Molecular monitoring reveals the presence of multiple insecticide resistance markers in mosquito disease vectors in Türkiye.

Insecticide resistance in mosquito vectors often involves multiple molecular mechanisms. Here, we analysed resistance-associated mechanisms in Culex pipiens and Aedes albopictus populations from 14 locations across Türkiye using a multi-marker molecular approach. We combined species identification, biotype resolution within the Cx. pipiens complex, and molecular screening of key target-site resistance markers (kdr, CHS1, and ace-1), together with genes associated with metabolic detoxification. Within Cx. pipiens, resistance-associated marker profiles varied among populations with heterogeneous biotype composition, including pipiens, molestus, and hybrid forms. All Cx. pipiens populations exhibited moderate to high frequencies of kdr mutations (L1014F/C; 50-80.8%). The CHS1 I1043M mutation was detected in a subset of populations, reaching frequencies of up to 64 %, whereas ace-1 G119S was detected sporadically at low frequencies (5-10%). In several populations, multiple resistance-associated markers were detected concurrently with varying frequencies, indicating potential complexity in resistance profiles. No target-site resistance mutations were detected in Ae. albopictus at the genotyped loci, and no esterase gene amplification was observed for the assessed markers. Taken together, our findings demonstrate variability in the distribution of resistance markers among mosquito populations across Türkiye. Further phenotypic and ecological investigations are needed to clarify the contribution of insecticide exposure and selection pressures to these patterns. These findings highlight the need for geographically matched and phenotypically validated surveillance frameworks to support evidence based and adaptive vector control strategies.