A tiger is not always a satyr: role of male mating behaviour in interspecific mating interactions between Aedes aegypti and Aedes albopictus.

BACKGROUND: Interspecific mating between Aedes aegypti and Aedes albopictus, which act as vectors of a wide range of arboviruses, is predicted to have an important influence on their future distributions and disease control efforts. While interspecific insemination has been documented in a range of laboratory and field studies, rates vary between populations. It has been suggested that the outcome of mating interactions is driven by evolved variation in both the male ability to mate interspecific females and ability of females to resist interspecific males. However, there has been relatively little dissection of the behaviours that underlie interspecific insemination rates. METHODS: We compared insemination rates between sympatric, allopatric, and lab-adapted strains of Ae. aegypti (Colombia, Arizona, and Liverpool, respectively) and allopatric and sympatric strains of Ae. albopictus (Montpellier and Colombia, respectively). We then used both live observations and high-speed videography to compare intraspecific and interspecific mating interactions. RESULTS: We found very low rates of interspecific mating across all strains used. Both behavioural observations and high-speed videography suggested that female resistance behaviours were not responsible for low interspecific mating. Interestingly, we documented male Ae. albopictus consistently aborting interspecific mating attempts. CONCLUSIONS: This study provides additional evidence for strong pre-copulatory species barriers between Ae. aegypti and Ae. albopictus and adds male avoidance as a possible mechanism to maintain these barriers. Considering female resistance, the ability of males to overcome that resistance, and male avoidance of interspecific matings together will be important for informing understanding of how we expect interspecific mating rates to vary across populations and respond to selective pressures such as mass-release strategies.