Short-Term Selection to Diflubenzuron and Var. Differentially Affects the Winter Survival of f. and f. (Diptera: Culicidae).

The (Diptera: Culicidae) mosquito is of high medical importance as it is considered the prime vector of West Nile virus. In Europe, this species consists of two forms, named and , that exhibit substantial differences in their overwintering biology. Diflubenzuron (DFB) and var. () are two of the most used larvicides in mosquito control, including that of . The high dependency on these two larvicides poses major concerns for resistance development. The evolution and stability of resistance to insecticides has been associated with fitness costs that may be manifested under stressful conditions, such as the winter period. This study investigated how short-term selection of and forms to both larvicides affect their overwintering success. Larvae from each form were subjected to the same selective pressure (80% mortality) for three successive generations with DFB and . At the end of this process, the winter survival between the selected populations and the controls (colonies without selection) was determined for each form. Selection to both larvicides significantly reduced the winter survival rates of but not of form, indicating potential differences in the persistence of the selected individuals from year to year between the two forms.