Toxicity of insecticides to resistant strain of Spodoptera litura (fab.) on cotton

Among the insecticides, emamectin benzoate was found to be the best with the highest relative toxicity (1093.2, 986.5, 870.6, 254.3 & 160.3 times) than triazophos, cypermethrin, deltamethrin, chlorpyriphos and quinalphos to which the pest was developed high levels resistance. Novaluron was the next best which showed better toxicity (134.2, 121.0, 106.8, 31.2 & 20.4 times) than triazophos, cypermethrin, deltamethrin, chlorpyriphos and quinalphos at LD₅₀ level, respectively. Indoxacarb was the third best in its relatively toxicity which was 91.9, 82.2, 72.6, 21.2 and 13.9 times more toxic than triazophos, cypermethrin, deltamethrin, chlorpyriphos and quinalphos at LD₅₀ level, respectively. Among the novel insecticides, thiodicarb and spinosad showed poor efficacy against the resistant Guntur strain of S. litura.