Project Overview

Reports

Commodities

• Fruits: berries (blueberries), berries (strawberries)

• Vegetables: cucurbits, peppers, tomatoes

Target Pests

• Target Pests: other

Practices

• Pest Management: chemical control, pesticide resistance management

Project Summary

       Western flower thrips (WFT) is a major pest of fruiting vegetable other specialty crops such as strawberry throughout the southeastern United States. Damage is the result of feeding and oviposition that causes scarring and gold fleck, and as a vector of tomato spotted wilt virus. In 2022, several growers in the Piedmont region of NC experienced crop losses of 50-75%, underscoring the urgent need for sustainable management solutions. Insecticides remain the primary control strategy for WFT, particularly in high-value crops that have low damage tolerances. We previously documented WFT populations in NC tomatoes with >1400-fold resistance to spinetoram, a reduced-risk insecticide compatible with beneficial insects, and the cornerstone insecticide for >20 years. Growers with resistant populations now rely on two older broad-spectrum insecticides dimethoate and methomyl (Lannate), both of which illicit concerns about environmental and farm worker health risks.

       Monitoring for insecticide resistance is a critical component of resistance management programs, but reliance on bioassays greatly limits the scope of monitoring programs. Fortunately, spinetoram resistance in WFT has been shown to be the result of a target-site mutation (G275E) in the nicotinic acetylcholine receptor ?6 subunit that disrupts the binding and modulatory of spinetoram. Using a validated allele-specific qPCR assay, this past summer we successfully assessed the frequency of the resistance alleles in tomato, pepper, cucumbers and strawberry crops on several vegetable farms in the Piedmont and Coastal Plains of NC.

       Building on this foundational work, we propose to expand resistance monitoring to additional southeastern states (SC, GA, FL, TN, MS, VA, and AL) to determine the regional prevalence and spatial distribution of the G275E mutation. This capstone project directly addresses an emerging issue that has been identified as a high priority by the Southern IPM Center and has support from the vegetable industry. To accomplish this, we will collaborate with 11 Extension and research partners at Land Grant universities to identify 3 to 4 sentinel sites per state for thrips collection, representing mixed vegetable and small fruit production systems and environments. Thrips will be sent to NC and analyzed using our validated qPCR assay to quantify the frequency of resistance alleles. Based on recent research identifying critical agroecosystem components that contribute to WFT hotspots, results will be visualized through GIS-based mapping to categorize and identify regions with high and low risk for WFT insecticide resistance. This project will help to identify potential resistance hotspots and provide early warnings on the emergence and spread of resistance within a region. This coordinated, multi-state effort will generate the first comprehensive dataset on spinetoram resistance across the southeastern U.S., strengthening regional collaboration and information sharing.

       Our Extension/outreach program will focus on translating these findings into practical recommendations. We will develop fact sheets and infographics, summarizing regional resistance trends and options for WFT management. Project outcomes and recommendations will be shared through stakeholder meetings, commodity conferences, a regional webinar, and via a recently developed WFT Website. A short survey will be used to assess stakeholder awareness and adoption of resistance management practices. Through this project, we aim to increase stakeholder engagement and their understanding of the risks associated with WFT insecticide resistance. Outcomes will directly guide stakeholders in making informed decisions, identifying areas where spinetoram can still be used effectively (i.e., susceptible WFT populations) and promoting alternative management strategies where resistance is established. Collectively, this project will strengthen regional resistance monitoring capacity, enhance collaboration among southeastern states, and provide critical resources for Extension specialists, pest management advisors and growers, and ensuring long-term effectiveness of IPM programs against WFT.