Rabbit biocontrol in New Zealand RHDV1 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 the 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 October 2017: RHDV1 K5 release
Key step made towards controlled release of new rabbit virus – seeking your submissions in support
Environment Canterbury is part of a national consortium of pest management agencies leading a programme to import and release a new strain of rabbit calicivirus known as RHDV1 K5. The consortium, that includes regional councils, Federated Farmers, the Department of Conservation and Land Information New Zealand, is targeting the release of the new strain in March/April 2018.
The consortium has taken another key step in preparing for the release through the submission of a series of comprehensive applications to the Ministry for Primary Industries (MPI). The applications seek approval to register, import and release RHDV1 K5 nationally. The application for registration will be open for public submissions in week commencing 2 November 2017 with further details to be posted on the MPI website http://www.mpi.govt.nz/news-and-resources/consultations/. Stakeholders with interests in the successful release are requested to prepare submissions in support.
RHDV1 K5 has now been released in Australia and initial monitoring (at some 200 participating sites) indicates a 42% average reduction in wild rabbit numbers. These results are very encouraging for the New Zealand release, and provide an indication of the potential benefits of RHDV1 K5 as part of an integrated pest management approach.
Some owners of domestic/pet rabbits have previously raised concerns regarding the new strain of calicivirus. However, the currently available RHDV vaccine will protect pet rabbits from the new strain.
A substantial risk to realising the full benefits of RHDV1 K5 is a potential illegal and unmanaged release. If this were to occur, there is a high likelihood of bringing the rouge RHDV2 virus into New Zealand. RHDV2 is already present in Australia and its potential impacts on native non-target species are unknown, therefore it is a significant biosecurity risk for New Zealand.
Ongoing support will be required from landowners and other stakeholders to ensure a successful controlled release. Success can be achieved through the combined collaborative efforts of the national consortium, regional councils and landowners working closely together.
Landowners and other stakeholders who are interested in getting involved in the release should contact their local Regional Council for more information.