Staying alive as a small insect in the shadows of spiders and lizards requires some cunning, one example of which is a crafty trick known as mimicry. This involves imitating the characteristics of other, less palatable beings, just as a stick insect mimics a plant or harmless frogs change color patterns to resemble their toxic siblings. Scientists in Australia have uncovered what they believe to be one of the largest mimicry systems on Earth, comprising more than 140 different golden-coated insect species that work together to ward of would-be predators.
Most of the species in this complex are ants, but the group also includes wasps, spiders, true bugs, beetles and leafhoppers. When it comes to food, some of these creatures are less desirable than others, with built-in defenses that can make them taste bad or hurt predators. The researchers say what is unique to this mimicry complex is the vivid golden coating displayed by the creatures that contrasts against the darker background of their bodies, a feature they say is known to be effective against predators. But why gold?
"Many animals use bright colors to warn a potential predator that they can defend themselves, and predators often learn to heed such warnings and avoid these animals in future," explains Professor Marie Herberstein from the Department of Biological Sciences at Macquarie University and co-author of the new study. "Wasps, for example, are armed with a harmful sting and advertise this fact through their distinctive yellow and black stripes."
Working with researchers from the Czech Republic's Masaryk University, the scientists explored this theory by peering into the stomachs of 12 local predator species including spiders, lizards and birds and found very few of them ate the golden mimics. Taking things one step further, they actually offered mimics to lizards and spiders, and found that they shunned the food on account of its golden sheen, regardless of whether or not it was afe to eat.
"Most of these common predators avoided the mimics regardless of whether they were palatable or unpalatable to eat," says Herberstein. "Therefore species with this gold color without defenses such as spines and foul-tasting chemicals can benefit by deceiving predators into thinking they are unpalatable."
The team says this is the largest mimicry system found in Australia and one of the largest in the world. From here, they plan to carry out further studies to explore some key questions raised by their work, for example, how the mimicry serves to protect against predators that cannot see and therefore don't recognize the golden-colored warning signs.
The research was published in the journal eLife.
Source: Macquarie University