In silico models for predicting vector control chemicals targeting Aedes aegypti

International audienc

Identification of Metabolic Insecticide Resistance Genes in Aedes Aegypti from Martinique (French West Indies): From Genotypes to Phenotypes

International audienc

Insecticide-driven patterns of genetic variation in the dengue vector Aedes aegypti in Martinique Island

Effective vector control is currently challenged worldwide by the evolution of resistance to all classes of chemical insecticides in mosquitoes. In Martinique, populations of the dengue vector Aedes aegypti have been intensively treated with temephos and deltamethrin insecticides over the last fifty years, resulting in heterogeneous levels of resistance across the island. Resistance spreading depends on standing genetic variation, selection intensity and gene flow among populations. To determine gene flow intensity, we first investigated neutral patterns of genetic variability in sixteen populations representative of the many environments found in Martinique and experiencing various levels of insecticide pressure, using 6 microsatellites. Allelic richness was lower in populations resistant to deltamethrin, and consanguinity was higher in populations resistant to temephos, consistent with a negative effect of insecticide pressure on neutral genetic diversity. The global genetic differentiation was low, suggesting high gene flow among populations, but significant structure was found, with a pattern of isolation-by-distance at the global scale. Then, we investigated adaptive patterns of divergence in six out of the 16 populations using 319 single nucleotide polymorphisms (SNPs). Five SNP outliers displaying levels of genetic differentiation out of neutral expectations were detected, including the kdr-V1016I mutation in the voltage-gated sodium channel gene. Association tests revealed a total of seven SNPs associated with deltamethrin resistance. Six other SNPs were associated with temephos resistance, including two non-synonymous substitutions in an alkaline phosphatase and in a sulfotransferase respectively. Altogether, both neutral and adaptive patterns of genetic variation in mosquito populations appear to be largely driven by insecticide pressure in Martinique

Insecticide resistance in the dengue vector Aedes aegypti from Martinique : distribution, mechanisms and relations with environmental factors

Dengue is an important mosquito borne viral disease in Martinique Island (French West Indies). The viruses responsible for dengue are transmitted by Aedes aegypti, an indoor day-biting mosquito. The most effective proven method for disease prevention has been by vector control by various chemical or biological means. Unfortunately insecticide resistance has already been observed on the Island and recently showed to significantly reduce the efficacy of vector control interventions. In this study, we investigated the distribution of resistance and the underlying mechanisms in nine Ae. aegypti populations. Statistical multifactorial approach was used to investigate the correlations between insecticide resistance levels, associated mechanisms and environmental factors characterizing the mosquito populations. Bioassays revealed high levels of resistance to temephos and deltamethrin and susceptibility to Bti in the 9 populations tested. Biochemical assays showed elevated detoxification enzyme activities of monooxygenases, carboxylesterases and glutathione S-tranferases in most of the populations. Molecular screening for common insecticide target-site mutations, revealed the presence of the "knockdown resistance' V1016I Kdr mutation at high frequency (> 87%). Real time quantitative RT-PCR showed the potential involvement of several candidate detoxification genes in insecticide resistance. Principal Component Analysis (PCA) performed with variables characterizing Ae. aegypti from Martinique permitted to underline potential links existing between resistance distribution and other variables such as agriculture practices, vector control interventions and urbanization. Insecticide resistance is widespread but not homogeneously distributed across Martinique. The influence of environmental and operational factors on the evolution of the resistance and mechanisms are discussed

Évaluation des risques liés aux pesticides pour les écosystèmes aquatiques : recommandations issues du programme de recherche « Pesticides »

Fiche techniqueLes recherches conduites dans le cadre du programme « Évaluation et réduction des risques liés à l’utilisation des pesticides » (plus communément nommé programme « Pesticides ») du ministère en charge de l’Écologie ont permis d’identifier des recommandations pour l’évaluation des risques sur les écosystèmes aquatiques et également de progresser dans les méthodes de suivi et d’évaluation des mesures de gestion. Désormais intégré dans le plan Écophyto II, ce programme a permis depuis 1999 l’acquisition de connaissances sur les risques liés à l’utilisation des pesticides afin d’aider les acteurs à mettre en ½oeuvre des mesures pour les réduire. Ce document s'adresse aux professionnels impliqués dans la gestion des pesticides qui souhaitent acquérir des connaissances récentes sur des outils d'évaluation et de gestion des risques environnementaux induits