Latest research shows that flowers’ iridescent petals, which may look plain to human eyes, are perfectly tailored to a bee’s-eye-view.
Iridescent flowers are never as dramatically rainbow-coloured as iridescent beetles, birds or fish, but their petals produce the perfect signal for bees, according to a new study published by Beverley Glover’s research group in Current Biology.
Bees need to be able to spot flowers and recognise which coloured flowers are full of food for them. Professor Beverley Glover and Dr Heather Whitney (now at the University of Bristol) found that iridescence – the shiny, colour-shifting effect seen on soap bubbles – makes flower petals more obvious to bees, but that too much iridescence confuses bees’ ability to distinguish colours. However, flowers use more subtle, or imperfect, iridescence on their petals, which doesn’t interfere with the bees’ ability to distinguish subtly different colours. Perfect iridescence, for example as found on the back of a CD, would make it more difficult for bees to distinguish between colour variations and cause them to make mistakes in their flower choices.
"In 2009 we showed that some flowers can be iridescent and that bees can see that iridescence, but since then we have wondered why floral iridescence is so much less striking than other examples of iridescence in nature," says Glover. "We have now discovered that floral iridescence is a trade-off that makes flower detection by bumblebees easier, but won’t interfere with their ability to recognise different colours."
Reference: Whitney, Heather et al "Flower Iridescence Increases Object Detection in the Insect Visual System without Compromising Object Identity" Current Biology (2016). DOI: http://dx.doi.org/10.1016/j.cub.2016.01.026.