Longer tongues and swifter handling: why do more bumble bees (Bombus spp.) than honey bees (Apis mellifera) forage on lavender (Lavandula spp.)?
Article first published online: 24 APR 2013
© 2013 The Royal Entomological Society
Volume 38, Issue 4, pages 323–329, August 2013
How to Cite
BALFOUR, N. J., GARBUZOV, M. and RATNIEKS, F. L.W. (2013), Longer tongues and swifter handling: why do more bumble bees (Bombus spp.) than honey bees (Apis mellifera) forage on lavender (Lavandula spp.)?. Ecological Entomology, 38: 323–329. doi: 10.1111/een.12019
- Issue published online: 11 JUL 2013
- Article first published online: 24 APR 2013
- Manuscript Accepted: 19 JAN 2013
- Manuscript Revised: 10 JAN 2013
- Manuscript Received: 19 APR 2012
- foraging preference;
- resource partitioning;
- tongue lengths
- Lavender (Lavandula spp.) flowers attract more bumble bees (Bombus spp.) than honey bees (Apis mellifera). Counts of bees foraging on Lavandula × intermedia ‘Grosso’ at the University of Sussex campus, showed that bumble bees (92%) greatly outnumbered honey bees (8%). This was not due to a scarcity of honey bees, as the reverse ratio (94% honey bees vs. 6% bumble bees) occurred on borage (Borago officinalis) at the same location.
Video analysis of free-flying bees revealed that all bumble bee species present (Bombus terrestris/lucorum, Bombus pascuorum, and Bombus lapidarius) handled lavender flowers three times faster than honey bees (mean extraction times: 0.38, 0.37, 0.34 s respectively, vs. 1.30 s; all P < 0.001). Honey bee tongue length (6.6 mm) was approximately 2 mm shorter than those of bumble bees (7.8–8.9 mm) and 1 mm shorter than the lavender corolla tube (c. 7 mm). In addition, bumble bees probed twice as many lavender flowers encountered than honey bees (86% vs. 46%).
- Experimentally reducing effective corolla tube length with scalpel incisions significantly decreased extraction time for honey bees (from 1.11 to 0.76 s; P < 0.001) but not for bumble bees (0.33 to 0.28 s; P = 0.266).
- Results suggest that honey bees are deterred from foraging on lavender because they are being outcompeted by bumble bees, which forage more efficiently.