Cold tolerance of the Asian tiger mosquito Aedes albopictus and its response to epigenetic alterations.

Phenotypic plasticity is considered as one of the key traits responsible for the establishment of populations of the invasive mosquito Aedes albopictus, an important vector of viral and parasitic pathogens. The successful spread of this species to higher altitudes and latitudes may be explained by its ability to rapidly induce a heritable low-temperature phenotype (cold hardiness in eggs). As a result of the low genetic diversity of founder populations, an epigenetic short-term mechanism has been suggested as the driver of this diversification. We investigated if random epigenetic alterations promoted the cold hardiness of Ae. albopictus eggs from a transgenerational study of two epigenetic agents (genistein and vinclozolin). To this end, we evaluated changes in lethal time for 50% of pharate larvae (Lt50) from eggs exposed to -2°C in two subsequent generations that used a new dose-response test design. We detected a significant diversification of the cold hardiness of eggs (up to 64.5%) that was associated with the epigenetic change in the two subsequent offspring generations. An effect size of epigenetically modulated cold hardiness of this magnitude is likely to have an impact on the spatial distribution of this species. Our results provide a framework for further research on epigenetic temperature adaptation of invasive species to better explain and predict their rapid range expansions.