Lethal and Sublethal Effects of Fluxametamide on Rice-Boring Pest, Rice Stem Borer Chilo suppressalis

Abstract

(1) Background: Fluxametamide is a novel isoxazoline insecticide. Rice stem borer Chilo suppressalis (Walker) is a destructive Lepidoptera pest of rice in China, and novel effective insecticides are required to be developed for controlling it due to its increasing resistance levels. (2) Results: In the lethal assay, the insecticidal activity of fluxametamide with median lethal dose (LD50) value of 1.308 mg/kg to the fourth-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 the sublethal (LD10 and LD30) assay, the duration of third to sixth-instar larvae, the pupal duration, pupation rate, and life cycle rate were significantly increased in F0 generation. Both the length and weight of the ovarian tube were decreased with the dose increase of fluxametamide, and were significantly smaller in the LD30 treatment than those of the control group. In F1 generation, only the duration of eggs was significantly increased with LD30 treatment of fluxametamide, whereas other developmental parameters had no significant change. (3) Conclusion: Fluxametamide had relatively strong lethal and sublethal effects on C. suppressalis and probably was able to affect the population growth and progeny of C. suppressalis.