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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #427767
Research Project: Novel Approaches for Managing Key Pests of Peach and Pecan

Location: Fruit and Tree Nut Research

Title: Beneficial nematodes provided pecan weevil control one year after application

Author
item Shapiro Ilan, David
item SLUSHER, EDDIE - Texas A&M University
item SHIELDS, ELSON - Cornell University
item HARGES, WILL - Strawberry Creek Ranch
item PERIER, JERMAINE - University Of Georgia

Submitted to: Pecan Grower
Publication Type: Trade Journal
Publication Acceptance Date: 7/11/2025
Publication Date: 8/1/2025
Citation: Shapiro Ilan, D.I., Slusher, E.K., Shields, E., Harges, W., Perier, J. 2025. Beneficial nematodes provided pecan weevil control one year after application. Pecan Grower. 37(4):52-57.

Interpretive Summary: Technical abstract only

Technical Abstract: Pecan weevil (Curculio caryae) is an economically important pest of pecans. Beneficial nematodes (also known as entomopathogenic nematodes) in the genera Steinernema and Heterorhabditis, when applied at standard rates (e.g., 1 billion nematodes per acres) can provide high levels of pecan weevil control (e.g., >90% control); however, the applications are costly. Additionally, in general, beneficial nematodes are re-applied every year. To reduce costs, we investigated whether substantially lower application rates would control pecan weevil, and whether pest control would carry over to the next year. In 2022, two different treatments of the beneficial nematodes, a combination of (Steinernema carpocapsae and S. feltiae), were applied to a pecan orchard in Byron GA and an orchard in Porter, OK. A commercial mixture of strains (“All” and “SN” strains) was compared to NY strains (“NY01” and “NY04”). The rate of nematodes applied was 20X lower than the standard rate. Pecan weevil populations in Byron, GA were very low in 2022 and 2023 (less than 0.1 weevil per trap) and so no reductive treatment effects were observed. In Oklahoma, in 2022 the commercial strains provided a slight reduction in pecan weevil the population whereas the NY strains did not. In 2023, one year after the initial application, the commercial nematode treatment provided approximately 79% control of the pecan weevil population in Oklahoma. This result indicates the potential for beneficial nematode effects to carry over to subsequent years even at low-rate applications (Slusher et al., 2025). However, 79% control is not sufficient. Therefore, future research will investigate pecan weevil control at other application rates (such as 10X lower than the standard, 5X lower, etc.) and explore the factors that may contribute to beneficial nematode persistence.