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. / Master of Science in Life Sciences / In 2022, the Environmental Protection Agency effectively banned the use of chlorpyrifos insecticide for food crops by revoking all food tolerances that had previously been set. In Virginia peanut, farmers were left with no alternatives to control subterranean insects that feed on the marketable portion of the crop, the pod. Virginia peanuts are grown in eight counties along the southern border of Virginia (Peanut Facts - Virginia-Carolina Peanut Promotions (aboutpeanuts.com)) and in 22 eastern North Carolina counties. My project focuses on the pod injuring of the southern corn rootworm (SCR), which were historically controlled by chlorpyrifos. Chlorpyrifos was applied at pegging as a granular product to protect peanut through the late-summer portion of the growing season. Larvae of SCR require moisture, usually in the form of moisture held in soil, to stay alive, and heavier soils and irrigated fields in our region are at higher risk for SCR. Injury is not seen until peanuts are dug for harvest. Host plant resistance would be a desirable non-chemical control alternative. In the following experiments, we evaluated cultivars and advanced breeding lines for SCR resistance, and adult populations were tracked to determine if infestation timing has changed since last documented in the growing season. Our goal is to provide peanut farmers with sustainable methods to manage a problematic below ground pest.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/119301 |
| Date | 05 June 2024 |
| Creators | Hoar, Elijah Kael |
| Contributors | Entomology, Rashed, Arash, Taylor, Sally Vann, Langston, David B. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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