Bitter-tasting caffeine primarily arose in plants as a toxic defense against herbivores like garden slugs. At high doses, caffeine can be toxic and repellent to pollinators.
However, at low concentrations, caffeine appears to have a secondary advantage, attracting honeybees and enhancing their long-term memory, said lead author Geraldine Wright, a neuroscientist at Newcastle University in England, whose study was published online March 7 in the journal Science."
Bees Buzzing on Caffeine
Christy Ullrich