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Saddler, Adam

Nom
Saddler, Adam
Affiliation principale
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https://libra.unine.ch/handle/123456789/779

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  • Publication
    Métadonnées seulement
  • Publication
    Accès libre
    Effects of Age and Larval Nutrition on Phenotypic Expression of Insecticide-Resistance in Anopheles Mosquitoes
    Kulma, Katarzyna
    ;
    Saddler, Adam 
    ;
    Koella, Jacob C
    Insecticide-resistance threatens the control of mosquito-borne diseases like malaria or dengue fever. To ensure sustainable vector control we need a full understanding of the factors driving the evolution of resistance. We test the hypothesis that the expression of insecticide-resistance depends on the available resources by rearing genetically DDT-resistant and sensitive larvae of Anopheles mosquitoes at three diet regimes, which correspond to 40%, 70% and 100% of the normal diet and exposing the adult females to DDT 5, 10 and 15 days after emergence. In both colonies post- exposure survival decreased with age at exposure. Additionally, the food levels and DDT-resistance were positively correlated in both colonies, although only in the DDT- resistant one was this relationship statistically significant. The impact of larval diet was smaller than the effect of age at exposure. We discuss our results and explain the implication of this study to resistance monitoring for public health and vector management.
  • Publication
    Accès libre
    Blocking the evolution of insecticide-resistant malaria vectors with a microsporidian
    Koella, Jacob C
    ;
    Saddler, Adam 
    ;
    Karacs, Thomas P. S
    Finding a way to block the evolution insecticide resistance would be a major breakthrough for the control of malaria. We suggest that this may be possible by introducing a stress into mosquito populations that restores the sensitivity of genetically resistant mosquitoes and that decreases their longevity when they are not exposed to insecticide. We use a mathematical model to show that, despite the intense selection pressure imposed by insecticides, moderate levels of stress might tip the evolutionary balance between costs and benefits of resistance toward maintaining sensitivity. Our experimental work with the microsporidian parasite Vavraia culicis infecting two lines of resistant mosquitoes and a sensitive line suggests that it may indeed be possible to stress the mosquitoes in the required way. The mortality of resistant mosquitoes 24 h after exposure to the insecticide was up to 8.8 times higher in infected than in uninfected ones; if mosquitoes were not exposed to the insecticide, resistant mosquitoes infected by the microsporidian lived about half as long as uninfected ones and insecticide-sensitive mosquitoes (with or without the parasite). Our results suggest that biopesticides or other insecticides that interfere with the expression of resistance may help to manage insecticide resistance in programs of malaria control.