What is happening to Bumblebees right now?

Wild bee populations, particularly of the genus Bombus, have been in alarming decline throughout the United States. In fact, some species’ relative abundances have decreased as much as 96% in the past twenty years (Cameron et al., 2010). This has caused great alarm as wild bees provide the essential ecosystem service of pollination (Potts et al., 2010; Klein et al., 2007). Consequently, understanding how and why the decline of native bees in occurring is essential to food security and their subsequent conservation.

Quite a number of reasons have been attributed to this decline, such as alien species and pathogens (Cameron et al., 2010; Vanbergen et al., 2013), as well as changes in land cover and habitat fragmentation  (Vanbergen et al., 2013; Power et al. 2012; Potts et al., 2010). In addition, cities and increasing urbanization provide a complex matrix, sometimes providing good habitat in some urban gardens (Osborne et al., 2008a; McFrederick and LeBuhn, 2006) or along roadsides (Hopwood, 2008), while increased impervious area can sometimes result in a reduction of available habitat (Zanette et al., 2005).

Data on Relative Abundance of Different Geographic Regions for Relevant Speices.
Black Bars are historic data from 1900-1999, grey bars are current data from 2007-2009.
Adapted from Cameron et al., 2011

While you could teach an entire class on this topic, I've broken it down in a few components. They are as follows:

• Why You Should Care (Why Bumble Bees Matter)
• Decline of Bumble Bees due to Habitat Loss
• Decline of Bumble Bees due to Parasites and Pathogens
• What You Can Do About This