The contribution of reproductive interference in population displacement of invasive Aedes species

Following its broad diaspora during the last three decades, Ae. albopictus has established in new continents and countries where its invaded distribution often overlaps that of Ae. aegypti. Many recent invasions have led to reductions in abundance and range of previously established Ae. aegypti. However, despite the potential impacts of such displacements on arbovirus epidemiology, our current understanding of causative mechanisms is poor. In this paper we show that a neglected potential mechanism, asymmetric reproductive interference, may contribute significantly to the observed patterns of rapid reductions of Ae. aegypti populations. Recent data from the field show the two species mate at sites of sympatry in Florida and that heterospecific male accessory gland products sterilize Ae. aegypti, but not Ae. albopictus, females. Therefore, the potential cost of mating an interspecific male is high for an Ae. aegypti female and evolutionary theory predicts avoidance of such behaviour to be beneficial. We demonstrate that Ae. aegypti females from populations with a history of contact with Ae. albopictus are, indeed, less likely to mate with interspecific males than females of allopatric origin. Furthermore, we show the rapid evolution of this trait in laboratory-based cage trials.