Background: The rapid spread of insecticide resistance in malaria vectors and the rebound in malaria cases observed recently in some endemic areas underscore the urgent need to evaluate and deploy new effective control interventions. A randomized control trial (RCT) was conducted with the aim to investigate the benefit of deploying complementary strategies, including indoor residual spraying (IRS) with pirimiphos-methyl in addition to long-lasting insecticidal nets (LLINs) in Diébougou, southwest Burkina Faso. Methods: We measured the susceptibility of the Anopheles gambiae (s.l.) population from Diébougou to conventional insecticides. We further monitored the efficacy and residual activity of pirimiphos-methyl on both cement and mud walls using a laboratory susceptible strain (Kisumu) and the local An. gambiae (s.l.) population. Results: An. gambiae (s.l.) from Diébougou was resistant to DDT, pyrethroids (deltamethrin, permethrin and alphacypermethrin) and bendiocarb but showed susceptibility to organophosphates (pirimiphos-methyl and chlorpyrimiphos-methyl). A mixed-effect generalized linear model predicted that pirimiphos-methyl applied on cement or mud walls was effective for 210 days against the laboratory susceptible strain and 247 days against the local population. The residual efficacy of pirimiphos-methyl against the local population on walls made of mud was similar to that of cement (OR = 0.792, [0.55–1.12], Tukey’s test p-value = 0.19). Conclusions: If data on malaria transmission and malaria cases (as measured trough the RCT) are consistent with data on residual activity of pirimiphos-methyl regardless of the type of wall, one round of IRS with pirimiphos-methyl would have the potential to control malaria in a context of multi-resistant An. gambiae (s.l.) for at least 7 months. Graphical

Background: Intensive deployment of insecticide based malaria vector control tools resulted in the rapid evolution of phenotypes resistant to these chemicals. Understanding this process at the genomic level is important for the deployment of successful vector control interventions. Therefore, longitudinal sampling followed by whole genome sequencing (WGS) is necessary to understand how these evolutionary processes evolve over time. This study investigated the change in genetic structure and the evolution of the insecticide resistance variants in natural populations of Anopheles gambiae over time and space from 2012 to 2017 in Burkina Faso. Methods: New genomic data have been generated from An. gambiae mosquitoes collected from three villages in the western part of Burkina Faso between 2012 and 2017. The samples were whole-genome sequenced and the data used in the An. gambiae 1000 genomes (Ag1000G) project as part of the Vector Observatory. Genomic data were analysed using the analysis pipeline previously designed by the Ag1000G project. Results: The results showed similar and consistent nucleotide diversity and negative Tajima’s D between An. gambiae sensu stricto (s.s.) and Anopheles coluzzii. Principal component analysis (PCA) and the fixation index (F_ST) showed a clear genetic structure in the An. gambiae sensu lato (s.l.) species. Genome-wide F_ST and H12 scans identified genomic regions under divergent selection that may have implications in the adaptation to ecological changes. Novel voltage-gated sodium channel pyrethroid resistance target-site alleles (V402L, I1527T) were identified at increasing frequencies alongside the established alleles (Vgsc-L995F, Vgsc-L995S and N1570Y) within the An. gambiae s.l. populations. Organophosphate metabolic resistance markers were also identified, at increasing frequencies, within the An. gambiae s.s. populations from 2012 to 2017, including the SNP Ace1-G280S and its associated duplication. Variants simultaneously identified in the same vector populations raise concerns about the long-term efficacy of new generation bed nets and the recently organophosphate pirimiphos-methyl indoor residual spraying in Burkina Faso. Conclusion: These findings highlighted the benefit of genomic surveillance of malaria vectors for the detection of new insecticide resistance variants, the monitoring of the existing resistance variants, and also to get insights into the evolutionary processes driving insecticide resistance.

