Toxicity and Efficacy of Thirty Insecticides Against Thrips flavus in Northeast China: Laboratory, Semifield, and Field Trials

In soybean fields across Northeast China, <i>Thrips flavus</i> Schrank (Thysanoptera, Thripidae) populations are increasing, posing a significant threat to soybean production. The aim of this study was to evaluate the toxicity, insecticide efficacy, and field performance of thirty insecticides against <i>T. flavus</i>. Laboratory bioassays revealed that fenthion (LC₅₀ = 2.26 mg/L), sulfoxaflor (LC₅₀ = 4.28 mg/L), cyetpyrafen (LC₅₀ = 4.94 mg/L), and imidacloprid (LC₅₀ = 6.16 mg/L) exhibited the highest toxicity against <i>T. flavus</i>. Pot experiments were subsequently conducted to assess insecticide efficacy. Seven days after application at the highest tested concentration, the insecticide efficacy of fenthion, sulfoxaflor, chlorantraniliprole, bifenazate, and malathion achieved 100% control efficacy. The four insecticides were selected for field trials based on their high toxicity and insecticide efficacy. Seven days after application, the field efficacy of fenthion at 11.25 g a.i.·hm^-2, sulfoxaflor at 1.19 g a.i.·hm^-2, cyetpyrafen at 8.10 g a.i.·hm^-2, and imidacloprid at 11.25 g a.i.·hm^-2 exceeded 80%. Thus, these four insecticides hold strong potential for integrated management of <i>T. flavus</i>. Overall, the findings provide a valuable reference for developing chemical control strategies against this pest.