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Key facts about rabbit biocontrol in Australia

A brief history of rabbits in Australia

1857-60 Primary releases of rabbits at Barwon Park (Vic), Anlaby Station (SA) and Point Lowly (SA) for hunting become established. Some farms abandoned as early as 1881.
Late 1940s Rabbit population increased to 600 million due to a number of high rainfall years and because WWII reduced manpower for trapping and fence maintenance. 1
1950 World’s first vertebrate pest biocontrol – myxoma virus (MV) – released and kills 99.8% of infected rabbits.
1951-52 Rapid selection of genetically resistant rabbits leads to attenuated forms of myxomatosis.
1969 Rabbit flea species (Spilopsyllus cuniculi) approved for release to act as an improved vector to spread MV in areas low in mosquitoes.
1993 Spanish rabbit flea (Xenophsylla cunicularis) adapted for arid conditions approved for release and improves transmission of MV.
1995 Rabbit population about 300 million and climbing. 2
1995 Rabbit haemorrhagic disease virus (RHDV1) introduced and kills up to 98% of rabbits in arid areas.
2000s Rabbits begin to develop resistance to RHDV1 infection. Increasing resistance results in increasing rabbit numbers being observed.
2009 Benign endemic rabbit calicivirus (RCV-A1) discovered and characterised.3 RCV-A1 confers partial protection to lethal RHDV1 infection and therefore impedes effective RHDV based biocontrol.
2009+ To counteract RCV-A1, new naturally occurring overseas RHDV1 strains are imported from Europe and Asia and evaluated as part of the RHD Boost project whose aim is to increase effectiveness of RHDV1 based biocontrol.
2012 Invasive Animals CRC develops 20-year rabbit biocontrol pipeline strategy and strategic rabbit biocontrol research program to boost RHDV1 effectiveness, assess feasibility of new potential rabbit biocontrol candidates, and increased capabilities to promote regional integrated rabbit control.
2014 Rabbit haemorrhagic disease virus 2 (RHDV2) arrives in Australia and spreads to all rabbit populations across Australia within 2 years. Reduces rabbit populations by 60% on average and up to 80% in some populations, including a proportion of rabbits with immunity to RHDV.
2017 First nationally coordinated release of new RHDV1 strain (RHDV1-K5) in 20 years based on former Invasive Animals CRC program. Delivers a 34% national average knockdown at release sites but is outcompeted by RHDV2 at landscape scale. 4
2016-18 RHDV2 becomes the dominant strain in the Australian landscape. 5
2017 Centre for Invasive Species Solutions formed as successor to IA CRC and continues to advance rabbit research, including the assessment of RHDV2 as a biocontrol agent.
2018 Discovered that rabbits that survive MV have 10% poorer survival when subsequently infected with RHDV1. The interaction between biocontrols is providing additional benefit. 6
2019 Intestinal Eimeria rabbit parasites assessed as an additional control agent but are found to be unsuitable as virulent Eimeria parasites are already widespread across Australia. 7
  1National Museum of Australia (2021). 2Ward (2011), 3Strive et al (2009). 4Cox et al (2019). 5Ramsey et al (2020). 6Barnett et al (2018), 7Peacock et al (under review)

Source: Adapted from the Victorian Department of Environment and Primary Industries (2011).

See Appendix 1 for description of each biocontrol technique mentioned above

Impacts of rabbits in Australia

  • Australia’s most costly pest animal, rabbits cause $206 million in losses each year to the agricultural industry1.
  • They compete with grazing stock for food, contribute to soil erosion, damage crops and destabilise the land, potentially leading to injury of livestock.
  • Rabbits threaten the survival of more than 300 Australian native  flora and fauna species2. This includes 24 critically endangered  species such as the pygmy possum, orange-bellied parrot and ballerina orchid.
  • Less than one rabbit per football field sized paddock is enough to  stop the growth of some native species and negatively affect  biodiversity.

Rabbit biocontrol in Australia

Myxoma virus: Trialled by the CSIRO in the late 1930’s and 40s. It was released into the feral rabbit population in the 1950s and  spread predominately by fleas and mosquitoes. Within months it  knocked over 90% of some rabbit populations but became less effective over time due to developing genetic resistance in the rabbits. Today it affects an estimated 40-50% of the rabbit population.

RHDV: Trialled by the CSIRO in the early 1990s and released into the  feral rabbit population in 1996. It initially knocked down 90% of  the feral rabbit population but was less effective in cooler climates. Immunity and again resistance have become an issue.

RHDV2: Found in Australia in May 2015, RHDV2 is a variant of RHDV that  was not released but has been detected in Europe and now Australia and may cause deaths to European rabbits. If RHDV2 is highly virulent it could potentially benefit rabbit biocontrol efforts  within Australia3.

Benefits of rabbit biocontrol in Australia

  • Significant regeneration of native vegetation and population  increases of native animal species.
  • Cumulative benefit of rabbit biocontrol to Australia’s pastoral  industries at ~$70 billion (over 60 years).

Genetic resistance, immunity and transmission of rabbit biocontrol

About RHDV1 K5

  • K5 is not a new virus. It is a Korean strain of the existing virus  already widespread in Australia.
  • K5 should work better in the cool-wet regions of Australia where the current strain has not been as successful.
  • K5 was selected because it can better overcome the protective effects  of the benign calicivirus (RCA-A1) which naturally occurs in the  feral rabbit population.
  • K5, like other RHDV1 variants is not infectious to any other  species except the European rabbit.
  • K5 will not result in a 90% reduction of wild rabbit populations, rather it is expected to ‘boost’ the effects of the existing variant and help slow down the increase in rabbit numbers.
  • K5 is not the silver bullet for rabbit eradication in Australia and  an integrated approach is required.
  • A vaccine to protect domestic rabbits against RHDV1 is available. Talk to a local vet for information.


  1. Gong W, Sinden J, Braysher M, Jones R (2009). TheEconomic Impacts of Vertebrate Pests in Australia. Invasive Animals  Cooperative Research Centre, Canberra.
  2. Australian Government, Department of the Environment (2015).  www.environment.gov.au, Department of the Environment,  Canberra.
  3. Rabbit Biocontrol Scientific Committee (2015). The arrival of  RHDV2 in Australia: implications for current rabbit biocontrol initiaitves. PestSmart Toolkit publication. Invasive Animals  Cooperative Research Centre, Canberra, Australia.
  4. Cox TE, Strive T, Mutze G, West P and Saunders G (2013). Benefits of Rabbit Biocontrol in Australia. PestSmart Toolkit publication, Invasive Animals Cooperative Research Centre, Canberra, Australia.
  5. Centre for Invasive Species Solutions (2015). RHDV K5: Frequently asked Questions.

The authors of these documents have taken care to validate the accuracy of the information at the time of writing. This information has been prepared with care but it is provided “as is”, without warranty of any kind, to the extent permitted by law. The views and opinions expressed in this publication are those of the authors and do not necessarily reflect those of the institutions the authors work for or those who funded the creation of this document.

How to reference this page:

Centre for Invasive Species Solutions, 2015. Key facts about rabbit biocontrol in Australia. Factsheet. PestSmart website. https://pestsmart.org.au/toolkit-resource/key-facts-about-rabbit-biocontrol-in-australia accessed 20-04-2024