Combined Action of Nuclear Polyhedrosis Virus and Neem Bitter against Spodoptera litura (Fabricius) Larvae

Laboratory experiments showed that neem bitter (0.1%), an ethanol-soluble concentrate of neem oil cake when combined with nuclear polyhedrosis virus [5×10⁵ polyhedral occlusion bodies (POBs/ml)] along with crude sugar (1%) caused a significantly higher mortality of Spodoptera litura (Fabricius) larvae. The NPV-neem bitter-crude sugar combination recorded the shortest LT_50. The enhanced action was seen even at a lower dose of neem bitter (0.025%) with NPV (1×10⁵ POBs/ml) and crude sugar (1%). Without crude sugar, the NPV-neem bitter combination was not effective in increasing the mortality. The larval weight and growth rate were significantly reduced in NPV-neem combination.