On the suitability of Aedes vexans to Wolbachia ‐based control strategies

Aedes vexans (Meigen) (Diptera: Culicidae) is a common mosquito species with worldwide distribution and it is a potential vector of various pathogens such as West Nile, Rift Valley, and Zika viruses, and Dirofilaria nematodes. Also due to its abundance, Ae. vexans could be a key species in determining new outbreaks of these important pathogens outside their present geographical range. Herein, we report on studies carried out in the laboratory to ascertain the suitability of the species for control strategies based on the exploitation of the endosymbiotic bacterium Wolbachia, known to induce reproductive incompatibility and/or virus resistance in the hosts. Aedes vexans showed low propensity to mate in narrow places, low male survival, and reduced hatchability of the eggs collected on artificial devices. Embryonic and adult transinfection with various Wolbachia strains were attempted. Whereas the first approach was barely tolerated by Ae. vexans eggs, transinfected progeny was obtained by adult microinjection using wAlbA and wAlbB Wolbachia but both strains were not efficiently transmitted vertically, leading to the loss of the infection by three generations. The present study highlights the low suitability of Ae. vexans to the infection by this bacterium and to the mass-rearing conditions generally required for Wolbachia-based control strategies.