Project description:Insecticide resistance is a worldwide threat for vector control around the world, and Aedes aegypti , the main vector of several arboviruses, is a particular concern. To better understand the mechanisms of resistance, four isofemale strains originally from French Guiana were isolated and analysed using combined approaches. The activity of detoxification enzymes involved in insecticide resistance was assayed, and mutations located at positions 1016 and 1534 of the sodium voltage-gated channel gene, which have been associated with pyrethroid resistance in Aedes aegypti populations in Latin America, were monitored. Resistance to other insecticide families (organophosphates and carbamates) was evaluated. A large-scale proteomic analysis was performed to identify proteins involved in insecticide resistance. Our results revealed a metabolic resistance and resistance associated with a mutation of the sodium voltage-gated channel gene at position 1016. Metabolic resistance was mediated through an increase of esterase activity in most strains but also through the shifts in the abundance of several cytochrome P450 (CYP450s). Overall, resistance to deltamethrin was linked in the isofemale strains to resistance to other class of insecticides, suggesting that cross- and multiple resistance occur through selection of mechanisms of metabolic resistance. These results give some insights into resistance to deltamethrin and into multiple resistance phenomena in populations of Ae. aegypti
Project description:Malaria control relies on insecticides targeting the mosquito vector, but is being increasingly compromised by insecticide resistance. Elevated expression of metabolic enzymes frequently drives resistance. In diploids, gene expression is regulated both in cis, by regulatory sequences on the same chromosome, and by trans acting factors, affecting both alleles equally. Differing levels of transcription can be caused by mutations in cis-regulatory modules, but few cis-regulatory modules controlling the expression of genes that determine insecticide resistance have been identified. Genes potentially under differential cis-regulation between bendiocarb resistant and susceptible Anopheles gambiae strains were identified by counting transcripts produced from maternal and paternal alleles in F1 hybrids of these strains (allelic specific expression). Cis regulatory module sequences controlling gene expression in insecticide resistance relevant tissues such as midgut, Malpighian tubules and legs were predicted using a previously established machine learning method. These predictions included CRM proximal to both genes under differential cis regulation and genes that show consistent differential expression patterns in multiple resistant Anopheles strains.
Project description:A frightening resurgence of bed bug infestations has occurred over the last 10 years in the US. Current chemical methods have been inadequate for controlling bed bugs due to widespread insecticide resistance. Little is known about the mechanisms of resistance present in US bed bug populations, making it extremely difficult to develop intelligent strategies to control this pest. We have identified bed bugs collected in Richmond, VA which exhibit both kdr-type (L925I) and metabolic resistance to pyrethroid insecticides. LD50 bioassays determined resistance ratios of ~6000-fold to the insecticide deltamethrin, with contact bioassays confirming cross-resistance to several other labeled formulations. To identify metabolic genes potentially involved in the detoxification of pyrethroids, we performed deep-sequencing of the adult bed bug transcriptome, obtaining more than 2.5 million reads on the 454 titanium platform. Following assembly, analysis of newly identified gene transcripts in both Harlan (susceptible) and Richmond (resistant) bed bugs revealed several candidate cytochrome P450 and carboxyesterase genes which were significantly over-expressed in the resistant strain, consistent with the idea of increased metabolic resistance. These data will accelerate efforts to understand the biochemical basis for insecticide resistance in bed bugs, and provide molecular markers to assist in the surveillance of metabolic resistance.
Project description:Transcription profiles of a field collection of Anopheles gambiae M molecular form (i.e. Anopheles coluzzii) from a population from Cote d'Ivoire (West Africa) were compared to two laboratory strains and to a wild caught field strain (all carbamate insecticide susceptible) to investigate their differences in insecticide resistance. Both carbamate-exposed and carbamate-unexposed Cote d'Ivoire samples were compared to each susceptible strain, and also directly to one another (i.e. exposed vs. unexposed).