Journal of economic entomology最新文献

Chemical control is currently the main strategy for managing brown marmorated stink bug, Halyomorpha halys (Stål). However, chemical pesticides can harm nontarget species, including natural enemies of H. halys. Pesticides with high toxicity to H. halys and low toxicity to its parasitoids need to be identified to support H. halys management. This is not only for natural biological control but also for preemptive classical biological control of H. halys by parasitoids. Here, we assessed the contact toxicity of residues of eight insecticides against H. halys and three of its main parasitoid species (Anastatus japonicus Ashmead (Hymenoptera: Eupelmidae), Trissolcus japonicus Ashmead (Hymenoptera: Scelionidae), Trissolcus cultratus Mayr (Hymenoptera: Scelionidae)). This study aims to provide valuable insights for preemptive classical biological control of H. halys using these parasitoids. Our results showed that A. japonicus exhibited higher tolerance to the tested pesticides, while T. japonicus was the most sensitive species. Among the pesticides, chlorantraniliprole had the lowest overall impact on all three parasitoid species. Additionally, acetamiprid, azadirachtin, and rotenone were found to be harmless to A. japonicus. Acetamiprid, however, was slightly harmful to T. cultratus. The remaining pesticides showed moderate to significant harmful effects on the parasitoids. For H. halys adults and fifth instars, the pesticides tested caused no mortality within the 24 h exposure. However, young nymphs were susceptible to the tested pesticides. Fenpropathrin had the highest toxicity to H. halys, killing 83.3%, 52.8%, and 19.4% of second, third, and fourth instars in a 24 h exposure. Fenpropathrin, acetamiprid, cyfluthrin, azadirachtin, and dinotefuran were all slightly harmful to the first instar nymphs. The other pesticides were harmless to H. halys in a 24 h exposure. Halyomorpha halys mortality increased with the contact time with the residue. Mortality of fourth and fifth instars of H. halys was >70% for fenpropathrin, cyfluthrin, dinotefuran, abamectin-aminomethyl, and acetamiprid if exposure continued for 7 d. Acetamiprid was effective in controlling H. halys nymphs but exhibited varying levels of toxicity towards the three tested parasitoid species, depending on the residue age and exposure time. Azadirachtin showed lower overall toxicity to beneficial insects, suggesting that these materials could be used to manage H. halys while minimizing harm to key beneficial species.

Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae) and Spodoptera exigua Hübner (Lepidoptera: Noctuidae) pose substantial threats to many crops, necessitating the exploration of biopesticides as potential chemical alternatives. One alternative is baculoviruses; however, their instability in the field has hindered their widespread use. Host plant phylloplane affects baculovirus activity at varying levels in different host plants. Formulation contributes significantly to optimizing the baculoviral stability on different phylloplanes against environmental conditions; however, it is expensive and difficult to make in developing or nondeveloped countries. In the current study, we developed a simple tank-mix application (MBF-Tm5) for immediate use, resembling the characteristics of a suspension concentrate formulation for Spodoptera littoralis nucleopolyhedrovirus (SpliNPV) and Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV). We examined their biological activity against 2nd instar larvae first on an artificial diet under laboratory conditions and on eggplant and pepper phylloplane in greenhouse conditions compared to plain viruses. This formulation exhibited no significant improvement in the biological activity of both viruses on an artificial diet under laboratory conditions but significantly improved the biological activity of both viruses on both plants under greenhouse conditions. The original activity remaining (OAR%) of both unformulated and formulated viruses decreased over time under greenhouse conditions; however, the OAR value of both viruses on eggplants was significantly higher than on pepper plants. Overall, the tank-mix simple formulation of baculoviruses might be a great alternative for improved stability in nature, providing better control.

Debate over resistance management tactics for genetically engineered (GE) crops expressing insecticidal toxins is not new. For several decades, researchers, regulators, and agricultural industry scientists have developed strategies to limit the evolution of resistance in populations of lepidopteran and coleopteran pests. A key attribute of many of these events was insecticide resistance management (IRM) strategies designed around a presumed high-dose expression sufficient to kill 99.5% of exposed larvae for some of the main target pests in corn, Zea mays L. and cotton, Gossypium hirsutum L. In contrast, other target pests did not meet this high-dose criterion. Similarly, the recent release of ThryvOn cotton that expresses thysanopteran and hemipteran active Mpp51Aa2.834_16 toxin is not high dose, working on a combination of behavioral and sublethal effects to suppress populations. This unique mode of control has generated considerable uncertainty about what IRM strategies will be most effective to limit field-evolved resistance to this unique spectrum of pests. The goal of this manuscript is to present several knowledge gaps that exist in proposed Mpp51Aa2 IRM plans, focusing on its activity on thrips, Frankliniella spp. Addressing these gaps will be crucial to limit resistance and preserve the benefits that this technology may provide by alleviating reliance on conventional insecticides and seed treatments. Broadly, these considerations will be important for future GE events that are non-high dose but remain valuable components of a more holistic insect management programs that integrate multiple tactics to reduce conventional insecticide use for challenging pests.

