Dynamics of resistance to imidacloprid,buprofezin,fipronil in Nilaparvata lugens(Stål) during the year 2006 to 2009 in China

Resistance of Nilaparvata lugens(Stål) to imidacloprid,buprofezin,fipronil was monitored using rice stem dipping method in 9 different regions,including Nanning,Yangjiang,Dong'an,Fuqing,Shanggao,Xiaogan,Jinhua,Tongzhou,Hexian from the year of 2006 to 2009.The results indicated that most of populations developed high level of resistance to imidacloprid(resistance ratios are 105.5- to 459.7-fold),but the data collected in 2009 revealed that populations from Dong'an,Xiaogan,Shanggao showed slightly decreasing resistance to imidacloprid,and increasing resistance to fipronil.During 2006-2009 populations of N.lugens changed their resistance to buprofezin from being susceptible or low level(resistance ratios are below 6.9-fold) to moderate or high level(resistance ratios are 13.5- to 43.3-fold).Because imidacloprid was prohibited in highly resistant regions beginning from 2005,N.lugens increased its resistance to buprofezin rapidly,and it was already at low or moderate level(the resistance ratios are 7.0- to 14.4-fold) in 2009.As a result,after imidacloprid and fipronil were prohibited,using buprofezin singly to control N.lugens in large areas will lead to resistance rapidly.