Project description:This microarray study aimed at evaluating the impact of mosquito chemical environment on the selection of insecticide resistance mechanisms. Here the mosquito Aedes aegypti was used as a model to perform a laboratory experiment combining mosquito larvae exposure to a sub-lethal dose of xenobiotic and their selection with the insecticide permethrin. After ten generations, bioassays and a transcriptome profiling with the 15K microarray Aedes detox chip plus microarray were performed comparatively on all strains.
2012-03-31 | E-MTAB-632 | biostudies-arrayexpress
Project description:circRNA analysis of mosquito insecticide resistance
Project description:Aedes aegypti (L.) is the primary vector of many emerging arboviruses. Insecticide resistance among mosquito populations is a consequence of the application of insecticides for mosquito control. We used RNA-sequencing to compare transcriptomes between permethrin resistant and susceptible strains of Florida Ae. aegypti in response to Zika virus infection. A total of 2,459 transcripts were expressed at significantly different levels between resistant and susceptible Ae. aegypti. Gene ontology analysis placed these genes into 7 categories of biological processes. The 863 transcripts were expressed at significantly different levels between two strains (up/down regulated) more than 2-fold. Quantitative real-time PCR analysis validated Zika-infected response, and suggested a highly overexpressed P450, with AAEL014617 and AAEL006798 as potential candidates for the molecular mechanism of permethrin resistance in Ae. aegypti. Our findings indicated that most detoxification enzymes and immune system enzymes altered their gene expression between the two strains of Ae. aegypti in response to Zika virus infection. Understanding the interactions of arboviruses with resistant mosquito vectors at the molecular level allows for the possible development of new approaches in mitigating arbovirus transmission. This information sheds light on Zika-induced changes in the insecticide resistance of Ae. aegypti with implications for mosquito control strategies.
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:Mosquitoes host and pass on to humans a variety of disease-causing pathogens such as infectious viruses and other parasitic microorganisms. The emergence and spread of insecticide resistance is threatening the effectiveness of current control measures for common mosquito vector borne diseases, such as malaria, dengue and Zika. Therefore, the emerging resistance to the widely used pyrethroid insecticides is an alarming problem for public health. Among the new approaches implemented for pest control, one of the most promising is RNA interference (RNAi). The aim of this study was to provide a feasible RNAi solution that can be applied on wild pyrethroid resistant mosquito populations in the near future. To achieve this, high dsRNA efficacy at economic quantities is required. It is recognized that the sodium channel transcript variability governs its functional diversity including the emergence of insecticide resistance. Therefore, to maximize the RNAi effect, we tiled a number of overlapping dsRNA constructs that together target about half of the voltage-gated sodium channel (VGSC) transcript variants annotated in this work. This strategy provided a refined dsRNA trigger that increased mortality with a three-fold decrease in dsRNA amounts compared to the primary VGSC dsRNA construct. Thus, we demonstrated the use of RNA interference (RNAi) to increase susceptibility of adult mosquitoes to a widely used pyrethroid insecticide. Small RNA sequences from 5 mosquitoes treated with Random or VGSC dsRNAs were generated using Illumina HiSeq 2500.
Project description:Mosquitoes host and pass on to humans a variety of disease-causing pathogens such as infectious viruses and other parasitic microorganisms. The emergence and spread of insecticide resistance is threatening the effectiveness of current control measures for common mosquito vector borne diseases, such as malaria, dengue and Zika. Therefore, the emerging resistance to the widely used pyrethroid insecticides is an alarming problem for public health. Among the new approaches implemented for pest control, one of the most promising is RNA interference (RNAi). The aim of this study was to provide a feasible RNAi solution that can be applied on wild pyrethroid resistant mosquito populations in the near future. To achieve this, high dsRNA efficacy at economic quantities is required. It is recognized that the sodium channel transcript variability governs its functional diversity including the emergence of insecticide resistance. Therefore, to maximize the RNAi effect, we tiled a number of overlapping dsRNA constructs that together target about half of the voltage-gated sodium channel (VGSC) transcript variants annotated in this work. This strategy provided a refined dsRNA trigger that increased mortality with a three-fold decrease in dsRNA amounts compared to the primary VGSC dsRNA construct. Thus, we demonstrated the use of RNA interference (RNAi) to increase susceptibility of adult mosquitoes to a widely used pyrethroid insecticide.
2016-07-06 | GSE84030 | GEO
Project description:Mosquito microbiota and pyrethroid resistance
Project description:Purpose: Next-generation transcriptome sequencing was done to understand host and eukaryotic microbiome changes in gene expression in association with defined insecticide selection pressures. The specific goal of this research was to understand whole-body physiological responses in German cockroaches and associated microbiota, at the metatranscriptome level, to defined insecticide selection pressures. Methods: We used the insecticide indoxacarb as the selecting insecticide, which is an important bait active ingredient for cockroach control. Six generations of selection with indoxacarb bait produced a strain with substantial (>20x) resistance relative to inbred control lines originating from the same parental stock. Results: Metatranscriptome sequencing revealed 1123 significantly differentially expressed genes in > two of three statistical models (81 upregulated and 1042 downregulated; FDR p<0.001; log2FC of +/- 1). The majority of upreglated genes were from the host cockroach while the majority of downregulated genes were from associated viruses and the eukaryotic microbiome. Conclusions: We show here significant impacts by insecticide selection on not only host stress-respnses like detoxification, but also on clearace of microbial parasites, pathogens, commensals and/or symbionts.
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:Resistance to chemical insecticides including pyrethroids, the main insecticide class used against mosquitoes, led to a regain of interest for neonicotinoids. In this context, the present study aims at characterizing the molecular basis of neonicotinoid resistance in the mosquito Aedes aegypti. Resistance mechanisms were studied by combining transcriptomic and genomic data obtained from a laboratory strain selected at the larval stage for 30 generations with imidacloprid (Imida-R line). After thirty generations of selection, larvae of Imida-R line showed a 8-fold increased resistance to imidacloprid and a significant cross-tolerance to the pyrethroids permethrin and deltamethrin. Cross-resistance to pyrethroids was only observed in adults when larvae were previously exposed to imidacloprid suggesting a low but inducible expression of resistance alleles at the adult stage. Resistance of the Imida-R line was associated with a slower larval development time in females. Multiple detoxification enzymes were over-transcribed in larvae in association with resistance including the P450s CYP6BB2, CYP9M9 and CYP6M11 previously associated with pyrethroid resistance. Some of them together with their redox partner NADPH P450 reductase were also affected by non-synonymous mutations associated with resistance. Combining genomic and transcriptomic data allowed identifying promoter variations associated with the up-regulation of CYP6BB2 in the resistant line. Overall, these data confirm the key role of P450s in neonicotinoid resistance in Ae. aegypti and their potential to confer cross-resistance to pyrethroids, raising concerns about the use of neonicotinoids for resistance management in this mosquito species.