Management of insecticide-resistant western flower thrips in North Carolina fruiting vegetable systems

The western flower thrips, Frankliniella occidentalis (Pergande), is a significant pest of fruiting vegetables in North Carolina. Insecticides are the primary tactic used to manage thrips in these systems, but resistance within F. occidentalis populations has reduced the number of effective products available. This has forced farmers to revert back to older, broad-spectrum chemistries that pose both health risks and incompatibility with natural enemies. To mitigate future complications, it will be critical to integrate non-chemical tactics, in addition to alternative insecticidal modes of action, into management strategies. A two-year study (2023 and 2024) was conducted to separately evaluate cultural tactics, specifically plastic mulches, and alternative insecticides with environmental- and health-friendly profiles. For the mulch trial, four plastic mulch types were observed in 2023 (bare ground, black, reflective, and white) and 2024 (black, reflective, reflective + black strip, and white). For the insecticide trial, 11 and 14 treatments were observed in 2023 and 2024, respectively. Applications occurred weekly for five weeks and these treatments included bioinsecticide products as well as industry standards. For both mulch and insecticide trials, thrips populations were monitored weekly via leaf and flower samples. Additionally, mature fruit were harvested and examined for insect damage and the presence of tomato spotted wilt virus. Results showed reflective mulches significantly reduced the number of thrips in both leaf and flower samples throughout the trial periods. Of the treatments tested, only one product (inactive Burkholderia rinojensis strain A396) controlled thrips populations as effectively as the observed industry standards.