Genetic variations of the Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae) in East-Adriatic populations inferred from NADH5 and COI sequence variability

In the last few decades, Aedes albopictus (Skuse) (Diptera: Culicidae) (= Stegomyia albopicta), the so-called “Asian tiger mosquito”, has spread from its native range in southeast Asia to Africa, Middle East, Europe, Americas and Pacific islands. The invasion of this species poses a risk to human health as it is considered to be one of the main vectors of dengue and other arboviruses. Aedes albopictus was reported in Croatia in 2004, thereafter it was discovered at several coastal localities in 2005 and to date it has spread to most coastal area and islands in Croatia. Here we investigated the genetic variability of 39 individuals of A. albopictus collected during the summer in 2009 along the East-Adriatic coast and islands of Croatia and Monte Negro, based on two mitochondrial molecular markers: cytochrome oxidase I (COI) and NADH dehydrogenase 5 (ND5). We identified a single ND5 haplotype, corresponding to the previously reported and worldwide-distributed haplotype H3. The COI marker was more variable and we identified four COI haplotypes. In order to identify the geographic origin of populations that colonized Croatia, we performed phylogenetic analyses of ND5 and COI haplotypes from Croatian populations and other A. albopictus populations retrieved from GenBank. The phylogenetic tree built from ND5 revealed two well supported clades where the unique Croatian ND5 haplotype clustered with the majority of haplotypes, originating from South-Asia, America, Europe and Africa. Another smaller cluster consisted of Brazilian haplotypes alone. The phylogenetic tree and haplotype network from COI analysis also shown that the three Croatian COI haplotypes clustered with European and American haplotypes. However the fourth Croatian COI haplotype was the only European haplotype found in a separate clade (group) with Indian, south-Asian and Brazilian haplotypes. Such data suggest several independent introduction events in Croatia.