title: Neonicotinoid resistance in rice brown planthopper, Nilaparvata lugens.
abstract: BACKGROUND
  Rice brown planthopper, Nilaparvata lugens Stål, is a primary insect pest of cultivated rice, and effective control is essential for economical crop production. Resistance to neonicotinoid insecticides, in particular imidacloprid, has been reported as an increasing constraint in recent years. In order to investigate the extent of resistance, 24 samples of N. lugens were collected from China, India, Indonesia, Malaysia, Thailand and Vietnam during 2005 and 2006. Their responses to two diagnostic doses of imidacloprid (corresponding approximately to the LC(95) and 5 x LC(95) of a susceptible strain) were examined.
  
  
  RESULTS
  Ten of the 12 samples collected during 2005 were found to be susceptible to imidacloprid, but two late-season samples from India showed reduced mortality at both diagnostic doses. All 13 strains collected in 2006 showed reduced mortality at both doses when compared with the susceptible strain. Dose-response lines showed resistance in one of the most resistant field strains to be approximately 100-fold compared with the susceptible standard.
  
  
  CONCLUSIONS
  The data demonstrate the development and spread of neonicotinoid resistance in N. lugens in Asia and support reports of reduced field efficacy of imidacloprid.
authors.affiliation: Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK. kevin.gorman@bbsrc.ac.uk
authors.forename: Kevin
authors.initials: K
authors.lastname: Gorman
authors.forename: Zewen
authors.initials: Z
authors.lastname: Liu
authors.forename: Ian
authors.initials: I
authors.lastname: Denholm
authors.forename: Kai-Uwe
authors.initials: KU
authors.lastname: Brüggen
authors.forename: Ralf
authors.initials: R
authors.lastname: Nauen
mesh_terms: D000818:Animals; D001208:Asia; D005260:Female; D005843:Geography; D006430:Hemiptera; D007093:Imidazoles; D007305:Insecticide Resistance; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; C082359:imidacloprid