Pathogenicity of Nucleopolyhedrovirus (NPV) against <i>Spodoptera litura</i> (Fabricius)

Abstract

The management of Spodoptera litura by entomopathogenic Nucleopolyhedrosis Viruses (NPVs) is one of the eco-friendly methods. The present study was aimed to evaluate Nucleopolyhedrosis Virus (NPV) against S. litura and its potential as a bio-pesticide. The Occlusion Bodies (OBs) of S. litura nucleopolyhedrosis virus was isolated from infected larvae collected from cabbage field. Pathogenicity studies evaluated three NPV suspensions viz. SpltNPV-native, SpltNPV-commercial and SpltNPV-NIPHM against second and fourth instar larvae of S. litura recorded maximum mortality at 1×109 OBs/ml. The LC50 values of the SpltNPV-native, SpltNPV-commercial and SpltNPV-NIPHM suspensions against second instar larvae were 0.584, 0.540, 0.625 OBs/mm2, respectively, which increased to 0.696, 0.620, 0.756 OBs/mm2 against the fourth instar larvae. The LT50 at 1×109 OBs/ml was found to increase from 146.33, 137.51 and 155.88 h for SpltNPV-native, SpltNPV-commercial and SpltNPV-NIPHM suspension, respectively, against the second instar larvae to 178.51, 162.07 and 187.67 h, respectively, against the fourth instar larvae. The cumulative per cent mortality, LC50 and LT50 suggested that the second instar larvae were more susceptible and easier to kill than the fourth instar larvae.