蜜蜂采蜜，靠感知花朵放电

LINDA WERTHEIMER, HOST: It's MORNING EDITION from NPR News. I'm Linda Wertheimer.

STEVE INSKEEP, HOST: And I'm Steve Inskeep.

We have a shocking development in the relationship between bees and flowers. Scientists have learned something about how bumblebees do their jobs. Turns out they're not really bumbling around. They apparently can sense the electric field around flowers and use that to help them to find nectar.

NPR's Adam Cole reports.

ADAM COLE, BYLINE: Flowers are in the ad business. If they can't attract pollinators, they won't be able to reproduce. So they really have to push their brand.

(SOUNDBITE OF AD)

UNIDENTIFIED PEOPLE: (Singing) Our nectar will make you say yum. So why not try chrysanthemum?

COLE: They may not resort cheesy jingles, but according to Dr. Anne Leonard, flowers have plenty of other strategies.

ANNE LEONARD: Oh yeah, flowers do...

(LAUGHTER)

LEONARD: ...I mean they do a lot of things that you might not expect.

COLE: Leonard is a professor at the University of Nevada who studies the relationship between bees and flowers.

LEONARD: We all see flowers every day. We observe they have these distinct bright beautiful colors, patterns, scents.

COLE: But we don't often stop to think about what this incredible display is all for: to attract bees and other pollinators. And it's not just things we humans notice; there's also patterns in the ultraviolet spectrum, petal temperatures and textures and shapes - and they all add up to the flower's particular brand.

LEONARD: And we found that by producing these combinations of sensory stimuli, the plant basically makes its flowers easier for the bee to learn and remember.

COLE: That means the bee can forage more efficiently and flowers are more likely to be pollinated.

GREGORY SUTTON: This is a magnificent interaction where you have an animal and a plant working together, and they both want this to go as well as possible.

COLE: That's Dr. Gregory Sutton. He and his colleagues at the University of Bristol have just uncovered a whole new layer to flower brands.

SUTTON: We found that the flowers actually can use electric fields.

COLE: That's right, electric fields. It turns out flowers have a slight negative charge relative to the air around them. And bumblebees have a charge too.

(SOUNDBITE OF BUZZING)

SUTTON: When bees are flying through the air, just the friction of the air and the friction of the body parts with one another causes a bee to be positively charged.

COLE: It's like shuffling across a carpet in wool socks. When a positively charged buzz bee lands on a flower, the negatively charged pollen grains naturally stick to it.

SUTTON: We wondered if this electrostatic interaction could actually be perceived by the bee.

COLE: So here's what they did. They set up a fake little flower patch with fake little flowers. And in half the flowers they put something nectar-like - basically just sugar water. And in the other half they put quinine - that stuff in tonic water.

SUTTON: The bees can't smell quinine but it's bitter to them and they don't like it.

COLE: When bumblebees were allowed explore this flower patch, they moved around randomly. They chose to land on sweet flowers just about as often as bitter flowers. But when the sweet flowers carried a small charge, the bees learned pretty quickly to choose the charged flowers.

SUTTON: They get to about 80 percent successful.

COLE: The bees had recognized the electric field and had learned to use it to find sweet flowers. The results are published in this week's Science magazine. And there's more to it.

SUTTON: So, in the seconds just before the bee lands there is electrical activity in the plant.

COLE: The plant's electric field is changed by the proximity of that positively charged bee. And once the bee leaves, the field stays changed for 100 seconds or so. Sutton says this probably helps the next bee that buzzes by. She won't stop to investigate a flower that's already been visited.

Adam Cole, NPR News.