Baseline toxicity of emamectin benzoate and spinosad to Earias vittella in cotton

Studies carried out to find the acute toxicity of emamectin benzoate and spinosad against spotted boll worm, Earias vittella revealed LD₅₀ value of 0.00266 μg larva⁻¹ and 0.00188 μg larva⁻¹, respectively insisting spinosad being the best when compared with emamectin benzoate. Discriminating dose was fixed for the above two chemicals after assessing the susceptibility of insect by culturing the insect through a number of generations without insecticide exposure so as to have a susceptible population. The discriminating doses were fixed as 0.02 and 0.012 μg larva⁻¹ for emamectin benzoate and spinosad, respectively which could be used in resistance monitoring programmes in future.