PM2.5 exposure impairs honeybee (Apis mellifera) antennal olfactory perception and gut microbiota structure

As one of nature's most vital pollinators, honeybees are inevitably exposed to airborne pollutants during foraging. Fine particulate matter (PM2.5, particle < 2.5 μm) poses potential threats to pollinators due to its small particle size, large surface area, high reactivity, and ability to carry toxic substances. For honeybees, the harm caused by the accumulation of PM2.5 on their antennae or in their food is likely underestimated. Here, we exposed Apis mellifera workers to high-concentration PM2.5 (500 μg/m³) to investigate its effects on olfactory perception and gut microbiota. Scanning electron microscopy (SEM) revealed that PM2.5 acccumulated on honeybee antennal sensilla, and behavioral tests (proboscis extension response) confirmed impaired olfactory sensitivity. 16S rRNA gene sequencing indicated that PM2.5 exposure increased gut microbiota diversity and altered the microbial community structure. Furthermore, PM2.5 induced oxidative stress in the honeybee gut. Integrative correlation analysis linked shifts in specific microbial genus abundances with changes in antioxidant enzyme activities, suggesting that PM2.5 may influence honeybee health and olfactory function via the gut microbiota-gut-brain axis. Our findings provides insights into host-microbiota interactions under environmental stress and implicate airborne pollution as a potential contributor to pollinator decline.