affinity and/or overexpression of detoxification enzyme genes, thereby facilitating cross-resistance or multiple resistance.

Most insects can fly. The acquisition of flight is a factor that allows insects to prosper on Earth. On the other hand, in the same species and population, individual differences in flight ability may occur. Flight ability can vary due to geographical conditions and cumulative rearing. Investigating these changes in flight performance is important for understanding dispersal polymorphism and the evolution of flight performance. Thus, in the present study, the flight behaviors between cumulative rearing and field strains and changes in flight behaviors between strains of the red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), which is distributed around the world were compared. Tribolium castaneum is a worldwide pest of stored grains. Its body length is about 3–4 mm. Previous studies have investigated the influence of environmental and physiological factors on the flight of this species, but no studies have examined individual differences or polymorphism in flight behaviors within this species. In this study, we developed a simple apparatus that can quantify the flight behavior of this species. The experimental apparatus was set up as a double structure with two different size containers. This apparatus was able to assess the flight activity of insects by counting individuals in a big container because insects transfer to the big container only by flight. Moreover, upward flight ability was possible to be assessed by the apparatus adding the barrier. Then, the flight behavior was compared between strains of this species that have been bred in the laboratory for more than 45 years and several strains of this species collected in the field. The results showed no variation in flight activity between strains, but flying ability was higher in strains originating from warmer regions. Here, we discussed the variations in flight behavior of T. castaneum.

Paracentrobia (Paracentrobia) fusca Lin (Hymenoptera: Trichogrammatidae), which was previously known only from mainland China, is newly recorded from Australia, India, Japan, Pakistan, Papua New Guinea, and Thailand. Its host associations were previously unknown. In Japan, it was reared for the first time from sentinel eggs of the green rice leafhopper, Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae), on rice plants exposed to parasitization in a rice field in Fukuoka Prefecture on Kyushu Island. All the individuals emerged as a single specimen per one host egg. This solitary egg parasitoid can be regarded as just an occasional natural enemy of N. cincticeps in Japan as it was reared from this rice pest only once and at one locality. Our finding expands the known distribution of P. fusca and provides the first record of its host association. To assist with identification, both sexes of P. fusca are for the first time illustrated with digital images to facilitate their recognition.

This study investigated whether the decision of thrips to invade fig (Ficus carica L.) fruits involves a preference for fruit age, in addition to the development of the ostiole opening. It is known that the ostiole of tested ‘Masui Dauphine’ (syn. ‘San Piero’) fig fruits opens widely from a young age and is thus often damaged by the thrips. In 2021, when young fruit of various sizes on basal nodes of the shoots were halved lengthwise, thrips were detected only in the fruits wider than 28–< 38 mm range in width (age estimated 19–26 days after fruit set), but not in fruits smaller (younger) than that, even when the ostioles opened enough to allow entry. In 2024, the ostioles of young fruits of various sizes growing at the same time were first sealed with wood glue, artificially opened for 5 days at different developmental stages by boring a hole, and then resealed. There was a peak in the rate of thrips detection in the fruits held open at age estimated 19–26 days after fruit set. These results suggest that thrips prefer to invade fig fruits 3–4 weeks after fruit set, and ignore both younger and older fruits, even if their ostioles are morphologically passable. Thrips detected in older fruits were considered to have invaded during a prior prefer period and their offspring.

Invasive insects have recently caused significant damage to agricultural and horticultural plants in Japan. In 2017, Thecobathra lambda (Moriuti, 1963) (Lepidoptera: Yponomeutidae) was first confirmed in Kyushu, Japan, as an invasive micromoth pest damaging American sweetgum (Liquidambar styraciflua L.). This study documented occurrence data for this moth at four sites in Hyogo Prefecture on Honshu and 12 sites in Ehime, Kagawa, and Tokushima on Shikoku, with confirmed occurrence at high density at one site per prefecture. The larvae were first observed in Japan feeding on leaves of Liquidambar formosana Hance in Tokushima. Genetic analyses based on partial nucleotide sequences of the cytochrome c oxidase subunit I (CO1) in T. lambda identified seven haplotypes, including two unique ones in the Hyogo and Kagoshima populations, suggesting multiple invasion events or a single invasion event involving large numbers of individuals. Additionally, five parasitoid wasps associated with the larval stage of T. lambda were identified: Diadegma armillatum (Gravenhorst, 1829) (Ichneumonidae; new to Japan), Goniozus japonicus (Ashmead, 1904) (Bethylidae), and Eulophidae gen. sp. 1–3. These wasps emerged from over half of the T. lambda individuals, suggesting their potential as important biocontrol agents in Japan. Notably, genetic analyses of D. armillatum revealed that a haplotype from Hyogo was identical to one from Europe. Given this finding and the broad host range of D. armillatum, it is likely that trans-Eurasian introduction events have occurred, potentially facilitated by human-mediated transportation of agricultural and horticultural plants.

