Location: Beneficial Insects Introduction Research Unit
2024 Annual Report
Objectives
Objective 1: Investigate key biotic factors influencing the spatial and temporal dynamics of wood-boring pest (including ALB and EAB) populations in their native range, focusing on exploration and quarantine service for effective, host-specific natural enemies (parasitoids) for biocontrol.[NP304, C1, PS1A; C3, PS3A, 3B, and 3C]
Objective 2: Conduct field releases and evaluate impacts of extant (indigenous) and previously introduced parasitoids on populations of wood-boring beetles such as EAB and ALB in the United States, while elucidating factors that influence successful establishment of introduced biological control agents, such as climate adaptation, release methodology, genetic variation in founder populations and risk-spreading (diapause) strategy.[NP304, C1, PS1A; C3, PS3A, 3B, and 3C]
Objective 3: For newly discovered parasitoids of ALB, EAB and other invasive pests, and based on studies of life histories and reproductive biology, develop effective rearing technologies for these natural enemies, focusing on optimizing host stage, host substrate complex, temperature, photoperiod and relative humidity.[NP304, C1, PS1A; C3, PS3A, 3B, and 3C]
Objective 4: Discover, identify, characterize the biology, evaluate the efficacy (using native-range studies and host-range specificity testing in quarantine), and determine the physiological, behavioral, and ecological basis of the host range of exotic predators and parasitoids as classical biological control agents of invasive arthropod pests of agricultural crops, with a focus on BMSB and SWD. [NP304, C1, PS1A; C3, PS3A, 3B and 3C]
Objective 5: Improve understanding of biological and environmental factors and processes that influence the successful establishment of introduced biological control agents, such as climate adaptation, release methodologies, genetic variation in source and founder populations, using natural enemies of current target pests as model systems. [NP304, C1, PS1A; C3, PS3A, 3B and 3C]
Objective 6: Prepare (with collaborators when appropriate) petitions to regulatory agencies for field release of candidate agents, conduct field releases for establishment of new agents, and monitor and evaluate the impact of the natural enemies on target populations and on non-target species in the field. [NP304, C1, PS1A; C3, PS3A 3B and 3C]
Objective 7: Determine the genetic basis of the host ranges and climatic tolerances of pest herbivorous insects and parasitoids of these pests with a focus on using molecular genetic methods to elucidate factors responsible for the evolution of host specificity, to predict responses to climate change, and to develop methods for management of pest impacts. [NP304, C1, PS1A; C3, PS3A, 3B and 3C]
Objective 8: Determine interactions between biological control, plant resistance, and aphid virulence in their effects on virulence frequencies. [NP304, C1, PS1A; C3, PS3A and 3B]
Objective 9: Determine molecular phylogenetic relationships, test host specificity, and introduce parasitoids for biological control of target aphids. [NP304, C1, PS1A; C3, PS3A and 3B]
Approach
Using the approaches relevant to the knowledge base of the targeted pests and their natural enemies, we will conduct foreign explorations for new natural enemies from the pests’ native home (Northeast Asia) and construct life tables of the target pest populations to evaluate the impact of the natural enemies on the pests’ population dynamics in Northeast Asia. After selecting the most promising (or efficient) natural enemies, we will test the selected natural enemies against non-target wood-boring insects in North America to delineate their host range for biological control introduction against the target pests. Upon regulatory approval for environmental releases of the discovered natural enemies in North America, we will conduct field experiments to assess their establishment, dispersal and impacts on the target pests’ population in the U.S. Laboratory studies will also be conducted to collect information on the parasitoid’s biology, risk-spreading and reproductive strategy and life history and to develop efficient rearing methods for mass-production of the introduced natural enemies for biological control releases. In addition, this project will provide quarantine services, host range data and mass-rearing technologies for natural enemies of high priority plant pests to state and federal agencies. This project will also investigate the genetic basis of host ranges and climatic tolerances of parasitoids and target pest insects; interactions between biological control, plant resistance, and aphid virulence; the molecular phylogenetic relationships among natural enemies of pests; and develop predictions on how impacts of introduced parasitoids are likely to be affected by climate change. This research will improve both the safety and efficacy of biological-control introductions against foreign, invasive pests, and thus benefit agriculture in the United States.
Progress Report
This report for the Project 8010-22000-031-000D includes the progress made both before and after its combination with two other projects (8010-22000-032-000D and 8010-22000-033-000D) that were terminated as of February 2024. Detailed progress reports for the terminated projects (8010-22000-032-000D and 8010-22000-033-000D) are also submitted under the terminated respective project numbers.
Asian longhorned beetle (ALB) research: In collaboration with Chinese and South Korean corporators, we quantified the role of discovered ALB larval parasitoids in Asia. Overall, the rate of ALB larval parasitism in Asia appears to be low (<20%), indicating its limited role in regulating ALB populations in the pest’s native range. Thus, additional efforts were taken in evaluating the possible use of native North American parasitoid (Ontsira mellipes) against ALB in quarantined zones in the United States (with all appropriate federal and state permits and permission to move regulated articles). In cooperation with researchers from Clemson University, thousands of O. mellipes adults reared on ALB larvae at the USDA ARS Beneficial Insects Introduction Research Unit were released on ALB-infested trees in an active quarantine zone in South Carolina in the summer of 2023 and 2024. Data collected after the 2023 releases showed that laboratory-reared parasitic wasp (O. mellipes) successfully attacked field-grown ALB in South Carolina, suggesting that new association biological control with field releases of North American parasitic wasps may be a useful supplement to the current ALB eradication strategy.
