RCD Proves Ineffective In Australia
Rabbit numbers in parts of Australia are on the increase amid fears they are building an immunity to the RCD calicivirus. John Howard reports.
News from Australia that despite RCD, rabbit numbers are on the increase, will concern New Zealand farmers who released the virus into New Zealand in an attempt to control the rabbit population.
Australian scientists are so concerned at the phenomenon they say further measures are needed to stop rabbits from once again ravaging grasses and crops.
Many farmers are already reverting to traditional rabbit-control methods, such as baiting and ploughing warrens.
Dr Brian Cooke of the CSIRO said he could not explain why numbers were rising - but scientists were examining ways to make the virus more lethal.
"We may be seeing the development of genetic resistance in the rabbit population, as occured with myxomatosis," he said.
Anecdotal evidence suggests rabbit numbers were increasing particularly in the wetter agriculture areas.
Farmers Federation natural resources chairman, Mike Gaden said, "A combination of calicivirus, myxomatosis and action by farmers was necessary to control an upsurge of rabbit numbers."
"They (rabbits) are starting to breed up," he said
Animal and Plant Control Commission research officer, Greg Mutze said, " It appeared the virus was behaving differently in some areas but the reasons for this, as yet, were unclear."
"There was preliminary evidence of immunity in some areas although I don't know that we have a clear picture of how extensive it is," he said.
Foundation for a Rabbit-Free Australia deputy chairman, Rob Morrison, said it was inevitable rabbits would develop an immunity to the disease.
"We were sounding warnings when calicivirus first struck that that would be the time it would be most effective," he said.
Dr Cooke said the CSIRO was studying ways to "enhance" the effect of the virus.
"The CSIRO would look at improving how the virus was transferred by insects and would consider allowing farmers to use baits to spread it further, he said.