Our most familiar image of the dung beetle shows one of them rolling a finely shaped ball of dung to a hiding place where it digs a hole and lays its eggs.
Along with the dung ball rollers, there are the “dwellers” that move into a dung pile and set up housekeeping.
“And there’s a third group that are called tunnelers. And they tunnel underneath cow pats, and create little brood chambers in these tunnels. So there are very different types of dung beetles that you find all across the globe,” said Patrick Rohner, a professor in the department of Ecology, Behavior and Evolution at UC San Diego.
Rohner has made dung beetles his research specialty and said there are over 5,000 different species of them.
A dung beetle’s occupation is pretty simple. Rohner keeps a children’s book in his lab entitled, “I Eat Poop.” But their ecological role is not always understood.
One thing is very clear, for the environment dung beetles are a great clean-up crew.
“For one, they physically remove cow dung from the surface of the soil into the soil, thereby making these nutrients accessible to plants and other organisms,” Rohner said. “But they also aerate the soil because they often produce these tunnels.”
In his lab he currently has a colony of tunnelers that are small enough you wouldn’t see them if you weren’t looking for them. Placed on a new cow pie they quickly dig their way into it, with the ultimate goal of digging tunnels underneath it to raise their young.
Rohner has a time-lapse video that shows dung beetles going to work on a fresh manure sample and reducing it to nothing.
Rohner said he became interested in dung beetles as a scientist because there are few creatures that adapt so readily to their environment. Biologists say they have a high level of plasticity.
Their level of nutrition determines whether males will grow long horns they use for fighting as they compete for mates. Environmental factors can determine their shape and size.
“They can look drastically different even though they are genetically identical,” he said.
There are native California dung beetles. But there are a lot of foreign species that were brought to the United States to solve what was perceived to be a shortage of them.
Their main purpose was to correct the damage cattle farming was doing to land that cows used as pasture.
“There are many species that were introduced by the U.S. Department of Agriculture in the 1960s and that is because dung beetles are very beneficial for cow pastures. And the USDA introduced them on purpose from other places, including Southern Africa and Europe,” Rohner said.
Whether being raised in brood tunnels or getting with one of those dung balls — Rohner said each beetle egg gets one ball — new beetle larvae are supplied with plenty of poop.
And we, at the top of the food chain, can appreciate their job well done.
