Caffeine gives bees a buzz, memory jolt


A friend of mine recently returned to the United States from military deployment to Afghanistan. One of the first things he did when he reached a Texas military base was to buy a cup of espresso.

Good coffee was a sure sign, he said, that he’d returned to civilization.

The magic in coffee is caffeine, a stimulant that keeps us drinkers going back for more. Many of us know that a dose of caffeine makes us perk up and concentrate better, and it generally greases the wheels of our workaholic world.

“I don’t think I can afford to stop drinking coffee, if it means I would have an even worse memory,” said Walter Sheppard, Washington State University. Entomology Department chair.

I was talking to him because of a study that shows people aren’t the only animals with a taste for caffeine. Scientists recently presented evidence that honey bees get a buzz from caffeine and their memory is enhanced by it.

Geraldine Wright is a scientist at England’s Newcastle University. She led the bee research reported in the journal Science.

It’s perhaps no surprise the nectar in coffee plant flowers have a bit of caffeine in them. But would you guess that some citrus flowers also are laced with a little caffeine?

It’s reasonable to think flowering plants might have certain chemicals in them specifically because of the way they affect bees. That’s because certain flowering plants “co-evolved” over time with the help of bees and shaped the insects even as the bees influenced the plants.

To put it bluntly, bees are helpful when plants want to have sex with one another. Nectar attracts bees to flowers and pollen covers them while they feed. When bees moves on to a new flower, the pollen is spread from the bee’s body hairs and helps the plant reproduce.

“It’s not hard to test learning in a bee,” Sheppard said. “You basically put a bee in a straw to hold it still. Then you blow a scent like lavender on them. When they extend their proboscis (or tongue) you can give them a sugar water reward.”

Over time, the bees will learn to extend their tongues when they smell lavender.

Now here’s the part that’s interesting. If the sugar water was laced with a tincture of caffeine, the bees were more likely when re-tested to stick out their tongues. That’s to say, they remembered their lesson better if a bit of caffeine was in their drink.

And this effect grew stronger over the passage of time for up to three days, a long time if you’re a bee.

“The bees can’t taste the caffeine, but it affects them,” Sheppard said.

I’ll drink to that.

E. Kirsten Peters, Ph.D., trained as a geologist. Her column is a service of Washington State University.


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