Susceptibility to several types of insecticides in the rice planthoppers Nilaparvata lugens (Sta。l) and Sogatella furcifera (Horváth) (Homoptera:Delphacidae)

To provide theoretic basis for the scientific application of insecticides and resistance management,the resistance of Nilaparvata lugens (Sta。l) to seven insecticides and the sensitivity of N. lugens and Sogatella furcifera (Horvath) in two field populations collected from Hangzhou city and Ningbo city,Zhejiang Province in July 2008 to sixteen insecticides were evaluated with rice stem-dipping method. Compared with the relative susceptible strain of N. lugens,the Hangzhou and Ningbo populations developed resistance to imidacloprid,imidaclothiz,thiamethoxam,buprofezin and fipronil,with the resistance ratios (RR) to imidacloprid were 479.0-fold and 366.1-fold,to imidaclothiz were 81.1-fold and 50.9-fold,to thiamethoxam were 10.3-fold and 9.4-fold,to buprofezin and fipronil were 5.0-8.6-fold and 15.8-17.0-fold,respectively,while the two populations remained susceptible to nitenpyram and acetamiprid (RR3-fold). The toxicity of sixteen insecticides to Hangzhou and Ningbo populations in N. lugens and S. furcifera was determined. The results showed the toxicity of thiamethoxam,buprofezin,nitenpyram,and chlorpyrifos was relative high to the two rice planthoppers. Therefore,thiamethoxam,buprofezin,nitenpyram and chlorpyrifos,instead of imidacloprid,imidaclothiz and fipronil,are recommended for controlling N. lugens and S. furcifera when they occur simultaneously.