Flowers and bees communicate with each other by using electrical fields, scientists revealed for the first time today.
Experts believe blooms give out electrical signals to attract bumblebees to their pollen – with their voltage changing to warn others when their nectar is low.
It was previously thought that flowers only used bright colours, patterns and enticing fragrances to attract their pollinators.
But new research found the flowers also use electrical signals which work in concert with their physical attributes – enhancing their advertising power to bees.
The team, from the University of Bristol, studied almost 200 bees collecting pollen from petunias to reveal the electrical relationship for the first time.
PhD student Dominic Clark, from the University of Bristol’s School of Biological Sciences, said: “Flowers are like giant advertising billboards for bees.
“We have known for a long time that flowers use colour and smell to advertise to their pollinators.
“More recently though, it is being discovered that flowers take advantage of more and more of their pollinators’ senses to send their messages.
“There is a bat-pollinated vine for example, with flowers that change shape when they’re empty of nectar so that they appear different to the bat’s echolocation radar and the bat can avoid them.
“We believe that the electric field is a previously unappreciated source of information for insects like bees and the plants they interact with.
“This ability might not be confined to bumblebees.”
Professor Daniel Robert, from the University of Bristol, who led the research, said differences in electrical charges allowed flowers and bees to communicate.
He added: “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 unrewarding flowers.
“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.”
The research, published in Science Express, took the team three years to complete and involved watching each bee visit a flower up to 50 times.
Plants are usually charged negatively and emit weak electric fields. Bees acquire a positive charge as they fly through the air.
No spark is produced as a charged bee approaches a charged flower – but a small electric force builds up to potentially convey information.
The researchers placed electrodes in the steams of petunias, discovering that when a bee lands, the flower’s charge changes and remains different for several minutes.
It is believed that this could be a way to warn bees that the flower has been recently visited, meaning the nectar content is low.
Bees are also able to tell the difference between different floral electric fields – knowing when a flower’s charge has changed.
It is not yet known how bees detect the electric fields but researchers believe hairy bumblebees bristle up under the electrostatic force.
Dr Heather Whitney, a co-author of the study, said the discovery of electric detection had opened up a “whole new understanding” of insect and flower communication.
She said: “This novel communication channel reveals how flowers can potentially inform their pollinators about the honest status of their precious nectar and pollen reserves.”
* ‘Detection and learning of floral electric fields by bumblebees’ by Dominic
Clarke, Heather Whitney, Gregory Sutton and Daniel Robert is published in Science Express.
