Plants use caffeine to ‘trick’ bees into pollination

Honey bees love caffeine and a few plants have developed methods of adding caffeine to the nectar the plants produce in order to keep bees coming back to the plants.

For the study, a team of biologists from the Univesity of Sussex set up two feeders containing a sugar solution, adding caffeine to one of the feeders in a concentration that would naturally occur in nectar.

In fact, it appears that bees may select caffeinated nectar over an uncaffeinated but otherwise equal-quality alternative.

New research in the United Kingdom shows flowers could be tricking bees into pollinating them by getting the bees buzzing on caffeine in their nectar, even though the nectar might not be the best quality.

The caffeine quadrupled the number of dances to get bees to the feeders compared to the non-caffeinated control. Loyalty to a single source is bad for the bees, good for the plant, as the study authors wrote: “Overall, caffeine causes bees to overestimate forage quality, tempting the colony into sub-optimal foraging strategies, which makes the relationship between pollinator and plant less mutualistic and more exploitative”.

The willingness to explore other options once a source has been exhausted, or what the researchers called “low site specificity”, is an adaptive behavior for bees: If one plant has yielded food, maybe its neighbors will, too.

At first, the team of biologists had the theory that caffeinated flowers might be beneficial to the honeybees by, in the words of Margaret Couvillon at the University of Sussex, making them “efficient pollinators”, but that proved not to be the case, according to an article in New Scientist.

After a visit to the caffeinated nectar, honeybees were much more likely to perform their waggle dance – a series of movements that communicate the location of a nectar source to their nest-mates. “They’re really hooked on that location”. Researchers have found that a few plants are spiking their own nectar with caffeine because, as it turns out, bees love to get wired. And, they note, caffeine isn’t the only secondary compound found in nectar.

“That’s a behavioral effect that’s similar to its primary goal in the stem and leaves”, Couvillon said.

The caffeine addiction isn’t exactly harmful, at least as far as Couvillon and her colleagues can tell.

“I think when people think about pollination, they think of the collaborative nature of it, the nice, sweet partnership of it”, Couvillon said. They’re not taking full advantage of their potential food sources.