Some people think theirs doesn’t stink, but a dung beetle will never fall into that trap. In fact, they’re particularly fussy about the aroma of poo.
That’s according to University of New England insect ecologist Amrit Pal Kaur, who said dung beetles have very refined tastes.
Dung beetles provide a priceless nutrient recycling service for graziers across the country, and estimated to generate $800 million of value a year for Australian agriculture, value-adding to the annual load of 42 million tonnes of dry dung from cattle, and 39mt from sheep.
"I have done so many trials, using all sorts of substances to devise artificial diets for beetles. I have five or six different poo-juice recipes that I am currently refining, but I am still trying to get the moisture levels and consistency right. It's quite a challenge,” said Ms Pal Kaur, a PhD candidate.
"I've found that fresh poo juice contains a varying abundance of different smells from one-hour poo-juice, and three-hour poo-juice is totally different again.
"It's the quality of these volatiles - and I've identified over 110 different chemical compounds - that influence where and when dung beetles feed.”
Ms Pal Kaur is part of UNE’s ongoing dung beetle program to breed dung beetles to help land managers utilise them in good numbers outside seasonal cycles, specifically during winter months when they become less active.
"In the winter, when their preferred food is more scarce, dung beetles generally become dormant," she said.
"I'm trying to replicate the high-quality summer dung they like, which is nutritious and rich in nitrogen, and of the right consistency and moisture content for tunnelling and making broods. If we can do that, then we might be able to help farmers to multiply their beetle numbers and guarantee their presence year-round."
After extracting its nutrients from a cow pat, dung beetles use the remaining particles to make up to 23 balls (called broods) per kilogram of dung, into which they lay their eggs.
These broods are made underground, and a single beetle can bury 200 times its body weight in a single night.
Beetle tunnels aerates the soil, allowing rain to percolate and boost soil moisture. Nutirents are recycled and carbon is sequestered in the soil. Microbes and invertebrates are encouraged to grow. Dung is broken down and polluting runoff is averted from waterways. Nematodes worms are deprived of breeding grounds, improving livestock health and reducing resistance to control chemicals.
When beetles process dung they deprive flies of breeding habitat, which has progressively the swarms of bush flies since CSIRO first introduced dung beetles in 1968. About 23 introduced species have formed sustainable populations.
There are about 500 natives species, but they aren’t suited to breaking down the livestock dung. Native dung beetles evolved to break down native marsupials’ hard, fibrous dung pellets, and thrive in forested areas.
Associate Professor of Entomology at UNE, Nigel Andrew said dung beetles increase the value of farms by making more fodder available and recycling nutrients back into the soil.
“But we need to understand more about what they do in the Australian context, and how our 500 native species interact with the 23 introduced dung beetle species."
"Once you start understanding their basic biology and how dung beetles function, you can potentially start to solve a range of agricultural and biological problems.
“For instance, some species can move the dung 20-25 centimetres into the soil, and that's where carbon can be stored for long periods of time. If we can get dung beetles moving the carbon into that area, there are some interesting interactions and potential carbon sequestration implications for land managers."