Preliminary considerations about the presence of Aedes albopictus (Skuse 1897) (Diptera: Culicidae) during winter in the Northwestern Italy.

Aedes albopictus, the Asian tiger mosquito, was unintentionally introduced in Italy at the beginning of the 1990s. In few decades it spread almost in the whole Country. In Piedmont, the first report dates back to 1994. Usually, temperate populations are affected by seasonal temperature and photoperiodicity and can overwinter by producing eggs that undergo a winter diapause. In Rome females of the species extended their trophic activity to the coldest months of the year, but there is no notice about a similar behaviour for northern areas of the Country. In our routine work, we often inspect residential and public buildings according to people requests due to the presence of annoying mosquitoes. During these inspections, we try to identify and solve the problem looking for adults and breeding sites of annoying species. Samples are conveniently collected and identified in the field or returning in the labs. We report seven cases of Ae. albopictus female trophic activity in both residential and public buildings, from November to March, in urban and rural areas in Piedmont, ranging between 44°33'11" N and 45°05'09" N. In one case, some larval breeding sites with a large number of larvae and pupae of this species were identified. Ae. albopictus can show trophic and reproductive activity during the winter in the northwestern Italy under favourable conditions. This evidence is of particular concern because of seasonality of Aedes mosquito-borne disease in returned travellers. Dengue, for example, has its higher morbidity in returned travellers from Caribbean and Central America typically during the winter period.