Toxicity of Insecticides to Larval Endoparasitoid, Cotesia plutellae (Kurdj.) of Diamondback Moth, Plutella xylostella (L.) under laboratory condition

Studies on safety evaluation of certain newer insecticides to larval endoparasitoid, Cotesia plutellae (Kurdj.) of diamond back moth, Plutella xylostella (L.) were undertaken in laboratory condition. Toxicity of insecticides on cocoons of C. plutellae revealed that novaluron and emamectin benzoate were highly safer to the parasitoid recording maximum of 93.33 and 90.00% adult emergence, respectively followed by azadirachtin (83.33%) and spinosad (76.67%). Indoxacarb was detrimental to C. plutellae which recorded least per cent adult emergence of 43.33. To the adults, rynaxypyr exhibited highest toxicity (LC₅₀ 0.0004%). The order of toxicity to the egg parasitoid C. plutellae based on median lethal concentration (LC₅₀) values was as follows: rynaxypyr (0.0004%) > indoxacarb (0.0005%) >flubendiamide (0.0006%) >azadirachtin (0.0405%) >emamectin benzoate (0.0468%) >spinosad (0.0475%) >novaluron (0.0621%). The 95% fiducial limits of LC₅₀ of indoxacarb, the highly toxic chemical, overlapped with the fiducial limits of LC₅₀ of the other insecticides, rynaxypyr and flubendiamide. Based on LC₅₀ values, rynaxypyr was 158, 119, 117 and 102 times more toxic than novaluron, spinosad, emamectin benzoate and azadirachtin, respectively.