Molecular characterization of invasive Aedes albopictus (Diptera: Culicidae) populations in northwest Iran: Insights into origin, insecticide resistance, and Wolbachia infection.

backgroundAedes albopictus, a major invasive mosquito species and competent vector for dengue, chikungunya and Zika viruses, has recently become established in northern Iran. Developing effective control strategies requires elucidating the population structure, genetic origins, insecticide resistance mechanisms and prevalence of Wolbachia infection in these established populations.

methodsEggs of Aedes species were collected in October 2024 using ovitraps deployed in high-risk areas of Tarom County, Zanjan Province, northwestern Iran. Egg specimens were reared to adulthood under standard laboratory conditions and subsequently subjected to molecular analyses, including sequencing of the mitochondrial cytochrome c oxidase subunit I gene (COI), screening for knockdown resistance (kdr) mutations in the voltage-sensitive sodium channel gene (vssc) and detecting Wolbachia infection via Wolbachia surface protein gene (wsp) amplification.

resultsA total of 258 Ae. albopictus eggs were collected, from which 86 viable adults were reared. Mitochondrial COI gene analysis (1433-bp fragment) revealed 99-100% similarity to temperate-adapted Eurasian populations from China and southern Europe. The F1534L kdr mutation was detected in 45% of specimens (all heterozygous), indicating pre-existing pyrethroid resistance, while the remaining 55% retained the wild-type allele. Over 85% of samples were superinfected with Wolbachia wAlbA and wAlbB strains, and 12.5% harbored only the wAlbB strain.

conclusionsThe establishment of a temperate-adapted Ae. albopictus population in Iran, coupled with a high prevalence of Wolbachia wAlbA and wAlbB superinfection strains and emerging insecticide resistance, underscores the urgent need for integrated vector management, continuous resistance monitoring and exploration of Wolbachia-based biocontrol strategies.