Combined effects of azadirachtin and nucleopolyhedrovirus (SpltNPV) on Spodoptera litura Fabricius (Lepidoptera: Noctuidae) larvae

The effects of azadirachtin (AZA) and Spodoptera nucleopolyhedrovirus (SpltNPV) on development and mortality of Spodoptera litura Fabricius (tobacco cutworm) were evaluated in the laboratory. The effective concentrations for AZA and SpltNPV were determined and tested as single and combination treatments. AZA and SpltNPV produced synergistic effects on tobacco cutworm mortality in higher dose combination treatment. Combinations of AZA + SpltNPV at 0.25 ppm + 1 × 103 OB and 0.50 ppm + 1 × 106 OB resulted in a significantly higher larval mortality than treatment with either virus/botanical insecticide alone at the corresponding concentrations. When consumed together (AZA and SpltNPV) larvae died significantly faster compared with larvae consuming SpltNPV or AZA. These results suggest that treatments with AZA and SpltNPV at appropriate combinations of concentration levels may result in improved control of tobacco cutworm compared with treatment with either AZA or virus alone.