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Logo of bmcgenoBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Genomics
 
BMC Genomics. 2009; 10: 494.
Published online Oct 26, 2009. doi:  10.1186/1471-2164-10-494
PMCID: PMC2770535
Exploring the molecular basis of insecticide resistance in the dengue vector Aedes aegypti: a case study in Martinique Island (French West Indies)
Sébastien Marcombe,1 Rodolphe Poupardin,2 Frederic Darriet,1 Stéphane Reynaud,2 Julien Bonnet,1 Clare Strode,3 Cecile Brengues,1 André Yébakima,4 Hilary Ranson,3 Vincent Corbel,1 and Jean-Philippe Davidcorresponding author2
1Laboratoire de Lutte contre les Insectes Nuisibles (LIN), Institut de Recherche Pour le Développement (IRD) Montpellier, France
2Laboratoire d'Ecologie Alpine (LECA, UMR 5553 CNRS - Université de Grenoble), Grenoble, France
3Vector Research group, Liverpool School of Tropical Medicine, Liverpool, UK
4Centre de démoustication, Conseil général de la Martinique, Fort de France, Martinique, France
corresponding authorCorresponding author.
Sébastien Marcombe: sebastien.marcombe/at/ird.fr; Rodolphe Poupardin: rodolphe.poupardin/at/e.ujf-grenoble.fr; Frederic Darriet: darriet/at/mpl.ird.fr; Stéphane Reynaud: stephane.reynaud/at/ujf-grenoble.fr; Julien Bonnet: bonnetj/at/mpl.ird.fr; Clare Strode: c.strode/at/liverpool.ac.uk; Cecile Brengues: cecile.brengue/at/ird.fr; André Yébakima: Yebakima/at/cg972.fr; Hilary Ranson: hranson/at/liverpool.ac.uk; Vincent Corbel: vincent.corbel/at/ird.fr; Jean-Philippe David: jean-philippe.david/at/ujf-grenoble.fr
Received May 25, 2009; Accepted October 26, 2009.
Abstract
Background
The yellow fever mosquito Aedes aegypti is a major vector of dengue and hemorrhagic fevers, causing up to 100 million dengue infections every year. As there is still no medicine and efficient vaccine available, vector control largely based on insecticide treatments remains the only method to reduce dengue virus transmission. Unfortunately, vector control programs are facing operational challenges with mosquitoes becoming resistant to commonly used insecticides. Resistance of Ae. aegypti to chemical insecticides has been reported worldwide and the underlying molecular mechanisms, including the identification of enzymes involved in insecticide detoxification are not completely understood.
Results
The present paper investigates the molecular basis of insecticide resistance in a population of Ae. aegypti collected in Martinique (French West Indies). Bioassays with insecticides on adults and larvae revealed high levels of resistance to organophosphate and pyrethroid insecticides. Molecular screening for common insecticide target-site mutations showed a high frequency (71%) of the sodium channel 'knock down resistance' (kdr) mutation. Exposing mosquitoes to detoxification enzymes inhibitors prior to bioassays induced a significant increased susceptibility of mosquitoes to insecticides, revealing the presence of metabolic-based resistance mechanisms. This trend was biochemically confirmed by significant elevated activities of cytochrome P450 monooxygenases, glutathione S-transferases and carboxylesterases at both larval and adult stages. Utilization of the microarray Aedes Detox Chip containing probes for all members of detoxification and other insecticide resistance-related enzymes revealed the significant constitutive over-transcription of multiple detoxification genes at both larval and adult stages. The over-transcription of detoxification genes in the resistant strain was confirmed by using real-time quantitative RT-PCR.
Conclusion
These results suggest that the high level of insecticide resistance found in Ae. aegypti mosquitoes from Martinique island is the consequence of both target-site and metabolic based resistance mechanisms. Insecticide resistance levels and associated mechanisms are discussed in relation with the environmental context of Martinique Island. These finding have important implications for dengue vector control in Martinique and emphasizes the need to develop new tools and strategies for maintaining an effective control of Aedes mosquito populations worldwide.
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