Imidacloprid susceptibility survey and selection risk assessment in field populations of Nilaparvata lugens (Homoptera: Delphacidae).

Imidacloprid has been used for many years to control planthopper Nilaparvata lugens (Stål) (Homoptera: Delphacidae) in China. To provide resistance assessment for the national insecticide resistance management program, we collected a total of 42 samples of the planthoppers from 27 locations covering eight provinces to monitor their dose responses and susceptibility changes to imidacloprid over an 11-yr period (1996-2006). Results showed that most field populations maintained susceptibility from 1996 to 2003 except for a population from Guilin, Guangxi, in 1997, which showed a low level of resistance to imidacloprid.