The Australian public will become the “most important” defence the nation has in fighting back against the spread of one of the worst-known tree killers on the planet, with thousands already forcibly cut down and calls mounting to immediately restrict domestic timber importations across the country.
The shot-hole borer, a highly invasive, introduced pest, is widely considered to be one of the most destructive bugs on earth, due to its unique biology, ability to spread rapidly, and its devastating impact on both urban and natural ecosystems.
In June, the federal government admitted it had lost the multimillion-dollar battle to eliminate the polyphagous shot-hole borer in Western Australia, a tiny beetle that originally stems from Southeast Asia and was detected in Australia for the first time just four years ago. So far, it’s infested over 4,500 trees in Perth, including 20 historic figs that were turned to mulch.
While the beetle doesn’t eat the wood, it introduces a type of fungus that it feeds on. The fungus blocks the tree’s vascular system, causing dieback and often death. It can destroy over 100 different types of trees — including many Australian natives and popular trees like avocados, figs and maples.
Incredibly, it also does not need a mate to reproduce, the Invasive Species Council’s Dr Carol Booth told Yahoo News Australia. “It can still lay eggs and then mate with one of the males that hatch out,” she explained, which means one single fertilised female can start a new colony.
“You just need one female in a piece of wood, and they can survive for months,” Booth said. “They’re very good travellers, and it’s a real risk that they will spread. Most experts are warning that it’s inevitable that they will eventually spread. We’re saying, we need to contain them for as long as possible so that we can develop some effective control methods.”
Australians are ‘the most important’ defence we have in fighting back against the highly invasive bug, which originated from Asia. Source: WA government
Where is the shot-hole borer causing chaos in Australia?
So far, the shot-hole borer has only been detected in Western Australia, but South Australia, in particular, is on high alert. Authorities are currently conducting a surveillance of some 500 sites across the state, including in Adelaide’s metro area, to check for infestations.
SA’s Department of Primary Industries has set movement controls on plant material, firewood, wood chips, and pot plants from entering from Western Australia. It’s a move arborists and botanists are pushing to be implemented in the east. They say that if the infestation makes its way to other cities, the result could be catastrophic.
The Sydney Royal Botanic Gardens’ Professor Brett Summerell said the matter requires urgent and swift attention. He said if the shot-hole borer arrived in the city, the impact would be “absolutely devastating”.
“We have a lot of heritage figs in the Botanic Gardens, Centennial Park, Hyde Park, pretty much in every major park and garden within Sydney is heavily populated with fig trees, which seem to be extremely susceptible to the beetle,” Summerell told The Sydney Morning Herald.
“We’ve been assuming it’s going to be coming any day for a year or two now. We’re working on the assumption that it could be tomorrow.” Earlier this year, senior botanist at Curtin University, Professor Kingsley Dixon, said no plant material whatsoever from the west should be allowed into the eastern states, warning trees could be “king-hit”.
The public has been urged to be on the lookout for telltale signs of the shot-hole border, including small, bullet-shaped burrows. Source: The City of Vincent
How can we fight back?
Booth agrees, saying the potential consequences can’t be overstated. “It’s the only way of stopping its spread,” she said. “The beetle itself doesn’t fly very far, so it will be up to people — both to spread it, if they don’t abide by the rules — but also to keep an eye out.
“The public is the most important part of this, because they will be responsible for detecting and reporting. So we are certainly encouraging everyone to understand the signs to look out for — that’s the entry and exit holes for the beetle in the trees — really tiny holes.
“People should be looking up online what they look like. And obviously, if trees or tree branches are dying, then investigate what’s going on there.”
Booth is calling for “strong” and immediate containment measures and investment in research on potential control methods, including biological options and a clearer understanding of the environmental risks. While the shot-hole borer’s impacts on urban environments and horticulture are relatively unknown, the threat to native ecosystems is still uncertain.
“Australia is unique, and we’ve got different species from elsewhere,” she said, pointing out that “the fungus that the beetle has come with is different from those known overseas”.
In Perth alone, just four years after the beetle was first detected, authorities have identified 15 native species that they’ve classified as “highly or very highly susceptible” and another 23 that are “moderately susceptible”. Booth would like to see an independent, transparent inquiry into the now-abandoned eradication program, which she said was “definitely worth the attempt”, and should be a learning opportunity.
“We need to continuously improve our approaches towards new invasive species,” she said. “And… we need to invest much more in prevention, because once something’s here in Australia, it’s really difficult to eradicate it.”
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