Flowers are electric, and can advertise themselves to pollinating insects using their own negative charge and a weak electric field. By contrast, many insects carry positive charges, and the attraction between these two opposing electric fields helps the insects sense the flowers. The electrical charge from visiting bees can even stimulate some flowers to release bursts of scent to draw the pollinators in. But once an insect visits a flower, the plant briefly loses its negative charge, as if telling other bees not to bother visiting.
A recent study at Bristol University also discovered that synthetic fertilisers and a pesticide interfered with the flowers’ electric fields for up to 25 minutes after spraying, discouraging insects from visiting the flowers. Even air pollutants altered the electric field of the flowers. When the electrical signature of the flower was artificially manipulated to mimic the effect of fertilisers, the bees tended to avoid these flowers too. And yet agricultural chemicals did not affect other cues from the flowers, such as vision and smell used by insects.
“It’s the first known example of anthropogenic ‘noise’ interfering with a terrestrial animal’s electrical sense,” said Sam England, one of the researchers.