Dung beetles could play a bigger role in reducing the climate impact of Australia’s livestock industry, with new research finding they cut methane emissions from cattle manure by up to 85 per cent.
The Southern Cross University study, published in Ecological Entomology, is the first Australian research to quantify the insects’ direct effect on greenhouse gas emissions from cattle dung.
Researchers found dung beetles reduced cumulative methane emissions by 85 per cent and lowered the overall greenhouse gas footprint of decomposing cattle manure by 18 per cent.
The study, conducted by researchers from Southern Cross University and the University of New England, monitored emissions from cattle dung over 90 days using gas analysis mesocosms. It compared dung pats colonised by four introduced dung beetle species with dung pats containing no beetles at a site in northern NSW.
“By tunnelling and aerating the dung, these beetles effectively repurpose greenhouse gases for low-emission decomposition,” Southern Cross University researcher and co-author Professor Nigel Andrew said.
“They disrupt the suffocating and anaerobic conditions required by methane-producing microbes and shift the pathway toward aerobic respiration. Essentially, they are providing the ideal conditions for high-impact methane to be converted into lower-impact carbon dioxide.”
Livestock production is a major source of greenhouse gas emissions, with cattle manure in open pastures producing methane, carbon dioxide and nitrous oxide as it decomposes.
Australia has more than 500 native dung beetle species, most of which are adapted to marsupial dung. Between 1968 and 1992, the CSIRO introduced more than 20 dung beetle species from Africa, Hawaii and southern Europe to improve the breakdown of livestock manure, boost pasture productivity and reduce pest flies.
The study examined four introduced species: Euoniticellus intermedius, Euoniticellus africanus, Euoniticellus fulvus and Onthophagus granulatus.
Researchers found dung pats without beetles produced methane peaks on days six and 16, while beetle-colonised pats maintained near-zero methane emissions throughout the 90-day trial. Beetle activity also accelerated decomposition by increasing the early release of lower-impact carbon dioxide during the first two weeks.
The researchers said the benefits persisted after most beetles had left the dung by day 23, indicating their tunnelling and aeration had lasting effects on the microbial environment.
The findings suggest encouraging healthy dung beetle populations could provide a relatively low-cost way to reduce emissions from grazing systems and may have implications for future agricultural carbon accounting.
The researchers said Australia’s variable climate influences dung beetle activity but supporting established populations could help lower the global warming potential of livestock production. They also said biological processes driven by invertebrates should be considered in national agricultural emissions inventories.
“This study adds to the already impressive repertoire of ecosystem services that the humble dung beetle provides to Australian agriculture. Not only do they recycle nutrients, reduce fly numbers and aerate the soil, but they may also help to mitigate greenhouse gas emissions from livestock production,” said Co-author Jean Holley.
Like what you’re reading? Support New England Times by making a small contribution today and help us keep delivering local news paywall-free. Donate now