title: A new mechanism conferring unprecedented high resistance to chlorpyrifos in Culex pipiens (Diptera: Culicidae).
abstract: The cause of high resistance to chlorpyrifos observed in Tunisian Culex pipiens (L.) was investigated by comparing a Tunisian strain G (> 10,000-fold resistance), a French strain T (approximately 50-fold resistance), and a susceptible reference strain S. Strains G and T had the same level of propoxur resistance (approximately 1,000-fold) and were homozygous for an autosomal propoux-insensitive acetylcholinesterase (AChE-1). In G and T strains, as well as in the offspring of different F1s and backcrosses using these F1s and the S strain, the effect of DEF and Pb synergists on chlorpyrifos resistance was low or absent, indicating that increased detoxification by enzymes inhibited by these chemicals had a minor role. Chlorpyrifos resistance in the G strain was caused by a major gene (or group of genes) tightly linked to the Ace-1 gene (coding AChE-1 enzyme). The possibility of allelism between this gene and the Ace-1R allele present in the T strain was rejected by showing that AChE-1 inhibition by chlorpyrifos-oxon was not different between G and T mosquitoes.
authors.affiliation: Institut des Sciences de l'Evolution (UMR CNRS 5554), Université de Montpellier 2, France.
authors.forename: N
authors.initials: N
authors.lastname: Pasteur
authors.forename: M
authors.initials: M
authors.lastname: Marquine
authors.forename: H
authors.initials: H
authors.lastname: Ben Cheikh
authors.forename: C
authors.initials: C
authors.lastname: Bernard
authors.forename: D
authors.initials: D
authors.lastname: Bourguet
mesh_terms: D000110:Acetylcholinesterase / Q000235:genetics; D000818:Animals; D004390:Chlorpyrifos; D003465:Culex / Q000201:enzymology / Q000235:genetics*; D005602:France; D007305:Insecticide Resistance; D010641:Phenotype; D001074:Propoxur / Q000633:toxicity; D013045:Species Specificity
chemical_list: D001074:Propoxur; D000110:Acetylcholinesterase; D004390:Chlorpyrifos