Iridescent wings of beetles protect against predators


For the first time, biologists have shown that the brilliant iridescence and sheen of beetles protects them by functioning as a deceptive warning coloration after being detected by avian predators, according to a researcher. recent study in the review animal behavior.

They found that iridescence can confer a survival advantage by inducing hesitation or even an aversion response in attacking birds, and that color shift, a key feature of iridescence, is the important characteristic for this effect.

Iridescence is a form of structural coloring, which means that the colors come from micro or nanostructures in the material, as opposed to pigments. Another famous form of structural coloring is the vibrant blue of the brilliant blue morpho butterflies of South America (Morpho peleides).

In iridescence, the hue and intensity of colors vary depending on the angle from which they are viewed. This striking feature has evolved independently in a wide range of organisms, from birds like the magpie and starling, to many insects, including rosemary beetles, rosemary beetles, and damselfish.

A team of researchers from CamoLab at the University of Bristol in the UK have investigated why this metallic coloration has evolved so many times in the animal kingdom and what makes it such an effective anti-predator strategy.

Previously, they had found that this iridescence can act as a very effective form of camouflage in the jewel beetle (Sternocera aequisignata), but it was unknown whether it could also protect its prey after being detected.

“One of the challenges in studying the functions of such highly reflective structural coloring has been separating the effects of color variability, the mark of iridescence, from the effects of simply having multiple colors at the same time. time, and also to separate the effects of brilliance from the effects of iridescence,” says lead author Dr Karin Kjernsmo, from the School of Biological Sciences at the University of Bristol.

Jewel beetle (Sternocera aequisignata). Credit: Dr. Karin Kjernsmo

The beauty of the beetle reduces the probability of attack

The team investigated this by presenting real and artificial jewel beetle wing cases (the hardened forewings, called elytra, which cover the functional wings) to 32 domestic fowl chicks, Gallus gallus domesticuswho had never seen this kind of prey before.

They tested the birds’ willingness to attack shiny and iridescent prey by presenting them with iridescent and non-iridescent wing cases (with the same overall color range) as well as shiny and matte versions of both.

These cases had mealworms placed underneath, so the birds had to peck and flip the artificial prey to eat the food reward. Interestingly, they found that iridescence reduced the likelihood of chicks attacking.

Birds were initially reluctant to attack iridescent prey, but not non-iridescent prey, suggesting that having multiple colors displayed at the same time is not enough to cause aversion, but color variability iridescence is the important characteristic for this protective effect.

This study is also the first to isolate the effects of gloss from iridescence, as an advantage of gloss over matte appeared in the third trial.

“Here we have, for the first time, successfully tested each of these two effects on their own, and shown that iridescence and brilliance can protect prey even after detection, providing yet another adaptive explanation for the evolution and the widespread existence of iridescence,” adds Kjernsmo.

Beetles are insects that form the order Beetles, and they are distinguished from most other insects by their pair of front wings. Hardened into elytra called elytra, these wings protect their functional second pair of flying wings from damage.

Beetles are an incredibly large and diverse group of organisms, with 169 families and 340,000 species known to science. the SCINEMA International Science Film Festival entrance, the gardianstakes us on a journey into the weird and wonderful lives of various beetle species and asks the question: what does the future hold for these incredibly important animals – and for us if they go extinct?

You can watch the movie here.


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