Characterization of a Novel High-Activity Esterase in Tunisian Populations of the Mosquito Culex pipiens
Authors: Ben Cheikh, Raja; Berticat, Claire; Berthomieu, Arnaud; Pasteur, Nicole; Ben Cheikh, Hassen; Weill, Mylène
Source: Journal of Economic Entomology, Volume 101, Number 2, April 2008 , pp. 484-491(8)
Publisher: Entomological Society of America
Abstract:In the mosquito Culex pipiens (L.) (Diptera: Culicidae) esterases contribute to insecticide resistance by their increased activity. These esterases display a heterogeneous geographical distribution, particularly in Tunisia, where they are very diverse. In this study, we extended the characterization of a highly active esterase first detected in 1996: B12. Esterase B12 displayed the fastest electrophoretic mobility of all the previously described highly active esterases. We showed that it was encoded by the Ester B12 allele at the Ester locus, and we isolated a strain, TunB12, homozygous for this allele. TunB12 displayed a low (approximately two- to three-fold) but significant resistance to the organophosphates temephos and chlorpyrifos, and to the pyrethroid permethrin. Only temephos resistance was synergized by S,S,S-tributyl-phosphorotrithioate. Real-time quantitative polymerase chain reaction revealed that the Ester B12 allele was not amplified in TunB12 strain, indicating that B12 high activity could be due to a gene up-regulation mechanism. Ester B12 allele frequencies also were estimated in 20 Tunisian populations collected in 2005. Analyses revealed a large distribution of this allele all over the country. Finally, sequences of Ester B12 were acquired and genetic distance trees were constructed with the resistance Ester alleles already published, providing indications about allele's origins. The diverse array of highly active esterases in C. pipiens from Tunisia and the possible scenario of the origin of their coding alleles are discussed in the context of their possible evolution.
Document Type: Research article
Publication date: 2008-04-01
- Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.
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