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La résistance aux insecticides est un phénomène naturel d'adaptation des insectes. Lorsqu'elle apparaît dans une population de vecteur, elle compromet les interventions de lutte anti-vectorielle, et limite les possibilités de contrôle des agents pathogènes qu'ils transmettent. La résistance aux insecticides chez les Culicidae vecteurs est largement répandue de par le monde, et on la retrouve notamment dans les territoires insulaires. Cependant, l'isolement géographique des îles influe sur la présence et la distribution des allèles de résistance. En travaillant sur quatre espèces de moustiques dans plusieurs contextes insulaires, nous nous sommes attachés à (i) évaluer les niveaux de résistance et à caractériser les mécanismes impliqués, (ii) identifier les facteurs, contextuels et/ou évolutifs, expliquant la présence et la distribution des gènes de résistance chez certaines de ces espèces, et (iii) évaluer de nouveaux outils de lutte pouvant être mis en place dans le contexte insulaire particulier que représente Mayotte. Nos résultats montrent une forte résistance de Culex p. quinquefasciatus à toutes les familles d'insecticides utilisées jusqu'à présent dans l'Océan Indien. Cependant, la distribution de ces mécanismes de résistance a présenté une forte hétérogénéité régionale, les allèles de résistance n'étant pas présents dans toutes les îles et/ou pas aux mêmes fréquences. De plus, à une échelle plus locale sur l'île de Mayotte, il existe de fortes disparités entre les espèces étudiées en terme de résistance. Ces différences inter-espèces, intra-île et inter-îles sont discutées en fonction de l'influence des pressions de sélections locales et de leurs sources, et du coût génétique des différents allèles présents. Des propositions d'évolution des pratiques de lutte à Mayotte sont énoncées, intégrant les nouveaux outils que nous avons évalués sur le terrain. / Insecticide resistance is a natural adaptation phenomenon of insects. When it occurs in a vector population, it compromises vector control interventions, and therefore limits the ability to control the diseases they transmit. Insecticide resistance in Culicidae is widespread throughout the world, and is also found in islands. However, their geographic isolation influences the presence and distribution of resistance alleles. We have worked on four mosquito species in several islands, and we tried to (i) assess the resistance levels and characterize the mechanisms involved, (ii) identify contextual and/or evolutionary factors explaining the presence and distribution of resistance genes in some of these species, and (iii) evaluate new control tools that can be implemented in the specific context of Mayotte island. Our results showed a strong resistance of Culex p. quinquefasciatus to all insecticide families used so far in the Indian Ocean. However, the distribution of resistance mechanisms showed a strong spatial heterogeneity. Indeed, some resistance alleles were not present on all islands and/or not at the same frequencies. In addition, at a more local scale in Mayotte, there were strong differences of resistance status between species. These differences between species and islands are discussed in relation to the influence of local selection pressures and their origins, and to the fitness cost of different alleles. Proposals for modification in vector control practices are set to Mayotte, integrating new tools we have evaluated on the field.

Made available in DSpace on 2014-07-29T15:13:45Z (GMT). No. of bitstreams: 1 TESE DE DOUTORADO FRANCISCO ANILTON.pdf: 1620939 bytes, checksum: 474cd6952a1d81661658894052ffbcee (MD5) Previous issue date: 2011-12-06 / This study determined the prevalence of hemagglutination-inhibition antibodies against alphaviruses in horses during an epizootic event by Eastern Equine Encephalitis virus in the state of Paraiba, Brazil, in 2009 and compared the results between the techniques of hemagglutination inhibition and serum neutralization test in microplates. The results of15 arboviruses obtained from serological surveys on horses in Brazil from 2007 to , as well as the results for the arboviruses found in two serological surveys on wild birds in the state of Para, between 2007 and 2008 2009 were analyzed,. In Paraiba, blood was collected from 188 horses during other surveys of 4.402 animals and 544 wild birds. The material was tested by the hemagglutination inhibition technique, neutralization was performed in microplates aiming at virus isolation. In Paraíba, we obtained a true prevalence of 62.2% for Eastern Equine Encephalitis and hemagglutination inhibition test had 79.5% sensitivity and 87.3% specificity . In Brazil, the prevalence rate was 33.3% for arboviruses, 20.6% for flaviviruses, 14.1% for alphavirus and 10.1% for bunyavirus. In birds, the positivity was 28.4%, being 14.7% for alphaviruses, 9.5% for flaviviruses and 7.4% for bunyavirus. There was a high circulation of antibodies against Eastern Equine Encephalitis in inapparent-host animals and the hemagglutination inhibition test can be recommended as screening method. The other arboviruses surveyed were found in animals of the nine states with a significant difference in the prevalence from the motivation of the survey. Migratory birds have proved to be important amplifiers of these agents . / Este estudo determinou a prevalência de anticorpos inibidores de hemaglutinação para alfavírus em equídeos durante uma epizootia pelo vírus da Encefalite Equina do Leste na Paraíba, em 2009 e comparou os resultados obtidos entre as técnicas de inibição de hemaglutinação e teste de soroneutralização em microplacas. Analisou os resultados obtidos para arbovírus em 15 inquéritos sorológicos realizados em equídeos no Brasil, entre 2007 a 2009 e analisou os resultados para os arbovírus encontrados em dois inquéritos sorológicos realizados em aves silvestres no Pará, entre 2007 a 2008. Na Paraíba, foi realizada coleta de sangue de 188 equideos, nos outros inquéritos de 4.402 animais e de 544 aves silvestres. O material foi testado pela técnica de inibição de hemaglutinação, soroneutralização em microplacas e foi feito tentativa de isolamento viral. Na Paraíba, obteve-se uma prevalência real de 62,2% para Encefalite Equina do Leste e o teste de inibição por hemaglutinação apresentou uma sensibilidade de 79,5% e especificidade de 87,3%. No Brasil, a prevalência observada foi de 33,3% para os arbovírus, sendo 20,6% para os flavivírus, 14,1% para os alfavírus e 10,1% para bunyavírus. Nas aves, a positividade foi de 28,4%, sendo 14,7% para os alfavírus, 9,5% para os flavivírus e 7,4% para os bunyavírus. Observou-se uma elevada circulação de anticorpos do vírus da Encefalite Equina do Leste em animais portadores inaparentes e que o teste de inibição por hemaglutinação pode ser recomendado como de triagem. Os outros arbovírus pesquisados foram encontrados em animais dos nove estados, havendo diferença na prevalência a partir da motivação do inquérito. As aves migratórias demonstraram ser importantes amplificadores desses agentes.