Effects of aqueous PM2.5 extract on developmental traits of Aedes aegypti mosquitoes

Abstract Seasonal biomass burning in Southeast Asia generates high concentrations of fine particulate matter (PM₂.₅), which can deposit into small aquatic habitats used by mosquito larvae. This study assessed the effects of PM₂.₅-contaminated water on key life-history traits of Aedes aegypti , comparing a pyrethroid-susceptible strain (PMD), a pyrethroid-resistant strain (PMD-R), and a newly established field-collected population (LML). PM₂.₅ samples collected in Chiang Mai, Thailand, during the 2023 haze period were extracted to prepare aqueous solutions at concentrations of 12.5–150 mg/L PM₂.₅. Larval bioassays revealed significant reductions in the percentage of larval survival to pupation and adult emergence at PM₂.₅ concentrations ≥ 100 mg/L across all three mosquito strains, with an earlier onset (75 mg/L) for survival to pupation in PMD-R. Increasing PM₂.₅ concentrations also prolonged developmental time and reduced adult wing length. However, no consistent significant differences among strains were detected in larval survival to pupation, adult emergence, or adult emergence time; a significant between-strain difference in pupation time was detected only at the highest PM₂.₅ concentration (150 mg/L), while wing length differed consistently among strains regardless of PM₂.₅ exposure. These findings demonstrate that PM₂.₅ adversely affected mosquito development across all three strains, while insecticide-resistance status alone did not explain differences in susceptibility under the experimental conditions. The results highlight the importance of evaluating environmentally relevant PM₂.₅ exposure in mosquito breeding habitats and its potential implications for mosquito ecology and vector control. Anthropogenic biomass burning, exacerbated by climate-change-related drought and prolonged dry seasons, may intensify the impacts of pollution, potentially altering mosquito fitness, resistance patterns, and disease transmission dynamics.