Cockroaches future-proofed against climate change

00:01 18 August 2009 by Shanta Barley

Hate cockroaches? Best pour yourself a stiff drink. The widely loathed insects can hold their breath to save water, a new study has found – and the trick could help them to thrive in the face of climate change.

When cockroaches are resting, they periodically stop breathing for as long as 40 minutes, though why they do so has been unclear.

To investigate the mystery, Natalie Schimpf and her colleagues at the University of Queensland in Brisbane, Australia, examined whether speckled cockroaches (Nauphoeta cinerea) change their breathing pattern in response to changes in carbon dioxide or oxygen concentration, or humidity.

They conclude that cockroaches close the spiracles through which they breathe primarily to save water. In dry environments the insects took shorter breaths than in moist conditions.

"Cockroaches lose water across their respiratory surfaces when they breathe," says Schimpf, "so taking shorter breaths in dry conditions reduces the amount of water they will lose."

Theories floored

The study deals a blow to the theory that cockroaches hold their breath to survive underground, where CO2 levels can be poisonous. "They held their breath no longer in high-CO2 than in low-CO2 conditions," says Schimpf.

Nor did the study support the idea that cockroaches hold their breath to avoid damage to their body tissue from chemical reactions with oxygen.

The same doesn't necessarily apply to other insects, warns John Terblanche at Stellenbosch University in South Africa. "Our research suggests that butterfly pupae hold their breath to prevent oxygen damage, rather than to conserve water," he says.

The ascent of cockroaches

The nifty breath-holding adaptation has allowed cockroaches to colonise drier habitats, says George McGavin of the University of Oxford, and may allow them to thrive in climate change.

"Cockroaches have an awesome array of adaptations to life on dry land," says McGavin. "Living in the humid conditions of a rainforest, where they evolved, might be plain sailing, but cockroaches are adaptable and can cope in a wide range of environmental conditions."

Will the sun ever set on the empire of the cockroach? Not any time soon, says McGavin. "Two hundred and fifty million years of physiological fine tuning has produced a creature that will be around for a long time to come," he says. "Cockroaches, I'm afraid to say, will do well in the face of climate change."

Journal reference: The Journal of Experimental Biology, DOI: 10.1242/jeb.031310

http://www.newscientist.com/article/dn17626-cockroaches-futureproofed-against-climate-change.html