Ambient PM_2.5 exposure alters mosquito feeding and reproductive traits during biomass-burning haze

Ambient fine particulate matter (PM) is a pervasive environmental stressor with well-established impacts on human health, yet its influence on vector-borne disease dynamics remains poorly understood. This study investigated whether ambient exposure to biomass-burning-derived PM_2.5 affects key biological traits of Aedes aegypti, a major vector of dengue, chikungunya, and Zika viruses. Size-fractionated particulate matter collected during the 2024 haze season in Chiang Mai, Thailand, was characterized for carbonaceous components, water-soluble ions, polycyclic aromatic hydrocarbons (PAHs), and oxidative potential (OP). Mosquitoes from two laboratory strains and one field-derived strain were exposed to clean air (0 - 7.8 μg/m³ PM_2.5) or ambient air during the biomass-burning haze period (57.6 - 283.1 μg/m³ PM_2.5) for seven days. Submicron particles (<0.49 μm) were enriched in carbonaceous aerosols, PAHs, and secondary inorganic ions, and exhibited elevated oxidative potential, indicating a chemically reactive exposure environment. Ambient PM exposure significantly reduced blood-feeding success, blood meal volume, and fecundity across all strains, with smaller reductions observed in the field-derived strain, suggesting enhanced tolerance associated with prior pollution exposure. These findings indicate that chemically reactive PM₂.₅ can disrupt mosquito feeding-reproduction processes under haze conditions. Although oxidative stress was not directly measured in mosquito tissues, the chemical reactivity and elevated oxidative potential of the particles suggest that oxidative stress-related mechanisms may represent a plausible contributing pathway. This study highlights air pollution as an environmental stressor with potential implications for mosquito ecology in regions affected by recurrent biomass-burning haze.