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Larvicide, Staphylococcus vitulinus and Spodoptera litura

Abstract: Spodoptera litura Fab. is one of the most destructive pest of cotton. Damage caused in spite of various control methods, the discovery of new entomopathogenic bacterial species and isolates bearing insecticidal traits against novel targets is needed in the near future. In this study, isolation, characterization of Staphylococcus vitulinus was assessed for insecticidal activity against Spodoptera litura. Bacterial isolation were performed from dead and live larvae of Spodoptera litura, bacterial isolates were characterized based on their morphological and biochemical characteristics. The application of concentration were conducted with five different bacterial concentrations (8.5 x 10⁷ cfu/ml, 12.2 x 10⁷ cfu/ml, 16 x 10⁷ cfu/ml, 20.2 x 10⁷ cfu/ml and 24.4 x 10⁷ cfu/ml) of the active cells and for insecticidal activity 1 ml of bacterial suspension were performed on the third instar larvae of S. litura with the leaves of Ricinus communis. The sub lethal and median lethal dose of Staphylococcus vitulinus was LD₁₀ = 87.06 cfu/ml and LD50 = 215.5 cfu/ml at 96 hrs against third instar larvae. Result revealed that, the mortality increase with increase in concentration of bacterial populations. The highest mortality of Spodoptera litura is found by bacterial strain Staphylococcus vitulinus at 24.4 x 10⁷ cfu/ml. Stastical variance, 95% confidence limits and regression equations are presented.

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