Where bees find their java jolt

Published 4:00 am Saturday, March 9, 2013

Nothing kicks the brain in gear like a jolt of caffeine. For bees, that is.

And they don’t need to stand in line for a triple soy latte. A new study shows that the naturally caffeine-laced nectar of some plants enhances the learning process for bees, so that they are more likely to return to those flowers.

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“The plant is using this as a drug to change a pollinator’s behavior for its own benefit,” said Geraldine Wright, a honeybee brain specialist at Newcastle University in England who, with her colleagues, reported those findings in Science on Thursday.

The research, other scientists said, not only casts a new light on the ancient evolutionary interaction between plants and pollinators, but also is an intriguing confirmation of deep similarities in brain chemistry across the animal kingdom.

Plants are known to go to great lengths to attract pollinators. They produce all sorts of chemicals that affect animal behavior: sugar in nectar, memorable fragrances, even substances in fruit that can act like laxatives in the service of quick seed dispersal.

Lars Chittka, who studies bee behavior at Queen Mary University of London, and wrote a commentary on the research in the same issue of Science, said that in the marketplace of plants seeking pollinators, the plants “want their customers to remain faithful,” thus the sugary nectar and distinctive scents.

“The trick here,” said Chittka, who was not involved in the research, “is actually to influence the memorability of the signal using a psychoactive drug. And that’s a new trick in the book for plants.”

Robert Raguso, who studies the interactions of plants and pollinators at Cornell University and was not part of the study, called the paper impressive, adding in an email, “It makes the reader think twice about where natural products that have economic importance to humans actually came from before we ‘discovered’ and co-opted their biology.”

Several varieties of coffee and citrus plants have toxic concentrations of caffeine in leaves and other tissues but low concentrations, similar to that in weak coffee, in the nectar itself. The toxic concentrations help plants to fend off predators.

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