National Geographic Daily News
Dung Beetle, Aphodius spp

A dung beetle rests on a leaf.

Photograph by Dr Larry Jernigan/Photolibrary/Getty Images

Jennifer S. Holland

for National Geographic

Published September 4, 2013

It may seem like an unlikely environmental hero. But the dung beetle, with its sordid habit of laying eggs in and eating cow poo, 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, fart, and poop around the world emit more greenhouse gases than does the transportation industry, according to the UN. (See an interactive on the greenhouse effect and global warming.)

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. (Watch a video of an African dung beetle at work.)

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.

 

 Dung beetle
An illustration of the poo-loving dung beetle.

Illustration by Kari Heliövaraa

 

Do Beetles Really Help?

The beetles' good work happens mainly as they dig around in the poop. 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. (Read about the effects of global warming.)

Importantly, the study also showed that the presence of the beetles in aging cowpats increased the release of another greenhouse gas, nitrous oxide. More studies will help clear up whether this cancels out their methane-related efforts.

"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 front and rear of 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.

Declining Dung—and Beetles

Sadly, like many animals these days, dung beetles are in decline. Roslin said that in Finland, for example, more than half of dung beetle species are threatened or near endangered.

The reasons include the lack of diversity in both dung and pasture that goes with fewer but more intensively managed farms, and the reduced quality of the dung—which nowadays contains more chemicals, such as anti-parasite drugs given to farm animals.

That's troubling, in part because even as the farm industry has suffered due to droughts, higher input costs, and the like, the worldwide demand for beef is only growing. (Related: "Will Your Next Burger Come From a Petri Dish?")

In the developing world in particular, emissions are on the rise as farms expand. Beetles alone can't contain greenhouse gases, of course, but "we do need to understand and account for the effects of such live agents in changing gas fluxes from dung," Roslin said. "We can't just think of [pats] as passive objects."

The best way to help beetles thrive and "do their thing on the gas fluxes" is to let cattle graze on variable types of outdoor pasture, Roslin said.

"If we lock our cattle into barns and treat their dung as waste, we will be blocking the very cycles" that might make a silent, but still significant, contribution to one of the world's hottest problems.

10 comments
john Duczek
john Duczek

Today the Wold is still a wonderful place with a vast amount of life, but Climate Change is a huge issue and will bring about massive Changes in this Planet. This is only a part of the problems our World faces. Man's pursuit of wealth and Power,  whilst trying to subdue Nature, is like playing Russian Roulette. Were playing God with this Planet without knowing the full consequences of our actions and worse still there are Corporation that just don't care, all they see is the Money.... Our indiscriminate use of a whole host of bad practices including herbicides virtually everywhere, indiscriminate use of Toxins in Industry, E-waste, too much use of plastics  and bad farming practices (Mono culture ) is generating a Mass Die off of creatures in all areas, be it land or ocean in every type of life. Many of us are developing diseases spawned from our ignorance of the interactions of man made chemicals and toxins in our environment. The way we are headed, it seems that the human race should look forward to a bleak future when a lot of the creatures we see as a normal part of our natural environment are gone, only those that are tough will survive. i.e...  ants, rats and cockroaches. The Environmental clock ticks away whilst  the Stock market keeps rolling along ignorant of the fragility of the World we live on. What good is money, if we live on a slowly dying World.  Future generations, will look back at us in loathing  for what we have allowed to happen. As they try and eke out a living on this World of ours...  Mankind as a species, started off with a strong reverence for Nature and then as we became more civilized and arrogant, forgot one basic premise.. ..For a good healthy life, we need clean air, water and food. Everything else is secondary. As a species were smart enough to go to the Moon, build Aircraft and computers, but stupid enough to Make War and poison and kill the Planet which we are totally dependant on in the pursuit of wealth....... 

Marisa Cruz
Marisa Cruz

Go Dung Beetles I'm with you...eheheh

Big John
Big John

Can Dung Beetles Battle Global Warming?

Yes, better than Algore.

Vanessa Ong
Vanessa Ong

I think you've both missed the point. 

Shane C.
Shane C.

I agree with Timothy Steele. Farmers in France are feeding their cows Valorex, which contains omega 3 and omega 6 fatty acids. This supposedly reduces methane gases that the animals produce by 40%. Just as in humans certain things we eat can create more or less digestive gases, so it makes sense with livestock.  This seems to be a better practical and scientific method than saturating farmers fields with dung beetles. Come to think of it I am surprized that National Geographic has not commented on this, At least not that I am aware of.

Timothy Steele
Timothy Steele

Anyone that thinks this is an actual solution to global warming has been smoking dung. 4 legged beasts have been roaming this earth a lot longer than man. Guess what? They've been taking craps the whole time. Imagine that. We went into an ice age WHILE they were taking craps. This is not the problem and beetles eating feces are not the solution.

Rent Strike
Rent Strike

Oh, good grief. Just quit eating cows. Problem solved.

Wayne Young
Wayne Young

what if our effect on natural climate change is good in that it will take longer until the next ice age?

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