Background: Aedes aegypti , the primary vector of Dengue fever in Burkina Faso, breeds in a variety of domestic and peri-domestic water holding containers. The influence of these water containers on the mosquitoes’ ability to survive exposure to chemical insecticides remains unclear. This study investigated the insecticide susceptibility profile of Aedes aegypti in relation to larval habitat types in three districts of Ouagadougou. Methods: Adult females reared from larvae collected in “domestic containers” and “car tires” were exposed separately to papers impregnated with deltamethrin, pirimiphos-methyl, and bendiocarb to determine their susceptibility profiles. A subsample of mosquitoes per locality and container type was screened for the F1534C, V1016I and V410L kdr mutations involved in pyrethroid resistance. Results: Mosquito population from the three localities showed high resistance to deltamethrin and pirimiphos-methyl and moderate resistance to bendiocarbe, with mortality rates ranging from 15% to 27%, 21% to 33% and 67% to 86%, respectively. Mosquitoes from the "domestic containers" were significantly more resistant to deltamethrin than those from tires (10% vs. 22%, p < 0.002). The frequency of the 1534C mutation was also significantly higher in the "domestic containers" compared to those from tires (0.88 vs. 0.76, p = 0.013).The other mutations 1016I and 410L, were reported with an overall frequency of 0.51 and 0.36, respectively. Conclusions: These findings suggest that larval habitat type may influence both the level and mechanisms of resistance in Aedes aegypti . This has important implications for the design of targeted vector control strategies in dengue-endemic settings.

Background: The introduction of next-generation insecticide-treated nets (ITNs) in Burkina Faso aims to mitigate pyrethroid resistance in malaria vectors. This study evaluated the impact of different ITN types on phenotypic resistance and kdr mutation frequencies in Anopheles gambiae sensus lacto (s.l.) populations across three health districts over 3 years. Methods: Annual mosquito collections were conducted in Banfora (where pyrethroid–chlorfenapyr nets had been distributed), Gaoua (pyrethroid-only ITNs) and Orodara (pyrethroid–piperonyl butoxide [PBO] ITNs). Two populations were analysed: adult females collected directly from the field and those reared from field-collected larvae. World Health Organization (WHO) susceptibility bioassays measured 24-h mortality after exposure to 1×, 5× and 10× concentrations of deltamethrin and alphacypermethrin, with and without pre-exposure to piperonyl butoxide. Frequencies of kdr mutations L995F and L995S were determined by polymerase chain reaction (PCR). Results: High-intensity resistance was observed in each study district, with mortality consistently below 45% and not reaching WHO thresholds even at 10× doses. PBO increased mortality, indicating metabolic resistance, but failed to restore full susceptibility. L995F predominated across all districts, years and mosquito populations. L995S remained low and variable. Pyr-only nets were associated with rising L995F frequencies and lower mortality in resistance assays. Pyrethroid (Pyr)–chlorfenapyr (CFR) nets improved mortality in resistance assays without increasing kdr prevalence. Pyr–PBO nets showed partial and inconsistent efficacy, with mosquitoes having mixed patterns in resistance assays. Similar patterns between field and laboratory-reared populations were observed. Conclusions: ITN type strongly influenced resistance dynamics. Dual-active ingredient (AI) nets, particularly Pyr–CFR, appear more effective in managing resistance. Integrated resistance management combining ITN rotation, routine monitoring and complementary interventions is essential to preserve vector control efficacy. Graphical

Enhancers are cis-regulatory elements that control most of the developmental and spatial gene expression in eukaryotes. Genetic variation of enhancer sequences is known to influence phenotypes, but the effect of enhancer variation upon enhancer functional activity and downstream phenotypes has barely been examined in any species. In the African malaria vector, Anopheles coluzzii , we identified a pilot set of candidate enhancers in the proximity of genes relevant for immunity, insecticide resistance, and development. The candidate enhancers were functionally validated using luciferase reporter assays, and their activity was found to be essentially independent of their physical orientation, a typical property of enhancers. All of the enhancer intervals segregated genetically polymorphic alleles, which displayed significantly different levels of functional activity, and inactive null alleles were also observed. Deletion mutagenesis and functional testing revealed a modular structure of positive and negative regulatory elements within the tested enhancers. The enhancer alleles carry genetic polymorphisms that also segregate in wild A. coluzzii populations in West Africa, indicating that enhancer variants with likely phenotypic consequences are frequent in nature. These results demonstrate the feasibility of screening for naturally polymorphic A. coluzzii enhancers that underlie important aspects of malaria transmission and vector biology.