Base line toxicity of emamectin and spinosad to Spodoptera litura

The results of the studies carried out on acute toxicity of emamectin and spinosad to Spodoptera litura for arriving at discriminating doses for resistance monitoring revealed that the pest was highly susceptible to these insecticides. The discriminating doses were fixed at 0.40 ppm for emamectin and 125 ppm for spinosad to Spodoptera litura. The discriminating doses when applied to the field collected populations of Coimbatore and Madurai areas, no resistance was detected, which was confirmed by very high % mortality.