Genomic insights into the spread and evolution of insecticide resistance variants in Anopheles gambiae s.l. from Burkina Faso

The intensive use of insecticide-based control tools has led to the rapid evolution of resistant phenotypes in malaria vector populations. Understanding the evolutionary processes underlying these resistances is essential to inform the development and deployment of effective control interventions. This study investigated the geographical spread and the genetic background of insecticide resistance variants in Anopheles gambiae s.l. in Burkina Faso. The study identified five pyrethroid-resistant mutations (995F, 995S, 402L(g > t,c), 1527T and 1570Y) at high frequencies. Six diplotype groups were identified, including novel combinations of the resistance-associated alleles (995F, 402L(g > t,c) and 1527T), which formed new genotypes within An. coluzzii populations. These results suggest the emergence of new resistance genotypes in An. coluzzii that are not associated with 995F, probably due to recombination and gene flow events. Interestingly, strong linkage disequilibrium (r2 = 0.821) was observed between 1527T and 402L(g > t) compared to 1527T and 402L(g > c). The PCA revealed three clusters of An. coluzzii populations, driven by 995F, 402L(g > t,c) and 1527T. Other insecticide resistance associated variants such as copy number variations and SNPs in the Ace1 gene (ace1-G280S), cytochrome P450s, esterases and glutathione S-transferases were identified at high frequencies in the same mosquito populations, indicating the intensity and diversity of resistance mechanisms in the country. The study underscores the extent and spreads of insecticide resistance variants in Burkina Faso. It highlights the importance of genomic surveillance of malaria vectors to monitor and detect new resistance variants and to understand the evolutionary processes in vector populations.