Contact toxicity of insecticides against honeybees, Apis mellifera L. under laboratory conditions

A study was conducted to evaluate the toxicity of insecticides against Apis mellifera L. (at half the recommended dose of insecticide + azadirachtin) by residual exposure method. consisted of seven treatments viz. Imidacloprid 17.80% SL + Azadirachtin 1500 ppm, Cypermethrin 10% EC + Azadirachtin ppm, Profenofos 50% EC + Azadirachtin 1500 ppm, Chlorantraniliprole 18.50% SC + Azadirachtin 1500 ppm, Emamectin benzoate 05% SG + Azadirachtin 1500 ppm, Chlorantraniliprole 09.30% + Lambda-cyhalothrin 04.60% ZC + Azadirachtin 1500 ppm and untreated control. Which revealed that at 72 hours, Chlorantraniliprole 18.50% SC + Azadirachtin 1500 ppm caused 50 percent cumulative mortality in honey bees. This was followed by Chlorantraniliprole 09.30% + Lambda cyhalothrin 04.60% ZC; + Azadirachtin 1500 ppm (70%). The treatment of Imidacloprid 17.80% SL + Azadirachtin 1500 ppm, Profenofos 50% EC + Azadirachtin 1500 ppm, Emamectin benzoate 05% SG + Azadirachtin 1500 ppm and Cypermethrin 10% EC + Azadirachtin 1500 ppm recorded cent percent mortality in bees. The LT50   values revealed the time required to cause 50% mortality of honeybees. It was as follows: Chlorantraniliprole + Azadirachtin 1500 ppm (61.18 h) Chlorantraniliprole + Lambda cyhalothrin + Azadirachtin 1500 ppm (33.53 h), Imidacloprid + Azadirachtin 1500 ppm (10.83 h), Profenofos + Azadirachtin 1500 ppm (8.98), Emamectin benzoate + Azadirachtin 1500 ppm (7.79 h) and Cypermethrin + Azadirachtin 1500 ppm (6.25 h).