Selective Toxicity of Four Insecticides on Green Peach Aphid and Predator Multicolored Asian Ladybird (Coleoptera: Coccinellidae) and the Coordination Evaluation of Biological & Chemical Control to Insect Pest

The comparative toxicity of four insecticides imidacloprid, rotenone, abamectin and azadirachtin on the green peach aphid Myzus persicae (Sulzer) and its predatory natural enemy multicolored Asian ladybird Harmonia axyridis (Pallas) adults was determined. The toxicity of these 4 insecticides on the green peach aphid was abamectin＞imidacloprid＞rotenone＞azadirachtin, the LC50 s were 0.042, 1.96, 6.54 and 10.17 mg/L, and LC50 s on multicolored Asian ladybird were 1009.42, 201.89, 8202.90 and＞7500 mg/L, the toxicity ratios (LC50 of insecticide on ladybird/LC50 of insecticide on aphid) were 24033.81, 103.01, 1254.27 and＞786.63,respectively. When giving effective control to the M. persicae, the safety of 4 insecticides to the natural enemy H. axyridis was abamectin＞rotenone＞azadirachtin＞imidacloprid. Abamectin, imidacloprid, azadirachtin and rotenone could be applied effectively in the integrated pest management program.