Dung beetles can be found on almost every continent including Africa, where it is almost impossible to set out on a safari without rolling past one of these scarabs hard at work! Though it may seem the most unlikely of environmental heroes, the dung beetle might just be a weapon in the battle against global warming.
Agriculture, you see, is a gassy business. The 1.3 billion large ruminants—dairy cows and beef cattle, buffalo, sheep, goats—that burp, pass gas, and and fertilize grounds around the world emit more greenhouse gases than does the transportation industry, according to the UN.
These animals are responsible for about a third of global emissions of methane, a gas that makes up half of farming’s contribution and is even more potent than the much-maligned CO2. (The other big methane offenders: the natural gas/petroleum industries and landfills.)
So any animal helping to quell gas release invites investigation. In a paper published August 7 in the journal PLOS ONE, Atte Penttilä and colleagues from the University of Helsinki report on experiments designed to see whether dung beetles affect how much methane is released from cow patties, the dung heaps that dot farm pastures. Dung beetles, by the way, dig burrows into pasture feces and feed on the droppings of cows and other ruminants. They also deposit their eggs in the excrement, and their hatchlings feed on the same stuff.
The answer to the methane question was yes. The scientists found that cow patties with beetles, specifically Aphodius species, rummaging around in them released nearly 40 percent less methane over a summer period than beetle-free cowpats did.
The beetles’ good work happens mainly as they dig around in the dung. Methane is born under anaerobic, or oxygen-free, conditions. So as the insects tunnel through the dung, they aerate it, changing the conditions so that less methane is produced within the pats. This translates to less methane gas released into the atmosphere.
“In terms of the net effect on global warming, I’d say the jury is still out,” said study co-author Tomas Roslin. “Much of the methane emission from cattle escapes from the gases emitted from the animal; less escapes from the dung pats. But the beetles’ actions should be weighed into any calculations of net effects, so we don’t miss the mark,” he said.
Story courtesy of National Geographic