Landmark new research has laid bare the staggering cost of feral pests that Australia pays each year.
The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services has released a first-of-its-kind report covering the damage done worldwide by invasive alien species – including animals, plants, and microbes.
With 143 participating countries, the total impact of invasive alien species was worth $423 billion in 2019 – and that figure is expected to quadruple every decade.
CSIRO chief research scientist for biosecurity Dr Andy Sheppard, who participated in the project, said an outsize part of that damage – nearly six per cent of the total – was suffered by Australia.
"Australia has close to 3000 invasive alien species estimated to cost Australia approximately $25 billion every year in losses to agriculture and management costs," Sheppard said.
The species doing the most damage
Australia has had some notorious tangles with invasive species, from cane toads to camels.
But Sheppard said the worst, in terms of its impact on native species and environments, was the feral cat on land, and the European carp in the rivers.
Rabbits still hold the title for most devastation wreaked on Australian agriculture, though Sheppard pointed to the national success in controlling and curtailing their numbers as a sign for how to manage other pests.
"Our most harmful invasive invertebrate is red imported fire ants, because they affect human health, the environment and agriculture," he said.
"From a purely agriculture perspective fruit flies top the list, however, there remain many exotic species yet to arrive like Khapra beetle that could be equally devastating."
This assessment matches with new, similar research out of Flinders University, which found feral cats, rabbits, and fire ants cause the most damage in terms of dollars.
In 2021, cats caused about $19 billion of damage alone, according to research from Professor Corey Bradshaw – followed by rabbits at $2 billion, with a long stretch of daylight between.
Bradshaw found in 2021 that Australia had lost the equivalent of $390 billion to invasive species in the past 60 years.
What can be done?
"Invasive alien species do not respect borders," Sheppard said.
Preventing invasive alien species from establishing footholds in Australia was the most cost-effective way to fight their spread, he said.
But intervention, such as the deployment of viruses to attack rabbit populations, had also been effective.
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"Eradication programmes are applicable when invasive alien species populations are small and slow-spreading," Sheppard said.
"They have a success rate of 88 per cent when conducted on islands. Eradication of alien plants presents more of a challenge because seeds can lie dormant in the soil."
And there's no time to lose if Australia is to face the problem.
"To achieve success Australia needs to work with other governments in our region and across sectors, NGOs and with Indigenous peoples and local communities on coordinated action," Sheppard said.