Coffee and citrus plants use caffeine to manipulate the memory of honeybees, a new study says.
A cup of coffee doesn't just provide a jolt for people in the morning. Bees may crave a buzz too. Scientists have found that some plants, like the coffee plant (Coffea), use caffeine to manipulate the memory of bees. The nectar in their flowers holds low levels of caffeine that pollinators find highly rewarding.
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.
"We show that caffeine—a compound whose ecological role is mainly to deter and poison herbivores—actually acts like a drug in an ecologically relevant context," Wright said. "The plant is secretly drugging the pollinator. It may help the bee, but the plant cares more about having a pollinator with high fidelity!"