Impacts of wastewater effluent on bees' microbial communities in soil vs wood cavity nesting

Wastewater effluent in the United States frequently contains pollutants, including pharmaceuticals, personal care products, hormones, and antibiotics. These substances can pass through wastewater treatment plants and enter natural ecosystems, potentially contaminating groundwater and soil. Pharmaceuticals, particularly antibiotics, exhibit high persistence and binding affinity in soils, leading to prolonged environmental presence and possible hotspots for microbial resistance development.

Unlike honeybees, wild bees obtain their microbiome from the environment. We explore the impact of these contaminants on microbial communities by leveraging wild bees' diverse nesting strategies. Our research assesses the movement of anthropogenic contaminants in urban wastewater systems across Southern and Central California by examining the gut microbiomes of two wild bee species: Halictus ligatus (soil-nesting) and Ceratina spp. (wood cavity-nesting). Preliminary findings indicate significant differences in the bacterial composition of ground-nesting bees between wastewater and non-wastewater areas, while wood cavity-nesting bees showed differences only in larval samples. This study is among the first to utilize wild bees as bioindicators for environmental contaminants, highlighting their potential to provide insights into microbial ecology shifts due to anthropogenic activities.