title: Amplified esterases B1 and A2-B2 in field populations of Culex pipiens from China.
abstract: The main organophosphate (OP) resistance mechanism in the Culex pipiens complex is increased activity of esterases A and B. Fourth-stage larvae from 2 field populations of C. pipiens from Gaomi and Kunming, China, were compared for tolerance to parathion, dichlorovos (OP), and bassa (carbamate) insecticides. Both populations were resistant to OPs but not to bassa. Starch gel electrophoresis indicated that elevated esterase activity was correlated with OP resistance. High frequencies of amplified esterase genes B1 and A2-B2 (0.85 and 0.50) were discovered in Gaomi and Kunming, respectively. However, only low levels of gene amplification were detected.
authors.affiliation: State Key Lab of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing.
authors.forename: J E
authors.initials: JE
authors.lastname: Liu
authors.forename: C L
authors.initials: CL
authors.lastname: Qiao
authors.forename: L P
authors.initials: LP
authors.lastname: Chen
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Sun
mesh_terms: D000818:Animals; D002681:China; D003465:Culex / Q000201:enzymology*; D004592:Electrophoresis, Starch Gel; D005784:Gene Amplification / Q000235:genetics; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides; D007814:Larva / Q000201:enzymology; D009943:Organophosphorus Compounds; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D007306:Insecticides; D009943:Organophosphorus Compounds; D012697:Serine Endopeptidases; C049262:esterase B