Optical Brighteners as UV Protectants and their Influence on the Virulence of Nuclear Polyhedrosis Virus of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae)

Laboratory screening of twelve optical brighteners as UV protectants for Spodoptera litura (Fabricius) NPV revealed that Ranipal BVN and 2B provided excellent protection (80% original activity remaining). Effect of optical brighteners in preserving NPV was concentration dependent and an increase in concentration from 0.001 to 1.00 per cent increased the retention of viral activity from 14.8 to 99.9 per cent and 10.8 to 99.9 per cent for Ranipal BVN and 2B, respectively. Addition of selected optical brighteners, Ranipal BVN and 2B at a range of 0.001 to 1.00 per cent with S. litura NPVincreased the virulence ofNPV by reducing the LC₅₀ and LT₅₀ of NPV.