The morphological characteristics of the prothoracic depressions in adult oak ambrosia beetles, Platypus koryoensis (Murayama) (Coleoptera: Curculionidae: Platypodinae), were investigated using electron microscopy and energy-dispersive X-ray spectroscopy. The depressions were categorized into three types based on their diameter: (i) small cavities, (ii) large cavities, and (iii) mycangia. Females exhibited all three types of depressions: (i) small cavities (10.04 μm), (ii) large cavities (13.21 μm), and (iii) mycangia (62.81 μm). In contrast, males possessed only two types: (i) small cavities (11.12 μm) and (ii) large cavities (15.88 μm). The prothoracic depressions were characterized by (i) cavity-filling masses containing filamentous fungi and yeasts and (ii) an inner process or sensillum on the depression sidewall. Overall, females had a greater number of depressions than males. A novel sawtooth morphology in the inner processes was observed in female mycangia, whereas smooth-margin inner processes were noted in the large cavities of males. Furthermore, crystals found in the cavities of males primarily consisted of calcium, silicon, and potassium, possibly derived from the penetration of oak stems. These findings provide a morphological basis for a deeper understanding of the symbiotic relationship between Platypus species and their ambrosia fungi.

Spinosad plays a crucial role in the control of Phthorimaea absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), a major pest of tomato, as it is approved for use in both conventional and organic tomato production. However, loss of efficacy due to resistance development has been reported. In this study, we assessed the susceptibility of five field-collected P. absoluta strains to spinosad. Additionally, comparative transcriptome analyses were performed to investigate expression changes of constitutively overexpressed and induced genes associated with spinosad resistance in P. absoluta. Reduced susceptibility (up to 79-fold resistance) to spinosad was identified in the field strains. Transcriptome analysis revealed 3438 genes with constitutive overexpression and 799 genes exhibiting differential expression following spinosad treatment. Further analysis showed that 117 constitutive and 245 spinosad-induced gene expressions related to defense, insecticide detoxification, transport, and stress response, which may play a role in spinosad resistance in P. absoluta. Gene Ontology (GO) enrichment analysis revealed that the up-regulated differentially expressed genes (DEGs) were significantly enriched in neural regulatory processes, potentially indicating neuronal adjustments following spinosad exposure. Our research lays an important basis for a better understanding of spinosad resistance and its management.

Female moths of the fall webworm, Hyphantria cunea Drury (Lepidoptera: Erebidae), produce sex pheromones consisting of four components derived from essential fatty acids: (9Z,12Z)-9,12-octadecdienal (component I), (9Z,12Z,15Z)-9,12,15-octadecatrienal (component II), cis-9,10-epoxy-(3Z,6Z)-3,6-henicosadiene (component III), and cis-9,10-epoxy-(3Z,6Z)-1,3,6-henicosatriene (component IV). Intraspecific variations in the blend ratio of these components have been reported from different countries. Although the blend ratio of the sex pheromone components in these moths is known to vary depending on their host plants, the molecular mechanism remains unclear. As linoleic acid (LA) and α-linolenic acid (ALA) are essential fatty acids that cannot be de novo biosynthesized or interconverted, dietary differences in these fatty acids may affect the blend ratio of the four pheromone components produced by adult female moths of the species. We found that H. cunea fed on an artificial diet (group AD) in larval stage secreted more significant amounts of sex pheromone component I than those reared on mulberry leaves (group M). The subsequent switching-diet assay revealed that dienyl aldehyde components were generated by ingesting linoleic acid for 7 days before pupation. Our results demonstrate that a shift in the component ratio of sex pheromones can occur within generations through diet change, not only by genetic variation.