Intensive deployment of insecticide based malaria vector control tools results in the rapid evolution of phenotypes resistant to these chemicals. Understanding this process on the genomic level is essential for the deployment of successful interventions. Using whole genome sequencing data of 1409 individual An. Gambiae s.l. collected from 2012 to 2017, we investigated the change in genetic structure and the evolution of the insecticide resistance variants in natural populations over time and space. The results showed similar and constant nucleotide diversity and negative Tajima’s D between An. gambiae s.s. and An. coluzzii . PCA and F _ST showed a clear genetic structure in the An. gambiae s.l. species. Genome-wide F _ST and H12 scans identified genomic regions under divergent selection and also having an implication in the adaptations to ecological changes. Novel voltage-gated sodium channel pyrethroid resistance target-site alleles ( V402L, I1527T ) were identified at increasing frequencies alongside the established kdr alleles ( Vgsc-L995F , Vgsc-L995S and N1570Y ) within the An. gambiae s.l. populations. Organophosphate metabolic resistance markers were also identified, at increasing frequencies, within the An. gambiae s.s. populations from 2012 to 2017, including the SNP Ace1-G280S and its associated duplication. Variants simultaneously identified in the same vector populations raise concerns about the long-term efficacy of new-generation bednets and the recently introduced organophosphate pirimiphos-methyl indoor residual spraying. These findings highlighted the benefit of genomic malaria vector surveillance for the detection of new insecticide resistance variants, the monitoring of the existing resistance variants, and also to get insights into the evolutionary processes driving insecticide resistance. Author Summary: Genomic surveillance of malaria vectors is crucial for understanding the genetic variation in natural vector populations and also guiding the implementation of novel and innovative vector control tools. Application of sequencing technologies in vector studies provide insights on the genetic and evolutionary phenomena of vectors that could have impact on vector control strategies. By analyzing the whole genome data of 1409 wild An. gambiae s.l. mosquito collected between 2012 and 2017, we showed an emergence of novel insecticide resistance markers alongside increasing frequencies of existing insecticide resistance variants over time in Burkina Faso. We showed the benefit of genomic surveillance of malaria vectors for the monitoring of the insecticide resistance variants and also providing insights into the evolutionary processes driving insecticide resistance.

Background: The recent success of a population control gene drive targeting the doublesex gene in Anopheles gambiae paved the way for developing self-sustaining and self-limiting genetic control strategies targeting the sex determination pathway to reduce and/or distort the reproductive capacity of insect vectors. However, targeting these genes for genetic control requires a better understanding of their genetic variation in natural populations to ensure effective gene drive spread. Using whole genome sequencing (WGS) data from the Ag1000G project (Ag3.0, 3.4 and 3.8), and Illumina pooled amplicon sequencing, we investigated the genetic polymorphism of the intron-4–exon-5 boundary of the doublesex gene in the natural populations of An. gambiae sensu lato (s.l.). Results: The analyses showed a very low variant density at the gRNA target sequence of the Ag(QFS)1 gene drive (previously called dsxF ^CRISPRh ) within the populations of West and East Africa. However, populations from the forest area in Central Africa exhibited four SNP at frequencies ranging from 0.011 to 0.26. The SNP (2R:48714641[C > T]) at high frequencies, i.e. 0.26 is identified within the An. coluzzii population from Angola. The analyses also identified 90 low frequency (1 − 5%) SNPs in the genomic region around the gRNA target sequence (intron-4–exon-5 boundary). Three of these SNPs (2R:48714472 A > T; 2R:48714486 C > A; 2R:48714516 C > T) were observed at frequencies higher than 5% in the UTR region of the doublesex gene. The results also showed a very low variant density and constant nucleotide diversity over a five-year survey in natural An. gambiae s.l. populations of Burkina Faso. Conclusion: These findings will guide the implementation of doublesex-targeted gene drives to support the current control tools in malaria elimination efforts. Our methods can be applied to efficiently monitor the evolution of any sequence of interest in a natural population via pooled amplicon sequencing, surpassing the need for WGS.