Rapid local adaptation to northern winters in the invasive Asian tiger mosquito Aedes albopictus: A moving target

Rapid adaptation in response to novel environments can facilitate species invasions and range expansions. Understanding how invasive disease vectors rapidly evolve to novel conditions-particularly at the edge of its non-native range-has important implications for mitigating the prevalence and spread of disease. Here, we evaluate the role of local adaptation in overwintering capability of the Asian tiger mosquito, Aedes albopictus. This species invaded the Southern United States in the 1980s and rapidly spread northward into novel climate compared to its native range. Photoperiodically induced egg diapause is a key trait contributing to the establishment and spread of Ae. albopictus in temperate latitudes, and diapause incidence rapidly developed a cline along a latitudinal gradient in the United States shortly after its initial invasion. However, variation in overwintering survival of diapause-induced eggs along this gradient is not known, but is critical to the fitness-related role of diapause evolution in the establishment of Ae. albopictus in its northern US range. Using reciprocal transplants, we detected local adaptation in overwinter survival of diapausing Aedes albopictus eggs. In northern range-edge winters, eggs produced by range-edge individuals survived better than those produced by range-core individuals. Diapause eggs from range-edge and range-core locations survived equally well in range-core winters, and no eggs survived a winter beyond the current northern range limit in the United States. Synthesis and applications. These results demonstrate rapid (similar to 3 decades) local adaptation of egg diapause, a key trait facilitating overwinter survival and range expansion for the invasive Asian tiger mosquito. In light of these results, control efforts could shift from targeting satellite populations to a focus on preventing dispersal into locally adapted, range-edge locations and to aim removal efforts towards areas surrounding locally adapted populations. Adopting new approaches to target rapidly adapting populations will require large-scale collaboration among control agencies and research institutions, and should begin in the northern US range to better control Aedes albopictus mosquito populations in the face of rapid adaptation.