Decoupling of active and passive reasons for the invasion dynamics of Aedes albopictus Skuse (Diptera: Culicidae): Comparisons of dispersal history in the Apennine and Florida peninsulas

Aedes albopictus is an important vector of several diseases including dengue-and Chikungunya fever and is a potential vector of Zika-fever. The invasion dynamics of Aedes albopictus was reconsidered by comparing the temperature-related development of the mosquito with the observed real geographical distribution in Florida and in Italy. The potential number of generations and the annual dispersal distances of the mosquito were calculated for the estimates. The estimated total dispersals are 3.6-4.6 km/year/generation in Italy and 4.6-5.3 km/year/generation in Florida, values that are at least five to six times higher than those derived from release and recapture studies and from the previously measured flying distances of female Asian tiger mosquitoes. Subtracting the calculated dispersal distances with the known active dispersal of female Ae. albopictus, the passive dispersal component of the total dispersal distances was found to be 2.8-4.1 km/year/generation in Italy and 3.8-4.8 km/year/generation in Florida. Our results confirm that the active dispersal of female mosquitoes plays a secondary role in determining the rate of areal expansion and, in contrast, passive factors may play a primary role. It was concluded, based on similar average values of the passive dispersal distances of the mosquito in Florida and Italy, that at large spatial scales the anthropogenic component can be well estimated.