Resistance level of Plutella xylostella to Permethrin and application of Permethrin

Toxicity of seveal Permethrins to Plutella xylostella and resistance of Plutella xylostella to Permethrin was conducted from different regions of Jiangsu. The results showed that resistance level of Plutella xylostella to three kinds of Permethrins had been high in the main vegetable regions of Jiangsu. Plutella xylostella had different degree of cross-resistance to Deltamethrin, Cypemethrin, DDVP and Methomyl, but no cross-resistance to Dimenypo, Fulingniao and Diafenthiuron, and had negative cross-resistance to Fipronil and Avermectin. Six single and three mixture insecticides with high effect and low toxicity were selected. Avermectin, Fipronil, Fulingniao, Chlorfluazron, Diafenthiuron and Dimenypo had high activity to Plutella xylostella with LC 50 of 0.018-71.83ppm. Field experiments showed that Avermectin with 8ppm had above 95% killing effect for 10 days. Among three mixtures, the efficacy and the speedy effect of the Avermectin+Alphcypermethrin was outstanding.