‘Halo’ effect attracts bees
Bees are drawn to certain flowers because of microscopic ridges on the petals, UK researchers have found. The tiny structures scatter light particles in the blue to ultraviolet colour spectrum that generate an effect scientists have dubbed the ‘blue halo’.
Bumblebees were attracted to artificial replicas of the structures, the halo effect they created allowing the insects to locate flowers more efficiently.
Examples include evening primrose Oenothera stricta, desert daisy Ursinia speciosa, blackeyed Susan Hibiscus trionum and penstemon. Further investigation found the structures to be irregular, massed on the petal surface ‘like a packet of dry spaghetti’, with different plants producing structures of different height, width and spacing.
The team, from Cambridge Botanic Garden, Kew and Switzerland, concluded the structures evolved independently between families and species many times, and as far back as 100 million years ago, but always achieving similar luminous intensities.
“It came as a real surprise to discover that the disorder (on petals) itself generated the optical signal that allowed bees to find flowers more effectively,” said Professor Beverley Glover, director of Cambridge Botanic Garden.