Journal of economic entomology最新文献

Sugar transporters play a crucial role in insect life activities, especially in energy metabolism and carbohydrate management. Sugar transporter 1 (St1) is a facilitative glucose transporter highly expressed in the midgut of Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), however its physiological function remains unclear. To explore its pest control potential, we used RNA interference (RNAi) to investigate St1's effects on sugar metabolism and female reproduction. Silencing St1 lowered membrane-bound trehalase (TRE2) activity and inhibited the hydrolysis of trehalose into glucose, impeding glycogen accumulation and glucose availability. Our findings show St1 regulates female reproduction by modulating trehalase activity. This study reveals St1's crucial role in insect physiology and highlights it as a potential target for new, eco-friendly insecticides.

The redlegged earth mite (RLEM, Halotydeus destructor (Tucker)), a major agricultural pest in Australia, is primarily managed by synthetic pesticides. However, the emergence of pesticide resistance in many field populations has prompted growing interest in alternative biopesticides. In the laboratory, Beauveria bassiana (Balsamo-Crivelli) Vuillemin significantly affected both RLEM adults and nymphs when applied in vial or agar-based bioassays, but not in a leaf dip assay. A field rate of a commercial formulation of Beauveria registered for control of 2-spotted spider mites significantly reduced RLEM survival and reproduction. Lower concentrations decreased mite survival but paradoxically increased reproductive output. In a microcosm 'semi-field' trial, all tested concentrations of Beauveria reduced the survival of RLEM adults but did not necessarily decrease net reproductive output. In conclusion, B. bassiana has efficacy against RLEM, however a hormetic effect at low concentrations may enhance offspring production. Further research is necessary to explore optimal concentrations, thermotolerance, product formulations, mite life stages, and field-based efficacy.

Odontotermes formosanus (Blattodea: Termitidae) is a social insect that significantly damages horticultural trees and water conservation infrastructure. Our previous studies confirmed that 1,2-dibenzoyl-1-tert-butylhydrazine (RH-5849) is toxic to O. -formosanus. However, insects have detoxification enzymes like cytochrome P450 (CYP) and glutathione S-transferase (GSTs) that can detoxify insecticides and mitigate their toxicity. To investigate CYP and GSTs in the defense of O. formosanus against RH-5849, we assessed the effects of the CYP inhibitor piperonyl butoxide and the GSTs inhibitor diethyl maleate on the toxicity of RH-5849 against O. formosanus. The results indicated that piperonyl butoxide and diethyl maleate significantly increased the lethality of RH-5849 to O. formosanus by 49.61% and 37.21%, respectively. Through RNA-seq and quantitative real-time PCR, OdfoCYP301A1 and OdfoGSTo1 were identified, with relative expression levels of 2.90 and 11.91, respectively. Moreover, we cloned OdfoCYP301A1 and OdfoGSTo1 and synthesized double-stranded RNA (dsRNA) based on these sequences. Furthermore, we evaluated the lethality of RH-5849 to O. formosanus following 24 h of dsRNA interference treatment. The results indicated a significant increase in the lethality of RH-5849 to O. formosanus following interference with OdfoCYP301A1 or OdfoGSTo1. These results suggest that OdfoCYP301A1 and OdfoGSTo1 play important roles in the defense of O. formosanus against RH-5849. Furthermore, this study provides new targets for the combined use of dsRNA and RH-5849 in the control of O. formosanus.

The pecan weevil, Curculio caryae (Horn) (Coleoptera: Curculionidae), is a direct pest of pecan nuts often causing economic injury. Larvae feed and develop within the pecan nut, mature fourth instars emerge from nuts during autumn, drop to the orchard floor and complete development underground. However, a proportion of pecan weevil larvae remain in nuts at harvest. We tested electron beam irradiation of pecan weevil larvae as a potential phytosanitary treatment against infested nuts being shipped to production regions free of pecan weevil. Irradiation doses of 0, 150, 400, 750, and 1,000 Gy were assayed against pecan weevil using different larval exposure methods (bare larvae [bare], larvae in microfuge tubes [tube], and larvae in microfuge tubes placed into empty pecan shells [nut]). After treatment application, larvae were held singly in Petri dishes at 15 °C and examined for 60 d to determine mortality. Results revealed that larval mortality increased with days after treatment for each irradiation dose, including 0 Gy, for the 3 exposure methods. Mortality was generally lower for larvae in the tube and nut at 400, 750, and 1,000 Gy than for bare larvae. Overall mortality was lower for lower irradiation doses but higher for higher doses, and over time no larvae survived 1,000 Gy. These results strongly suggest that irradiation is an effective method to control in-shell pecan weevil larvae.

Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is highly invasive lepidopteran pest of global significance. Differentiating S. frugiperda from similar species, especially in non-adult stages, remains challenging. Rapid molecular identification techniques, such as multienzyme isothermal rapid amplification (MIRA) combined with lateral flow dipstick (MIRA-LFD), play a crucial role in early monitoring and safeguarding agricultural production. Our study introduces this platform for the rapid visual identification of S. frugiperda. The specific MIRA primers and the LFD probe were designed based on the COX1 genes. The MIRA reaction conditions were optimized (at 37 °C for 15 min) for effective template DNA amplification. The MIRA-LFD system achieved precise identification of the target species within 12 min at 37 °C. This method exhibited high specificity and sensitivity, allowing for detection from 1.0 ng·μl-1 of DNA. Combined with rapid DNA extraction, expedited identification of individual S. frugiperda at different developmental stages was achieved, enhancing the practicality and convenience of the established methods. In summary, our research demonstrates that the MIRA-LFD method for S. frugiperda detection achieved high accuracy with rapid results (entire workflow completion within 22 min at 37 °C, including crude DNA extraction, MIRA amplification, and LFD dipstick interpretation). This approach does not require expensive equipment, making it highly practical for field applications. It offers an improved solution for early detection of invasive arthropod pests and enhances field surveillance capabilities, thereby advancing precision pest management strategies.

Fatty acid synthase (FAS) plays a central role in lipid metabolism, influencing critical physiological processes such as reproduction and diapause in insects. In this study, we investigated the function of FAS in Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae), a key egg parasitoid used in biological pest control. Using RNA interference (RNAi), we achieved significant knockdown of FAS expression (>60%), which led to a 28.4% reduction in diapause proportion and a 37.5% decrease in parasitization rates compared to controls. FAS silencing also reduced ovarian egg load by 33.2% and mature egg proportion by 41.7%, demonstrating its essential role in oocyte maturation. Notably, vitellogenin receptor (VgR) expression was dramatically suppressed (84.3%) following FAS knockdown, suggesting a regulatory link between lipid metabolism and yolk precursor uptake, despite the absence of canonical vitellogenin in T. dendrolimi. Intriguingly, while FAS knockdown impaired reproductive output, adult longevity remained unaffected, indicating a decoupling of fecundity and lifespan trade-offs in this species. Additionally, transgenerational effects were observed, with offspring emergence rates declining by 28.4% in the F2 generation. Our findings establish FAS as a master regulator of reproduction in T. dendrolimi, mediating lipid allocation, diapause plasticity, and vitellogenic efficiency. These results provide novel insights into the metabolic adaptations underlying enhanced reproductive fitness in parasitic wasps and have implications for optimizing mass-rearing protocols in biological control programs.

Since its detection in the continental United States in 2008, spotted-wing drosophila (Drosophila suzukii Matsumura) has become a significant pest of thin-skinned fruits. Current management strategies largely depend on calendar-based insecticide applications, which have disrupted previously established integrated pest management programs. Alternative control tactics, such as behavioral manipulation with phagostimulants, are being explored to reduce dependence on insecticides. In this study, we evaluated the effects of adding the commercial phagostimulant Combi-protec Insect Bait Attractant on the efficacy of insecticides targeting D. suzukii. The study was conducted across 6 US states (New Jersey, Georgia, Michigan, Oregon, Maine, and New York) under field conditions using highbush blueberries, lowbush blueberries, and raspberries. Treatments were applied in the field under caged conditions in 2021 and open conditions in 2022, followed by laboratory bioassays to assess adult mortality, oviposition, and larval infestation/emergence. When adults were exposed to freshly treated materials, insecticide treatments combined with Combi-protec generally performed as well as, or better than, insecticides alone in highbush blueberries (particularly spinetoram and phosmet); however, inconsistent results were observed in lowbush blueberries and raspberries. As materials aged in the field, efficacy across treatments declined, leading to variable results. Oviposition patterns closely mirrored adult mortality, but the treatment effects on developing larvae and emerged progeny were inconsistent or negligible. Overall, Combi-protec enhanced the efficacy of insecticides against adult D. suzukii, though its benefits for subsequent life stages were inconsistent. These findings provide new insights into the potential role of phagostimulants for improving insecticide effectiveness for D. suzukii control.

