ScienceShot: When Sparks Fly

Along with sight and smell, bumblebees can detect flowers via their electric fields. Scientists already knew that as bumblebees fly, their wings generate positively charged static electricity. Flowers usually have a negative charge compared with the air, a difference that helps carry pollen from a flower to a bumblebee pollinating it (shown here). Now, lab tests reveal that bumblebees can learn to distinguish artificial flowers providing a sweet solution and having a certain pattern of electric field from similar artificial blossoms dosed with bitter liquids that sport a distinctly different electric field. These results suggest that the insects can also distinguish among natural flowers by their electric charge, researchers report online in Science. This matters because a flower's charge changes temporarily after a bumblebee visits it, possibly helping other bees avoid a flower that's now low in pollen. Furthermore, the researchers contend, if bumblebees can distinguish among blossoms with a lot or a little nectar, the insects won't be turned off by an entire species of flower after a few low-reward experiences.

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