Phenotyped Anopheles darlingi colony
Following the successful establishment of the malaria vector colonies Anopheles darlingi and An. deaneorum in Brazil, insecticide resistance characterisation and investigation of potential resistance mechanisms is essential. This study reports the phenotypic response to insecticides and genomic analysis for these two colonies. Phenotypic testing showed susceptibility to the pyrethroid etofenprox and carbamate bendiocarb, and possible resistance to the pyrethroid alpha-cypermethrin, in both colonies. Molecular analysis targeting the voltage-gated sodium channel (vgsc) gene revealed the absence of the widely distributed L995F/S mutation (L1014F in Musca domestica), which is commonly associated with pyrethroid resistance in major African malaria vector species. Haplotype analysis identified a single vgsc amplicon haplotype in An. darlingi and three closely related haplotypes in An. deaneorum. Notably, these haplotype sequences represent the first vgsc fragment sequences from An. deaneorum available. Whole genome sequencing was conducted on a subset of An. darlingi pyrethroid susceptible and resistant colony mosquitoes. Genome-wide FST scores were low, with regions of highest differentiation including the GPCR Mth2-like gene, a gene family previously associated with resistance to pyrethroids in Culex mosquitoes. Targeted analysis of key resistance-associated genes (vgsc, ace1, gste2, and ace1) identified no mutations previously associated with insecticide resistance. However, 21 novel non-synonymous variants were detected. Selection scans identified regions of the genome under selection pressure within the pyrethroid resistant An. darlingi, including the cytochrome P450 gene cyp313a4, the tipE gene required for the expression of insect sodium channels including vgsc, and cuticular proteins (protein yellow and cuticle protein-19 like). Structural variant analysis identified one duplication and four inversions at higher frequency in the resistant An. darlingi population. Together, these findings provide essential phenotypic and genomic characterisation of An. darlingi and An. deaneorum laboratory colonies and support their use as reference strains for insecticide resistance monitoring and mechanistic studies.
Following the successful establishment of the malaria vector colonies Anopheles darlingi and An. deaneorum in Brazil, insecticide resistance characterisation and investigation of potential resistance mechanisms is essential. This study reports the phenotypic response to insecticides and genomic analysis for these two colonies. Phenotypic testing showed susceptibility to the pyrethroid etofenprox and carbamate bendiocarb, and possible resistance to the pyrethroid alpha-cypermethrin, in both colonies. Molecular analysis targeting the voltage-gated sodium channel (vgsc) gene revealed the absence of the widely distributed L995F/S mutation (L1014F in Musca domestica), which is commonly associated with pyrethroid resistance in major African malaria vector species. Haplotype analysis identified a single vgsc amplicon haplotype in An. darlingi and three closely related haplotypes in An. deaneorum. Notably, these haplotype sequences represent the first vgsc fragment sequences from An. deaneorum available. Whole genome sequencing was conducted on a subset of An. darlingi pyrethroid susceptible and resistant colony mosquitoes. Genome-wide FST scores were low, with regions of highest differentiation including the GPCR Mth2-like gene, a gene family previously associated with resistance to pyrethroids in Culex mosquitoes. Targeted analysis of key resistance-associated genes (vgsc, ace1, gste2, and ace1) identified no mutations previously associated with insecticide resistance. However, 21 novel non-synonymous variants were detected. Selection scans identified regions of the genome under selection pressure within the pyrethroid resistant An. darlingi, including the cytochrome P450 gene cyp313a4, the tipE gene required for the expression of insect sodium channels including vgsc, and cuticular proteins (protein yellow and cuticle protein-19 like). Structural variant analysis identified one duplication and four inversions at higher frequency in the resistant An. darlingi population. Together, these findings provide essential phenotypic and genomic characterisation of An. darlingi and An. deaneorum laboratory colonies and support their use as reference strains for insecticide resistance monitoring and mechanistic studies.
london school of hygiene and tropical medicine