Urban pollutions effects on Asian tiger mosquito and its microbiota

Aedes albopictus mosquitoes face numerous anthropic stressors in urban areas. These xenobiotics not only impact mosquito physiology but also shape the composition of their microbiota, which play important roles in host physiological traits. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants known to alter mosquito metabolism, but no studies have yet investigated their impact on microbiota. Using a bespoke indoor mesocosm tailored for Ae. albopictus mosquitoes, we investigated the dynamics of bacterial communities in both mosquitoes and their larval breeding sites following chronic exposure to a cocktail of PAHs consisting of benzo[a]pyrene, benz[a]anthracene, chrysene, and benzo[b]fluoranthene. Our findings revealed a stage-specific impact of PAHs on mosquito microbiota, with a higher impact observed in larvae compared to adults, accounting for 12.5% and 4.5% of the PAHs-mediated observed differences, respectively. Moreover, taxa capable of catabolizing PAHs, such as Comamondaceae and Raoultella, were enriched within the insect microbiota from the treated mesocosm, at the expense of major taxa like Wolbachia or Cedecea. GC-MS analysis of PAH levels in the water of breeding sites showed the persistence of PAHs only during the first 45 days of the experiment. Moreover, Benzo[a]pyrene and benzo[b]fluoranthene were more susceptible to bioaccumulation in larval tissues over time. Further studies are still needed, for example, assessing the effect of a manipulated microbiota on microbiota-mediated host response to pollution. Specifically, it could expose how PAH-induced microbial shifts affect host fitness, immunity, and vector competence on an urban-thriving vector insect.