The lesser mealworm Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae), an important insect pest of stored-product commodities and poultry production systems, is regarded among the most difficult species to control. It has developed resistance to many chemical insecticides, and though various cultural and biological methods have been assessed and identified as possible factors for its control, none are currently implemented. Entomopathogenic nematodes are often successfully employed as alternative to chemicals biocontrol agents of various insect species, including pests of stored products; nevertheless, their evaluation as potential biocontrol factors of the lesser mealworm is not efficiently scrutinized. In the current study, single A. diaperinus larvae were exposed to six doses of Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), and Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae), for 4 and 8 d, and mortality was recorded at 3 different temperature regimes, i.e., 25 oC, 30 oC, and 35 oC. The study concludes that S. carpocapsae and S. feltiae are both highly virulent against A. diaperinus larvae and may be considered as promising biological control agents for reducing lesser mealworm infestations when applied at a rate of 70 IJs/cm2 at 25 oC. When assessed at 30 oC, both species were effective at the same rate though causing lower mortality of ~60% and ~50%, respectively, whereas their efficacy was low at 35 oC.

Controlling crop pests while conserving pollinators is challenging, particularly when prophylactically applying broad-spectrum, systemic insecticides such as neonicotinoids. Systemic insecticides are often used in conventional agriculture in commercial settings, but the conditions that optimally balance pest management and pollination are poorly understood. We investigated how insecticide application strategies control pests and expose pollinators to insecticides with an observational study of cucurbit crops in the Midwestern United States. To define the window of protection and potential pollinator exposure resulting from alternative insecticide application strategies, we surveyed 62 farms cultivating cucumber, watermelon, or pumpkin across 2 yr. We evaluated insecticide regimes, abundance of striped and spotted cucumber beetles (Acalymma vittatum [Fabricius] and Diabrotica undecimpunctata Mannerheim), and insecticide residues in leaves, pollen, and nectar. We found that growers used neonicotinoids (thiamethoxam and imidacloprid) at planting in all cucumber and pumpkin and approximately half of watermelon farms. In cucumber, foliar thiamethoxam levels were orders of magnitude higher than the other crops, excluding nearly all beetles from fields. In watermelon and pumpkin, neonicotinoids applied at planting resulted in 4-8 wk of protection before beetle populations increased. Floral insecticide concentrations correlated strongly with foliar concentrations across all crops, resulting in high potential exposure to pollinators in cucumber and low-moderate exposure in pumpkin and watermelon. Thus, the highest-input insecticide regimes maintained cucumber beetles far below economic thresholds while also exposing pollinators to the highest pollen and nectar insecticide concentrations. In cucurbits, reducing pesticide inputs will likely better balance crop protection and pollination, reduce costs, and improve yields.

Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), is a pest in southern California citrus orchards because it protects honeydew-producing hemipteran pests from natural enemies. A major impediment to controlling L. humile is estimating ant densities in orchards. Ants use irrigation lines to travel across orchard floors to reach trees infested with hemipterans. However, for making ant control decisions, it is the number of ants in trees, not on pipes that is critical. Work completed here demonstrates that the number of ants counted on pipes is highly correlated with the number of ants counted on trunks. Densities of ants counted on trunks are correlated with trunk diameter, citrus variety, and time of year and time of day counts. Six regression models, linear regression, zero-inflated Poisson regression, and zero-inflated negative binomial regression models, and each of their mixed model extensions, indicated a strong positive relationship between ant counts on irrigation pipes and ant counts on tree trunks. Mean squared prediction error and 5-fold cross-validation analyses indicated that the best performing of these 6 models was the zero-inflated Poisson mixed regression model. A binary classification model developed using support vector machine learning for ant infestation severity levels, categorized as low (<100 ants counted in 1 min) or high (≥100 ants counted in minutes), predicted ant densities on trunks with 85% accuracy. These models can be used to estimate the number of ants on the trunks of citrus trees by using counts of ants made on irrigation pipes.

