Sensitivities and toxic symptoms of Athetis dissimilis (Hampson) to different insecticides

To search for the effective insecticides against the newly discovered pest Athetis dissimilis, the sensitivities of A. dissimilis larvae at different instars to 18 insecticides (eight categories) were determined using leaf dipping method, and the toxic symptoms of A. dissimilis treated with different insecticides were also investigated. The results showed that instar larvae of A. dissimilis form 3rd to 6th were sensitive to phoxim, bifenthrin, lambda-cyhalothrin, deltamethrin, emamectin benzoate, chlorantraniliprole and cyantraniliprole with LC50 values ranging from 0.138 1 mg/L to 27.40 mg/L. The 3rd- and 4th-instar larvae of A. dissimilis were sensitive to chlorpyrifos, beta-cypermethrin, chlorfluazuron, indoxacarb and chlorfenapyr (LC5022.63 mg/L), whereas the 5th- and 6th-instar larvae were less sensitive to all those insecticides (LC5038.13 mg/L). Different instar larvae of A. dissimilis were insensitive to pirimiphos-methyl, chlorbenzuron and neonicotinoids insecticides (LC5040.83 mg/L). Meanwhile, the toxic symptoms of A. dissimilis larvae differed with treatments of different insecticides. When the larvae were treated with organophosphorus, neonicotinoids, phenylpyrazole and oxadiazine insecticides, the integument of the larvae became dry and shrank. However, the integument of the larvae turned soft and overwhelmed with body fluid while they were treated with pyrethroids. The bioassay results demonstrated that cyantraniliprole, chlorantraniliprole, phoxim, bifenthrin, lambda-cyhalothrin, deltamethrin and emamectin benzoate could be considered as the emergency control insecticides to A. dissimilis.