US Fish & Wildlife Service


Date of this Version



Published in New Directions in Conservation Medicine: Applied Cases in Ecological Health, edited by A. Alonso Aguirre, Richard S. Ostfield, and Peter Daszak (New York: Oxford University Press, 2012).


U.S. Government Work


In the late 1990S, scientists first noticed mysterious declines in several wild bumble bee species (Bombus spp.) in both eastern and western North America, with one species now possibly extinct (Colla and Packer 2008). These bumble bee losses mirrored declines in the abundance of many other native pollinators (National Research Council 2007). Interestingly, the timing of bumble bee declines in the United States coincided with reports of disease outbreaks in commercial- reared bumble bees sold for use in the production of greenhouse tomatoes and peppers (Evans et al. 2008). This observation, together with reports of a higher incidence of key pathogens, including the trypanosome Crithidia bambi and the micros poridian Nosema bambi in wild bumble bees foraging near greenhouse colonies (Colla et al. 2006), suggests that the spread of pathogens from commercial to wild bees could play a role in observed declines. Although details are still emerging on the incidence and effects of different bumble bee pathogens in North America, this example could be one of the first cases of pathogen spillover from domestically reared to wild populations of an insect host. More generally, this example points to the potential for pathogens to cause insect declines, and underscores the need for more baseline data on pathogen prevalence in wild insect populations.