Nest ecology-associated impacts of wastewater on wild bee microbiomes.

Wastewater exposure explains a much larger proportion of variance in the gut microbiome of the ground-nesting bee Halictus ligatus than in wood cavity-nesting Ceratina adults, larvae, or pollen provisions.

• Why it matters: Pollution impacts vary with proximity, exposure route, and species ecology, but the relative susceptibility of bee nesting strategies to wastewater-driven microbiome disruption is unclear.
• What they did: Bees, flowers, and soil were collected upstream and downstream of wastewater, and bacterial microbiomes were profiled using 16S rRNA sequencing to compare directly exposed H. ligatus versus indirectly exposed Ceratina life stages and provisions.
• The result: Soil and flower microbiomes remained stable, indicating higher environmental stability, while wastewater-linked host-associated disruption was strongest in ground-nesting H. ligatus, implying route-specific vulnerability.