Are Yellow-banded Bumble Bee (YBBB) Bombus terricola and Gypsy Cuckoo Bumble Bee (GCBB) Bombus bohemicus at risk in Cape Breton?

Abstract

Two Cape Breton bumble bees have been assessed as at risk by The Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Yellow-banded Bumble Bee (Bombus terricola) was assessed as Special Concern in 2015, meaning it is likely to become threatened or endangered in 10 years given our current understanding of ongoing threats. The Gypsy Cuckoo Bumble Bee (Bombus bohemicus), an obligate nest parasite of Yellow-banded Bumble Bee was assessed as Endangered in 2014, meaning there is a reasonable chance of extirpation in the next 10 years. Bombus terricola populations have recovered somewhat since 2010 but are still lower than they were in the early 1990s. Bombus bohemicus declined dramatically between 1990 to 2010 and has not been found in Cape Breton since 2001. Bombus terricola was assessed based on declining populations and threats such as pathogen spillover and exposure to insecticide. The main threat for Bombus bohemicus was the decline of its host Bombus terricola. I searched for imported bumble bees (source of pathogens) and asked about insecticide use in forestry and agriculture on Cape Breton Island. Threats to Bombus terricola need to be documented even if they have a small effect on them. I recommend repeatable surveys for Bombus bohemicus in locations that Bombus terricola is most frequent on Cape Breton Island.