Incidence of Wolbachia In Wild Insects And Its Effect on Mosquito Host

Abstract

Mosquito-borne diseases are a considerable threat to human and animal health. Over decades, different strategies have been attempted to alleviate this burden with limited success. The use of Wolbachia, an endosymbiotic alpha-proteobacterium, is one of the most promising approaches used to limit virus transmission from mosquito to humans. Wolbachia is thought to infect 20 -70% of all arthropod species and several nematodes. However, there are conflicting estimates regarding the percentage of insects infected with Wolbachia. Here, we will study the incidence of Wolbachia in a broad range of insect species, collected from different regions in Lebanon and the coevolution of Wolbachia with their host. Previous studies showed that Wolbachia’s presence is responsible for pathogen blocking, while other studies showed that in its native host the protective effects of the endosymbiont are not detected. In this context, we aim to analyze the effect of Wolbachia on Culex mosquito host physiology particularly immunity and midgut homeostasis. While performing this study, we identified a pathogenic strain of Aeromonas hydrophila, accidentally introduced into the insectary, that causes mortality to both Culex pipiens and Aedes albopictus mosquitoes upon ingestion. In addition, we showed that A. hydrophila breaches the gut epithelium and gains access to the hemolymph. Parallel to gut damage, we detected a significant increase in the number of proliferative cells in the midguts of A. hydrophila-fed mosquitoes. Moreover, we found that this bacterium induces a local immune response in the gut leading to the production of anti-microbial peptides.