Researchers have reported that honey bees seem to like caffeine. As a result, plants may be lacing their nectar with caffeine as a way to pass off cheaper goods.
“The effect of caffeine is akin to drugging, where the honey bees are tricked into valuing the forage as a higher quality than it really is,” said Roger Schürch of the University of Sussex and the University of Bern. “The duped pollinators forage and recruit accordingly.”
Schürch and his colleagues were aware of earlier studies that found that honey bees are better at learning and remembering particular scents when they are under the influence of caffeine. The findings suggested a role for reward pathways in the bees’ brains.
To investigate, the researchers tested bees’ responses to a sucrose solution with field-realistic doses of caffeine or without. They found that the caffeine caused honey bees to forage more and to direct their friends to the caffeinated forage more frequently with waggle dances — movements that point other bees in the right direction of a good food source. The caffeine quadrupled the recruitment dances of bees to those feeders in comparison to uncaffeinated controls. Watch the following video and pay attention at the two-minute mark when they explain the waggle dance:
Bees were more persistent about returning to sites where they’d previously found caffeinated nectar, even after the feeder had run dry. After sipping caffeine, bees were also less inclined to search for other resources, a behavior that could be useful when the well runs dry.
“We were surprised at how, across the board, we saw an effect of caffeine just about everywhere we looked in foraging and recruitment, and all in the direction to make the colony more faithful to the caffeinated source compared to an equal-quality, uncaffeinated source,” Schürch said.
Based on their observations of the individual bees’ behaviors, the researchers’ model suggests that caffeinated nectar could reduce honey production in colonies if indeed plants reduce the sweetness of their nectar. The findings come as a reminder that the interests of plants and their pollinators don’t always align.
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