Dung Beetles Are Small, But Mighty Beneficial Pasture Insects
Dung beetles are a vital component of a healthy, functioning pasture ecosystem. Without their presence, dung can accumulate in pastures leading to suppressed plant growth, foul pastures, and increased pest pressure.
“The cycle goes like this,” says entomologist Jonathan Lundgren,”You have nutrients down in your soil and then the plants take it up. Then the cows come by and eat those plants and poop out all that nutrition. So the only way the nutrients get back down into the soil so that the next generation of plants can be fertilized is with these dung insects.”
Lundgren is Director and CEO of Blue Dasher Farms, a for-profit enterprise, research facility, and demonstration farm in eastern South Dakota focused on investigating regenerative agriculture practices and farming systems.
Drivers of biodiversity
Lundgren’s work has shown, despite making up only a small percentage (3%) of the insect community in pastures, dung beetles are an important driver in pasture biodiversity and productivity. As manure-motivated bugs, they eat the dung of grazing livestock and distribute it throughout the pasture which, in turn, helps to recycle, re-incorporate, and re-distribute nutrients in the soil.
“A lot of the nutrients that are available from cattle feces, only become accessible to plants because of this recycling pattern that goes on,” says Lundgren.
Scientists estimate there are approximately 30,000 species of dung beetles worldwide, 1500 of which are in North America. In a recent study Lundgren conducted examining dung pats on several eastern South Dakota ranches, his team identified over 175 different insect species in cattle dung in the small sample they visited. Each species was found to be important in varying ways.
“There’s a whole food web that ends up living in that pat,” says Lundgren. “Some of them are predators (eating things like flies and maggots) that you’re trying to get rid of in your operation. Then some of them are recyclers and doing a similar action to what the dung beetles do.”
While dung beetles make up only a small portion of this complex food web in the dung pat, Lundgren points out, they pave the way for this diverse insect community to exist and propagate. Shortly after a cow pat hits the ground, a crust starts to form over it. This crust is impenetrable to the majority of the insect community.
“What it takes is a big, burly insect (like a dung beetle) that can burrow or tunnel through that pat and make a highway system,” says Lundgren. “The dung beetles end up opening that pat up as a resource for everything else in the system.”
Dung beetles face challenges
Regardless of their vital role, however, the presence of these pioneers of poop in many pastures is under threat. Chemical use on operations, including livestock dewormers such as ivermectin and pesticides like nematicides or insecticide, have been shown to directly lead to dung beetles’ decline on many farms and ranches affecting both their ability to reproduce and larvae mortality.
“Most of the chemicals we put into our animals come out in the poop,” says Lundgren.
Longtime Oklahoma rancher, Walt Davis, elaborates on this further noting, “Toxins tend to be concentrated by the digestion process, so the manure tends to have a higher level of toxins than does the original feed.”
Both Lundgren and Davis agree the first step in the process to conserve dung beetles is getting off the dewormers. The way producers can replace dewormers is through good grazing management.
Rotate and rest pastures
Practices like continuous grazing, whether in the form of planting a monoculture pasture or grazing in such a pattern that only certain species of plants end up proliferating, limit this plant diversity. In turn, this adversely affects insect communities as insect diversity has been shown to be directly tied to plant diversity.
“By continuous grazing, you are actually fostering a lot of parasites in your animals because they just keep cycling,” says Lundgren.
Instead, Lundgren recommends livestock producers follow the examples of the wild migratory ungulates like bison that used to roam the plains.
“What did the bison do to avoid their parasites?,” says Lundgren. “They always moved and kept on moving. Now, we don’t allow our animals to make those kind of movements and it ends up causing trouble.”
Producers can mimic this natural system by using high-intensity grazing methods to graze livestock.
“Keep your herd tight and rotate them very frequently,” says Lundgren. “What’s inherent in that system is a long rest period and that fosters biodiversity on your ranch.”
Stopping pests in their tracks
By not putting animals back on a particular patch of ground for several weeks to months, parasite life cycles are broken and long rest periods ensure animals won’t be exposed to them. When Davis was ranching full-time, he notes, the use of high density grazing combined with the presence of dung beetles in his pastures helped to decrease pests like horn flies, face flies, and internal parasites.
“I was grazing at around 30-40,000 pounds stock density,” says Davis. “I’d come out of the paddock, after a couple days and in 48 hours there was no manure. It was either buried or totally desiccated. The only manure you could find in one of those paddocks is where it got hung up on grass or something and kept it up off the ground. But if it’s on the ground, the manure was gone.”
Davis notes that in Australia, until dung beetles adapted to eating livestock manure were brought in, the country had severe fly pest problems on cattle stations. After their introduction, fly problems dropped 70%, suggesting a direct inverse relationship between the number of dung beetles and number of flies.
Mixing herds and species
One last method Lundgren suggests for making pastures more dung beetle friendly is integrating herds and grazing different livestock species together. This practice helps to eliminate parasite issues in pasture systems without the use of chemicals.
“Even if it’s just using a different genetics of cattle, it can be helpful,” says Lundgren. “But, mixing different species usually ends up having a really positive effect. Cause if you for example, follow chickens behind your cattle or you graze sheep and cattle together, they have different parasites. They use resources differently and they’re able to challenge that system in ways that pests have trouble surviving and proliferating.”
Overall, Lundgren’s research and Davis’ experiences have shown dung beetles are a vital part of pasture ecology. Their presence enhances not only soil productivity, but the health of the whole ecological complex. However, to ensure their survival producers must embrace more regenerative methods and manage more proactively.
“We must stop managing for what we don’t want and instead focus on creating the environment we want,” says Davis.
Learn more about Lundgren’s work studying dung beetles and other regenerative agriculture practices on his research farm’swebsiteand by following him on Twitter (@BugLundgren). You can also follow Blue Dasher Farm onFacebookand Twitter (@BlueDasherFarm).
More information on Walt Davis’ ranching insights can be found on hiswebsiteand in his regular columns forBeef Producer.