Rabbit biocontrol in New Zealand RHDV K5
European rabbits are significant agricultural and ecological pests in New Zealand. They compete very effectively with livestock for pasture, and 7 to 10 rabbits may consume as much feed as one ewe. Rabbits also provide a stable food source for ferrets, which are carriers of bovine tuberculosis. Burrowing and scrapes cause extensive damage on erosion-prone soils, so much so that agricultural land can be rendered useless and water quality declines. Historically, rabbit-infested farms were abandoned because owners could not make a living.
Rabbits also threaten native biodiversity and conservation values by over-browsing vulnerable plant communities, and, as year-round prey, support increased numbers of mammalian pests (stoats, cats, ferrets) that predate on native birds and animals.
Following extensive research, a new variant of rabbit haemorrhagic virus known as RHDV1 K5 has been approved for registration in Australia by the Australian Pesticides and Veterinary Medicines Authority (APMVA). The Australian release of RHDV1 K5 is currently underway.
RHDV1 K5 is also a potentially significant biological control tool for pest rabbits in New Zealand. While exact figures are unknown, it is expected there will be improved knockdown in those areas where the current strain of RHDV is less effective. This could be anywhere from 0 to 40% and will depend on the location of the rabbit population and the number of susceptible animals within the population.
About RHDV1 K5
- RHDV1 K5 is not a new virus. It is a Korean strain of the existing RHDV1 virus already widespread in New Zealand.
- RHDV1 K5 was selected for release in Australia because it can better overcome the protective effects of the benign calicivirus (RCA-A1), which occurs naturally in the feral rabbit populations in both Australia and New Zealand.
- Replacing the existing virus with a new strain may assist in overcoming resistance to the old virus.
- RHDV1 K5, like other RHDV1 variants, only infects the European rabbit and no other species.
- RHDV1 K5 is expected to ‘boost’ the effects of the existing RHDV1 strain and help slow the increase in rabbit numbers.
- RHDV1 K5 is not a silver bullet for rabbit eradication in New Zealand, and a long-term integrated approach to controlling pest rabbits is required.
- The currently available RHDV vaccine will protect domestic/pet rabbits against RHDV1. There are no human health risks associated with RHDV.
- A controlled release is needed to ensure a higher-quality commercially prepared product is made available and that the release can be appropriately managed and monitored. This approach will increase the likelihood of success and maximise benefits to farmers and the environment.
RHDV1 K5 release project
Environment Canterbury is part of a national consortium of pest management agencies leading a programme to import and release RHDV1 K5 into New Zealand. The consortium, that includes regional councils, Federated Farmers, the Department of Conservation and Land Information New Zealand, is targeting to release of the new strain in March 2018.
RHDV1 K5 is expected to boost the effects of the existing RHDV1 strain and help slow the increase in wild rabbit numbers. While exact figures are unknown, it was expected that there would be improved knockdown in areas where the current strain is less effective. Research shows that autumn is the optimal time to release the virus as immune young rabbit numbers are low and the vectors, such as flies, are active.
Support will be required from landowners, farmers and other stakeholders that are likely to benefit from the release. The highest likelihood for success will be through the combined collaborative efforts of the national consortium, regional councils and landowners working closely together. A controlled release will also ensure that a high quality commercially prepared product can be made available to landowners to improve effectiveness.
Latest project update – August 2017
In February 2017 the Environmental Protection Authority confirmed that RHDV1 K5 was not regarding as a new organism to NZ and that no approvals were required under the Hazardous Substances and New Organisms Act to import and release.
Approvals to import and release RHDV1 K5 are required from the Ministry for Primary Industries (MPI) under the Agricultural Compounds and Veterinary Medicines (ACVM) Act and the Biosecurity Act. The ACVM application is by far the most comprehensive application required and will address animal welfare, efficacy and chemistry and manufacturing considerations. The development of this highly technical application is nearing completion. Information deviations have been sought from ACVM as part of the pre-application process. Thereafter the application will be formally submitted for public notification.
The approvals process is being run in parallel with a Sustainable Farming Fund project, as part of which Landcare Research are preparing a release strategy for RHDV1-K5 in conjunction with local authorities. The strategy will assist participating regional and district councils to effectively release RHDV1 K5 in rabbit-prone areas of New Zealand. The strategy also includes pre- and post-release monitoring at specific sites to measure impacts and inform future research. The process of identifying release and monitoring sites is underway.
Landowners and other stakeholders who are interested in getting involved in the release should contact their local Regional Council for more information.