Winter survival of Culex pipiens biotype pipiens adults in Central Greece

Winter survival is a key life-history trait of insect vectors in temperate ecosystems, shaping early seasonal population growth and vector-borne disease epidemiology. For West Nile virus infection in Europe, including Greece, Culex pipiens is the principal vector. We conducted overwintering experiments in three areas in Central Greece, to assess winter survival of adult Culex pipiens biotype pipiens under coastal (Nea Anchialos and Volos) and inland (Kalamaki) conditions. A proportion of females survived winter at all sites, whereas males did not overwinter. Female survival reached 23.9% in Kalamaki and 25.3% in Nea Anchialos, while in Volos it ranged from 9.4 to 15.7% across treatments. Surviving females were able to blood-feed and oviposit in spring, producing viable offspring. The proportion of fertile females was 52.3% in Kalamaki and 47.4% in Nea Anchialos, whereas in Volos it ranged from 20.8 to 47.2%. Survival varied among locations and treatments, suggesting an effect of local environmental conditions on overwintering success. The results provide evidence that females of Cx. pipiens biotype pipiens can survive winter conditions in the study areas and subsequently initiate reproduction in spring. This study contributes to improving the understanding of the overwintering ecology of an important vector and highlights the need for further studies in different habitats.