Anopheles funestus amidst a South/North shift in the role of key resistance genes across Malawi
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ABSTRACT: Resistance to pyrethroids, the only insecticide approved for bednets, threatens control of the major malaria vector, Anopheles funestus, in Malawi. To improve the management of such resistance countrywide, it is crucial to understand the dynamics and mechanisms driving resistance in the field. In this study the levels of insecticide resistance were determined across the highly endemic densely populated lake and southern agricultural area. Insecticide resistance to pyrethoids was assessed using standardized WHO bioassay methods and resistant mosquitoes were hybridized to susceptible mosquitoes. This microarray analysis revealed the key role of cytochrome P450 genes such as CYP6P9a, CYP6P9b and CYP6M7. However, a significant shift in the over-expression of these CYP450s was detected across a south/north transect, with CYP6M7 more highly over-transcribed in the two northern collection sites and the tandemly duplicated genes, CYP6P9a and CYP6P9b, more greatly over-transcribed in the south.
Project description:Identification of genes associated with bendiocarb resistance. Mosquitoes collected as larvae from Nagongera and Kihihi, Uganda. Bendiocarb-resistant and unexposed female mosquitoes selected using standard WHO tube bioassays. RNA was extracted from pools of five individuals identified as An. gambiae s.s. Insecticide-susceptible mosquitoes from the Kisumu strain were included as controls. RNA hybridized in an interwoven loop design to compare four biological replicates each of resistant, unexposed, and laboratory mosquitoes.
Project description:Transcriptome profiling of Anopheles coluzzi mosquitoes collected from two sites in south west Burkina Faso (Vallee du Kou & Tengrela) displaying a deltamethrin resistant phenotype. The resistant insects were compared to two laboratory insecticide susceptible strains.
Project description:Comparison of insecticide resistant mosquitoes (An. arabiensis) with control samples, comparison of resistant samples with susceptible (Dongola) strain and comparison of resistant (Sennar) strain with susceptible (Dongola) strain
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:Transcriptome profiling of pyrethroid resistant field populations of Anopheles funestus from Malawi and Mozambique compared to a susceptible lab strain FANG
Project description:Anopheles gambiae isofemale families from Tororo, Uganda were assayed for resistance to lambda-cyhalothrin (1.5hr exposure). Resistant families were compared to susceptible families. A portion of each family was exposed to 0.05% lambda-cyhalothrin in order to determine the family phenotype. The families used for the array were of known phenotype but were themselves unexposed.
Project description:Nine Anopheles gambiae populations were sampled in three areas of Tanzania showing contrasting agriculture activity, urbanization and usage of insecticides for vector control. Insecticide resistance levels were measured in larvae and adults through bioassays with deltamethrin, DDT and bendiocarb. A microarray approach was used for identifying transcription level variations associated to different environments and insecticide resistance. the Ifakara strain originating from central Tanzania and susceptible to all insecticides was used as a reference strain.
Project description:The aim of this experiment was to compare the transciptome of the fall armyworm (Spodoptera frugiperda) strain SUS (a laboratory insecticide-susceptible standard) with organophosphate (OP) and pyrethroid (PYR) resistant strains were collected in cornfields located in Minas Gerais and Mato Grosso States, Brazil, in 2008 and maintained in the laboratory under selection with chlorpyrifos (at increasing discriminating doses from 100 up to 400 M-BM-5g of insecticide/g of insect in a topical bioassay) or lambda-cyhalothrin (from 8.4 up to 27 M-BM-5g of insecticide/g of insect) respectively The custom microarray used in this study was designed using the Agilent eArray platform (Agilent Technologies). A SurePrint HD (8M-CM-^W15k) expression array was designed using the base composition and the best probe methodologies to design sense orientation 60-mer probes with a 3M-bM-^@M-2 bias. The FAW EST database (SPODOBASE) was used as the reference transcriptome (Negre, Hotelier et al. 2006). These sequences are derived from 8 cDNA libraries as follows: Sf1F: Fat body, Sf1H: Hemocyte, Sf1M: Midgut, Sf1P: Pool of various tissues, Sf2H: Immune Challenged hemocytes, Sf2L: Sf21 Cell lines sequences, Sf2M: Xenobiotic Induced Midgut and Sf9L: Sf9 cell lines sequences. All assembled contigs and singlets were kindly sent by the website maintainers. The BLAST2GO software v.2.3.1 (http://www.blast2go.org) was used to annotate the EST database. 60-mer probes were designed for all 7,552 assembled contigs and 5,519 annotated singlets (BlastX), totaling 13,071 sequences. For contigs encoding detoxification enzymes (P450s, GSTs and CEs) three probes were designed. Additional probe groups for 15 control genes were also included. For reference all sequences are included in the zip file with array data. References: Negre, V., T. Hotelier, et al. (2006). "SPODOBASE : an EST database for the lepidopteran crop pest Spodoptera." BMC Bioinformatics 7: 322. Two-condition experiment. Slide 1: SUS vs. OP S. fugiperda strains. Slide 2: SUS vs. PYR S. fugiperda strains. Biological replicates: 4 pools of RNA extracted from four pools of 5 second instar larvae. Technical Replicates: None, the biological replicates incorporated a dye swap. Total replication: four replicates for each strain.
Project description:Transcription profiles of three field collections of Anopheles arabiensis from Tanzania were compared to investigate their phenotypic differences in insecticide resistance
Project description:Transcription profiles of three field collections of Anopheles arabiensis from Tanzania were compared to investigate their phenotypic differences in insecticide resistance