Journal of economic entomology最新文献

The deployment of resistant cultivars is an effective strategy for managing cereal aphids. The English grain aphid, Sitobion avenae (Fabricius), is a major pest of oat (Avena sativa L.), significantly affecting both yield and quality. In this study, the aphid resistance levels of oat varieties were evaluated using the aphid quantity ratio method, the age-stage, 2-sex life table, and the electrical penetration graph technique. One oat variety with moderate resistance, 12 with low resistance, 14 with low susceptibility, 6 with moderate susceptibility, and 1 with high susceptibility were identified by the aphid quantity ratio method. Life table analyses showed that aphid individuals feeding on resistant cultivars (Baler II, Longyan No. 4, Baiyan No. 7, Jizhangyan No. 4, and Leader) exhibited prolonged nymphal development duration, reduced fecundity, intrinsic rate of natural increase (rm), and finite rate of increase (λ), compared to those on the susceptible cultivar Longyan No. 3. Electrical penetration graph results demonstrated that aphid individuals on resistant varieties had longer durations of non-probing (Np), pathway (C), and phloem salivation phases, but substantially shorter durations of phloem ingestion (E2). These findings suggest that resistance of oat varieties against S. avenae may occur at the phloem phase. This study provides support for the screening and breeding efforts of aphid-resistant oat cultivars for S. avenae control.

Novel active ingredients from new insecticide classes are urgently needed to complement existing control tools and support rotation strategies for effective resistance management in the German cockroach, Blatella germanica (L.) (Blattodea: Ectobiidae). Broflanilide is a novel meta-diamide insecticide that acts as a noncompetitive antagonist of γ-aminobutyric acid (GABA)-gated chloride channels. This study evaluated the toxicity and synergism, residual efficacy, and secondary transfer potential of broflanilide against field populations of German cockroach. The baseline toxicity of broflanilide in a laboratory-susceptible strain was determined, with LD50 = 0.015 μg/insect and LD95 = 0.030 μg/insect at 48 h post-exposure. Topical application of broflanilide achieved >90% mortality at 3× LD95 against most of the field populations resistant to pyrethroid, fipronil, and imidacloprid. Piperonyl butoxide (PBO) acted antagonistically across all populations, whereas diethyl maleate (DEM) showed variable effects. Residual assays demonstrated that broflanilide applied at 12.5 mg/m2 on plywood surfaces produced a performance index (PI) >90 within 7 d, caused complete mortality, and exhibited no repellency. Residual efficacy persisted for 90-120 d. Secondary transfer through necrophagy on cadavers exposed to treated surfaces yielded PIs of 39-90, indicating partial but inconsistent indirect mortality. Overall, broflanilide provides strong residual efficacy, non-repellency, and prolonged control of resistant German cockroach populations at low application rates. Given its novel mode of action and the apparent lack of P450-mediated detoxification, cross-resistance with conventional insecticides is expected to be minimal. Broflanilide represents a promising addition to insecticide resistance management programs for the German cockroach.

The spread of red imported fire ants, Solenopsis invicta Buren, has been linked to the shipment of infested nursery plants, and their movement is regulated under the Federal Imported Fire Ant Quarantine. Fire ants are difficult to disinfest from large, field-grown plants with roots and soil wrapped in burlap (root balls). The efficacy of non-repellent insecticides to eliminate red imported fire ants from root balls was evaluated. We hypothesized that non-repellent insecticides sprayed on root balls would be effective because they would not deter red imported fire ants contact with treated substrate. Surface spray applications of non-repellent insecticides with the active ingredients of dinotefuran or indoxacarb disinfested 75% of root balls harboring red imported fire ants. Dinotefuran was tested at lower concentrations to potentially reduce treatment costs. While reductions in adult counts and brood volume were >90%, which differed significantly from the control, no differences were detected in the numbers of infested root balls among dinotefuran concentrations. The residual efficacy of dinotefuran at the full label rate prevented red imported fire ant infestations for 6 mo, while the half-rate of dinotefuran, a bifenthrin drench, and the control all had infested root balls. Based on the results of these studies, the surface spray application of the non-repellent dinotefuran to root balls should be examined further as a potential Federal Imported Fire Ant Quarantine treatment for field-grown nursery plants.

