Dung Beetles: the World’s Best Waste Management

Some species of dung beetle use their hind legs to roll balls of dung back to their homes. Photo courtesy of Flickr Creative Commons user Craig ONeal.
Some species of dung beetle use their hind legs to roll balls of dung back to their homes. Photo courtesy of Flickr Creative Commons user Craig ONeal.

 

By Poncie Rutsch
BU News Service

This just in, along with being some of the weirdest animals in the kingdom, dung beetles might just help reduce methane emissions on farms.

For those unfamiliar with the dung beetle, it is a group of insect species that eat, roll, and burrow in feces. Some species live and raise their children inside of big piles of poop. It sounds gross, except when you consider everywhere else that feces could be if it weren’t for these insects. Digesting the world’s poop by dung beetle doesn’t sound so bad.

Part of moving fecal matter around is that it helps the nutrients inside decompose – and decompose faster than they would without help. Scientists have known this for a while. In the tropics, for example, dung beetles can get rid of a cow pie in as little as 24 hours.

Now, one team of scientists is saying that dung beetles also reduce the amount of methane that dung emits as it decomposes. Generally, as any organic material decomposes, it releases a number of gases, methane included. Methane is one of the most potent greenhouse gases; a pound of methane in the atmosphere could have hundreds of times the impact as a pound of carbon dioxide.

But by aerating organic material, a different decomposition reaction takes place. This is why people who compost their food or yard scraps physically stir or turn their compost. In the presence of oxygen, the material reduces less methane.

Eleanor Slade supposed that dung beetles could be reducing the methane that comes from farms – specifically from livestock farms. She enclosed cow pies (she calls them dung pats, must be a British thing) in small chambers to keep dung beetles in or out. She then collected a small amount of gas from each chamber, and used a chromatograph to see what kinds of gases came off of dung pats as they decomposed.

She and her colleagues found that with dung beetles present, the cow pies released about a third less methane than they would without any insect help.

Unfortunately, cow dung isn’t the only source of greenhouse gases on a farm; nor do all farmers keep cows. Slade suspects that overall, adding dung beetles to a farm would reduce the greenhouse emissions from agriculture by about 3%.

People like to argue about how much agriculture contributes to climate change. Depending on the country, agriculture could make up 20% to over half of a country’s emissions. But here’s the thing – adding dung beetles would be easy. Cutting 3% off of agricultural greenhouse gas emissions would make a huge difference worldwide.

These cows would like some dung beetles, please and thank you. Photo courtesy of Flickr Creative Commons User Emmett Tullos
These cows would like some dung beetles, please and thank you. Photo courtesy of Flickr Creative Commons User Emmett Tullos

There are about seven thousand different species of dung beetle. They exist on every continent except Antarctica, so introducing species to local farms wouldn’t be so hard. If you’re a farmer, all you have to do is call your local dung beetle breeder.

One gross postscript though – if the dung is too runny, the dung beetles won’t burrow in it. And according to Slade, this is a legitimate problem. Cows eating over-fertilized grass tend to produce runny dung…and a lot of farmers over-fertilize.

Looks like we’ll still need an overhaul of the farming system after all.

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