Applied Entomology and Zoology最新文献

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.

The predatory ladybird, Adalia bipunctata (Linnaeus) (Coleoptera: Coccinellidae), is a polyphagous species that primarily feeds on aphids. In this study, we assessed the demographic parameters and antioxidant activities of A. bipunctata individuals that were fed on Sitobion avenae (Fabricius) (Hemiptera: Aphididae) reared on wheat treated with Plant Growth-Promoting Rhizobacteria (PGPRs) (Biofarm and Probio96) and micronutrients (Librel Zinc and Alpha-Iron). The results showed that the shortest preadult period of A. bipunctata was recorded for individuals reared under Probio96 and Biofarm treatments. Additionally, the highest values of intrinsic rate (r) and net reproductive rate (R₀) of the predator were recorded under the Probio96 treatment, while the lowest values were observed with Alpha-Iron. The lowest activity levels of catalase, oxidized/reduced thiols ratio, peroxidase, and superoxide dismutase were found in 4th instar larvae. In contrast, the lowest antioxidant activities, except ascorbate peroxidase, were observed in adults. These findings were attributed to aphids reared on wheat fertilized with Probio96. It can be concluded that combining host plant resistance with Plant Growth-Promoting Rhizobacteria and biological control may offer an effective strategy for the integrated management of aphids.

The larvae of carpet beetles of the genus Anthrenus (Coleoptera: Dermestidae) are indoor pests that feed on dry animal matter. The varied carpet beetle, Anthrenus verbasci, which pupates in spring, controls the larval period using a circannual clock responding to changes in photoperiod. However, there is a lack of research on the mechanism controlling the larval period of Anthrenus beetles that pupate in autumn. The effect of photoperiod on larval development and pupation timing was examined at 20°C in Anthrenus nipponensis Kalík & Ohbayashi that pupates in autumn. The larvae developed well under constant long days of light/dark (LD) 16:8 h, and pupation occurred approximately 29 weeks after hatching. Under constant short days of LD 12:12 h, larval development was strongly suppressed, and only a few individuals were able to pupate. The median larval weight at 26 weeks after hatching under LD 12:12 h was 0.22 mg, 3.7% of that under LD 16:8 h (5.96 mg). Because of this suppression of larval development, it was inconclusive whether the larval period of A. nipponensis is controlled by a circannual clock. In addition, the transfer from LD 16:8 h to LD 12:12 h at 15 weeks after hatching resulted in pupation 9 weeks earlier than that at constant LD 16:8 h. It is probable that in the field, young larvae develop by exposure to long days in early summer and mature larvae exposed to decreasing daylength in late summer achieve synchronized pupation in autumn.

Trissolcus japonicus (Ashmead), native to Japan, has been known as an egg parasitoid of stink bugs. In particular, T. japonicus has been regarded as a potential biological control agent against the brown marmorated stink bug, Halyomorpha halys (Stål), which has spread to North America, South America, and Europe. While previous studies have suggested that T. japonicus has multiple strains with different genetic backgrounds that may lead to host-associated genetic differentiation, there has been limited research on this topic in the native range of T. japonicus. Additionally, it is suggested that T. japonicus contains multiple mitochondrial DNA lineages and varies in their ability to utilize different host species. This study aimed to investigate the genetic groups within T. japonicus specimens in Japan and their relation to geographic distribution, host use, and morphological characters using a mitochondrial DNA fragment and 429 genome-wide single nucleotide polymorphisms. The results of this study suggest the presence of multiple distinct genetic groups within T. japonicus specimens. These genetic differences did not align with clear differences in host specificity and/or availability; however, each genetic group was found in association with different host species, suggesting that they had potential differences in host range. Furthermore, multiple strains of T. japonicus were found to be distributed sympatrically with potential variation in host preferences. The use of such DNA sequence data was useful in recognizing and distinguishing between genetic strains of T. japonicus and will be important for identifying species through characteristics other than morphology. The importance of an integrated classification method and accurate identification database was also discussed.

