New research from Dr. Daniel Robert and colleagues at the University of Bristol shows that bees are not only attracted to the bright colors and smells of flowers, they can also sense their electrical field.
It has been known that bees develop positive charges as they bump into small charged molecules during flight, resulting in a loss of electrons from their surface. In contrast, flowers accumulate negative charges on their petals as they lose positive charges to the surrounding air. The interaction between a positively charged bee and a negatively charged flower causes pollen to “jump” and land on the bee.
What Dr. Robert and colleagues wanted to study was whether bees were aware of this electrical exchange. So he and his research team developed artificial flowers with designer electrical fields called e-flowers. Bees were given a choice between a charged flower with sugary liquid or flowers devoid of charges that had a bitter fluid. The bees chose the charged flowers with 81% accuracy. If the researchers removed the charge, the bees were unable to find the sugary flowers. They also discovered the bees were able to distinguish flowers with different shapes, and hence varying electrical fields. Dr. Robert suspects that bees may sense the electrical field through sensing small movements in the hairs on its body.
The electrical exchange between bees and flowers also changes the charge of the flowers they land on, which may let other bees know that the flower is not ready for another landing. In fact, Dr. Roberts and his team measured a 25 millivolt increase in the electrical potential of a petunia stem just before a bee landed. The change lasted about two minutes.
It will be interesting to see if anyone comes up with evidence on the mechanism by which bees sense the electrical field.
Clarke, Whitney, Sutton & Robert. Detection and Learning of Floral Electric Fields by Bumblebees. Science http:/dx.doi.org/10.1126/science.1230883