Emerald ash borer (EAB) research: We continued field evaluations of the establishment, persistence, and impact of previously introduced biocontrol agents (egg and larval parasitoids) against emerald ash borer (EAB) in mid-Atlantic (Maryland and Delaware), Midwest (Michigan) and Northeast (Massachusetts, New York, and Connecticut) regions of the U.S. on the emerald ash borer (Agrilus planipennisi) in FY 2024. Findings from our field studies demonstrated the successful establishment, spread, and persistence of the newly introduced Asian larval parasitoids (Spathius galina, Tetrastichus planipennisi, and Oobius agrili) in Michigan and Delaware. Using manipulated field experiments, we determined how local environment and seasonality affect the cold tolerance of this introduced larval EAB larval parasitoid (T. planipennisi) for overwintering survival. Our findings indicate that the cold tolerance of T. planipennisi is affected by the insect’s exposure to the minimum and/or maximum ambient temperatures of the local environment as well as seasonality, and local environmental conditions and seasonality can have significant impacts on the overwintering survival of the biocontrol agents in more Northern regions. Using controlled laboratory experiments, we showed that parasitoid attacks reduce feeding activity of EAB larvae and thus benefit protection of ash trees. However, the parasitic wasp has limited ability to optimize its offspring development and fitness through regulations of the host metabolism and feeding activity. Thus, the availability and abundance of suitable stages of EAB are critical for successful parasitoid progeny production and population growth in the field. In FY2024, we continued to improve the methods for mass production of the egg parasitoids O. agrili through optimization for long-term storage of host eggs and diapaused parasitoid larvae.
Russian aphid research: See final report for project 8010-22000-032-000D.
Brown marmorated stink bugs, spotted wing fruit fly, and spotted lantern fly: See final report for project 8010-22000-033-000D.
Quarantine activities: We continued to propagate and ship several species of natural enemies to state and university cooperators for releases against several invasive species across the United States. These included Aphelinus hordei as mummified aphids to Colorado State Universities for field releases against Russian wheat aphids, Spathius galinae, Oobius agrili and Tetrastichus planipennisi to Oregon Department of Agriculture for emerald ash borer biocontrol, and Trissolcus japonicus to Plant & Food Research, New Zealand for biocontrol of brown marmorated stink bugs, and Ganaspis brasiliensis to University of Cornell, University of New Hampshire, and New York State University for rearing and releases against spotted wing drosophila.
Accomplishments
1. Invention of the emerald ash borer oviposition trap. The emerald ash borer (EAB) is one of the most destructive invasive forest pests in North America. The beetle lay eggs between bark crevices or under loose barks of ash trees. Because of such cryptic egg-laying behavior, it has been extremely difficult to detect EAB eggs in the field. ARS scientists at Newark, Delaware, discovered that strips of burlap fabric or polypropylene curling ribbon wound tightly around tree trunks or branches in a spiraling pattern induce EAB adults to lay eggs on surfaces of the trunks or branches of ash covered with these materials in the field. This oviposition trap is an effective tool for field studies of egg parasitoids associated with EAB and other jewel beetles and is currently being used by university researchers.
Review Publications
Lee, S., Park, D., Wang, X., Duan, J.J., Gould, J.R., Kim, I., Lee, S. 2023. Exploration for Asian longhorned beetle parasitoids in Korea using an improved sentinel log trap. Parasite. 30(57):10. https://doi.org/10.1051/parasite/2023062.
Dang, Y., Duan, J.J., Li, A.Y. 2023. Parasitoid-induced changes in metabolic rate and feeding activity of the emerald ash borer (Coleoptera: Buprestidae): implications for biological control. Scientific Reports. 13. Article 22663(2023). https://doi.org/10.1038/s41598-023-50147-8.
Duan, J.J. 2024. A novel oviposition trap for studying the egg-laying behavior of emerald ash borer (Coleoptera: Buprestidae). Journal of Economic Entomology. 97:1-5. https://doi.org/10.1007/s10340-024-01770-5.
Barker, B.S., Coop, L., Duan, J.J., Petrice, T. 2023. An integrative phenology and climatic suitability model for emerald ash borer. Frontiers in Insect Science. https://doi.org/10.3389/finsc.2023.1239173.
Duan, J.J., Schmude, J.M., Petrice, T., Bauer, L.S., Poland, T., Chandler, J., Crandall, T., Elkinton, J.S., Van Driesche, R. 2023. Successful establishment, spread, and impact of the introduced parasitoid spathius galinae (Hymenoptera: Braconidae) on emerald ash borer (Coleoptera: Buprestidae) populations in post-invasion forests in Michigan. Journal of Economic Entomology. https://doi.org/10.1093/jee/toad149.