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 betweenAedes aegyptiandAedes 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 ofAe. aegypti(Colombia, Arizona, and Liverpool, respectively) and allopatric and sympatric strains ofAe. 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 maleAe. albopictusconsistently aborting interspecific mating attempts.

Conclusions

This study provides additional evidence for strong pre-copulatory species barriers betweenAe. aegyptiandAe. albopictusand 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.