Evaluating the impact of soil type on the synergy between chemical and biological control strategies for Asiatic garden beetle in mint

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Evaluating the impact of soil type on the synergy between chemical and biological control strategies for Asiatic garden beetle in mint

Asiatic garden beetle (AGB) has become an increasingly important economic pest in peppermint production in Indiana, where larvae feed on mint roots for nearly ten months of the year, causing plant mortality and reduction in oil yields. A single insecticide is labeled for use against this pest in Indiana; however, relying on chemical strategies alone is unlikely to be sustainable. This project proposes to evaluate whether the integration of a biological control agent, an endemic entomopathogenic nematode (EPN) with the labeled insecticide, chlorantraniliprole, can enhance larval AGB suppression across different soil textures encountered in Indiana mint fields. The approach will include replicated greenhouse and field experiments, where AGB larvae will be exposed to these IPM strategies according to four treatments: untreated control, chlorantraniliprole alone, the endemic EPN alone, and chlorantraniliprole + the endemic EPN, in three soil textures: sandy loam, clay, and pure sand. Field experiments will be conducted in commercial peppermint fields, in collaboration with partnering Indiana growers to enhance our understanding of the efficacy of these strategies in real-world conditions where larval infestations occur. Results from this project will directly address questions from mint growers regarding the efficacy and feasibility of chemical and biological control strategies for AGB in mint and support knowledge and implementation of these IPM strategies for growers that are experiencing this pest challenge. We will disseminate findings with growers and stakeholders of the midwest and national mint industry via an Extension Entomology bulletin, presentations at field days and grower conferences, and measure short- and medium-term changes in grower knowledge, attitudes, and willingness to adopt tested IPM strategies with pre- and post-project surveys. The ultimate goal is to generate region-specific, research-based recommendations for mint growers that will support adoption of alternative, sustainable pest management practices that reduce chemical inputs and improve long-term crop resilience.

This project aims to deliver implementable results for commercial mint growers for AGB larvae control by evaluating the effectiveness of a possible synergy between an endemic EPN strain and an insecticide, that will be tested both individually and in combination, across different soil textures.

Expected learning outcomes are to increase knowledge of how to integrate biological control to current pest management, creating a greater awareness of sustainable alternatives to chemical insecticides, and a better understanding of EPNs potential under different soil conditions in the mint production systems. These outcomes will be assessed through pre- and post-surveys oriented to participant farmers, workshops and through participation in field days at Purdue University, capturing shifts in knowledge, attitudes, and confidence in using biological control. At the end of the project, using Likert-scale we can determine more. At the end of the project, using Likert-scale post-surveys, we can determine more precisely the degree of change in participants' knowledge, and willingness to adopt biological control practices, providing measurable evidence of learning and intent to act.

Action outcomes focus on grower engagement in the gradual integration of biological control strategies. While a complete transition away from chemical control is not expected, farmers will be encouraged to explore EPN-based approaches as a complementary tool within their existing systems. They will provide practical feedback on treatment protocols and collaborate by sharing on-farm data to support the refinement of application methods to future applicability.