Dung beetles may revive mines
Their digging has sublime effects on the soil, study found
DUNG beetles are known for hauling poo, but soon an army of these critters could be at the vanguard of an effort to green rehabilitated mines.
Scientists have just concluded a three-year-long study into the possible use of dung beetles to help in mine rehabilitation.
What they found, according to the leader of the study Dr Jackie Dabrowski, is encouraging – so much that she is keen to begin the next step in the research.
But this will require her having to identify a suitable cow herd, that is at pasture on an old rehabilitated mine.
“We need to now trial it, but the problem is that mines don’t generally encourage having herds of cattle on rehabilitated land. But some do, and the next step will be to approach a mining company with a herd and try out our dung beetles,” she said.
The three-year-study was done by the University of Pretoria and the research took place near the Mpumalanga city of emalahleni, at several coal mine rehabilitation sites. The three species used in the experiments occur naturally in this Highveld region.
As part of their life cycle, dung beetles gather dung and then bury it.
The dung ball is used as food by the dung beetle larva. It is this process that helps in rejuvenating the soil.
“The problem with highly compacted soils typical of rehabilitated mines is that water simply runs off the surface,” says Dabrowski.
Jess Badenhorst, a Master’s student on the project, found that the dung beetles’ digging had positive effects on the soil. By tunnelling into the soil, it was found that water infiltration rates improved by 30 to 300%.
The scientists also found that the vegetation biomass increased markedly due to the process of dung burial, as nutrients were added to the soil.
In recent years, dung beetles have become the darlings of scientists, farmers and conservationists.
In Australia and New Zealand, South African dung beetles helped sort out their fly problems that were caused by cattle and sheep.
More than 1.7 million dung beetles were exported to Australia to bury the dung of their livestock, helping to eliminate the flies’ breeding medium.
Scientists are also studying how dung beetles can move their dung balls in a straight line.
They discovered they were using the sun, moon and even the Milky Way as a bearing so as to maintain a straight line.
By understanding how these insects can do this, researchers may in the future use the concept to develop navigational systems that don’t rely on GPS satellite networks.
This might come in handy if during a war, a hostile nation knocks out navigational satellites.
Another Master’s student on the project, Gustav Venter, discovered that dung beetles are also remarkable tunnellers that can dig into extremely hard compacted soil, which other insects are unable to do.
But before Dabrowski can move onto the trial, there are a couple of challenges besides finding a cattle herd willing to supply dung.
“This is not just a process of chucking beetles into a field, and telling them to go for it. A lot of thought has to go into it,” Dabrowski said.
To clean up after one cow, on a daily basis, will require between 500 and 1 200 beetles – a number not uncommon in natural ecosystems, but rather a lot in highly disturbed ecosystems. Therefore, a dung beetle breeding programme would have to be set up, says Dabrowski.
Another challenge will be making sure that the cattle, on whose poop the beetles will be feeding on, are not treated with toxic parasiticides that will kill the insects.
Other academics are favourable to the idea of dung beetles being used to rehab mines.
“It is the way to go,” says Professor Marcus Byrne of Wits University, who wasn’t part of the study.
“Dung beetles are critical for soil health and soil health is the new sexy thing in biology,” he said.
But it is likely to take time and money before Dabrowski will be able to raise her army of critters who will do their bit to save the planet.