Sexual selection theory meets disease vector control: Testing harmonic convergence as a "good genes" signal in Aedes aegypti mosquitoes.

BACKGROUND: The mosquito Aedes aegypti is a medically important, globally distributed vector of the viruses that cause dengue, yellow fever, chikungunya, and Zika. Although reproduction and mate choice are key components of vector population dynamics and control, our understanding of the mechanisms of sexual selection in mosquitoes remains poor. In "good genes" models of sexual selection, females use male cues as an indicator of both mate and offspring genetic quality. Recent studies in Ae. aegypti provide evidence that male wingbeats may signal aspects of offspring quality and performance during mate selection in a process known as harmonic convergence. However, the extent to which harmonic convergence may signal overall inherent quality of mates and their offspring remains unknown. METHODOLOGY/PRINCIPAL FINDINGS: To examine this, we measured the relationship between acoustic signaling and a broad panel of parent and offspring fitness traits in two generations of field-derived Ae. aegypti originating from dengue-endemic field sites in Thailand. Our data show that in this population of mosquitoes, harmonic convergence does not signal male fertility, female fecundity, or male flight performance traits, which despite displaying robust variability in both parents and their offspring were only weakly heritable. CONCLUSIONS/SIGNIFICANCE: Together, our findings suggest that vector reproductive control programs should treat harmonic convergence as an indicator of some, but not all aspects of inherent quality, and that sexual selection likely affects Ae. aegypti in a trait-, population-, and environment-dependent manner.

Male accessory gland molecules inhibit harmonic convergence in the mosquito Aedes aegypti.

Aedes aegypti mosquitoes transmit pathogens such as yellow fever, dengue, Zika, and chikungunya viruses to millions of human hosts annually [1]. As such, understanding Ae. aegypti courtship and mating biology could prove crucial to the success of disease control efforts that target reproduction. Potentially to communicate reproductive fitness [2,3], mosquito males and females harmonize their flight tones prior to mating in a behavior known as harmonic convergence (HC) [4]. Furthermore, after mating or treatment with extracts from male accessory glands (MAG), which make seminal fluid molecules, female Ae. aegypti become resistant, or refractory, to re-mating [5]. To test the hypothesis that mating and MAG fluids inhibit a female's ability to induce HC in males, we recorded audio of pre-copulatory flight interactions between virgin males and either virgin, mated, or MAG extract-injected females and analyzed these recordings for the presence or absence of HC. We found that mating and MAG extract lower HC occurrence by 53% compared with all other controls. Our results further suggest that mating may inhibit HC indirectly via the broader range of MAG-induced female refractory mating behaviors. Together, our results demonstrate an important new role for MAG molecules in mediating female post-mating behavior.