Geotrupes spiniger, otherwise known as the Pāua Beetle. Photo / Dung Beetle Innovations
Geotrupes spiniger, otherwise known as the Pāua Beetle. Photo / Dung Beetle Innovations
They may be small, but they’re mighty.
Dung beetles are hard at work cleaning up three Katikati properties as part of a 10-year trial.
The insects are a self-sustainable, low-cost solution to one of our farming industry’s biggest environmental concerns: cleaning up livestock manure.
The ideato introduce them locally was proposed six years ago by the former head of Project Parore, Lawrie Donald, who saw research that dung beetles increase the rate of dung decomposition, improve nutrient cycling, bioturbation and plant growth, and suppress parasites.
“When early settlers brought livestock into New Zealand in the 1800s, no one was thinking about how to deal with the waste they produced,” he said.
Donald said bacteria and worms do a certain amount of clean-up, but the dung beetles are faster.
They pair up and burrow beneath cow pats, making balls of manure deep in the ground to create their nests.
“They do it quickly and efficiently, improving soil permeability and reducing the levels of nutrient and E-coli run off into waterways,” Donald said.
Internationally recognised entomologist and founder of Dung Beetle Innovations in Auckland, Dr Shaun Forgie, described it as the 40 million-year-old solution.
Dung beetles hard at work. Photo / Dung Beetle Innovations
“Dung beetles are an essential part of the ecosystem,” he said.
“The dire state of New Zealand’s pastoral environment is a classic example of not having the sustained services provided by dung beetles since the importation of livestock.”
It’s estimated the 6.5 million dairy cows in New Zealand each produce an average of 27kg of dung a day.
Add another 3.6 million cattle and 27.4 million sheep and that’s over 100 million tonnes of manure each year.
“We breed the clean-up crew,” Forgie said.
“The dung beetles have been bought in from similar climate zones around the world like the Mediterranean, Southern Africa and Central America.”
Dung Beetle Innovations is now the largest breeding facility of its kind in the world, providing eight different varieties that range in size from 10 to 25mm.
“The largest of them are now among the biggest beetles in New Zealand,” Forgie said.
Dr Shaun Forgie is the founder of Dung Beetle Innovations. Photo / Dung Beetle Innovations
“We call them Pāua Beetles because of their colour.
“A pair of those can clean up 2 litres of cow poo in just two days.
“The Mexican dung beetles are about 15mm, but the smaller varieties make up their size with sheer numbers.”
In 2020, six colonies of 1000 dung beetles were released on three local properties with the idea that they’ll naturally “go forth and multiply”.
“In Katikati, we introduced two species of beetles that are active during the day and two during the night, so you have two shifts of workers,” Forgie said.
“Each species has its own time of the year when it’s seasonally abundant which means a year-round presence of dung beetles,”
It will be around 10 years before the full environmental, ecological and economic benefits are seen but already one of the landowners, Rod Calver, is noticing the difference on his 20-hectare beef farm, Aberfeldy.
MaryAnne and Rod Calver at their property, Aberfeldy, just north of Katikati, with Lawrie Donald. Photo / Debbie Griffiths
“We’ve been focusing on riparian planting along the Tahawai Stream and we already can see evidence that the beetles are working on the cow pats,” he said.
“It will be some time before their numbers build up to the point where there are enough of these beetles to bury poo piles within a day or two throughout the catchments but they’re great at aerating the soil and improving the soil profile.”
That’s because the beetles burrow up to 60cm below the ground in clay but can reach a metre in regular soil.
“In burying the dung quickly, they can help reduce the E. coli bacteria in the streams and decrease rain runoff and phosphates to waterways,” Donald said.
“The tunnelling improves the physical structure of the soil which helps water infiltration, reduces surface ponding, assists fertilisers to enter the upper soil profile and lowers the contaminants entering the waterways.”
For sheep and beef farmer Rick Burke, the dung beetles are another tool he draws on to reduce the environmental footprint of his 300ha property at the foothills of the Kaimai Range.
Cattle on the property. Photo / Debbie Griffiths
About 20 years ago, he found that runoff from Pukekauri Farm was contributing to sediment pollution in Tauranga Harbour and harming freshwater tributaries.
The only drinking access for stock was from waterways that were rated 2/10 for stream health.
With a philosophy of “farming for the future,” Burke set about redesigning the farm, planting trees, introducing troughed water and jumping at the opportunity to add dung beetles to the land.
“We couldn’t help being a bit sceptical but it’s amazing how the beetles spread through the farm attacking the cow pats and just working away,” he said.
“I think the beetles are helping the biology of the soil, getting that nutrient transfer and making it more porous.”
His work is paying off with recent testing rating his streams 9/10 in terms of invertebrate and fish health.
“On the farm, every little thing to improve soil health and reduce environmental impacts is huge,” he said.
“If you think about it, we’re all grass farmers working to grow high-quality feed and the beetles are another tool to help with that.”
