Pathogen prevalence in commercially reared bumble bees and evidence of spillover in conspecific populations

► We determine the permeability of cropping systems to commercial bumble bees. ► We quantify the prevalence of pathogens in bumble bees adjacent to greenhouses. ► Up to 97% of pollen returning to commercial bumble bee hives was non-crop pollen. ► The prevalence of two gut parasites was greatest within 2 km of greenhouses. ► Pathogen spillover in this system compels national and international regulation.