Bees on caffeine!

Previously we explored the effects of bees on cocaine so it seemed appropriate to highlight a recent study by Couvillon et al. delving into the complex relationship between bees and caffeine.   Much like nicotine or cocaine, plants produce caffeine as an insect deterrent.  While its bitterness and general toxicity make caffeine-containing leaves unpalatable to most insects, the presence of caffeine in the seeds and nectar of these plants is more puzzling.  Plants rely heavily on pollinators to help them generate offspring so it is in their best interest to keep their pollinators happy and coming back for more.  So what exactly does caffeine-containing nectar do for bees?  Similar to our cocaine example, caffeine seemed to increase bees’ general enthusiasm for their nectar source.  The waggle dancing increased and the bees convinced their hive mates to return to this delectable resource.  Taken at face value this seems like a real win-win situation – the plant provides a resource for the bees, the bees help the plant reproduce – but there’s something vaguely nefarious at work here.  While the bees are happy to feed solely on this caffeine-containing nectar, they neglect to notice that it may not actually be the best quality (based on sugar content).  In other words, rather than shop around, they limit their focus to the caffeine-containing nectar, ultimately decreasing the honey production of the hive.   While brief, this study raises some interesting points:  For one, it may inspire some to reassess their own complex relationship with caffeine – or more specifically their perceived productivity after ingesting this alluring yet deceitful substance.  More generally though this study reveals the convoluted nature of symbiotic interactions.  We generally view the partnership between bees and plants as mutualistic, and while this perception is probably true overall, like (many) relationships, one partner is benefitting at the slight cost of the other.