Dung beetles hold dairy farm hopes

Landcare Research invertebrate ecologist Shaun Forgie holds some of the dung beetles released on...
Landcare Research invertebrate ecologist Shaun Forgie holds some of the dung beetles released on a Southland dairy farm last week.
Dr Forgie holds a dung beetle.
Dr Forgie holds a dung beetle.
Dung Beetle Release Strategy Group John Pearce holds some brood balls, in which female dung...
Dung Beetle Release Strategy Group John Pearce holds some brood balls, in which female dung beetles lay an individual egg. Photos by Allison Rudd.

Could dung beetles be the environmental warriors New Zealand dairy farmers have been waiting for?

They happily chew through the poo, turning waste into soil fertiliser. And with the average dairy cow producing 11 cow pats every day, the beetles have plenty of work ahead of them.

The national Dung Beetle Release Strategy Group (DBRSG) this week released its first 500 dung beetles into the ''wild'' on an organic dairy farm at Tuturau, near Wyndham. Beetles will also be released soon on three other farms elsewhere in the country.

DBRSG chairman John Pearce, who flew from Auckland to supervise the release, said the beetles were expected to naturally spread to all properties, although that would take many years.

Their potential to reduce the amount of dung deposited on farm paddocks, especially intensively farmed dairy properties, was huge, he said.

''There is nothing else that is going to work in the medium term like beetles.''

The DBRSG had been working towards yesterday's release for more than 10 years and it was exciting to see their introduction finally happening, he said.

In 2011, the group gained permission to import 11 species of beetles from several countries, including South Africa. They were reared at Landcare Research facilities at Lincoln, near Christchurch, and Auckland.

Two species of beetle were released in Southland, both about the size of a house fly.

Environment Southland, which invested in the DBRSG programme early on, will monitor the release to see how well the beetles multiply and spread.

Landcare Research invertebrate ecologist Shaun Forgie also flew from Auckland for the release. He said he expected the ''fast-breeding'' beetles to multiply and begin their work very quickly.

There would be up to 600 beetles on one cow pat, he said.

''I've seen cow pats with 500-600 beetles on them festooned like a writhing mass. They can decimate a cow pat within 24 hours.''

Tuturau dairy farmer Robin Greer said he offered his 350-cow property as a release site because he and his wife Lois ran an organic farm. He was keen to support a biological agent for dung disposal and wanted to see how quickly cow pats would disappear.

''It gives a whole new meaning to going out and checking the paddocks.''

Federated Farmers national president Bruce Wills said the release had the possibility to assist with future environmental aspects of animal dung disposal.

It was estimated that animal dung covered 700,000ha of pastoral land in New Zealand. Dung beetles would process that dung for food and reproduction, eventually breaking it down into a sawdust-like material. Without them, it could take up to a month for the dung to break down.

''The process not only gets rid of the dung, it also improves soil health and pasture productivity, reduces water and nutrient run-off, and has been shown to reduce parasitic infection in livestock,'' Mr Wills said.

''There is also the potential to reduce the reliance on drenching stock in the longer term as dung beetle populations grow.''

Concise introduction
Eat animal faeces.
Tunnel down into the ground, also build dung brood balls into which females lay a single egg.
Hatched larvae eat their dung ball as they grow, turning faeces into a sawdust-like material.
Larvae grow to adulthood in 8-10 weeks.
Adult beetles live for about three months. Females can produce 150 eggs over their lifetime.
Dung beetle activity improves soil health, aeration and pasture productivity, and reduces water and nutrient run-off.
Grass roots grow deeper into the soil, which makes pasture more drought resistant. Process has also been shown to reduce parasitic infection in livestock.

Source: Dung Beetle Release Strategy Group


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