title: Quantitative and qualitative changes of the carboxylesterase associated with beta-cypermethrin resistance in the housefly, Musca domestica (Diptera: Muscidae).
abstract: Mechanisms of esterase-mediated pyrethroid resistance were analyzed based on our previous works in a strain of the housefly, Musca domestica. The carboxylesterase gene, MdalphaE7, was cloned and sequenced from susceptible (CSS) and resistant (CRR) strains, and a total of nine amino acid substitutions were found. The mutation, Trp(251)-Ser appeared to play a role in beta-cypermethrin resistance and cross-resistance between organophosphates (OPs) and pyrethroids in the CRR strain. Quantitative real-time PCR showed that MdalphaE7 was over-expressed in the CRR strain, the reciprocal cross progeny F(1) and back-cross progeny BC(2) compared with the CSS strain, respectively. Two alpha-cynaoester substrates as surrogates for beta-cypermethrin and deltamethrin, were synthesized to determine the pyrethroid hydrolase activity. Results showed that carboxylesterases from the CRR strain hydrolyzed cypermethrin/deltamethrin-like substrate 9.05- and 13.53-fold more efficiently than those from the CSS strain, respectively. Our studies suggested that quantitative and qualitative changes in the carboxylesterase might contribute together to pyrethroid resistance in the CRR strain.
authors.affiliation: Department of Entomology, China Agricultural University, Beijing, PR China.
authors.forename: Lan
authors.initials: L
authors.lastname: Zhang
authors.forename: Jing
authors.initials: J
authors.lastname: Shi
authors.forename: Xueyan
authors.initials: X
authors.lastname: Shi
authors.forename: Pei
authors.initials: P
authors.lastname: Liang
authors.forename: Junping
authors.initials: J
authors.lastname: Gao
authors.forename: Xiwu
authors.initials: X
authors.lastname: Gao
mesh_terms: D000818:Animals; D043182:Carboxylesterase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006793:Houseflies / Q000187:drug effects* / Q000378:metabolism; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides / Q000737:chemistry / Q000494:pharmacology*; D011722:Pyrethrins / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D011722:Pyrethrins; C017160:cypermethrin; D043182:Carboxylesterase