Concerns biological controls losing their edge as rabbit populations climb
By Selina Green
ABC Rural
Topic:Pests
18m ago18 minutes agoWed 11 Dec 2024 at 10:53pm
Three brown rabbits in a green field.
Myxomatosis and calicivirus have helped bring down rabbit numbers across Australia in recent decades. (Supplied: Landscape Hills and Fleurieu)
In short:
Researchers are studying how two biological tools used to control rabbits have evolved decades after their release in Australia.
Landholders are reporting increasing rabbit numbers amid concerns the controls are losing their effectiveness.
What's next?
Researchers are asking people to send in tissue samples of dead rabbits and to implement integrated rabbit control methods.
Scientists are researching whether two biological tools used to control Australia's rabbit populations are still working, amid concerns the calicivirus and myxomatosis disease are losing their potency.
With rabbit numbers up across the country, researchers are asking the public to collect and share tissue samples of dead rabbits to help track the extent of the viruses.
Rabbit Free Australia chair Craig Magnussen said booming rabbit numbers had been accompanied by reports of a surge in calicivirus (RHDV) and myxomatosis.
A man stands at a podium.
Craig Magnussen says rabbits are able to breed resistance to biological controls. (Supplied: Rabbit Free Australia)
"We want to see these viruses out there, doing their job, but what's really important is to monitor how those viruses and the rabbits are behaving in the environment because they both evolve over time," Mr Magnussen said.
Australia's rabbit numbers were drastically reduced after the release of myxomatosis in 1950, followed by RHDV in 1995.
"Rabbit's superpower is their ability to breed so rapidly, they're able to breed resistance to myxomatosis and to subsequent biological controls as well," Ms Magnussen said.
"We're getting to the stage where we're seeing the efficacy wane again, so that's why it's so important to always continue research into what the next agent might be."
A rabbit infected with calicivirus
Researchers hope to collect tissue samples from dead rabbits right across Australia. (Supplied: DAFWA/Brian Lukins)
Rabbit samples needed
Tissue samples from dead rabbits are being sought for two research projects by the University of Adelaide and CSIRO, with sample kits available from the CSIRO or RabbitScan websites.
"If people see dead rabbits in the field, what we're asking is that they collect a sample and submit it for these research purposes," Mr Magnussen said.
"It really is invaluable to get that information from as far and wide as possible, so we really rely on people out there taking samples and submitting them.
"With viruses — and COVID's a case in point — it's mutated and we're seeing different strains of it popping up here and there.
"And just as medical professionals are trying to keep in front of the different strains of COVID, we are always on the lookout of new strains of RHDV."
Numbers continue to grow
Landscapes Hills and Fleurieu stewardship team leader Susan Ivory said reports were growing of rabbits digging under sheds and houses, and spreading fleas, in the peri-urban areas around Adelaide.
"The community are telling us that rabbits are a bigger problem than they've ever been before, and that's the feedback we've been getting for the last three or four years now," Ms Ivory said.
She said the population boom is a result of a mix of mild summers, reasonable rainfall levels and waning bio-control methods.
"[That], together with … their impact on the population starting to wane, have resulted in rabbit population, particularly up here in the Adelaide Hills, to explode really."
No silver bullet
Mr Magnussen said biological controls were great for controlling rabbits, but could not be used in isolation.
"[Myxomatosis] had an absolutely huge impact on rabbit populations, and unfortunately people thought that was the silver bullet and they didn't need to do anything else," he said.
"Biologic controls are great … however you can't just rely on those."
He urged landholders to integrate pest management using biological controls with methods such as warren removal and fumigation.
A man stands into front of a farm gate and a sign that reads Rabbit Free Australia.
Craig Magnussen says biological agents should not be used in isolation. (Supplied: Craig Magnussen)
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Posted18m ago18 minutes agoWed 11 Dec 2024 at 10:53pm
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