Bees dance worse after pesticides hit them
For a bee to be successful, it needs to shake its honey maker. Scientists have long known honey bees jiggle their bodies to let nestmates know the location of nearby nectar and pollen. Bees choreograph their twists and turns with cues about the direction, distance and even the deliciousness of flowers around the hive.
“The waggle dance is thought of as one of the most remarkable innovations of animal communication — a symbolic language in an insect. But it was previously dismissed as ‘just innate’ — and therefore in many people’s understanding, less impressive,” Lars Chittka, an ecologist at Queen Mary University of London, wrote in an email.
Today, though, there’s a threat to the dance party. Research shows widely used pesticides can harm the pollinators’ ability to learn and therefor their ability to share the information their hive needs.
Bees work so well together — some scientists call hives “superorganisms” — that people have long thought they had a sophisticated way of communicating. In the 4th century B.C.E., Aristotle observed the waggle dance and noted bees kept returning to the same flowers. In 1973, Austrian biologist Karl von Frisch won a Nobel Prize in part for translating the dance’s meaning.
More recently, researchers have trained bees to pull a string and even to teach each other how to play a miniature game of soccer. (The goal: tug a tiny ball to the center of a platform.)
A new study in the journal Science shows that honey bees aren’t entirely born to boogie. To perform their tail-wagging waltz well, young bees need to watch the adults on the dance floor.
“There’s a lot that can go wrong with the waggle dance,” said James C. Nieh, a professor of biological sciences at the University of California at San Diego who co-wrote the paper. “So it’s interesting that it’s beneficial for bees to learn from more experienced bees to reduce these errors.”
A number of recent experiments show bees and other insects aren’t simply genetically hard-wired to perform certain tasks. Instead, they are capable of imitating one another, a behavior called “social learning” usually associated with bigger-brained creatures, like monkeys and birds.
Bees may have small brains, but they work together to do mighty things with them. “This is social learning of a really complex communication system,” Nieh said. “One of the most complicated animal communication systems known.”
For their research, the team recorded and analyzed footage of European honey bees in 10 colonies in the lab of Ken Tan, a senior professor at the Chinese Academy of Sciences and another paper co-author. Tan has endured thousand of bee stings over his research career. “I love bees,” he laughed. “For me, it’s nothing.”
Young bees in half the hives could observe old ones doing what bee biologists call the “waggle dance.” In the other half, young bees were deprived of experienced dance partners with which to practice.
To the human eye, bees dance at breakneck speed. To perform the waggle, the insect shuffles forward while furiously wiggling its abdomen back and forth — “so fast,” Nieh said, “that it usually is a blur.” The bee circles back around to do that gyration again and again, forming a figure-eight pattern on the honeycomb.
The routine is encoded with oodles of information. The angle of the middle of the figure-eight tells foraging bees which direction to fly. More repetitions means richer food. And the more a bee wiggles, the farther away the food is.
Bees about 10 days old without experienced dance partners performed the waggle dance more inconsistently than their 10-day-old counterparts in hives with experienced bees, the study found.
Over time, the bees became better at conveying the direction of the nearby food, but they could never get the dance moves for communicating distance quite right.
But widely used pesticides, which harm the bees’ ability to learn, remain a serious problem. After exposure to the poisons, “the waggle dance changed,” Tan said. “They have more errors.”