RABBIT populations in the Wheatbelt and across the South West could be reduced by around 40 per cent in coming weeks as the calicivirus (Korean variant – RHDV1 K5) is released throughout the region.
This follows the national release of the Korean strain of Rabbit Haemorrhagic Disease Virus, known as RHDV1 K5, that took place during the first week of March 2017.
It was the first time in 20 years that a new rabbit biocontrol agent had been released into Australia.
More than 600 release sites were selected nationally, with 117 sites across WA.
The release of this virus strain is part of a 20-year national biocontrol plan for rabbits.
Since June 2017, there have been confirmed cases of the virus in Bridgetown, Donnybrook, Milyeannup National Park, Esperance, Mandurah and Albany.
Nationally, preliminary analysis based on pre and post rabbit counts from 52 release sites, has shown a 42pc average reduction in wild rabbit numbers at sites where RHDV1 K5 was released.
Rabbits infected with K5 develop symptoms between 24 and 72 hours after infection and usually die within six to 36 hours after the initial symptoms appeared.
Natural resource management group, Wheatbelt NRM, has been co-ordinating the controlled release with 16 landholders in the Wheatbelt who have chosen to participate in the carefully planned release.
Wheatbelt NRM healthy environment program manager Rowan Hegglun said sites in the Wheatbelt had been “especially selected using a science, based on co-ordinated predator control (to minimise prey switching) and rabbit activity tracked by landholders, to ensure that we have the best opportunity of creating an epidemic and high elimination rate”.
“The K5 virus, which only affects the European rabbit, may provide us with the opportunity to reduce rabbit numbers to make them more manageable,” Mr Hegglun said.
“Rabbits are an environmentally damaging pest, causing over $200 million in losses to agriculture through soil degradation and loss of vegetation cover and are a major threat to biodiversity, impacting on the survival of many native species.
“High numbers of rabbits support a higher level of feral cat and fox numbers, thereby increasing the impact that these species have on native species.”
Department of Primary Industries and Regional Development (DPIRD) senior development officer Henry Brockman said RHDV1-K5 had been released at 117 sites in the agricultural region since the first release in autumn last year.
“Reports indicate that it has resulted in a substantial reduction in rabbit numbers,” Mr Brockman said.
“Workshops on control methods other than biological control (virus) had been held through the agricultural region and more is being planned for later in the year.”
Mr Brockman said under the Biosecurity and Agriculture Management Act 2007 online training must be completed to become an authorised user of RHDV1-K5.
“It is recommended that land managers contact their local Biosecurity Group or Regional NRM group before applying for the virus, to ensure releases are co-ordinated or to determine if a release has already occurred within their area,” he said.
“Co-ordinated, large scale release of rabbit biological control viruses will maximise effectiveness.”
The two main diseases previously released in Australia to control the population of rabbits, calicivirus (Czech strain) and myxomatosis, have become less effective, although it is estimated that their presence has limited rabbit numbers to 15pc of their potential population.
RHDV1 K5 is not a new virus, but a naturally-occurring Korean variant of the Rabbit Haemorrhagic Disease Virus (RHDV).
Its release is expected to ‘boost’ current management and help slow down the increase in rabbit numbers.
RHDV1 K5 is highly contagious, can be spread by insect vectors and other animals feeding on infected carcasses may excrete the virus.
Domestic rabbits can be immunised against it with the vaccine currently used to protect rabbits against infection from other strains of calicivirus.
Landholders are reminded to report any rabbit sightings or suspected signs of disease, and submit samples.
Reports should be provided online via the RabbitScan website or the RabbitScan smartphone app – available via iTunes and GooglePlay.
More information on the release in WA and training is available from the DPIRD website agric.wa.gov.au
