Plants make bees remember them fondly with a jolt of caffeine

Ars Technica » Scientific Method 2013-03-07

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As tiny as they are, bees are an incredible source of information for scientists, contributing to our knowledge in areas from agriculture to navigation. Just last week, we reported that bees use the electric fields of flowers to identify profitable plants, an ability that helps them forage more efficiently. A study in today’s issue of Science identifies another surprising cue that can play a significant role in bees' foraging behavior: caffeine.

Several plants, including species in the genuses Coffea and Citrus, produce nectar that contains caffeine; the concentration of caffeine in some of these flowers rivals that in a cup of instant coffee. We know what effects caffeine has on humans, but how does caffeinated nectar affect bees pollinating these plants?

To answer this question, the researchers taught bees to associate the odor of a particular chemical, called 1-hexanol, with a sugary reward. For some of the bees, the scientists added a small dose of caffeine to the sucrose reward solution in order to determine whether the consumption of caffeine affected how well the bees learned or remembered the association.

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