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 and Bacillus subtilis was assessed for insecticidal activity against Spodoptera litura. Bacterial isolation were performed from dead and alive 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 and for Bacillus subtilis was LD10 = 31.61 cfu/ml and LD50 = 113.9 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 and for Bacillus subtilis at 20.2 x 107 cfu/ml. Stastical variance, 95% confidence limits and regression equations are presented.
