WA scientists band together to control spread of invasive polyphagous shot-hole borer

WA scientists are banding together to tackle the mammoth task of controlling and managing the polyphagous shot-hole borer, with three research projects to minimise the risk of infestation beyond the Perth metro area.

The WA Agricultural Research Collaboration will invest $2.17 million across three projects led by the University of Western Australia, Murdoch University, and Curtin University.

As of June, there had been 764 active infested premises identified, 1161 trees pruned, and 4794 trees removed in the fight against the Polphagous shot-hole borer.

The first project to increase tools for control of the beetle will be led by UWA Associate Professor Theo Evans.

The project will research the beetle’s dispersal behaviour and survival, chemical control methods, biological control, and increasing community engagement and reporting of shot-hole borer infection.

Dr Evans said the outcomes of the project would include a better understanding of the beetle’s dispersal behaviour and survival, preventative control through tree trunk injections and new biocontrol agents, and new management tools to save trees from being destroyed.

Labor MLC Dr Parwinder Kaur, who represented WA Agriculture Minister Jackie Jarvis at the forum, said the borer had a “reproductive superpower” that hastens the spread of the invasive beetle — that an entire colony can spring from a female beetle.

“From a scientific point of view it’s really interesting as an example of a one-woman army,” she said.

“A single female — just one female — is enough to start an entire colony.”

Female polyphagous shot-hole borers carry a symbiotic fungus in their bodies, Fusarium fungus, which is used by the beetle as a food source.

Dr Kaur said the beetles were farmer’s themselves, but that it was the fungus that is killing trees — not the borer — and that it had the potential to devastate WA horticulture.

“They’re turning the tree into a mushroom farm, but unfortunately, it kills the tree from the inside out,” she said.

“It’s not just bad news for the metro community, this pest would have serious consequences for biodiversity and horticulture, and I think that’s where the urgency is coming from.”

The polyphagous shot-hole borer has never been eradicated in other parts of the world it has invaded, like California.

“WA is not alone in facing these challenges, but we do have an opportunity to lead and manage it effectively.”

A quarantine area remains in place for the Perth metro area, covering 30 local governments across more than 6400sqkm.

The second project led by Murdoch University’s Harry Butler Institute executive director Treena Burgess and ArborCarbon will develop an integrated pest containment strategy for long-term control of the invasive beetle.

The biology and host susceptibility of the beetle will be studied as part of the project with the expectation of gaining a greater understanding of the biology of the pathogen, as well as environmental risk factors influencing the severity of damage to trees.

Avocados Australia WA director Duncan Wells said growers were concerned about the vulnerability faced by orchards, awareness in the nursery and supply chain, mitigation of the pest, and quarantine and movement restrictions, but welcomed the commitment from the Department of Primary Industry and Regional Development to liaise with industry, community, and local government to manage the invasive beetle.

“We also welcome DPIRD’s commitment to build upon the WA Agriculture Research Collaboration research projects to explore improved surveillance and treatment options to support the long-term management of the pest,” he said.

The third project led by Curtin University’s professor Ben Phillips, a population biologist, will develop decision support tools for the management of the beetle including predictive models and risk maps which will be used to prioritise surveillance control efforts, efficient resource allocation, and decision-making.

WAARC director Kelly Pearce said the research and response to the beetle was being watched closely by the rest of the country as WA transitions to management on the invasion.

“We now move to the challenge of control, management, and long-term management.”

“Our goal is to look forward.

“We’re here to focus on what happens next and how research can contribute to coordinate an effective response — we know the rest of Australia is watching our responses closely.”