How do bumblebees find the best flowers in the field? It's not just by smell, as you might think. It turns out that flowers generate a small electric field that bees can sense, drawing them in for a delicious taste of nectar.
A team of researchers from the University of Bristol in the U.K. has studied these electric fields and published the buzz about the revelation in this week's issue of Science.
The researchers found that flowers generate a very slight negative electric charge from their connection to the ground. The bees, by comparison, have a positive charge generated by their physical activity. "When bees are flying through the air, just the friction of the air and the friction of the body parts on one another causes the bee to become positively charged," researcher Gregory Sutton told NPR.
The electricity has two purposes. At its most basic level, the electric charges help pollen stick to a visiting bee, allowing the insect the take the pollen back to its hive or to a neighboring plant. But the scientists found that the bees also use the electricity to find the flowers in the first place.
The experiment they designed to prove this was pretty buzz-worthy. They filled a room full of fake flowers — each containing potential food for bees — and put a small electric charge into half of them. Free-ranging bees added to the experiment were automatically attracted to the electrified petals instead of the non-electrified flowers. When the electricity was turned off, the bees responded by landing on random flowers to sample their wares. The researchers say this proves that the bees were attracted to the electric charges, which helped them decide on which flowers to land.
But wait, there's more. The act of a bee landing on a charged flower brought the negative and positive charges together, briefly changing the electric field of the charged plant. This was enough to stop other bees from landing on the same flower too quickly, so they wouldn't waste their time on a flower that had recently been investigated.
Electricity isn't the only factor a bee uses when making decisions about which flower to land on — scent, temperature, texture and ultraviolet colors also come into play — but as the researchers write in the abstract to their paper, "electric field information contributes to the complex array of floral cues that together improve a pollinator's memory of floral rewards."
Lead author Daniel Robert told Discovery News that this symbiotic, electric relationship between bees and flowers is "another example of the beauty of evolution" where the system is beneficial to both parties.
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