Lethal and Sublethal Effects of Spinosad on Spodoptera exigua (Lepidoptera: Noctuidae)

ABSTRACT As a selective biological insecticide1 spinosad has been used widely for the control of pests including beet armyworm, Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae). To form effective pest control strategies, lethal and sublethal effects should be considered for a complete analysis of spinosad impact. However, few studies have been reported to investigate sublethal effects of spinosad on S. exigua. This study attempts to evaluate the lethal and sublethal effects of spinosad on this pest by recording and analyzing various toxicological and physiological parameters. The toxicity of spinosad against S. exigua was determined under laboratory conditions by oral exposure of late second-instar larvae to the compound. The LC50 values of spinosad to S. exigua at 48 and 72 h after treatment were 0.317 and 0.293 mg·kg-1, respectively. Spinosad at sublethal concentrations significantly extended the developmental period of survivor larvae, and reduced larval wet weight. Postexposure effects were indicat...