Flowers Discovered to Use Electric Force to Signal Bees

Flowers and bees can apparently communicate through electrical fields. Experiments by researchers from the University of Bristol showed for the first time that pollinators such as bumblebees are able to find and distinguish electric signals given out by flowers.

Everyone knows that flowers produce a wide variety of fragrances, colors and shapes to attract and select for pollinator insects like bees. But all those are impossible or at least difficult to change in a short time. It is thus very interesting that flowers seem to be able to switch and adapt the electrical field they emit in correspondence to the behavior of bees. The team at Bristol's School of Biological Sciences, led by Professor Daniel Robert, found that flowers can enhance floral advertising power through this channel, in concert with the flower’s other attractive signals.

Plants are usually charged negatively and emit weak electric fields. On their side, bees acquire a positive charge as they fly through the air. The electrical potential built up by this is to small to produce a spark, but when a charged bee approaches a charged flower, the small electric force can still potentially convey information.

By placing electrodes in the stems of petunias, the researchers measured that when a bee lands, the flower’s potential changes and remains so for several minutes. This could be a way by which flowers tell bees another bee has recently been visiting, for example. To their surprise, the researchers discovered that bumblebees can detect and distinguish between different floral electric fields.

Dr Heather Whitney, a co-author of the study said: "This novel communication channel reveals how flowers can potentially inform their pollinators about the honest status of their precious nectar and pollen reserves."

Also, the researchers found that when bees were given a learning test, they were faster at learning the difference between two colors when electric signals were also available.

Professor Robert said: “The last thing a flower wants is to attract a bee and then fail to provide nectar: a lesson in honest advertising since bees are good learners and would soon lose interest in such an unrewarding flower.

"The co-evolution between flowers and bees has a long and beneficial history, so perhaps it's not entirely surprising that we are still discovering today how remarkably sophisticated their communication is."

It is not known until now how bees detect electric fields, although the researchers speculate that hairy bumblebees bristle up under the electrostatic force, just like one’s hair in front of an old television screen.

The discovery of such electric detection has opened up a whole new understanding of insect perception and flower communication.

Paper:
'Detection and learning of floral electric fields by bumblebees' by Dominic Clarke, Heather Whitney, Gregory Sutton and Daniel Robert