Commercial Bombus impatiens as reservoirs of emerging infectious diseases in central México

The rapid decline in range and relative abundance of some wild North American bumble bee species, combined with the commercialization of bumble bee colonies as agricultural pollinators, and recent evidence that bumble bees can be infected by honey bee viruses, suggest the possibility that invasive and emerging infectious diseases (EIDs) may play a substantial current and future role in the decline of wild bumble bee populations. Pollination in North American greenhouses is primarily mediated by industrially produced Bombus impatiens colonies. The use of B. impatiens is preferred in greenhouses because it is a native species of East North America and they are very efficient pollinators. However, B. impatiens is also host of various viruses that have been associated with colony collapse disorder in honey bees, as well as hosts to a number of bumble bee-specific pathogens and parasites. In this study, we used qPCR to screen adult worker bumble bees collected from 120 different greenhouses in central Mexico. Fifty-four locations were positive for one or more pathogens (45 %). The most frequently detected pathogen was Apicystis bombi, which was present in 32 colonies. Of these 32 A. bombi positive colonies, 15 were co-infected with at least one other pathogen or parasite, such as Locustacarus buchneri, Nosema bombi, or the viral pathogens ABPV, CBPV, DWV, IAPV and KBV. Routine use of this type of screening technology together with policy changes to restrict pathogen infested commercial bumble bees should help improve the selection of healthy commercial colonies of B. impatiens and could lead to a higher efficiency in greenhouse pollination thus providing better environmental conservation of natural Bombus spp. by preventing spillover of EIDs.