Applied Entomology and Zoology最新文献

Although classical biological controls aim to permanently minimize numbers of invasive pests using exotic natural enemies, few long-term studies have been conducted on this subject. In this study, we investigated the population dynamics of the chestnut gall wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae), and an introduced parasitoid, Torymus sinensis Kamijo (Hymenoptera: Torymidae), over 40 years (1982–2023) at a site at which the parasitoid was first released (Tsukuba City, Ibaraki Prefecture) in Japan. Because the gall formation rate per 100 chestnut buds, an indicator of pest density, had decreased from 42.5 to 0.7% in the first 10 years after the release, the biocontrol program was deemed successful. However, further research showed fluctuations in the pest density over the next 30 years. It usually remained at low levels but occasionally increased dramatically, with three peaks exceeding the economic injury level (30%). Simultaneously, an indicator of parasitoid density (the number of parasitoids emerging from 100 galls × the gall formation rate) also fluctuated, in synchronization with the pest density indicator. These results suggest that T. sinensis has played an important role in suppressing D. kuriphilus at the releasing site over 40 years.

Hydrogel baits are composed of an insecticide and sugar water solution that is sustained by a super-absorbent polymer. This novel bait formulation has been increasingly used for controlling invasive ant species, as they prefer liquid foods and bait stations, which can be both costly and wasteful, are not required. Despite usage trends, the preference of invasive ants for hydrogel baits when compared with other food sources has not yet been widely demonstrated. This study evaluated the recruitment of the invasive Argentine ant Linepithema humile (Mayr) to various food sources, including hydrogel bait formulations containing sugar and insecticides (thiamethoxam, clothianidin), sugar water, tap water, a commercial paste-type fipronil bait, and a shrimp-flavored snack. The hydrogel baits and sugar water had equal recruitment levels for L. humile, irrespective of the sugar and insecticide concentrations (average 100–500 ants to approximately 4 × 4 cm placement). The recruitment levels for the hydrogel baits were also equal to or greater than those for the commercial paste bait (50–150 ants). However, overall, the shrimp-flavored snack was the food source with the highest levels of recruitment (500–800 ants). The results suggest that in the field, L. humile is moderately to highly interested in hydrogel baits. Hydrogel baits may not be the most efficient bait formulation for recruiting L. humile, but they are a powerful control option due to their advantages such as low cost, which enables thorough treatment. The addition of attractants could help to improve this method in the future.

The brown marmorated stink bug Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an agricultural pest with a unique odor, aggregating near human habitats during the cold season. In the present study, we evaluated the suitability of H. halys as an edible insect. We observed that the one-time administration of 2000 mg/kg raw stink bugs to female rats via oral gavage did not affect their weight or cause mortality, suggesting that the medium lethal dose of H. halys adults was > 2000 mg/kg for female rats. Moreover, the presence of microorganisms or heavy metals was not observed in heated and raw insects, respectively, except for cadmium, suggesting that they met food hygiene and safety standards. Nutrient composition analysis revealed that the levels of useful compounds in H. halys were comparable to those in general hemipterans. The ratio of polyunsaturated fatty acids in H. halys adults was 44.3%, whereas that of saturated fatty acids was 16.8%. Moreover, H. halys was rich in β-carotene, astaxanthin, lutein, and zeaxanthin. Therefore, H. halys is a potential edible carotenoid source. Consumption of this insect would become a solution to managing the pest and nuisance. Further studies are needed to ensure food safety and human consumption.

Trunk injection is a relatively new, environmentally friendly method to apply insecticides to trees which does not cause insecticide drift and environmental runoff. However, little is known about the effect of insecticide trunk injection on non-target arboreal ants (Hymenoptera: Formicidae) which can act as biological control agents of target tree pests. This study evaluated the effect of trunk injections on arboreal ants found on cherry trees treated with neonicotinoids (dinotefuran and thiamethoxam) for controlling the invasive longhorn beetle Aromia bungii (Faldermann) (Coleoptera: Cerambycidae). Arboreal ants represented by Crematogaster matsumurai Forel can prey on A. bungii eggs. Results of visual sampling 1 and 3 months after injections showed that injections did not reduce the number of ant species occurring on tree trunks. Additionally, injections did not eliminate 3 of 4 most abundant species on tree trunks or extrafloral nectaries including C. matsumurai. However, a decline of Lasius japonicus Santschi was observed on injected trees. Our preliminary short-term survey suggests the possibility that chemical control by trunk injection and biological control by arboreal ants are compatible in A. bungii management. However, further research is needed to clarify the mechanism of L. japonicus decline and long-term consequences of trunk injection on arboreal ant composition.

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.