The “Green” Beetle
When looking at pest and parasite control in cattle, there’s a bug that is friendly to mankind and livestock – the dung beetle. The economic benefit of dung beetles is difficult to pin-point, but a 2006 study by Losey and Vaughan suggested dung beetle activities were worth close to $380 million annually in the U.S.
Many old-timers recall watching dung beetles roll ball-shaped pieces of cattle manure. The beetles work as Mother Nature’s recyclers, breaking up pats of manure that are ultimately used to feed their young in underground tunnels. Research has shown that because dung beetles compete with flies and internal cattle parasites for dung material, the beetles serve as biocontrol agents of pest populations.
A 1970 study showed that dung beetles can reduce the number of emerging horn flies by 95 percent, according to a white paper by Dr. Justin G. Fiene. Subsequent studies in the mid-1970s demonstrated reduced nematode infection rates of cattle were 55 to 89% lower in the presence of dung beetles.
In addition to the beetles’ work in the dung pat, they have also been shown to promote pasture productivity. As nature’s “nitrogen haulers,” the beetles have been shown to bury up to 78% of cattle manure applied to the surface of pastures.
This is important because undegraded cattle manure can reduce the carrying capacity of the pasture by smothering the underlying forage, states Fiene, and creates an area around the pat that is not grazed.
Dung beetles fall into three categories: tunnelers, who build tunnels beneath the dung pat; dwellers, who live in the dung pat and lay their eggs; and rollers, bettles who roll a dung ball way from the pat to a tunnel where they lay their eggs. “Dung beetles, particularly the tunneler and roller types, can promote pasture productivity by enriching the soil, modifying soil properties and promoting pasture retention,” says Fience in his white paper.
“Essentially, if the beetles carry the dung down into tunnels in the soil, you get more nitrogen into the soil,” explained Dr. Jerry Woodruff with Boeringer Ingelheim. “The tunnels the beetles dig also provide aeriation to the soil. We classify those as below ground benefits.”
A study in Australia showed the burial of manure by dung beetles resulted in a 30% increase in pasture production. This was also associated with increased earthworm populations, water retention and organic matter of the soil. A separate study showed that pastures with beetles have been demonstrated to have improved grass yield, the equivalent to applying 200 pounds per acre of nitrogen fertilizer. Nearly 130% deeper water permeation was noted in pastures with dung beetles than in pasture without.
“When you add it all together, dung beetles have a huge benefit to cattle and livestock operations,” Woodruff said.
However dung beetle populations can be negatively affected by parasiticides that are used to treat internal and external parasites in cattle, according to Fiene. “The active ingredient in the parasiticides gets excreted in cattle manure where the dung beetle will make contact with it. The impact of parasiticides on dung beetles can vary depending on the formulation and dose, route and frequency of administration, and regional and seasonal differences in climate,” he says.
Woodruff encourages cattlemen to consider the health of the dung beetle when choosing parasite control products. “Some products are more toxic than others when it comes to the dung beetle. Over the years, it crept up on us. We were revolutionizing how we control parasites, but one of the down sides is we have had a negative impact on the dung beetle population.”
Toxicity of parasiticides depends on the formulation and route of administration. Fiene cited that slow release bolus, pour-ons and injectables are generally more toxic to dung beetles, while ear tags are the least toxic. The active ingredients in parasiticides can also make a difference, Fiene stated, noting that macrocyclic lactones appear to have more of an impact on dung beetles, while maxidectins appear to have less of an effect. Synthetic pyrethroids can also affect dung beetles. However, according to Fiene, limited information exists on the effects of organophosphates, growth regulators and amines.