Lethal and sublethal effects of fluxametamide on rice-boring pest, rice stem borer Chilo suppressalis

Abstract

Abstract Fluxametamide is a novel isoxazoline insecticide and has been registered in Korea and Japan to control Lepidoptera pests. Rice stem borer, Chilo suppressalis (Walker), is a destructive Lepidoptera pest of rice in China, and novel effectively insecticides are required to be developed for controlling it due to its increasing resistance levels. Therefore, the lethal and sublethal effects of fluxametamide on C. suppressalis were investigated in the present study. In the lethal assay, the insecticidal activity of fluxametamide with median lethal dose (LD50) value of 1.308 mg/kg to the 4th instar larvae of C. suppressalis was higher than that of chlorantraniliprole (LD50, 3.112 mg/kg) and lower than that of emamectin benzoate (LD50, 0.006 mg/kg). In addition, the 3rd instar larvae of C. suppressalis were sensitive to fluxametamide than the 4th instar larvae. In the sublethal (LD10 and LD30) assay, the duration of 3rd to 6th instar larvae was significantly increased, whereas the pupal duration, pupation rate, and life-cycle rate were also significantly increased in F0 generation. Both length and weight of ovarian tube were decreased with the increase of fluxametamide dose, and they in the LD30 treatment were significantly lower than those of the control group. In F1 generation, only the duration of eggs was significantly increased with LD30 treatment of fluxametamide, other developmental parameters has no significant change. These results suggest that fluxametamide has excellent lethal and sublethal effects on C. suppressalis and probably is able to suppress the population growth and progeny of C. suppressalis.