Managed bumble bee colonies influence pathogen and parasite prevalence in bumble bee communities

Bumble bees are common pollinators of a wide range of agricultural and wild plants. They play a critical role in pollination services for high-quality crop production, especially in controlled environments. Several bumble bee species are at-risk in North America due to multiple stressors, including habitat fragmentation and loss, climate change, and pesticide exposure. One major threat to bumble bees is pathogen and parasite spillover from managed bee colonies. Through identifying the pathogen and parasite prevalence in different bumble bee communities, our aim was to assess the impact of managed bumble bee colonies on wild bumble bee species and to elucidate host-pathogen dynamics. In total, 3,618 bumble bee samples representing 15 species were collected from paired commercial and wild sites across 15 states. For each specimen, the presence of Crithidia spp. (C. expoeki, C. bombi), Microsporidia spp. (Vairimorpha bombi, V. ceranae) Apicystis bombi, the RNA viruses black queen cell virus (BQCV), Israeli acute bee paralysis virus (IAPV), deformed wing virus (DWV), sacbrood virus (SBV), tracheal mites, and dipterans were confirmed using contrast microscopy and molecular identification (PCR). Here, we report pathogen and parasite profiles and co-infections across bumble bee communities including different caste members. Particularly, we illustrate that BQCV and Crithidia spp., Microsporidia spp., and Apicystis bombi were significantly more abundant in bumble bees collected from commercial sites compared to wild sites. Overall, our survey elucidated pathogenic vulnerabilities of bumble bees across the US and highlights the potential contribution of commercial colonies to bumble bee declines.