Introducing Beneficial Entomopathogenic Nematodes for Biological Control and Enhanced Plant Resistance to Improve Pest Management in Cucurbit Crops

View the project final report

Commodities

• Vegetables: cucurbits

Practices

• Pest Management: biological control, integrated pest management

To combat heavy reliance on synthetic insecticides among conventional growers, and improve pest management options for organic growers, this project aims to evaluate the potential for biological control with beneficial entomopathogenic nematodes (EPNs) to help manage cucumber beetles and other pests of cucurbit crops. Biological control using EPNs can be part of an effective strategy for controlling many soil-dwelling insect pests, including cucumber beetles. However, despite promising results from previous studies, EPN biological control is still not widely used in U.S. agriculture and represents only a small fraction (about 0.03%) of the U.S. pest control market, indicating a critical need for continued research into EPN-based biocontrol strategies, as well as education and outreach to encourage greater use among U.S. producers. Research from our lab has revealed that applications of EPNs to plant roots can directly boost plant resistance to a variety of insect pests and pathogens, which suggests that growers can receive multiple benefits from EPN biological control, as EPNs both directly kill pest insects and boost plant resistance. We hypothesized that introducing EPNs would reduce insect damage and boost yield of cucurbit crops through two mechanisms, including both direct mortality of cucumber beetle larvae by EPNs and increased plant resistance against pests following plant exposure to EPNs. Furthermore, because EPNs were only be applied to soil near roots, we predicted that they would not reduce numbers of beneficial insects visiting plants. We evaluated EPN introductions for 3 different cucurbit crops, including cucumbers (Cucumis sativus), summer squash (Cucurbita pepo), and watermelon (Citrullus lanatus) in 2021 and bitter melon (Momordica charantia) in 2022. Overall, we found some evidence of reduced damage and increased yields for plants treated with EPNs. We did not observe differences in numbers of beneficial insects, suggesting EPN treatments did not harm pollinator or natural enemy populations. This research provided new insights into pest management for 3 important crops for our cooperator and the U.S. cucurbit market, and is likely to benefit growers on diversified farms seeking better management options.

Project Objectives
We evaluated the potential for entomopathogenic nematodes (EPNs) to provide biological control and boost plant resistance to improve pest management in cucurbit crops following two specific objectives:

1. Determine the effectiveness of EPN biocontrol in cucurbit crops for reducing numbers of pest insects and plant damage, while preserving beneficial insect populations.
2. Assess how introducing EPNs affects plant growth and yield.