It turns out that honeybees can be quite the little caffeine addicts. And just as your local coffee shop takes advantage of your addiction to keep you coming back, flowers with caffeine-laced nectar keep bees buzzing for more.
"If a bee goes to a caffeinated plant, it's still getting nectar -- it's getting a reward, so it's not a complete and total disaster," lead study author Margaret Couvillon of the University of Sussex told The Post.
But it makes them forage less optimally, she explained.
The study was inspired by earlier research, which found that bees exposed to caffeine could learn new flowers more quickly and remember them for longer periods of time. In theory, that would make bees into more efficient pollinators. But Couvillon and her colleagues wanted to test the behavior in the field.
Bees exposed to caffeinated nectar did indeed forage more often. But while they checked their caffeinated flowers almost obsessively -- and did four times the usual number of dances to alert the rest of the colony to the flower's presence -- they ignored equally nutritious, decaf flowers.
"One thing that really surprised me was how long the effect lasted," Couvillon said. "We saw that if they just had one, three-hour exposure to the caffeinated nectar on the first day, they would come back [to the empty feeder] for many more days, and more often within each day."
The control bees -- the ones who hadn't had caffeine -- would check the flower they'd fed at previously, but would quickly move on to forage for food elsewhere.
"If they've had caffeine, they're less likely to check the surrounding area," Couvillon said. "They're really hooked on that location."
Caffeine can be found in the nectar of coffee and citrus plants, among others. This drugging effect helps explain why caffeine -- which plants put in their roots and leaves to turn off herbivores with the bitter taste -- also shows up in nectar, which is meant to be sweet and appetizing. Researchers had previously investigated nicotine in nectar for the same reason, but found that these plants actually used nectar bitterness to their advantage: Bees, repulsed by the bitter taste of the nicotine, would move more quickly from flower to flower.
"That's a behavioral effect that's similar to its primary purpose in the stem and leaves," Couvillon said. "But the caffeine seems to be drugging the bees."
The caffeine addiction isn't exactly harmful, at least as far as Couvillon and her colleagues can tell. But it throws off the efficiency of the colony. By ignoring identical plants that lack caffeine, they're foraging sub-optimally. They're not taking full advantage of their potential food sources.
"I think when people think about pollination, they think of the collaborative nature of it, the nice, sweet partnership of it," Couvillon said. "But as with many partnerships, there’s potential for conflict. One side will always want to cheat the other if they could get away with it."