Bzzz! Bees get a caffeine buzz too
Many of us need our daily cup of coffee to get ourselves awake, and some of us are even addicted to the caffeine and can’t go without it. A new study has revealed that bees may similarly like caffeine to, well, get their buzz.
The honeybee, or Apis mellifera, is known to collect nectar from flowers which helps to pollinate the flowers. A study by Wright et al (2013) found that certain flowers such as the Citrus and Coffea includes low doses of caffeine in their nectar so as to attract honeybees and keep them returning!
Caffeine is a known stimulant that is mildly rewarding and enhances human cognitive performance and memory retention at appropriate doses(Nehlig, 1999). Would caffeine have similar effects on honeybees?
A study by Wright et al (2013) employed a classical conditioning procedure (watch this video for a visual depiction of the procedure; Felsenberg et al, 2011) to investigate the effects of the caffeine-dosed nectar on honeybees. They found that 1) bees did find caffeine mildly rewarding and 2) low doses of caffeine actually had a strong effect on long-term memory of honeybees, with three times as many bees remembering the odour of caffeine 24 hours later, and up to two times as many bees remembering the scent up after 72 hours!
It seems like this caffeine-laced nectar is evolutionary adaptive for the flowers, as this helps to ensure that the honeybee remembers where it got the nectar from, and encourages the bee to return to its source to ‘get its buzz’ again. This in turn ensures the pollination of the flowers due to the fidelity of the honeybee, furthering the flowers’ reproductive success.
What makes this more amazing is that the primary purpose of caffeine in the plants is actually to ward off/poison herbivores/plant pests (Kim et al, 2006)! Thus, caffeine serves a dual purpose: to protect the plant, and to attract and retain honeybees.
Bee and coffee image by Full Spectrum Biology.
URL: http://fullspectrumbiology.blogspot.sg/2012/03/buzzing-workers-of-global-economy.html, accessed on 28 March 2013)
Bee image by Beneficialbugs.org.
URL: http://beneficialbugs.org/bugs/Honeybee/honey_bee.htm, accessed on 28 March 2013)
Felsenberg, J., Gehring, K. B., Antemann, V., Eisenhardt, D. (2011). Behavioural Pharmacology in Classical Conditioning of the Proboscis Extension Response in Honeybees (Apis mellifera). J. Vis. Exp. (47), e2282, doi:10.3791/2282. Video retrieved from http://www.jove.com/video/2282/behavioural-pharmacology-classical-conditioning-proboscis-extension on 28th March, 2013.
Kim, Y. S., Uefuji, H., Ogita, S., & Sano, H. (2006). Transgenic tobacco plants producing caffeine: a potential new strategy for insect pest control. Transgenic research, 15(6), 667-672.
Nehlig, A. (1999). Are we dependent upon coffee and caffeine? A review on human and animal data. Neuroscience & Biobehavioral Reviews, 23(4), 563-576.
Wright, G. A., Baker, D. D., Palmer, M. J., Stabler, D., Mustard, J. A., Power, E. F., Borland, A. M. & Stevenson, P. C. (2013). Caffeine in Floral Nectar Enhances a Pollinator’s Memory of Reward. Science, 339(6124), 1202-1204.