A CLOSER LOOK
Sugar Thief! By Dr Ken Marr, Curator, Botany and Claudia Copley, Senior Collections Manager, Entomology
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n 2014, while in an alpine meadow in the northern Rockies, we observed a bumble bee crawling on, but not entering, the flower of a common alpine plant, Four-parted Gentian (Gentianella propinqua). Look closely at the second image and you will see a hole at the base of the flower. The Cryptic Bumble Bee (Bombus cryptarum) is a member of the “short-tongued” bumble bee group, so normally the flowers it visits are shallow, like Potentillas and Senecios. But some of these “short-tongued” bumble bees also have mouthparts designed for cutting that gives them another option when faced with a deep flower such as Four-parted Gentian. Instead of trying and failing to reach deep into the flower for nectar, they circumvent the problem by cutting a hole in the side to access the flowers’ sugary nectar. This strategy, known as nectar robbing, ensures the bee gets the energy it needs but doesn’t pollinate the plant. It’s possible that this plant is pollinated by small insects that can enter the narrow opening, or another species of bumble bee with a long tongue. It is even possible that this species ‘self-pollinates’, as do beans, where pollination happens within a single flower and no pollinator is needed.
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Learn more about the Royal BC Museum’s findings during their trip to the Northern Rockies on the Learning Portal: royalbcmuseum.bc.ca/botanyvideo 1 Cryptic Bumble Bee stealing the nectar from the base of a Four-parted Gentian Gentianella propinqua 2 Evidence of nectar robbing observed in the Northern Rockies. 2
royalbcmuseum.bc.ca
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