Intercropping with barley enhances natural enemy populations, leading to effective pest suppression in cabbage and onion cropping. However, excessive barley growth can reduce crop yield under certain field and weather conditions. Here, we compared the effects of intercropping with barley and clover, a lower-growing alternative to barley, on pest suppression and yield. In spring cabbage, clover intercropping suppressed multiple insect pests to a similar extent as did barley. However, in autumn cabbage and spring onions, while clover still reduced pest pressure below the control, its effect was significantly lower than that of barley. Barley intercropping significantly reduced the weight of both cabbage heads and onion bulbs, whereas clover intercropping did not. There were no significant differences between barley and clover in the availability of alternative prey for natural enemies or the occurrence of ground-dwelling insects, such as carabid beetles. While clover intercropping had a lower pest suppression effect than barley, its ability to mitigate yield loss is an important advantage. However, since it provides less weed suppression than barley, careful consideration is needed in fields with high weed density.

Behavioral responses of the cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), to ultrasonic echolocation calls of insectivorous bats remain unclear for nocturnal predator–prey interactions. This study addressed ultrasonic pulse temporal characteristics that elicit escape responses from T. ni by subjecting tethered, flying moths of both sexes and host-searching mated females in particular to controlled ultrasound stimulation. By comparing moths flight response to bat call simulations with pulse-repetition rates (PRRs) ranging from 1 to 160 pulse/s, we show that ultrasonic pulses broadcast at 20 pulse/s (PRR20) are more effective in triggering T. ni evasive flight behaviors, especially for males which more frequently show flight cessation than females under tethered flight conditions. Focusing on mated females, the offspring (larvae) of which damage crops, ultrasonic pulses with PRR20 significantly reduced moth orientation towards host plants and decreased egg-laying frequency near them. These findings, provided by a quantitative assessment of T. ni response towards bat-like ultrasounds, demonstrates PRR20 as a major temporal parameter for ultrasonic pulse-induced evasive behavior in this species.

CRISPR/Cas9-mediated gene editing in insects conventionally relies on embryonic microinjection, which is challenging for non-model species. Therefore, adult injection-based methods have been developed to overcome this obstacle. One such simple and accessible method—direct parental CRISPR (DIPA-CRISPR)—enables gene editing by injecting the Cas9 ribonucleoprotein (RNP) into adult females. Subsequently, a modified approach called SYNCAS was developed by supplementing Cas9 RNPs with branched amphipathic peptide capsules and saponins as delivery enhancers. SYNCAS has been reported to yield higher gene editing efficiency (GEF) than DIPA-CRISPR in the spider mite. However, a direct experimental comparison of these methods under consistent conditions has not been conducted in insects. In the present study, we compared DIPA-CRISPR and SYNCAS methods in the predatory flower bug Orius strigicollis (Poppius) (Hemiptera: Anthocoridae), an important biocontrol agent. While peak GEF values were comparably high for both methods, SYNCAS-treated females continued to lay eggs with higher editing efficiency over a longer period than DIPA-CRISPR-treated females. It resulted in up to 4.8-fold higher yield of gene-edited progeny in the former group than in the latter group. These findings suggested that SYNCAS offers greater flexibility in terms of overall experimental design and gene editing outcomes than DIPA-CRISPR.

Sterols are essential for the growth, development, and survival of insects. Changes in the dietary sterol composition can cause significant metabolic and physiological effects. In this study, using a sterol-free artificial diet formulation supplemented with one of six sterols including (+)-4-cholesten-3-one, brassicasterol, campesterol, β-sitosterol, cholesterol, and stigmasterol, we investigated the effect of dietary sterols in larval growth of the tobacco cutworm Spodoptera litura (Lepidoptera: Noctuidae). We first confirmed by gas chromatography–mass spectrometry (GC–MS) analysis that our artificial diet contained extremely low amount of sterols. Tobacco cutworm fed the artificial diet supplemented with brassicasterol, campesterol, cholesterol, β-sitosterol, or stigmasterol showed higher survival rate and growth of S. litura larvae compared with those supplemented with (+)-4-cholesten-3-one or without sterol supplementation, leading to the preparation of more optimized diets for S. litura larvae. GC–MS analysis also revealed that the larvae fed on the diet supplemented with (+)-4-cholesten-3-one and without sterols showed little sterol content. This study indicated that sterols whose backbone is the same as that of cholesterol were utilizable by S. litura, while (+)-4-cholesten-3-one, which had different backbone, was not. By utilizing this sterol-free artificial diet, further research will be able to identify utilizable and non-utilizable sterols, establishing a comprehensive framework for sterol utilization in S. litura.