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Evolution de la résistance au bactério-insecticide Bti chez les moustiques

Abstract : Mosquito control represents a major public health concern, as mosquitoes transmit many severe human diseases. After the massive use of chemical insecticides since the fifties, the bacterio-insecticide Bacillus thuringiensis subsp. israelensis (Bti) represents a safe alternative and is now widely used to control mosquito populations. High toxicity due to commercial Bti proliferation and persistence was found in decaying leaf litter collected in mosquito breeding sites. In order to evaluate the evolution of resistance, a laboratory Aedes aegypti strain was selected with field-collected leaf litter containing Bti toxins. Resistance of Aedes aegypti to Bti Cry toxins evolved after only few generations of larval selection. Several approaches were used to study the genetic bases of Bti resistance in the resistant strain. First, the genetic comparison by two genome scans (one with markers linked to transposable elements and one with neutral AFLP markers) of the sensible and the resistant strains revealed genetic loci related to this resistance. Those loci were sequenced and located in the Ae. aegypti genome and allowed the detection of several genomic regions under selection. Then, a transcriptome scan allowed the comparison of the transcription of more than 6000 between the susceptible and the resistant strain. Several genes potentially involved in Bti resistance were detected by combining these results with a candidate gene approach. Among them, a cadherin gene displayed patterns of nucleotide polymorphisms consistent with the action of positive selection and appeared a good candidate for Bti resistance. Furthermore, signatures of selection linked to Bti treatment and high gene flow were detected by a population genomic approach in the Rhône-Alpine mosquito strain Aedes rusticus. Information about genetic factors linked to Bti resistance and biological factors linked to treated species are essential to use adapted resistance management strategies.
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https://tel.archives-ouvertes.fr/tel-00629116
Contributor : Margot Paris <>
Submitted on : Wednesday, October 5, 2011 - 10:06:29 AM
Last modification on : Friday, November 6, 2020 - 3:41:19 AM
Long-term archiving on: : Monday, December 5, 2016 - 12:00:41 AM

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  • HAL Id : tel-00629116, version 1

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Margot Paris. Evolution de la résistance au bactério-insecticide Bti chez les moustiques. Ecologie, Environnement. Université de Grenoble, 2010. Français. ⟨tel-00629116⟩

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