Honeybees can tell one another when they find a particularly sweet patch of flowers by using an intricate back-and-forth motion called a “waggle dance.” Their highly attuned ability to identify the best spots for pollination in their immediate surroundings holds potential for helping naturalists to determine the health of a particular ecosystem.
In a new study, published today in Current Biology, scientists have used bee dances to find out which parts of a patchwork landscape the insects prefer to visit. They’re using this information to determine what types of land management are effective at improving habitat for pollinators and other wildlife.
The focus of their research was the waggle dance, which ethologist Karl von Frisch deciphered in the 1940s (earning him a Nobel Prize in 1973). The bee boogie consists of a figure-8 movement that the bees make repeatedly in the hive in the presence of other bees. Von Frisch discovered that the angle of the waggle portion of the dance, which connects the upper and lower loops of the movement, corresponded to the direction relative to the sun where the good flower patch or other food source could be found. Additionally, the longer the bee waggled, the farther the distance (roughly) the sweet spot was from the hive.
Margaret Couvillon, the lead author of the new study and a researcher at the University of Sussex, wondered whether the bees could be used to evaluate the environmental health of the landscape surrounding three hives. The researchers chose an area of 94 square kilometers around the hives that included urban, agricultural and protected areas, and divided that area into 60 square blocks. Then, by videotaping and painstakingly decoding over 5,000 waggle dances over the course of two years, they could see where the bees preferred to go.
Couvillon and her co-authors, Roger Schürch and Francis Ratnieks, wanted to see specifically whether efforts to improve the landscape for wildlife were in fact helping bees and other pollinators. In the U.K. “agri-environment schemes” reward landowners for farming or managing their land in environmentally and wildlife-friendly ways. Couvillon and her co-authors wrote in their paper, there is “either a lack of or mixed evidence-based support for the schemes.” The bees, she says, are a good proxy for other insect pollinators, which have seen recent declines. “Where they collect their food other insect pollinators will also be collecting their food,” she says. The a honeybee can act as an “ecological monitor.”
The scientists found that overall, bees were significantly more likely to give an approving waggle to land that had been targeted for more intensive restoration of grasslands or of margins around the edges of agricultural fields compared with areas having less stringent requirements. Oddly, they also found that bees seemed to specifically avoid some areas that had been targeted for low-level restoration. Couvillon says that this may be due to how these schemes are managed—frequent mowing, for instance, may reduce the number of flowers. But the bees were often on target. The scientists found that two blocks most frequently tagged with a waggle—after correcting for distance from the hives—each contained a protected nature reserve.
James Nieh, a professor at the University of California, San Diego, who studies bees but was not involved in the research, says the work is an interesting use for waggle dance data. Whereas other studies have used similar techniques to see where bees are foraging, he says, “This is the first real broadscale evaluation that I know of to really evaluate, ‘How good is this agricultural environmental scheme?’”
Couvillon points out that her team’s observations are only one example at a single site. But she hopes that other groups will attempt similar studies elsewhere. She thinks that this work might help combat the widespread declines of bees and other pollinators. Bees face a variety of challenges, “from pesticides to pathogens to pests,” she says, but a fundamental challenge persists: “Healthy or sick, your bee still needs to eat.”