From the exploration of mosquito bioacoustics towards the development of novel approaches of surveillance and control

Abstract

ABSTRACT: Diseases transmitted by mosquitoes cause public-health problems worldwide. In the absence of cost-effective treatments, the impact of these diseases is mitigated mainly by controlling mosquito populations. As current control methods exhibit serious difficulties, optimized and sustainable solutions are required. Due to the relevance of acoustic signals in mosquito reproduction, acoustic-based surveillance and control strategies are promising. In this thesis, three possible research approaches are explored: 1) Studying mosquito bioacoustics. 2) Designing acoustic traps. 3) Recognizing mosquitoes by their flight-tones. First, the study of mosquito bioacoustics provides valuable information to improve control strategies that rely on reproduction. Here, we study Aedes aegypti and Anopheles (Nyssorhynchus) albimanus bioacoustics from the receiver and the emitter perspective. By investigating audition from the receiver perspective, we describe general characteristics of the auditory organs of mosquitoes and evaluate the particular auditory response of each one of the studied species. Moreover, we establish similarities and differences between the species and address questions regarding mosquito sound reception. From the emitter perspective, we analyse the acoustic signals produced by tethered and free-flying mosquitoes, describing the effect of the recording protocol on the characteristics of flight-tones. Lastly, we use tethered and free-flying An. albimanus mosquitoes to uncover sex-specific acoustic behaviours related to reproduction and to establish a relationship between flight-trajectories and flight-tones. Second, the use of traps to collect mosquitoes is one of the operational foundations of mosquito control programs. Here, we use the inherent ability of male mosquitoes to locate a sound source in order to develop a novel acoustic trap prototype. By using acoustic attractants synthesized from mosquito flight-tone recordings, promising capture rates are obtained under indoor and semi-field conditions. Finally, using flight-tones to recognize mosquito species has proven to be a promising surveillance technic. In this thesis, we evaluate classification algorithms to differentiate species that share flight-tones with comparable frequency characteristics. Our results demonstrate that, by using the spectral information of flight-tones, it is possible to obtain a classification accuracy higher than 70 %, when classifying species with similar wingbeat frequency distributions. Overall, this thesis combines basic and applied research oriented towards the study of mosquito bioacoustics. Our results contribute to the literature that is actively studying mosquito biology and constitute a step forward in the fight against mosquito-borne diseases. We hope the methods and the technology developed during the execution of this research will be used in the future to accomplish innovative research projects.