Scientists Discover A Clever Trick Bumblebees Use To Make Flowers Bloom Earlier

May 21, 2020
Originally published on May 22, 2020 4:38 am
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MARY LOUISE KELLY, HOST:

Springtime is in full swing. Flowers are out, and pollinators are abuzz. But what about when flowers are not yet in bloom? Well, scientists have found some bumblebees have a clever trick that might be designed to help that process along. They nibble on leaves instead.

CONSUELO DE MORAES: They use the mandibles, and they will cut these little half-moon shape. And it's quite characteristic.

ARI SHAPIRO, HOST:

That's Consuelo De Moraes of the Swiss Federal Institute of Technology. She says when her team first saw the bees punching little half-moons in the leaves, they were mystified.

DE MORAES: We're like, oh, maybe this is some rogue beehive.

KELLY: Turns out it was not rogue at all. Other bumblebees did it, too, especially hungry ones.

SHAPIRO: But the bees didn't seem to be eating the greenery. Instead, in lab experiments, plants with the bees' tiny bite marks burst into bloom as much as a month earlier than undamaged plants, perhaps due to a chemical in the bees' saliva.

HOLLIS WOODARD: Well, my first thought was woah, this is pretty - you know, this is pretty crazy.

KELLY: Hollis Woodard is a bee biologist at UC Riverside. She wasn't involved in the work, but she says the more she thought about it, it reminded her of something.

WOODARD: Bumblebees, including the three species that they observed doing this behavior, do another behavior that at least superficially seems a little similar. It's nectar robbing, where they'll use their mandibles almost like little scissors to cut an incision at the base of a flower.

SHAPIRO: By slicing a shortcut to nectar, the bees cheat their way to a sweet reward. It's easy to imagine how nectar robbing might evolve. The payoff is immediate.

KELLY: But biting leaves and then waiting weeks for flowers to appear?

LARS CHITTKA: As much as I think that bees are indeed very intelligent insects and very impressive in their learning capacities and so on, I don't think this particular phenomenon can be explained by individual bees figuring out, ah, if I bite this plant, then a few weeks later, there's a reward to be had.

KELLY: That's Lars Chittka. He studies bee intelligence at Queen Mary University of London and wrote an editorial accompanying the study. Both appear in the journal Science.

SHAPIRO: Chittka says leaf biting is likely the result of a long-ago mutation plus evolutionary trial and error.

KELLY: Well, whether it's intentional or not remains to be seen, but it provides a deeper glimpse into one of the world's most ancient dances between the pollinator and the plant. Transcript provided by NPR, Copyright NPR.