Applied Entomology and Zoology最新文献

Originally endemic to Asia, Drosophila suzukii (Matsumura, 1931) is a serious agricultural pest that is spreading rapidly throughout the world. To suppress the growing D. suzukii populations, several pest management programs have been implemented. Researchers have searched for natural enemies, such as predators, parasites, parasitoids, and pathogens. We discovered an obligate ectobiont fungus, Stigmatomyces majewskii H. L. Dainat, Manier & Balazuc, 1974, which is associated with D. suzukii. Our laboratory experiments revealed that S. majewskii infection was successfully transmitted through self-grooming and sexual contact during the courtship behavior of D. suzukii, although non-sexual contact through other behaviors may also be involved. Infected flies lived long enough for S. majewskii to mature on the host. Other fitness traits, such as fecundity, are necessary to evaluate the effect of S. majewskii on D. suzukii.

The gut bacteria of insects are associated with digestion, nutrition, and reproduction. The midgut bacteria of Anopheles mosquitoes have been examined predominantly for their effects on the transmission of Plasmodium parasites. However, the effects of midgut bacteria on Anopheles mosquitoes have not been studied. In this study, we investigated the effects of midgut bacteria on adult female An. stephensi mosquitoes. These mosquitoes were fed antibiotics mixed with 10% sucrose for 2 weeks to alter the composition of their midgut bacteria. The results showed that the mosquitoes fed with streptomycin (ST) or kanamycin (KM) showed inhibited egg maturation 2 days after blood feeding. Methylobacterium sp. was the predominant bacterium in the midgut of mosquitoes fed KM or ST for 2 weeks (ST/2 weeks). Mosquitoes that were fed suspensions of Methylobacterium sp. isolated from the midgut of ST/2 weeks after blood feeding for 3 days showed inhibited egg maturation. Furthermore, egg maturation was inhibited in mosquitoes that were fed supernatant and precipitate obtained by boiling and centrifuging Methylobacterium sp. suspension. Thus, this study demonstrated that Methylobacterium sp. isolated from the midgut of An. stephensi mosquitoes after blood feeding inhibited egg maturation.

The insect integument, which consists mainly of chitin microfibrils and cuticular proteins, is an extracellular matrix that covers the entire external and some internal surfaces of the insect body and serves as a primary barrier against several environmental stresses. Using RNAi-mediated gene knockdown procedure, we performed functional analyses of three adult-specific cuticular protein genes, CPR4, CPR18, and CPR27, regarding their involvement in repelling chemical insecticides in the red flour beetles, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). The depletion of these CPRs produced adult phenotypes with malformed (wrinkled/dimpled) elytra as well as thinner and disorganized cuticle of abdominal sternite. After knocking down the CPR genes, the beetles were exposed to six types of neonicotinoid-class insecticides, and the short-term neurotoxic effects were evaluated. The knockdown of any of CPR genes, either singly or in combination, increased the beetles’ susceptibility to neonicotinoids compared to negative control beetles. The results suggested that CPR4, CPR18, and CPR27 have an indispensable role in organizing the insect integument structure that can regulate the penetration rate of xenobiotics such as neonicotinoid insecticides, presumably by helping built proper structural features of cuticular layer.

The concealed gall inducers represent a significant challenge for both study and control within the realm of pest management. Gaining an understanding of the natural enemies that influence gall inducer populations is essential for the development of effective integrated pest control strategies. Haloxylon spp. are dominant xerophyte species that possess substantial ecological importance due to their roles in shelter provision and sand fixation. This study aimed to determine the main gall inducers that induce globular galls on both H. ammodendron and H. persicum and the parasitoid complex associated with them. Totally, two species of gall inducers and four species of parasitoids were obtained from the globular galls. Suaediola sp. was recorded as the predominant gall inducer, exhibiting biannual generational turnover. Both Torymus sp. and Mesopolobus quadrimaculatus were primary solitary koinobiont ectoparasitoids of gall midges, while only Platygaster sp. was endoparasitoid. Torymus sp. established dominance among the parasitoids, demonstrating a predilection for attacking first instar larvae. We also found that temperature variations significantly influenced the emergence and lifespan of the insects recorded from the galls, with a consistent trend of shortened wasp lifespan correlating with increasing temperature. According to these results, we conclude Torymus sp. could have an important potential to control gall inducers within closed galls and, therefore, should be considered for inclusion in the integrated pest management programs of Haloxylon forests in China.

Beta-1,3-glucan recognition protein (βGRP) is an important pattern recognition receptor, which induces an immune response by recognizing and binding the pathogenic bacteria. In this study, we identified two βGRP genes in S. furcifera, βGRP1 and βGRP2. Both βGRP1 and βGRP2 proteins have a glycosyl hydrolases family 16 (GH16) domain  and a concanavalin A-like lectin/glucanase domain near the C-terminal. Quantitative polymerase chain reaction (qRT-PCR) analysis showed that the transcript levels of βGRP1 and βGRP2 in the fat body and gut were higher than those in other tissues. Furthermore, both were upregulated in response to challenges with Escherichia coli and Staphylococcus aureus. Recombinant βGRP1 and βGRP2 had a strong affinity for E. coli and S. aureus and caused bacteria to agglutinate. However, the results of the CCK-8 and bacteriostatic zone methods showed that recombinant βGRP1 and βGRP2 inhibited S. aureus but did not inhibit the growth of E. coli. Moreover, the silencing of βGRP1 or βGRP2 using dsRNA significantly downregulated the expression of the Toll pathway gene Dorsal after S. aureus challenge, while it did not affect the Imd pathway gene Relish.