Global temperature increases require the reevaluation of pesticide efficacy under thermal stress conditions; however, most studies have focused on acute high-temperature exposure, neglecting the effects of natural diurnal temperature fluctuations and cumulative acclimation. This study investigated the effect of thermal acclimation during developmental on the sensitivity of Mythimna separata (Walker) (Lepidoptera: Noctuidae) to emamectin benzoate (EB). Larvae were reared under cyclic thermal regimes (25→34/38→25 °C), experiencing daily high-temperature exposures of 2, 4, or 6 hours from the egg stage. Continuous fluctuating high-temperature exposure did not have a detrimental effect on the life-history traits of M. separata but substantially increased its sensitivity to EB. Daily 6-hour exposure to either 34 °C or 38 °C significantly increased LC10 EB-induced mortality and reactive oxygen species (ROS) levels compared to constant 25 °C. Increasing thermal intensity progressively suppressed the levels of heat shock proteins (MsHsp70 and MsHsp90) and the enzymatic activities of superoxide dismutase and glutathione-S-transferase in the EB-exposed larvae. A pronounced temperature-dependent increase in cytochrome P450 monooxygenases (P450s) activity accompanied this suppression, suggesting an adaptive metabolic response that could accelerate the development of EB resistance under climate warming scenarios. Thus, thermal acclimation during insect development increases EB toxicity, potentially through ROS accumulation caused by inhibiting heat shock proteins and antioxidant enzymes. These findings demonstrate that fluctuating thermal conditions amplify EB toxicity and underscore the potential role of P450s in long-term resistance to global temperature increases. This study guides the development of climate-adaptive pesticide applications and region-specific integrated pest management strategies.

Red clover, Trifolium pratense L., is a perennial forage legume grown for seed production in Western Canada, contributing significantly to regional agricultural economies. The lesser clover leaf weevil, Hypera nigrirostris Fab. (Coleoptera: Curculionidae), is a key pest of red clover seed crops, with larval feeding capable of reducing seed yields by up to 50%. Despite its impact, no economic thresholds (ET) currently exist to guide insecticide application for this pest. As a result, prophylactic treatments are used that increase production costs, increase the potential for insecticide resistance, and pose risks to pollinators, which are essential for red clover seed production. This study established a quantitative relationship between larval density and red clover seed yield under field conditions and used these data to develop economic injury levels (EIL) and practical ETs across a range of seed price scenarios. Yield losses were strongly associated with increasing larval densities, and thresholds varied with changing economic conditions. These resulting thresholds provide the first data-driven guidance for managing H. nigrirostris in North American red clover seed systems, offering a foundation for cost-effective, pollinator-conscious pest management strategies.

The Asiatic garden beetle (AGB) Maladera formosae (Brenske) has become a damaging pest of commercial mint in northern Indiana. The larvae feed on plant roots, causing stunting and plant death when damage is severe. However, the seasonal relationship between AGB larval density and above-ground mint biomass (foliage and stems) is unclear, leaving farmers without fundamental knowledge necessary to implement sound IPM strategies. We assessed AGB larval density and above-ground biomass in 3 mint fields during the spring and fall of 2021 and 2022 to establish a damage boundary and develop an economic injury level (EIL) based on currently available management tactics. A soil-quadrat excavation method was used to estimate AGB larval density and above-ground biomass in 15 replicate 0.25 m2 sampling areas in each field. AGB larval densities varied annually and seasonally and although fall and spring AGB larval densities were correlated, the highest densities within each larval cohort were observed during fall. Accordingly, a significant negative relationship between larval density and above-ground biomass was only observed in the fall, when mean larval densities surpassed 15 larvae/0.25 m2. Moreover, our damage probability model estimated 50% probability of reduced above-ground biomass at larval densities of 15/0.25 m2. A conservative EIL of 19.4 to 23.3 AGB larvae/0.25 m2 was estimated based on use of chemical or biological control strategies available to farmers. Results indicate that field estimation of AGB larval densities can support management decisions in mint production, and estimates of larval density based on summer/fall populations are most likely to predict economic damage.