Toxicity of Several Pesticides on Myzus persicae and Safety Evaluation to Predator Harmonia axyridis

The toxicity of several tobacco recommended pesticides on Myzus persicae (Sulzer) (Hemiptera: Aphididae) and its predatory natural enemy Harmonia axyridis (Pallas) adults was determined by means of spray and residual film, and the safety to the ladybirds was also evaluated. The result showed that the LC50 of 3% acetamiprid, 200 g/L imidacloprid, 70% imidacloprid, 5% imidacloprid and 1.7% avermectin·imidacloprid were 7.89,12.91,178.91,33.34, 2.60 mg/L,respectively. Therefore, the toxicity of these pesticides on M.persicae was 1.7% avermectin·imidacloprid>3% acetamiprid>200 g/L imidacloprid>5% imidacloprid>70% imidacloprid. In addition, the toxicity of 3% acetamiprid on Harmonia axyridis was the highest, and the LC50 was 8.61 mg/L,and then were 1.7% avermectin·imidacloprid, 5% imidacloprid, 200 g/L imidacloprid and 70% imidacloprid, respectively, the toxicity of 70% imidacloprid was the lowest, which was 393.28 mg/L. According to toxicity ratio and safety coefficient, 5% imidacloprid, 200 g/L imidacloprid and 70% imidacloprid had high selection to M. persicae and H. axyridis, and they were suitable for using alternately with H. axyridis in controlling M. persicae.