More Than 1,500 Bee Dance Moves Decoded by Scientists

Scientists have decoded the meaning of more than 1,500 honey bee "waggle dances," which the insects use to communicate information about food sources.

According to a study published in the journal PLOS ONE, the results shed light on the dietary preferences of bees and could have significant implications for conservation efforts.

"The thing I think is the most interesting about bees is their communication," Morgan Carr-Markell, lead author of the study from the University of Minnesota, told AFP.

"So I wanted to be able to use that to help land managers who are interested in planting for bees, and give them on-the-ground information," she said.

Honey bees provide valuable pollination services, however, colony mortality has grown to unsustainable levels in some countries, including the United States, according to the researchers.

One of the main factors in this increasing mortality—alongside pesticides, pathogens and parasites—is the conversion of land from native prairie habitats to monocrop agriculture, which can reduce the amount of food available to bees.

Some conservationists in the Upper Midwest have proposed restoring or reconstructing native prairie in a bid to improve the nutritional intake of bee colonies.

"If the colonies are well nourished they're better able to deal with pesticides and pathogens—they're better able to deal with every other stressor," Carr-Markell said.

Before the arrival of Europeans in the Americas, the Upper Midwest mainly consisted of prairie lands. However, less than two percent of this habitat remains today.

Despite proposals to restore these habitats, there is still much that scientists don't known about the foraging strategies of bees, and therefore, how effective such initiatives would be.

In order to provide new insights into the foraging strategies of honeybees, Carr-Markell and her team placed bee colonies in hives at two sites in Minnesota near two large, reconstructed prairies. These hives were made of glass so that the researchers could observe what was going on inside.

The team wanted to find out what types of flowers the bees targeted when seeking out food—mainly pollen and nectar—and what time of year they most actively foraged.

They observed waggle dances of female bees in the hives between 2015 and 2017. These performances involve the insects flying in a figure-of-eight formation.

In the straight part of this figure-of-eight, the bees waggle their bodies in order to communicate the direction of a flower patch. The length of these waggles also contains information about how far away the flower patch is.

Meanwhile, the number of repetitions of the dance—and speed with which it is carried out—seem to be related to the value of the food source in question.

In total, the researchers decoded 1,528 waggle dances finding that most advertised flower patches outside of reconstructed prairies.

However, the number of dances advertising nectar sources within prairies increased dramatically in the late summer and fall—toward the end of the foraging season—at one site. The researchers suggest this is because the bees were trying to stock up for the coming winter.

In addition to these experiments, the team also collected pollen from some of the bees and analyzed it to shed light on which flowers were most highly valued by the insects.

They found that the bees advertised seven different plant groups native to prairies as highly profitable pollen sources, such as goldenrods and prairie clovers. These findings could have implications for prairie restoration efforts, the scientists say.

"Our results suggest that including certain native prairie [flowers] in reconstructed prairies may increase the chances that colonies will use those prairies as major food sources during the period of greatest colony growth and honey production," the authors wrote in the study.