Slight electric fields that form around flowers may lure pollinators much as colors and fragrances do. In lab setups, bumblebees learned to distinguish fake flowers by their electrical fields, says sensory biologist Daniel Robert at the University of Bristol in England. Combining an electrical charge with a color helped the bees learn faster, Robert and his colleagues report online February 21 in Science. A bit like lightning rods, plants tend to conduct electrical charges to the ground, Robert says. And bees pick up a positive charge from the atmosphere's invisible rain of charged particles. Robert and his colleagues checked whether bees could choose flowers based solely on the electric fields the plants produce. Metal disks (topped by purple plastic so as not to shock bees) stood in for flowers. Half of them, wired for 30 volts, held sips of sugar water. The unwired ones offered a bitter quinine solution that bees don't like.
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