Screening of Insecticides for the Control of Myzus persicae and Safety Evaluation to Its Predator Harmonia axyridis

The toxicity of five tobacco recommended pesticides on Myzus persicae (Sulzer)(Hemiptera:Aphididae) and three instars and adults of its predatory natural enemy Harmonia axyridis (Pallas) was determined by means of spray, and the safety to the ladybirds was also evaluated. The results showed that the LC₅₀ of 5% abamectin, 3% acetamiprid, 70% imidacloprid, 1% matrine, and 50% pymetrozine were 7.75, 9.20, 23.07, 24.85, and 40.63 mg/L respectively. In addition, the toxicity of 3% acetamiprid on three instars Harmonia axyridis was the highest, with the LC₅₀ being 7.84 mg/L,and then was 5% abamectin, the toxicity of 50% pymetrozine was the lowest, which was 270.66 mg/L. The toxicity of 3% acetamiprid on Harmonia axyridis adults was the highest, and the LC₅₀ was 17.00 mg/L, and then was 5% abamectin, the toxicity of 50% pymetrozine was the lowest, which was 541.33 mg/L. According to toxicity ratio and safety coefficient, 1% matrine and 50% pymetrozine had high selectivity to M. persicae and H.axyridis, and they are suitable for using alternately with H.axyridis in controlling M. persicae.