An integrated approach to understand the expansion of Aedes albopictus in Greece using COI barcoding, microsatellite markers, and Wolbachia

The invasive mosquito species Aedes albopictus , commonly known as the Asian Tiger Mosquito, constitutes a significant global health concern due to its role as a vector for diseases, such as Dengue, Zika, and Chikungunya. In Greece, Ae. albopictus was first detected in 2005, with subsequent widespread establishment across the country. This study investigates the recent steps of the within Greece range expansion of Ae. albopictus , using and analyzing specimens collected between 2016 and 2022 from different parts of the country. Greek Ae. albopictus populations were genotyped using the standard mitochondrial cytochrome oxidase I (COI) barcoding, a set of eight microsatellite markers. In addition, we explored the presence of the endosymbiont bacterium Wolbachia pipiens in Greek populations. A total of 408 female individuals were analyzed for COI variation, and all Greek samples were assigned to a single haplotype. Microsatellite analysis revealed a relatively low degree of genetic differentiation, attributed mainly to intra-population rather than inter-population differences. Wolbachia genotyping suggested the fixed presence of double infections with supergroups A and B (reaching to 100%). Our data are in accordance to an invasion scenario from one or very few genetically related sources. The recent expansion of Ae. albopictus in Greece is accompanied by the fixation of double Wolbachia infections, which may account for both the reduced genetic diversity observed and a possible selective sweep of additional mitochondrial haplotypes. Our findings underscore the importance of combining molecular tools of mitochondrial, nuclear, and symbiotic origin for thorough understanding of invasion dynamics and information regarding targeted surveillance and control interventions. In addition, our data provide a solid foundation for the genetic structure of the Greek populations of Ae. albopictus and the prevalence of Wolbachia .