Starbucks for bees?
Did you know, humans are not the only species in the animal kingdom that enjoy consuming caffeine! Recent studies have shown that when honeybees (Apis mellifera) consume small quantities of caffeine in nectar, their memory capabilities are increased.
Fig. 1: The common honeybee (Apis mellifera) (Amsel, 2013).
In their paper on the effects of caffeine on honeybees, Wright, et al. (2013) measured the concentration of caffeine in the nectar of both Citrus and Coffea plants. Here is an interesting fact: nectar from Coffea plants have almost the same concentration of caffeine as a cup of instant coffee! (Fig. 2). Citrus plants in contrast have much lower concentrations of caffeine (Fig. 2). Honeybees are attracted to the flowers of both the Coffea and Citrus plants because of the small amounts of caffeine found in their nectar.
Fig. 2: Caffeine concentration in Coffea and Citrus plants (Wright, et al., 2013)
Wright, et al. (2013) conditioned honeybees with floral scents and fed them with sugar solutions. They found out that honeybees that were fed with caffeine-laced sugar solutions were three times more likely to associate the floral scent with a reward of sugar solution, even after 24 hours had passed(Wright, et al., 2013)! This shows the positive effect of low doses of caffeine on long-term memory retention. This positive effect increases the bee’s foraging efficiency as it is then able to communicate accurate directions to recommended foraging spots to other bees back at the hive.
Fig. 3: Honeybee pollinating a Meyer Lemon flower (Pickhrun, 2008)
As a result, flowers with caffeine in their nectar are more likely to be pollinated as honeybees will remember their scent signals and guide fellow honeybees back to the same flower, leading to a mutually beneficial relationship. However, bees are repelled by caffeine in concentrations that are greater than 1nM, as they are too bitter (Wright, et al., 2013; Chittka & Peng, 2013).
That’s not all, caffeine also makes honeybees smarter, faster! According to Si, et, al. (2005), juvenile bees that consume caffeine experience faster rates of brain development. Now, if only caffeine could make us smarter too…
Literature Cited
“Bees Get a Buzz from Flower Nectar containing Caffeine,” by Newcastle University, 7 Mar 2013. Hosted on ScienceDaily: http://www.sciencedaily.com/releases/2013/03/130307145257.htm (accessed 9 Apr 2013).
Chittka, L., & F. Peng, 2013. Caffeine Boosts Bees’ Memories. Science, 339(6124): 1157-1159.
“From Seed to Store,” by Pickhrun, M. Blogger, 2008. URL: http://bioweb.uwlax.edu/bio203/s2012/pickruhn_mega/reproduction.htm (accessed 9 Apr 2013).
“Insecta: Honeybee,” by Amsel, S. Exploring Nature Educational Resource, © 2005 – 2013. URL: http://exploringnature.org/db/detail.php?dbID=43&detID=2667 (accessed on 9 April 2013).
Si, A., S. Zhang & R. Maleszka, 2005. Effects of caffeine on olfactory and visual learning in the honey bee (Apis mellifera). Pharmacology Biochemistry and Behavior, 82(4): 664-672.
Wright, G. A., D. D. Baker, M. J. Palmer, D. Stabler, J. A. Mustard, E. F. Power, A. M. Borland & P. C. Stevenson, 2013. Caffeine in Floral Nectar Enhances a Pollinator’s Memory of Reward. Science, 339(6124): 1202-1204.