Let's roll... dung beetle to combat global warming

Photo / Supplied

The humble dung beetle, which spends its life rolling and burying balls of poo, could become a weapon against global warming.

Environmental regulators are seeking permission to release in New Zealand up to 11 foreign species of the beetle, which hoover up animal dung for food.

The Dung Beetle Release Strategy Group - made up of farmers and other interest groups - says the introduction will lead to a reduction in the greenhouse gas byproduct of dung, nitrous oxide.

Their toil will also help the condition of New Zealand's soil.

Adult dung beetles bury animal dung and lay their eggs in it, and the grubs feed on the dung - effectively spreading the manure under the soil.

Group spokesman Andrew Barber said the introduction of the beetles from Australia, the south of France, Spain and South Africa, would bring several benefits for farmers.

Among these were the beetles' ability to improve pastures and soil profile by tunnelling 30cm to 60cm to bury manure, aerating the soil and enabling better water penetration, reducing the need for fertilisers.

Mr Barber said they would also reduce greenhouse gas emissions from dung.

The beetles aid carbon sequestration by storing the carbon contained in the organic matter deep in the soil.

"These will have a big impact potentially reducing nitrous oxide emissions as well as lower fertiliser costs, which would be a big benefit for all of New Zealand.

"They are basically the ideal farm worker," he said.

Entomologist Ruud Kleinpaste doubted the introduction of dung beetles would cause an ecological upheaval, despite earlier animal imports such as possums, rabbits and mustelids that have become expensive problems.

He said it was unlikely that they would compete with the 17 species of native dung beetles in native forests. But he urged caution.

"We have mammals here now and the poo is causing nitrification and causing major pollution on our farms," he said.

"From that point of view it would be really good to get rid of the poo, it's a serious job so why not get the experts in to do it. Still, you have to be cautious with what you import and Erma [the Environmental Risk Management Authority] will have some serious thinking to do."

Mr Barber said that if the idea were approved it could take 15 to 20 years for the beetles to become fully established and for their labours to become obvious.

HAPPY IMMIGRANTS

Other introduced species that have done spectacularly well:

Possums: The Australian brushtail possum was introduced to New Zealand for the fur trade from the mid 19th century and was a protected species except from licensed hunters until 1938. It is now our most serious pest. In the early 2000s it was believed there were more than 65 million of them in the country.

Rabbits: Cute to look at but second in line as the biggest pest. Brought here in the 1830s for sport, rabbits compete with livestock for pasture, kill trees and shrubs and contribute to soil erosion by removing vegetation during burrow construction, ticking up an annual cost of millions to farmers and landowners.

Gorse: Introduced in 1835, its seeds spread and germinated on farmed land, forming impenetrable, spiny thickets. Declared a noxious weed by act of Parliament in 1900, farmers consider it a curse but environmentalists like it because forest regenerates beneath it.