Sustainable Parasite Management

History of dung beetle importation into Australia (1966 - 1986):

European settlement in Australia has permanently changed the nature of the landscape. Key changes include partial or total clearing of vegetated areas, the introduction of pasture plants, undesirable plants, cattle and other domestic animals. A large proportion of the annual dry matter production of a pasture is consumed by cattle and converted into dung, increasing the need for efficient recycling of faecal nutrients. Australia has its own rich and unique fauna of dung beetles that evolved with the marsupials, which usually produce relatively dry and fibrous dung pellets. These beetles, with some exceptions, are not adapted to use cattle dung effectively, nor do most of them colonise dung in cleared open habitats. Hence in most areas of Australia, prior to the introduction of exotic dung beetles, cattle dung was not buried or shredded to any extent, except in a few areas where native beetles were able to have an impact.

This gave rise to various problems, of which the main ones were:

• Cattle dung is the only breeding medium for the introduced buffalo fly and is a major breeding site for the native bush fly and four species of Culicoides biting midges, some of which are known vectors of diseases such as ephemeral fever.
• Dung fouls pasture, obstructing plant growth and promoting rank unpalatable growth around the edge of dung pats.
• Plant nutrients are immobilised in undecomposed dung pats, retarding the recycling process.
• There is some loss of nitrogen to the atmosphere from unburied dung.
• Methane and carbon dioxide are released into the atmosphere

On other continents where ruminants evolved, such as Africa, India and in Europe, there was a parallel evolution of diverse dung beetle faunas that utilize dung for feeding and breeding. This ensured that much of the dung was buried or shredded during the growing season.

Thus cattle arrived in Australia without any of the dung beetles that are adapted to bovine dung overseas. This fact was noted by Dr George Bornemissza, of the CSIRO Division of Entomology, who recalled that in his native Hungary it was commonplace to see dung beetles removing large quantities of dung from cattle pats. He proposed that foreign bovine dung beetles be imported into Australia to bury cattle dung, thus reducing the problems associated with unburied dung.

In mid-1960 George Bornemissza travelled to South Africa to set up a research unit in Pretoria for a dung beetle introduction project funded by CSIRO and the Australian Meat Research Committee. By the end of 1970, eggs of three species had been sent to Canberra, followed by another five species by March 1971. These early species were all selected for north Queensland. There followed almost a decade of work selecting and collecting beetles for shipment to Australia. Matters at the Australian end were co-ordinated in Canberra, where the quarantine and mass breeding work occurred. Consignments of the new beetles were shipped from Canberra to pre-arranged co-operators around Australia.

Impact of the introduced dung beetles:

By 1980 there were up to several species of dung beetles established at some release sites in Australia. Here dung beetles often appeared in huge numbers, although their activity fluctuated considerably throughout the growing season. Dung burial and shredding was spectacular at times and during such episodes; buffalo fly breeding in dung pats was much reduced. When intensive dung beetle activity persisted for more than a couple of weeks, longer than the lifespan of the flies, buffalo fly numbers on cattle declined, often to rise again as beetle activity decreased. This was clear evidence that the beetles were having some impact on fly breeding, but the effect was generally not sustained throughout the buffalo fly season. Anecdotal reports from western Queensland at that time indicated that bush fly populations had declined markedly since the beetles had become established.