Cicadas' Antibacterial Trick May Help Humans

Image: Swinburne University of Technology.

When humans need to fight off dangerous bacteria, we tend to use chemicals. Microbes, unlike mosquitoes and other squashable vermin, are too small for us to kill directly.

But thanks to a team of scientists and an Australian cicada, we may soon have a new weapon in our antibacterial arsenal. A study published in Biophysical Journal reveals how the clanger cicada, a locust-like insect from eastern Australia, kills bacteria with tiny, blunted spikes on its wings. If this can be replicated in manmade materials, it might thwart bacterial growth on public surfaces like stair banisters, bus handrails or bathroom doors — and possibly without the environmental side effects of chemicals like Triclosan.

Called "nanopillars," the spikes are small enough to kill bacteria with their physical structure alone, one of the first such surfaces found in nature. But as the animation below shows, it's not as simple as stabbing them to death. When a bacterium lands on a cicada's wing, the nanopillars hold it in place without actually puncturing it. Instead, they prop it up in some places and let it sink in others, stretching out its cell membrane until it rips:

This is like "the stretching of an elastic sheet of some kind, such as a latex glove," explains lead author Elena Ivanova, a professor at Australia's Swinburne University of Technology. "If you take hold of a piece of latex in both hands and slowly stretch it, it will become thinner at the center [and] will begin to tear," she tells the journal Nature.

Clanger cicada wings aren't always death traps, though. The researchers tested their effectiveness against bacteria with varying degrees of membrane toughness, finding that only softer-skinned microbes were torn apart. More research is likely needed to know if this is a flaw of nanopillars, but the study has nonetheless raised hopes that people can borrow the cicadas' tactic, reducing the need for broad-spectrum antibacterials.

"This would provide a passive bacteria-killing surface," a chemical engineer who wasn't involved with the study tells Nature, adding that it "does not require active agents like detergents, which are often environmentally harmful."

clanger cicada
The study's muse, a male clanger cicada. (Photo: L.W. Popple/University of Queensland)