Efficacy of Conventional and Biorational Insecticides against the Invasive Pest Thrips parvispinus (Thysanoptera: Thripidae) under Containment Conditions

Simple Summary: Thrips parvispinus (Karny) is an invasive and polyphagous pest that attacks a wide range of plants, including ornamentals, vegetables, and fruits. Since its detection in Florida in 2020, T. parvispinus has emerged as a serious threat to agriculture in the United States, and it is currently a regulated pest in Florida. Immediate efforts are needed to develop strategies that can effectively safeguard crops from the detrimental impacts of this pest. With that in mind, we identified efficacious conventional and biorational insecticides that can control T. parvispinus infestations rapidly in ornamental plants. Larvae and adults were exposed to each insecticide either directly or through residue toxicity routes. For the direct assays, each product was applied on larvae and adults using a Potter Spray Tower. For the residue toxicity assays, each product was applied on bean plants. Larvae and adults were released after the plant tissue dried. From the 21 conventional insecticides tested against T. parvispinus, chlorfenapyr, sulfoxaflor-spinetoram, and spinosad caused the highest mortality and leaf-feeding damage across all stages in both assays. Among the 11 biorational insecticides tested, mineral oil (3%) and sesame oil caused the highest mortality and lowest leaf-feeding damage. We recommend implementing a rotation program that integrates these products, considering their various modes of action. In 2020, the invasive Thrips parvispinus (Karny) was first detected in Florida, United States. In response to the implemented regulatory restrictions, we conducted laboratory experiments under containment conditions. Thrips larvae and adults were exposed to 32 products (conventional and biorational insecticides) either directly or indirectly. Direct exposure was performed using a Spray Potter Tower, while indirect exposure was conducted by evaluating residue toxicity against the thrips. Water served as a control. We assessed mortality and leaf-feeding damage 48 h post-treatment. Among the conventional insecticides, chlorfenapyr, sulfoxaflor-spinetoram, and spinosad caused high mortality across all stages in both direct and residue toxicity assays. Pyridalyl, acetamiprid, tolfenpyrad, cyclaniliprole-flonicamid, acephate, novaluron, abamectin, cyantraniliprole, imidacloprid, cyclaniliprole, spirotetramat, and carbaryl displayed moderate toxicity, affecting at least two stages in either exposure route. Additionally, chlorfenapyr, spinosad, sulfoxaflor-spinetoram, pyridalyl, acetamiprid, cyclaniliprole, cyclaniliprole-flonicamid, abamectin, and acephate inhibited larvae and adult's leaf-feeding damage in both direct and residue toxicity assays. Regarding biorational insecticides, mineral oil (3%) and sesame oil caused the highest mortality and lowest leaf-feeding damage. Greenhouse evaluations of spinosad, chlorfenapyr, sulfoxaflor-spinetoram, and pyridalyl are recommended. Also, a rotation program incorporating these products, while considering different modes of action, is advised for ornamental growers to avoid resistance and to comply with regulations.