The process not only removes manure but has been shown to improve soil health and pasture productivity, reduce water and nutrient runoff, and reduce parasitic infections in livestock.
The release was welcomed by Federated Farmers, which said it was watching with interest. But it has also been criticised by Auckland University's Dean of Science, Professor Grant Guilford, who earlier this year labelled it a potential biosecurity disaster and a risky experiment.
Dung Beetle Release Strategy Group project manager Andrew Barber said the release was an extremely exciting step in improving New Zealand's agricultural performance.
"I truly believe that dung beetles have the potential to transform New Zealand's pastoral-based agricultural system. More production at a lower environmental cost - it is a terrific story.''
Federated Farmers national president Bruce Wills said dung beetles had long been paired with livestock to process their dung overseas, but New Zealand had not yet had the right species to withstand open fields.
He was looking forward to two new species - Onthophagus taurus and Onthophagus binodus - making their debut on some of the estimated 700,000 hectares of pastoral land that is covered by dung in New Zealand.
Mr Wills said the release could, in the future, help with the environmental aspects of the disposal of animal dung, which can take up to a month to break down without the beetles.
"There is also the potential to reduce the reliance on drenching stock in the longer term as dung beetle populations grow.''
Environment Southland biosecurity manager Richard Bowman said it already had a lot of experience with the biological control of weeds, so it was a logical step to use a biological method to help improve soil and water quality.
"While this is new, the principle is well established,'' he said.
EPA new organisms applications manager Asela Atapattu said the decision to allow the release of the beetles had gone through a comprehensive evaluation process, which included seeking submissions from the public and a hearing.
"It was considered by a panel of experts, who made a decision based on extensive scientific evidence and research. This resulted in a robust decision, and the EPA stands by it.''
The Environmental Risk Management Authority, now the EPA, granted permission to import and release 11 species of beetles in February 2011.
The beetles were held in containment at Landcare Research, where they underwent a comprehensive approval process including disease clearance by the Ministry for Primary Industries. They were then mass reared at both Landcare Researches campuses in Lincoln and Tamaki.
Today's release comes after caged field trials and a technical advisory group, which also supported the introduction of the dung beetles.
