A growing problem
Rabbits arrived with the first fleet in Australia but the main wild population is widely regarded as being descended from 1859. Within 70 years they spread to 70 per cent of Australia's land mass, the fastest known invasion by a mammal anywhere in the world. They compete with livestock and native animals for feed and occupy burrows that were once home to bilbies. They destroy tree seedlings destined for forestry, horticulture or bush revegetation, and their eating habits change the types of plants that survive in bushland or in the outback. Ground degraded by rabbits is less able to absorb rain, sending water, nutrients and sediment into river systems.
Biocontrol with viruses
CSIRO's predecessor, the Council for Scientific and Industrial Research (CSIR), carried out initial trials that ultimately resulted in the successful release of myxoma virus for the biological control of rabbits in 1950. This resulted in a dramatic reduction of Australia's rabbit population. It was the world's first successful biological control program of a mammalian pest.
However, by the late 1950s, host-pathogen co-evolution led to development of genetic resistance in rabbits and the appearance of less virulent virus strains, and rabbit numbers increased again. CSIRO began a project to investigate the possibility of Rabbit Haemorrhagic Disease Virus (RHDV) in 1989. The virus was brought to CSIRO in 1991 and was extensively assessed for its suitability as Australia's second rabbit biocontrol agent. The releases of the virus began in late 1996. RHDV reduced rabbit numbers to very low levels, with greatest impacts observed in arid zones and lesser impact seen in high rainfall areas.
The current rabbit biocontrol program is based on 10 years of research into increasing the effectiveness of RHDV and identifying factors limiting the effectiveness of RHDV in the field. CSIRO has worked with a series of national and international collaborators on a series of projects funded through the Invasive Animals Cooperative Research Centre (IACRC), the Department of Agriculture and Water Resources (DAWR, formerly Department of Agriculture, Fisheries and Forestry) and CSIRO.
An ongoing battle
CSIRO's biocontrol research is continually generating options (opportunities for impact) for the future. Even where explicit social and economic outcomes are not yet evident, there can be value in outcomes such as enhanced capability, improved knowledge, better research infrastructure, and a clearer understanding of prospective areas for future research.
Looking at a range of impacts, our conservative estimates suggest that the real research and development expenditure of $6.5 million per year will lead to (not including extension and implementation costs):
- Total benefits (measured as avoided loss in agricultural production and savings in control costs, in real, present value terms) between $9.5 million and $230.6 million over the next 10 years, depending on the assumptions made.
- A benefit cost ratio between 2.5:1 and 36.3:1.
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