A New Mechanism Conferring Unprecedented High Resistance to Chlorpyrifos in Culex pipiens (Diptera: Culicidae)
Authors: Pasteur, Nicole; Marquine, Maïté; Cheikh, Hassen Ben; Bernard, Clotilde; 1 and Denis Bourguet3 ,
Source: Journal of Medical Entomology, Volume 36, Number 6, November 1999 , pp. 794-802(9)
Publisher: Entomological Society of America
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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 (≈50-fold resistance), and a susceptible reference strain S. Strains G and T had the same level of propoxur resistance (≈1,000-fold) and were homozygous for an autosomal propoxur-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-1 R 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.Keywords: Culex pipiens pipiens; organophosphate resistance; over-produced esterase; insensitive acetylcholinesterase; resistance inheritance
Document Type: Research article
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