What to Do with too much Poo?

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What to do with too much poo?

by Becky Crew
web.archive.org/web/20121105033930/http://www.cosmosmagazine.com/features/online/5803/on-a-roll

The average cow will drop between 10 and 12 pads of about one litre of dung covering 0.82 square metres every day – and each one has the capacity to produce up to 3,000 flies within a fortnight.

Besides facilitating the excessive and unnatural abundance of bush flies in Australian farmland, large volumes of dung left unburied and unprocessed can remain for up to four years – its natural fertilisers locked up inside forever and wasted, or ending up in nearby waterways. Cattle will not graze near their own faeces, and accumulated dung can prevent the growth of vegetation, so large areas of dung-covered pasture can remain ungrazed for up to two years. Combined with the damage caused by large numbers of parasitic flies, this costs the cattle industry hundreds of millions of dollars every year.

The introduction of cattle to Australia with European settlement has brought with it the significant challenge of managing the accumulation of dung, because while we have around 400 species of native dung beetle, they are used to breaking down the dry, fibrous and pelletised droppings of marsupials such as kangaroos, wallabies and wombats. They can’t cope with the enormous volumes of dung produced by introduced livestock each day, so between 1969 and 1987, and again from 1990 to 1992, scientists from the national Australian science agency, the CSIRO, shipped in a range of exotic dung beetle species to address this problem. More recently, CSIRO scientists led by entomologists Jane Wright and Keith Wardhaugh, have introduced two species of European dung beetle to “finish the job”, according to a report released on the May 31 this year.



The idea of introducing dung beetle species from the origins of our livestock was first conceived by Hungarian entomologist and ecologist, George Bornemissza. Upon arriving in Australia from his native Hungary in 1951, Bornemissza remarked on how starkly different the cattle fields of Western Australia looked from the cattle fields back home. While the cattle fields of Hungary were clear and virtually dung-free, the cattle fields Bornemissza saw near a little town called Wooroloo were littered with scores of dried-up dung pads. So in 1965, Bornemissza led a team of scientists at the CSIRO in launching the Australian Dung Beetle Project, researching the particulars of species from 32 countries around the world, including their adaptive capacity to Australian climates, seasonal occurrence, rate of breeding, and dung collecting abilities. Since the establishment of this project, CSIRO has imported 43 species of dung beetle from Africa, Europe, Asia and North America, 23 of which have become established in their new environments.

Dung beetles belong to the superfamily Scarabaeoidea, which contains around 5,000 species and are often referred to as scarab beetles. They are found on all continents except Antarctica, and can live in a range of habitats, including desert, forest, farmland and grassland. Other organisms such as earthworms, ants and termites also have the ability to break down dung, but none can do it to quite the extent of the dung beetle - dung beetle larvae are able to consume up to 100% of their body weight of dung per day until pupation. Adult dung beetles will feed on what’s known as dung juice – or what postdoctoral research associate at the University of Nebraska-Lincoln, Sean Whipple, refers to as a “dung slurpie” in his thesis published in 2011 – which is primarily the moisture within the dung pad. This is because once they hit adulthood, the dung beetles develop filtering mouthparts that cannot bite through both moisture and fibre as the larvae’s biting mouthparts do. Dung is not only essential for dung beetle survival as a primary food source, the insects cannot reproduce without it, as it provides the materials needed to produce ‘brood balls’ into which eggs are laid and hatched.

Extensive research has been done on the environmental benefits brought by dung beetles, which includes cycling nutrients into the soil to create healthier pastures, reducing greenhouse gas emissions, and increasing soil aeration by tunneling, which lowers the runoff of surface wastes and the reduction of water contamination and algal blooms. In 2004, a thesis published by Matthew Bertone from the Department of Entomology at North Carolina State University in the U.S. found that by burying dung, dung beetles are having a positive impact on soil nutrients and pH and the growth of plant material, and in 1970, a study by Bornemissza and Williams found that dung beetles could almost double the yield of a Japanese cereal crop called millet.