Spodoptera littoralis (Boisd) is globally known as an important polyphagous pest that causes considerable damage to agricultural crops in the world. In this study, the effects of different mung bean (Vigna radiata L.) varieties, including Parto, Simite1, Simite2, VC6371, VC3960, VC6173A, and VC6368 were investigated on the life history variables, biological characteristics, and population growth parameters of S. littoralis. Our purpose was to identify potential tolerance characteristics of mung bean varieties against S. littoralis. Our findings showed that various mung bean varieties significantly impact the life history and demographical parameters of S. littoralis. The results revealed that the longest and shortest developmental time across all immature stages were recorded on Simite2 (42.52 days) and VC6371 (37.40 days) varieties, respectively. The lowest fecundity values were observed on the Simite2 host (89.27 eggs), while the highest was on the VC6173A host (626.59 eggs). The highest and lowest values of net reproductive rate (R₀) were 233.17 and 25.36 offspring on VC6173A and Simite2 varieties, respectively. Furthermore, S. littoralis showed the highest intrinsic rate of increase (r) when reared on the VC6371 variety (0.99 day⁻¹), while the lowest value was on the Simite2 (0.11 day⁻¹) variety. Moreover, S. littoralis fed on the Simite2 (46.47 days) and VC6371 varieties (42.27 days) achieved the longest and shortest generation time (T). The cluster analysis results indicated that VC6173A was a susceptible variety, while the Simite2 variety revealed tolerance behaviors against S. littoralis and can be considered for IPM strategies.

Animals possess a mouth for feeding, an anus for defecation, and a gut structurally and functionally connecting them for digestion and absorption. In some stinkbugs, strikingly, the mouth and the anus are functionally disconnected in the middle. The constricted region blocks food flow and selectively allows passing of a specific bacterial symbiont to maintain the posterior midgut region as an exclusive space for symbiosis. In the stinkbug Plautia stali, the constricted region was reported to open during the last nymphal instar, thereby restoring the normal gut passage in adult insects. Here, we experimentally investigated how the structural gut reorganization upon metamorphosis of P. stali affects the processing of liquid food and solid food using blue coloring and fluorescent microbeads. In nymphal insects, both coloring and microbeads were blocked at the constricted region, and only coloring was excreted to the hindgut via Malpighian tubules. In adult insects, both coloring and microbeads passed through the constricted region and excreted to the hindgut. These results suggested that nymphal P. stali can utilize liquid food only whereas adult P. stali can live on both liquid food and solid suspension food, which may be relevant to nutritional and reproductive differences between nymphal and adult stinkbugs.

Biological observations of Paramblynotus koreanus Choi and Suh (Hymenoptera: Cynipoidea: Liopteridae) occurred on Quercus serrata Thunb. Trees suggested that their host was Carcilia strigicollis Roelofs (Coleoptera: Curculionidae). The species-specific loop-mediated isothermal amplification (LAMP) assay designed for C. strigicollis successfully detected C. strigicollis DNA in the residue of P. koreanus pupal chamber, which demonstrated that this species is a host of P. koreanus. This is the first definitive host record for the Liopteridae.

The bean webworm, Pleuroptya ruralis (Scopoli) (Lepidoptera: Crambidae), is a serious soybean pest in northern Japan. Monitoring P. ruralis has been carried out by beating the soybean canopy and counting the number of displaced adults; however, this method is laborious and time-consuming. To develop attractant lures for monitoring traps, the sex pheromone of P. ruralis has already been identified; however, pheromone-baited traps have failed to catch a sufficient number of moths. Previous trials solely utilized delta traps; cone traps, which are demonstrated to be effective for trapping some crambid species, have not yet been evaluated in P. ruralis. In this study, we compared the capture efficiency of pheromone-baited cone traps with those of pheromone-baited delta traps along with the beating method. The number of P. ruralis caught by the cone traps was significantly and 25 times larger than those caught by the delta traps. This result indicates that the trap design dramatically affects the capture efficiency of P. ruralis, and the cone trap is efficient for capturing P. ruralis. Moreover, the cone traps detected P. ruralis earlier than the beating method. The present data results suggest that pheromone-baited cone traps are useful for monitoring P. ruralis.

Outbreaks of herbivorous insects result in serious damage to forest trees. The gall midge Schizomyia castanopsisae (Diptera: Cecidomyiidae) induces inflorescence galls and causes severe loss of acorn production for Castanopsis sieboldii (Fagaceae). The outbreaks of gall midge have been occurring in these decades in the southern parts of the Izu Islands, Tokyo, Japan. In this study, we first found S. castanopsisae on Toshima Island, the Izu Islands, and in Izu Peninsula, Honshu. A genetic analysis showed that the genotype of the gall midge collected from the Izu Peninsula was identical to that from the Izu Islands, and only the haplotype was distributed in these areas. In contrast, the analysis of S. castanopsisae populations on the Nansei Islands of Japan found five haplotypes, including the one common to the Izu Peninsula and the Izu Islands. These results support the hypothesis that the gall midge populations occurring on the Izu Islands originate from the Nansei Islands, and the invaded populations have been expanding their range to the northern areas there. To monitor the distribution range and abundance of S. castanopsisae and its influences on the acorn production of C. sieboldii in Honshu are of urgent necessity.