Diamondback moth (DBM), Plutella xylostella (L.), is a ubiquitous pest of Brassicaceae crops, causing a global economic burden of $4 to 5 billion annually. Although natural enemies can suppress DBM populations through high parasitism rates (>80%), growers' reliance on insecticides reduces beneficial insects and drives DBM insecticide resistance. Therefore, a sustainable DBM management approach is needed. We conducted a 2-yr field study to investigate the potential of sweet alyssum flowers in enhancing DBM biocontrol. Experiments included 4 treatments: (i) nontreated collards, (ii) collards with interspersed alyssum, (iii) collards with interspersed alyssum and Bacillus thuringiensis (Bt) sprays, and (iv) collards with bifenthrin sprays. Weekly sampling of DBM larvae, pupae, and parasitoid pupae was done to evaluate DBM pressure and parasitism rates. Additionally, collards were harvested to assess marketable yield. The alyssum + Bt treatment maintained the lowest DBM pressure and had significantly higher marketable yield. The bifenthrin-treated plots had significantly higher DBM pressure. Parasitism rate averaged up to 86%, but there were no differences among treatments. Predation may explain DBM pressure differences among treatments, although pitfall trapping did not detect significant differences in predator abundance, possibly due to small-plot size and interplot insect movement. In 2023, cross-striped cabbageworm (CSCW) Evergestis rimosalis (Guenée) also became a significant pest but was effectively managed by both insecticides. However, differences in severely damaged plants and marketable yield suggested a drawback of alyssum for CSCW management. Overall, planting alyssum, maintaining nontreated refuge, and using selective insecticides can conserve natural enemies and reduce pest pressure, supporting agricultural and environmental sustainability.

Effective cold storage is a key strategy for extending the shelf life of biological control agents and ensuring a reliable and timely supply for pest management programs. In this study, we evaluated the effects of different cold storage durations (0, 10, 15, 20, 25, 30, and 35 d at 10 °C) on the performance, pest control potential, and flight capacity of Encarsia formosa Gahan (Hymenoptera: Aphelinidae) reared on yacon (Smallanthus sonchifolius Poeppig & Endlicher) as an alternative host plant. Our results showed that the parental adult emergence rate remained high (>82%) for parasitoids stored up to 20 d, while offspring emergence exceeded 95% for all treatments except the 35-d storage. Parasitoids stored up to 20 d retained body size (head width, body length, hind tibia length), and those stored up to 10 d preserved total and mature egg loads as well as parasitism and host-killing capacities comparable to the control (0 d cold storage duration). Adults from the 15-d storage treatment maintained strong host-feeding and flight abilities. These findings demonstrate that E. formosa reared on yacon can be cold-stored at 10 °C for up to 10 d without compromising key biological traits, providing practical guidance for mass-rearing, storage, and field release strategies. This work highlights the innovative use of yacon as an alternative host plant to enhance cold tolerance and biocontrol efficiency, offering a promising approach for improving the industrial production and application of E. formosa against whitefly pests.

The growing urgency of climate change, particularly the rising frequency and severity of extreme heat events, has spotlighted the need for the thermal resilience of natural enemy in pest management. To understand the plasticity of predatory mite in response to thermal adaptation, 3 irradiated strains of Phytoseiulus persimilis Athias-Henriot were induced by Cobalt-60 gamma rays to evaluate the thermotolerance. We integrated both DNA- and RNA-based 16S rRNA gene sequencing to explore whether irradiation and heat stress could impact the microbiome of the predatory mites. Our findings revealed that irradiation enhanced the heat tolerance of predatory mites without compromising fecundity or predation efficiency. Unexpectedly, irradiation had minimal impacts on overall microbial diversity, whereas RNA-based 16S rRNA gene sequencing unveiled irradiation strain-specific enrichment of stress-responsive taxa (e.g., Bacillus sp.), while no such specific enrichment was observed at the DNA level. Furthermore, heat stress significantly restructured the microbiome of P. persimilis, particularly enriching Limnobacter thiooxidans. Methodologically, the DNA/RNA microbial profiles highlighted divergent functional partitioning: Gammaproteobacteria dominated at DNA level, while transcriptionally active Actinobacteria prevailed in RNA level. In conclusion, these results establish a "host-microbiota co-regulation" paradigm for resistance breeding, offering a sustainable pathway to reinforce biological control systems against global warming challenges.

The invasive pest Tuta absoluta (Meyrick) poses a significant threat to tomato production worldwide. The use of different classes of insecticides to control T. absoluta led to the development of resistance. Presently, insecticides such as chlorantraniliprole, flubendiamide, emamectin benzoate, indoxacarb, and spinosad are widely used worldwide. Insecticide resistance in South Indian field populations of T. absoluta from Tamil Nadu (Coimbatore, Krishnagiri, and Dharmapuri), Andhra Pradesh (Kalikiri and Tirupati), and Karnataka (Bengaluru and Kolar) has been reported. Resistance-associated mutations were identified by analyzing insecticide target sites, thereby elucidating the molecular mechanisms underlying target-site alterations. In all seven populations, two mutations in the ryanodine receptor gene, positioned at I4746M and G4903E, both linked to diamide (chlorantraniliprole and flubendiamide) resistance, were observed. Homology modeling and molecular docking revealed reduced binding affinity of flubendiamide to ryanodine receptor in resistant populations compared to susceptible ones, supporting diamide resistance. Though the T. absoluta populations had shown moderate resistance to insecticides other than diamides, we found no target-site mutations in the glutamate-gated chloride channel, voltage-gated sodium channel, and nicotinic acetylcholine receptor genes, respectively, associated with emamectin benzoate, indoxacarb, and spinosad resistance, suggesting a focus on other mechanisms such as metabolic detoxification. This study presents the first report of target-site mutations in Indian populations of T. absoluta and highlights the need for insecticide resistance management strategies to mitigate further resistance development.

The oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is an invasive and highly polyphagous insect species that affects more than 470 plant species. In recent years, its presence has been repeatedly recorded in trap networks in Europe, raising concern about the potential pest establishment in that area. Currently, early detection of its presence relies on the use of traps baited with methyl eugenol, which is highly effective in attracting males. However, there are currently no particularly effective or specific attractants for adult females. Identifying new attractants, particularly targeting females, is therefore crucial to improve trap efficacy. Female olfactory responses and oviposition behavior are influenced by chemical cues emitted from host fruits. The aim of this study was to evaluate the ovipositional responses of 14 volatile organic compounds emitted by fruits of preferred hosts and to determine their attractiveness to laboratory-reared oriental fruit fly adult females under controlled conditions. To this end, no choice and dual choice ovipositional experiments, as well as dual choice behavioral assays, were conducted. Many of these volatile organic compounds were found to stimulate oviposition and being attractive to B. dorsalis females with γ-octalactone showing the highest activity. Overall, ethyl octanoate, ethyl hexanoate, butyl hexanoate, hexyl hexanoate, γ-octalactone, and linalyl acetate were the most effective compounds in attracting adult females and eliciting high ovipositional responses. These chemicals appear promising for the development of new, female-specific attractants that can be used in new tools for integrated pest management programs.

Honey bee (Apis mellifera L.) breeders seek to enhance disease resistance by selecting for behavioral resistance traits such as hygienic behavior and Varroa-sensitive hygiene. However, traditional phenotypic assays for these traits are labor-intensive, limiting scalability. Antennal protein biomarkers correlated with these behaviors offer a promising tool for marker-assisted selection (MAS), potentially increasing phenotyping efficiency and accelerating genetic gains. This study evaluated the performance of honey bee colonies from 4 stocks: those selected using field-based phenotypic assays (FAS) or MAS, versus unselected domestic stock (BEN) or imported commercial (IMP) stock. Colonies were situated across 3 distinct geographic regions and were managed with or without acaricide treatment for the treatment of Varroa destructor mites to assess both the benefits of resistance under parasitic stress and potential fitness costs under low-stress conditions. Across regions, MAS and FAS stocks performed comparably in productivity and pathogen metrics and were equal to or more productive than the unselected BEN and IMP stocks. At specific locations and time points, MAS and FAS colonies maintained significantly lower Varroa destructor populations in the absence of acaricides, demonstrating enhanced natural mite suppression. Selection for hygienic behavior was positively associated with colony health and fitness, with no evidence of biologically meaningful trade-offs. Increased overwinter food consumption in selected colonies reflected larger fall populations rather than a direct cost of resistance.

The oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), is a globally significant pest of fruit crops. Its management has long relied on abamectin, yet resistance evolution threatens its effectiveness. In this study, a laboratory relative susceptible strain (AM-S) was subjected to 19 consecutive generations of selection with abamectin, resulting in a resistant strain (AM-R) showing a 132.5-fold increase in LD50. The AM-R strain displayed significant cross-resistance to emamectin benzoate (43.8-fold), imidacloprid (16.5-fold), but little to no cross-resistance to lambda-cyhalothrin, bifenthrin, thiamethoxam, or chlorpyrifos. Genetic analyses indicated that abamectin resistance was autosomal, incompletely dominant (D = 0.11-0.30), and polygenic, as shown by significant deviations from monogenic inheritance in backcross tests. Resistance incurred substantial fitness costs, including extended larval and pupal durations, reduced larval and pupal weights (by 20-25%), lower fecundity (1.45-fold fewer eggs), and shortened adult longevity. Synergism assays revealed that piperonyl butoxide (SR = 2.87) and diethyl maleate (SR = 2.23) significantly enhanced abamectin toxicity, and biochemical assays showed 3.65-fold higher cytochrome P450 and 2.75-fold higher glutathione S-transferase activities in the resistant strain, implicating metabolic detoxification as the major mechanism. These results demonstrate that abamectin resistance in G. molesta evolves rapidly under continuous exposure, is polyfactorial and metabolically mediated, and imposes measurable biological trade-offs. Together, these insights clarify how physiological trade-offs and metabolic adaptation shape abamectin resistance in G. molesta, informing longer-term strategies for more sustainable pest management systems.