Evaluating botanical insecticides for control of Megalurothrips usitatus

Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae), native to the Asian tropics, is a serious pest of leguminous crops. First reported in Florida in 2020, it has since spread throughout Central America and the Caribbean, where it threatens food security by causing significant losses in common bean. In Florida, M. usitatus has caused major losses to the snap bean (Phaseolus vulgaris L.) (Fabales: Fabaceae) industry, increasing the application of insecticides. The objective of this study is to evaluate the efficacy and identify the mode of action of botanical formulations as sustainable control options. Botanical insecticides, especially essential oil-based formulations, offer promising alternatives due to their combined effects, including contact toxicity, repellency, and feeding and oviposition deterrence. Laboratory bioassays were conducted under controlled conditions. Contact toxicity was evaluated at three concentrations, and 72-hour mortality guided dose selection. Repellency was assessed using leaf-disc assays under no-choice and multiple-choice setups. Residual activity was measured by treating plants at staggered intervals. Deterrence was also evaluated through feeding damage and oviposition over 24 hours, using both multiple-choice and no-choice leaf-disc setups. Understanding how repellents influence insect behavior is critical to using these products effectively against M. usitatus. Future research will focus on expanding these findings under more realistic conditions using cage studies with whole plants.