Study on the Toxicity and the Effectiveness of Chlorfenapyr to Spodoptera exigua

The result of the test in laboratory showed that the control rate of hatching to Spodoptera exigua (Hübner) was 43.11% with 20 mg/L chlorfenapyr EC. The toxicity of chlorfenapyr to S.exigua deduced with the increase of instar. Larva in 1~2 instar was the most sensitive. In pot test,the mortality was 91.43%~100% and residual activity was over 15 days at concentration of 20 mg/L.The result of trial in field indicated that the control effects of 5% chlorfenapyr EC to S. exigua at 1 200 mL/hm2 was 95% and the high effectiveness was maintained for 20 days.