Bombus distinguendus is classified as Nationally Scarce.
Multiple factors threaten B. distinguendus, chief among which is often habitat removal, particularly with the reduction of red clover cultivation since 1940 due to changes in farming practices.
The main driver of decline is believed to be a reduction in the density of food plants with deep flowers over large areas of suitable grassland habitat (Williams & Osborne, 2009). Continuous availability of suitable habitat within and across years is important, because the bees may not be good dispersers, and are not known to have colonised any new areas across barriers of unsuitable habitat.
Climate change is unlikely to have been the main driver of decline in the past. Although there is an interaction between the effect of food-plant availability and climatic specialisation and a future impact is possible (Williams et al., 2007).
The impact of pesticides is unknown.
B. distinguendus is showing a gradual decline in recorded distribution range within Britain against a background of increasing recorded ranges for the common species.
Graph showing a gradual decline of the recorded distribution range of Bombus distinguendus in Britain. © Williams and Osborne (2009)
See the UK Biodiversity Action Plan.