Coffee Enhances Honeybee Memory

(Photo of honeybee on arabica coffee flowers courtesy tonx, of flickr)

Research published in Science magazine online March 7, 2013 suggests that flowers can use caffeine content in their nectar to increase the chance of further pollination by enhancing memory in the sipping honeybees. New meaning for the term buzz?

-----

ABSTRACT

Science 8 March 2013: Vol. 339 no. 6124 pp. 1202-1204 DOI: 10.1126/science.1228806

REPORT Caffeine in Floral Nectar Enhances a Pollinator's Memory of Reward G. A. Wright1,*, D. D. Baker2, M. J. Palmer3, D. Stabler1,2, J. A. Mustard4, E. F. Power1,2, A. M. Borland2, P. C. Stevenson5,6

1Centre for Behaviour and Evolution, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE1 7RU, UK. 2School of Biology, Newcastle University, Newcastle upon Tyne NE1 7RU, UK. 3Division of Neuroscience, Medical Research Institute, Ninewells Medical School, University of Dundee, Dundee DD1 9SY, UK. 4School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA. 5Jodrell Laboratory, Royal Botanic Gardens, Kew, Surrey TW9 3AB, UK. 6Natural Resources Institute, University of Greenwich, Chatham, Kent ME4 4TB, UK. ↵*To whom correspondence should be addressed. E-mail: jeri.wright@ncl.ac.uk

Plant defense compounds occur in floral nectar, but their ecological role is not well understood. We provide evidence that plant compounds pharmacologically alter pollinator behavior by enhancing their memory of reward. Honeybees rewarded with caffeine, which occurs naturally in nectar of Coffea and Citrus species, were three times as likely to remember a learned floral scent as were honeybees rewarded with sucrose alone. Caffeine potentiated responses of mushroom body neurons involved in olfactory learning and memory by acting as an adenosine receptor antagonist. Caffeine concentrations in nectar did not exceed the bees' bitter taste threshold, implying that pollinators impose selection for nectar that is pharmacologically active but not repellent. By using a drug to enhance memories of reward, plants secure pollinator fidelity and improve reproductive success.

---