Bumblebees are pretty smart little creatures, but even they probably can’t keep track of all the different flowers they visit in a given day. So how do the little insects make sure they aren’t dipping into the same nectar well again and again? New research shows that bees leave smelly little footprints on flowers that help them know what buds they and their family members have recently visited, reports New Scientist.
Researchers at the University of Bristol put bumblebees through a set of experiments where they exposed the bees to flowers that had been visited by their nestmates and by unfamiliar bees, a press release explains. Bumblebees leave a sticky secretion wherever they land, creating a scent mark. When exposing the bees to different flowers, the researchers found that the insects could distinguish between scent marks left by themselves, by their nestmates and by strangers.
“This is the first time it has been shown that bumblebees can tell the difference between their scent and the scent of their family members. This ability could help them to remember which flowers they have visited recently,” biologist Richard Pearce, lead author of the study in the journal Scientific Reports, said in the release. “Bumblebees are flexible learners and, as we have discovered, can detect whether or not it is they or a different bumblebee that has visited a flower recently. These impressive abilities allows them to be cleverer in their search for food, which will help them to be more successful.”
Jeanna Bryner at LiveScience reports that Pearce and his colleagues conducted three experiments with buff-tailed bumblebees, a common European bumblebee, in which they offered the bees a choice between artificial flowers. Some of the flowers were filled with plain water and some contained sugar water.
The bees were trained to discriminate between flowers marked by their nestmates versus strangers, with the flowers visited by their sisters containing sugar water and the stranger-tagged flowers containing plain water. Next, the flowers were all filled with plain water, yet the bees still spent more time visiting the flowers marked by their nestmates.
In the next phase, the bees were trained to learn that flowers they marked contained plain water, but those marked by their nestmates contained sugar water. When all of the flowers were switched to water, the bumblebees also spent more time investigating flowers with the footprints of their sister bees.
The study shows that the bees can distinguish between the differnet types of footprints, but it doesn’t explain how they use that information in the wild. They may detect the footprints of their friends and keep moving on, since that flower may be tapped out. Or they may smell a bit of familiar foot odor and dive in, seeing it as a marker that nectar is present.
“It may be that other bumblebees visited some flowers a different length of time ago compared to the bee searching for nectar, which may affect the amount of nectar in the flowers,” Pearce tells Bryner. “Or even that other bees take less or more of the nectar than the bee searching for nectar would. So being able to distinguish between the different types of scent-marks might help a bumblebee to select flowers with more nectar inside.”