Efficacy of nucleopolyhedrovirus and azadirachtin on Spodoptera litura Fabricius (Lepidoptera: Noctuidae)

Spodoptera litura Fabricius (Lepidoptera: Noctuidae) is a destructive pest of subtropical and tropical agriculture, and has the potential to be a serious pest of forage crops in Asia. The effects of azadirachtin (AZA) and nucleopolyhedrovirus (NPV) on feeding and mortality of S. litura were evaluated in the laboratory. The nutritional indices were significantly affected. Gross dietary utilization (efficiency of conversion of ingested and digested food) of S. litura was also decreased after treatment with AZA and NPV. Food consumption, efficiency of conversion of ingested and digested food, relative growth rate, and consumption index values declined significantly, but at the same time an increase in approximate digestibility was also observed. Maximum larval weight (fifth instar) loss (68%) occurred, when AZA and NPV were combined. When consumed together (AZA and NPV) larvae died significantly faster compared with larvae that consumed NPV or AZA. Dose and larval instar dependent growth retardation was observed after treatment with NPV and AZA. Upon combination of AZA with NPV, nutritional indices decreased twofold even at reduced concentration of both.