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Some Plants Produce Caffeine to Draw Bees, Researchers Say

  • Jeff Custer

FILE - A honeybee colony, filled with busy bees tending their brood and food storage. (Maj Rundlöf)

FILE - A honeybee colony, filled with busy bees tending their brood and food storage. (Maj Rundlöf)

Researchers in Britain have discovered that certain plants actually produce caffeine to attract bees and help in pollination.

Scientists at the University of Sussex said they thought the plants produce the caffeine in their nectar to fool bees into thinking it contains more sugar than it actually does. The insects will repeatedly visit those flowers, helping the plants maximize pollination.

Francis Ratnieks, a professor of apiculture at the university, said bees communicate by moving their abdomens a certain way — or, as he calls it, "dancing." He said the caffeine increases that dancing.

In their experiments, Ratnieks and his colleagues used two artificial flowers that contained sucrose and water, and one contained caffeine as well. "The one with caffeine attracted more bees," he said, and "the bees who were foraging made more dances — about four times as many dances."

Identification numbers were glued to those bees exposed to caffeine, and the bees were then sent back to the hive. Those bees' dances then influenced the behavior of others in the hive, and many bees were directed to revisit sites where caffeinated nectar had been found, even after the feeder ran dry.

The scientists theorized that plants use caffeine to manipulate bees in a way that is good for the plant, but not so good for the bees. The caffeine, they said, tricks bees into thinking that the nectar is of a higher quality and has more sugar than it really does.

The scientists said the research has been a reminder that although plants and pollinators depend on one another, their interests can conflict.

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