Dung beetles to the rescue

by Ann van Engelen

Dr Shaun Forgie grew up travelling the world and is now helping New Zealand farmers transform animal dung into a useful product through dung beetles.

“Most of my childhood was in New Zealand, and as an adult, I lived in places like Argentina and South Africa,” said Shaun.

Shaun gained his bachelor’s degree majoring in marine biology and a master’s degree in zoology with honours in entomology — the study of insects.

“I investigated dung beetles here in New Zealand, then completed my PhD in Pretoria, South Africa on ball-rolling dung beetles. Dung beetles in New Zealand are restricted to native forests and bush habitats. When we started importing livestock, no one thought about needing dung beetles to clean up the poo. That is where the problem started, as an abundance of poo creates a loss of productivity as it sits on the paddock and creates a habitat for flies and can contain disease pathogens, gut parasites, contaminants like pesticide residuals plus disease pathogens such as E coli, salmonella and giardia — mainly because dung is not getting buried into the soil rapidly.

“Hawaii and Australia pioneered the way and imported exotic pastoral dung beetles as their native ones were not doing the job.

I could see a problem here in New Zealand and set about establishing a solution.

We have water contamination problems in high rainfall areas with water coming off pastures getting into the waterways.

We went through a very fastidious process through the government and the Environmental Protection Authority to bring in 11 different types of beetles mainly from South-West Europe and Southern Africa suitable to our conditions and climate.

“The beetles get rid of a pile in around 24 hours to a few days. They fly from dung pat to dung pat and make tunnels 30cm and 90cm in the soil underneath the pats for nesting. These are filled with dung made into balls or sausages each containing an egg. The hatching larvae feed on the ball, and the new adults, emerge leaving organic carbon and nutrients.”

Tunnelling and excavating subsoils to the surface opens up the soil, improving aeration and soil structure — allowing greater infiltration of fertilisers and urine.

“Burial of nutrient-rich manure means nutrients go into the ground instead of running across the surface to our waterways.

We are getting more than 80 per cent reduction in surface flow of waterway contaminants like sediments following dung beetle nesting activity, and nutrient loading deep in the soil enables grass roots to grow down deep improving drought tolerance.

“We are finding earthworms that we introduced have increased fivefold and can occur at a greater depth. Many studies report dung beetle activity results in at least 70 per cent reduction in gut parasites.

A four-seasons pack comprising seeding colonies of three to four different types of dung beetle is required for roughly 300 cows or 2,000 sheep, and beetle saturation off manure from this many stock happens by year nine.

You release them and leave them to reproduce. We have fencing and planting, but we need a self-sustainable low-cost solution on-pasture at the root of the problem.

“The economic saving through dung beetle use in Western Australia alone is estimated to be one billion dollars per annum. Dung beetles to my mind are the best tool out there to do the job.”

For more information go to dungbeetles.co.nz.