Over the last several decades evidence has been accumulating that many bumblebee species (Bombus sp.) are declining around the world, including the United Kingdom, continental Europe, North America, South America and Japan (Williams 1982; Buchmann and Nabhan 1996; Inari et al. 2005; Kosier et al. 2007; National Resource Council 2007; Colla and Packer 2008; Goulson et al. 2008; Inoue et al. 2008; Williams and Osborne 2009; Cameron et al. 2011a; Morales et al. 2013; Nieto et al. 2014). Species declines have been attributed to habitat loss (Williams, 1986; Goulson et al. 2002; Biesmeijer et al. 2006; Carvell et al. 2006), pesticide use (Whitehorn et al. 2012; Feltham et al. 2014), competition with honey bees (Goulson and Sparrow 2009) and non-native bumblebees (Inari et al. 2005; Inoue et al. 2008; Goulson 2010a, 2010b; Morales et al. 2013), pathogen spillover from commercially reared bumblebees (Colla et al. 2006; Goka et al. 2001a, 2006; Otterstatter and Thomson 2008; Goulson 2010a; Arbetman et al. 2013; Graystock et al. 2014; Schmid-Hempel et al. 2014) and managed honey bees (Singh et al. 2010; Graystock et al. 2013; McMahon et al. 2015; Manley et al. 2015), hybridization with non-native bumblebees (Kanbe et al. 2008; Kondo et al. 2009, Yoon et al. 2011), loss of genetic diversity (Whitehorn et al. 2014), climate change (Rasmont et al. 2015) or a combination of factors (Goulson et al. 2015).