Alternatives to chlorpyrifos in Virginia type peanut production for control of southern corn rootworm

Historically, the organophosphate insecticide chlorpyrifos was used to protect peanuts (Arachis hypogaea L.) from soil-dwelling insect pests. In 2022, its registration was canceled by the Environmental Protection Agency (EPA) for all food crops. The southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae) (SCR), was the major pest of developing peanut previously managed by chlorpyrifos and there are no known alternative insecticides for its control. The SCR larvae can cause economic damage by feeding on developing pods and pegs. Field condition is an important factor in SCR survival as the larvae rely on soil moisture to survive, and larvae cannot feed on fully developed pods. The dependency of SCR on soil moisture and host availability allows for cultural modifications (e.g., planting date, judicious irrigation practices, selecting fields based on soil characteristics) to reduce losses to this pest. Alternatively, or in addition to these strategies, identifying varieties with resistance to SCR can provide growers with non-chemical methods to mitigate losses. Therefore, this project was developed to identify sources of resistance in commercial cultivars and advanced breeding lines of Virginia type peanuts to SCR and examine whether early digging can reduce SCR injury. Implementing an effective integrated pest management (IPM) plan relies on a clear understanding of the pest life cycle in relation to the susceptible stage of the crop. We also evaluated SCR phenology in relation to peanut development. Replicated field trials were used to screen cultivars and investigate the effect, if any, of early digging in reducing pod injury. We monitored SCR adult populations over time using sticky traps. Our research will help manage a problematic pest in this region with limited, or no, reliance on insecticides.