Shot-hole borer researchers team up against tree-killing beetle in Perth

Australia Broadcast Center

a day ago

Whether it is development, mining, or dwindling groundwater, Perth's tree canopy is facing a myriad of challenges.
In addition, since 2021 the city has been struggling to contain a tree-killing invasive beetle — the polyphagous shot-hole borer.
The pest, which produces a deadly fungus, mainly infects exotic trees, but native varieties like melaleucas are also at risk.
To quell the spread of the beetle, the state government has to date removed 4,794 trees, some from Perth's most popular green spaces — Kings Park, Hyde Park and Stirling Gardens.
Last month, a national biosecurity taskforce moved from an eradication response to long-term management, worrying many working in the space, particularly those in WA's agriculture sector.
Teams of researchers are working on new methods to identify, contain and kill the beetle.
Funded by the WA government through the WA Agriculture Research Centre (WAARC), three major projects have received $2.17 million, paying for three years of research.
Key stakeholders met this week at a symposium to hear from the funding recipients about their research so far.
Theo Evans, associate professor of applied entomology at the University of Western Australia, told the symposium two trials, which commenced in September 2024, showed very promising early results.
He has been trialling two methods to combat the borer — a chemical injection into infected trees and using commercially available nematodes to eat the beetle.
Treena Burgess, forest pathologist and director of the Harry Butler Institute, has been overseeing several studies at Murdoch University, most notably one into the fungus the beetle produces.
"A key piece of our research is going to be trying to understand how susceptible different tree species are to the fungus," Professor Burgess said.
"The beetle is the vector, and the fungus is the killer of trees, and different tree species seem to be varying considerably in their susceptibility."
She said some trees responded better than others to the infection.
Professor Burgess said the need for information on the beetle was so acute that the universities and stakeholders would share data as it came to hand, rather than waiting for the lengthy peer-review process.
"The purpose of this is to solve the problem," she said.
Managing director of environmental consultancy ArborCarbon and adjunct professor at Murdoch University Paul Barber will use funding to send up an "ArborCam" to map Perth's tree coverage.
ArborCarbon has already led biosecurity responses in the eastern states.
"The ArborCam is special because it can collect 11 bands of data across the spectrum, and it measures things like the condition of vegetation, height, surface temperatures," Professor Barber said.
ArborCarbon will use the technology to identify where the most susceptible trees are, to focus on-the-ground efforts.
Professor Barber said the goal was to make the ArborCam data available online for stakeholders and researchers.
Ben Phillips, professor of population biology at Curtin University, is creating models to understand how the shot-hole borer might spread, and measure how effective current methods of detection are.
He has taken information from dozens of studies to create a model of population growth, and his team has discovered population growth is dependent on temperature.
"Most of the eastern seaboard of Queensland is looking like a spot for the borer, particularly the area around Cairns."
He said considering Perth did not even have the ideal climate, the beetle had an incredibly high growth rate.
The female borer does not require a male to reproduce, and Professor Phillip's modelling showed the population could grow in Perth conditions from one to a million in just a year.
All the researchers the ABC spoke to were optimistic their efforts would lead to better management tools for the dreaded pest.