At first, all Gregory Sutton really wanted to know was why flowers looked so different. He was “naive,” the University of Bristol biologist told the Christian Science Monitor. He didn’t know then that the question would launch him on a years-long quest to understand the invisible interaction between flowers and the bees that pollinate them.
It turned out that flowers develop varied sizes and shapes in order to force bees into a monogamous relationship with them — since the insects have to invest a lot of time in learning how to extract nectar, once they figure out how to do so they’re reluctant to keep flying around. But even more surprising was how bees are able to tell what kind of flower they’re looking at.
In a study published in the Proceedings of the National Academy of Sciences last week, Sutton reported that the fuzz that covers bees’ bodies helps the tiny critters sense flowers’ natural electric fields, allowing them to home in on their favourite plants to pollinate.
“The bumblebees can feel that hair bend and use that feeling to tell the difference between flowers,” Sutton told NPR.
The 2013 discovery that bees can sense electric fields came as a surprise to Sutton and his colleagues. Though lots of creatures have that ability — sharks, eels, platypuses — they all need to be in water to use it.
But the bees that the British researchers studied seemed able to discern minute fluctuations in the electric charge of an artificial flower (flowers generate a faint electric field through their interactions with the earth and air around them), which helped them track down the sweet treats at the bottom. They could also sense the natural changes in charge emitted by petunias. Indeed, bees could tell when the charge of a flower had been altered by another bee landing on it.
But how did they do it?
Initially, Sutton suspected that the bees were using their antennae. But when he tested that theory, the feelers weren’t particularly responsive.
“So, we looked at the big fuzzy hairs on the bumblebees: they’re so fuzzy!” Sutton told the Christian Science Monitor.
So fuzzy indeed. Using a laser beam capable of detecting very small motions in the bees’ hairs — and a electrode that could record activity in nerve cells at the bottoms of the hairs — they found that the fuzzy strands bent in response to the electric fields, much the same way human hair will stand up when mussed with a balloon. Watch how bees detect flowers’ electric fields:
The bee hairs then sent signals to the bees’ nervous system, allowing them to sense the electric fields and react accordingly.
“I’m very excited by this because these little mechanically sensitive hairs are common all over the insect world. I think this might be something we see in more insects than just bumblebees.”
Robert Gegear, who studies pollinating insects at Worcester Polytechnic Institute in Worcester, Mass., agrees. “Basically this just adds to the long list of incredible things that bees can do,” he told NPR. But it’s still not clear whether the bees are really using their electric sensors to find the flowers they like, he added. Flowers have plenty of other distinguishing characteristics, and it’s possible that the bees rely on the hairs for another purpose entirely — such as navigation.
“And so the one question I have is ‘What is the functional relevance?’” Gegear said. “Not just from the bee side but from the plant side as well.”