Mosquito repellency mediated by skin commensal Bacillus species via volatile metabolite reprogramming

Individual variation in human attractiveness to mosquitoes critically influences vector-borne disease transmission, and this phenomenon arises from multiple underlying factors. This study integrated human skin microbiome profiling, non-human primate in situ intervention, and volatilomics to uncover a microbial-mediated mechanism underlying host-specific mosquito repellency. Bacillus species were identified as a microbial signature associated with reduced mosquito attraction in humans. Targeted Intervention of B. licheniformis and B. paralicheniformis on primate skin was sufficient to significantly reduce mosquito attraction, thereby establishing a causal microbial contribution beyond descriptive correlations. Mechanistic analyses revealed that Bacillus enrichment reprogrammed the skin volatilome, specifically increasing the abundance of aromatic and fatty acid-derived effectors, such as p-Cresol and decanoic acid, which are associated with repellency phenotypes. Together, these findings revealed a potential role of skin commensals in shaping mosquito host-seeking behavior, providing a molecular basis for microbiome-informed and bio-inspired strategies for mosquito disease control. Why some people get bitten by mosquitoes more than others has been a long-standing question. Here, the authors uncover specific chemical compounds produced by two resident skin microbes that, when applied to animals, reduce their “attractiveness” to mosquitoes and increases repellent time.