Project Overview

Reports

Commodities

Target Pests

Practices

The western flower thrips is a pest of fruiting vegetable crops (tomato, pepper, eggplant, etc.) that has been increasing in severity in the southern region since about 2015. Crop losses due to direct feeding on fruit and transmission of tomato spotted wilt virus (TSWV) have been particularly severe in the past two to three years, especially on tomatoes; several growers in the Piedmont of NC suffered crop losses of 50-75% in 2022. Increased crop losses have also been reported from SC and TN. The increased severity of WFT appears to be associated with populations resistant to the insecticide spinetoram (Radiant®), which, along with its parent compound spinosad (Entrust®), has been used extensively for its control for >20 years. In response to resistance development, growers have increased the use of insecticides that are broad-spectrum in activity and have high mammalian toxicity (e.g., Dimethoate and Lannate), with poor results.  Clearly, alternative strategies are needed to manage resistant populations.

This seed project addresses an emerging issue that is documented as a high priority and has the support of the vegetable industry in NC and surrounding states. We propose to determine the extent of the causation of the problem (i.e., spinetoram resistance), and evaluate, demonstrate and disseminate information on improved integrated pest management of WFT. Knowledge of the resistance status of WFT populations on a regional scale is needed to inform stakeholders of areas where spinetoram remains a viable management tool (i.e., susceptible populations), and where resistance dictates the need for alternative management strategies. Hence, we will collect thrips populations from a diversity of locations and vegetable production systems in NC, SC and TN and test them for resistance using diagnostic dose bioassays. We will also cooperate with a commercial tomato grower in the Piedmont of NC to conduct an experiment to compare non-chemical WFT management strategies to conventional insecticides. Specifically, we will evaluate reflective mulches in combination with biorational pesticides (i.e., biopesticides and kaolin clay). In addition to comparing the efficacy in reducing thrips numbers, a partial budget analysis will be used to estimate net profitability of the various treatments. We will also conduct greenhouse studies at NC State University to assess the potential of a unique method of exposing thrips to the fungal entomopathogen Beauveria bassiana. This will involve use of an endophytic strain that colonizes tomato plants and is reported to both suppress insect pests and enhance plant grow. Finally, an outreach program will add a WFT webpage to our Vegetable IPM website, and use field days and commodity meetings to disseminate results and conduct a survey to collect baseline data for future evaluations of our efforts to develop and implement more sustainable WFT IPM programs.

In the short term, we anticipate stakeholder engagement and adoption of WFT management tactics that are supported by outreach and grower resources. Specifically, there will be improved stakeholder knowledge of factors that promote WFT resistance to insecticides, and the need to adopt non-chemical management strategies such as reflective mulches and biorational pesticides. In the longer term, growers will become less reliant on insecticide intervention for managing WFT, which will become an occasional pest that is easily suppressed with judicious use of IPM compatible insecticides. In addition, extension resources and research publications will be used by other southern region extension specialists to inform their stakeholders of new approaches to managing WFT on fruiting vegetables.

1. Monitor spinetoram resistance in western flower thrips populations from different geographic areas and vegetable production systems.
2. Evaluate reflective mulches and biorational pesticides as an alternative to conventional insecticides for management of western flower thirps on tomatoes.
3. Conduct an outreach program to deliver project information to stakeholders.