We assessed the utility of a Bayesian analysis of dose-mortality curves using probit analysis. A Bayesian equivalent of a conventional single population probit analysis using Abbott's correction demonstrated the ability of the Bayesian model to recover parameters from generative data. We then developed a model that removed Abbott's correction and estimated natural survivorship as part of the overall model fitting process. Based on WAIC (information content) scores, this model was selected over the model using Abbott's corrected data in 196 out of 200 randomly generated datasets. This suggests that considerable information on control survivorship exists in response to treated doses in a bioassay, information that is partially removed when using Abbott's correction. Overdispersion in count data is common in ecological data, and a final model was developed that estimated overdispersion (kappa) as part of the model fitting process. When this model was compared to a model without overdispersion, it was selected as the best model in all 200 randomly generated datasets when kappa was low (5-20, high levels of overdispersion), while the 2 models performed equally well when kappa was large (500-2,000, low levels of overdispersion). The model with overdispersion was used to estimate parameters from bioassays of 10 populations of Helicoverpa zea (Lepidoptera: Noctuidae) exposed to Vip3a toxin, identifying 26 out of 45 pairwise comparisons that showed strong evidence of differences in LC50 estimates, adjusted for multiple comparisons.

Defensive metabolites and nutrient restriction of host plants are 2 major obstacles to the colonization of insect herbivores. The green peach aphid (GPA) Myzus persicae (Sulzer) broadly colonizes plants with diverse nutritional and defensive traits. However, how GPA adapts to nutritional and defensive traits within different plants remains largely unknown. To elucidate this, we first investigated the performances and transcriptomes of GPA feeding on cabbage Brassica oleracea and pepper Capsicum annuum. The green peach aphid had lower weight and fecundity when feeding on cabbage than on pepper. The transcriptomic analysis found 824 differentially expressed genes (DEGs), and 13 of the top 20 Kyoto Encyclopedia of Genes and Genomes pathways are related to nutrient metabolism, energy metabolism, and detoxification. Specifically, we found 160 DEGs associated with the metabolism of protein and amino acids, sugar and lipids, and xenobiotic substances, 86 upregulated in cabbage-fed GPA. Fourteen cathepsin B genes were strongly upregulated in cabbage-fed GPA, and were enriched in lysosome pathway and 2 dominated gene ontology terms peptidase activity and proteolysis. In addition, cabbage-fed GPA upregulated sugar and lipid digestion, while downregulated lipid biosynthesis processes. Furthermore, 55 metabolic detoxification enzyme genes were differentially expressed between GPA on 2 hosts, and detoxification enzyme activities of GPA indeed changed accordingly to the host. Then, we found that cabbage has lower amino acids nutrition quality for GPA compared to pepper. Our results suggested that adjustment of nitrogen nutrient metabolism, sugar and lipid metabolism, and metabolic detoxification in a host-specific manner play crucial roles in the adaptations of GPA to different host plants.

Ceratapion basicorne (Illiger) (Coleoptera: Apionidae), a weevil native to Europe and western Asia, shows promise for enhancing the control of yellow starthistle (Centaurea solstitialis L.), an invasive annual forb in the western United States. However, a paucity of data on this biocontrol agent's environmental constraints has made it difficult to assess the suitability of potential release locations. Climate matching models were developed for C. basicorne to help identify areas of the western United States with similar climates to the source area of breeding colonies being used for releases (home location). The models used climate variables derived from daily estimates of minimum temperature, maximum temperature, precipitation, and soil moisture for a 30-yr period spanning 1991-2020 at 1 km2 resolution. Of the areas where C. solstitialis is known to occur, the Central California Foothills, Eastern Cascades Foothills, Columbia Plateau, and mountainous parts of northcentral Utah had the most similar climates to the home location. Of these areas, the Eastern Cascades foothills in northeastern California and Wasatch Range in Utah occurred at a similar latitude as the home location, which may be important to consider if C. basicorne has photoperiodic diapause. The least similar climates occurred in wet coastal regions, high-elevation (cold) mountains, and hot deserts; however, C. solstitialis has not been detected in most of these areas. The development of process-based models for predicting the establishment of this agent will require a more detailed understanding of the agent's requirements for development and survival.

The strategic use of refuge areas is a well-known method for delaying the development of pest resistance to Bacillus thuringiensis (Bt) crop. A lesser-known method to control against resistance development is sterile insect releases. In this article, an agent-based simulation model is used to test the effectiveness of combining the use of Bt sugarcane, refuge areas, and sterile insect releases as an integrated strategy against Eldana saccharina Walker (Lepidoptera: Pyralidae) infestation and resistance development. Individual insects are modeled with their own genetic traits on a simulated sugarcane field that represents either Bt or refuge area. The model is applied to 2 hypothetical case studies. In the first experiment, resistance development and infestation dynamics in Bt sugarcane without refuge areas are considered using various sterile:wild sterile release ratios, and different release distributions. In the second experiment, the inclusion of a refuge area in Bt sugarcane is considered, using various sterile:wild releases ratios and different release distributions. A trade-off between sterile insect releases and the use of the refuge area was observed, and could, in some cases, work against each other.