Livestock exports is a major source of income for Australia. Australia was estimated to have exported around 67.5 million sheep and 25 million cattle in 2016, generating profits of $5.23 billion and $16.85 billion Australian dollars respectively1,2. However, cattle dung had once caused a major problem in Australia, which was first noted by Hungarian scientist George Francis Bornemissza3. When he arrived in Australia in 1950, he noticed the build-up of cow dung in pastures, something which did not occur in Hungary, where dung beetles buried the dung below ground3. The dung beetles in Hungary and other countries such as Africa had evolved to break down dung from large ruminant animals.
However, Australian dung beetles had evolved to breakdown the smaller, drier and more fibrous dung of native marsupials, such as kangaroos and wallabies4. Few native dung beetle species could feed on and raise larvae in wet cowpats, and only during short time periods each year4. Because of this, high numbers of cowpats could harden and remain on the soil surface for months or even years until they eventually degraded4.
Mr Bornemissza’s idea was to import dung beetles from other countries that are adapted to feed on ruminant dung, with the aim to speed up cowpat degradation in Australia. Mr Bornemissza established the Australian Dung Beetle Project, where from 1967 to 1982, Fifty-five species were introduced to Australia, of which 23 remained established5. Two species in particular have had a significant effect on dung and fly levels: Onthophagus taurus from Europe, and Onthophagus binodis from South Africa6.
A benefit of cowpat degradation was a reduction in bush fly (Musca vetustissima) populations that bred in them, which previously were plague like in population size. However, there was a period when no introduced dung beetle was active in early spring, leading to a short period where bush fly populations increased5. To combat this, two new dung beetle species that are active in early spring were recently introduced in 2014; Bubas babulus, and Onthophagus vacca5. It is hoped that these beetles will help prevent bush fly population booms in early spring once they are established5.
Dung beetles either roll dung into a ball, push small clumps of dung along the ground, or simply tunnel through the dung6. In all instances, the beetles digs a hole and buries the dung underground; the female lay their eggs inside the dung ball6. Adults feed on dung by squeezing some of it between their mandibles to drink the fluid, whilst larvae can eat the solids in dung6.
The bush fly (Musca vetustissima) is a very annoying but relatively harmless fly – it does not “vomit” on human food as often as house flies do (Musca domestica), it is not an agricultural pest, it does not bite, and it is not a major disease vector7. However, large bush fly swarms from farms can be blown into cities8, and their presence spoils any relaxing outdoor activities such as picnics, when the flies land on people’s faces to feed on their sweat, tears and saliva7.
A cow excretes on average 10-12 cowpats per day, and 3000 bush flies can emerge from a single large cowpat in as little as 2 weeks, leading to a massive growth of the bush fly population4. The nutrition in the dung determines the size of adult bush flies, which is important because larger female flies lay more eggs throughout their lives and at an earlier age, than a smaller sized bush fly6.
Bush flies lay their eggs in the cracks around the edges of the hardened cow pat, for the larvae to feed on fluid inside the dung5. However, the majority of fly eggs are smothered and killed as dung beetles destroy the hardened cowpat structure5. The few fly larvae that emerge then starve to death, as many adult dung beetles have drunk the cowpat fluid (sometimes within a day) before fly larvae can9. The feeding behaviour of dung beetles also decimates the number of parasitic intestinal worm larvae that occur within dung6.
Earthworms begin to feed on the dung, leaving worm castings in their wake approximately 3-4 weeks after dung beetles leave9. The tunnels created by burrowing beetles and earthworms improve soil nutrition and aeration, whilst also increasing water permeation into the soil9.
- Meat and Livestock Australia. Fast facts: Australia’s sheep industry 2017. Accessed 2nd September 2018, available from: https://www.mla.com.au/globalassets/mla-corporate/prices--markets/documents/trends--analysis/fast-facts--maps/mla_sheep-fast-facts-2017_final.pdf
- Meat and Livestock Australia. fast facts: Australia’s beef industry 2017. Accessed 2nd September 2018, https://www.mla.com.au/globalassets/mla-corporate/prices--markets/documents/trends--analysis/fast-facts--maps/mla_beef-fast-facts-2017_final.pdf
- CSIROpedia. George Francis Bornemissza. Accessed 3rd September 2018, available from: https://csiropedia.csiro.au/bornemissza-george-francis/
- CSIRO (2016) New dung beetles to bury dung and reduce bush flies. last updated 31st May 2016, accessed 3rd September 2018, available from: https://www.csiro.au/en/Research/BF/Areas/Invasive-species-and-diseases/Biological-control/Exotic-dung-beetle-to-tackle-Aussie-flies
- Dr Bernard Doube. Dung Beetles and bush flies. Dung Beetle Solutions Australia, accessed 3rd September 2018, available from: http://www.dungbeetlesolutions.com.au/about-dung-beetles/bush-flies-and-dung-beetles/
- David Cousins (2018). Control of bush flies by dung beetles. Department of Primary Industries and Regional Development, Government of Western Australia. Updated 13th June 2018, Accessed 3rd September 2018, available from: https://www.agric.wa.gov.au/land-use/control-bush-flies-dung-beetles?nopaging=1
- Genelle Weule. Saluting a great Australian: The bush fly, ABC, published 26th January 2017, updated 30th January 2017, accessed 3rd September 2017, available from: http://www.abc.net.au/news/science/2017-01-26/salute-the-great-australian-bush-fly/8211770
- Dr Bernard Doube. About dung beetles. Dung beetle solutions Australia, accessed 3rd September 2018, available from: http://www.dungbeetlesolutions.com.au/about-dung-beetles/
- CSIROpedia. Dung beetle program. accessed 3rd September 2018, available from: https://csiropedia.csiro.au/dung-beetle-program/
https://cosmosmagazine.com/climate/can-dung-beetles-rein-in-cattle-s-methane-emissions article discussing possible greenhouse gas reductions from dung beetles consuming cow dung
https://www.youtube.com/watch?v=yAG3wLkqMBo&t=2s Dung down under, a 20 minute documentary of the Dung Beetle program in Australia, produced by the CSIRO in 1972.
Credit: GALLO IMAGES-ANTHONY BANNISTER / GETTY IMAGES