Polyphagous shot-hole borer threat overshadowed by bird flu in Western Australia

It was only a couple of years ago when everyone was talking about a tiny but deadly invasive beetle that could wipe out Perth's tree canopy and wreak havoc in agriculture and native forests.

People were on high alert for signs of the polyphagous shot-hole borer and distressed when beautiful big trees in Kings Park and Hyde Park had to be chopped down to stop the spread.

A quarantine zone was placed around the metropolitan area as part of a national response to the pest, and when eradication failed, the response shifted to a long-term management plan.

But now it seems to have gone quiet.

In fact, it is more that another deadly biosecurity threat has grabbed our attention, the H5N1 bird flu.

People are being told to keep their eyes peeled for sick birds and wildlife and quickly report to authorities.

In the background, shot-hole borers, which burrow into trees with devastating consequences, are still crawling, flying and looking for new hosts to chew on.

Measuring just 1 to 2 millimetres, the beetles were detected for the first time in an avocado orchard in the Perth suburb of Carabooda in December.

The softer wood of the avocado trees makes them particularly susceptible to the borer, with crops in other countries devastated by the pest.

That makes the south-west of WA the new front line.

It is where more than 51,000 of the 131,000 tonnes of avocados grown around Australia were produced last financial year, according to Avocados Australia.

Beetle poses 'real threat'

Manjimup avocado grower and WA director of Avocados Australia Brad Rodgers said there had been no signs of the beetle in the region so far.

"It's a real threat and it's a real concern to farmers," he said.

"It's very critical for our livelihood and for us to grow the fruit that Australians and West Australians love. We would like to contain it if we can."

He and other farmers regularly check their crops, and the Department of Primary Industries and Regional Development is helping with information and advice on pruning to manage the borer.

Under the microscope

The department is also involved in a research project with Murdoch University studying Australia's only laboratory colony of shot-hole borers.

The team is led by Wei Xu, who showed the ABC a series of test tubes filled with sawdust from different trees, while pointing out the tunnels made by the borers.

"They build the gallery so they can grow fungi. There are some insects inside," Dr Xu said.

They are studying what repels the borer but also what attracts them.

"Then we can use that in the trap for example to monitor their population in the field, to detect them or to trap and kill them," he said.

He said early detection was the key to stopping the spread out of the Perth quarantine zone and potentially to the rest of the country, especially northern regions of the east coast where the borers would thrive in the warmer, more humid conditions.

"So they may amplify quickly and spread quickly and that would be a big threat to the whole of Australia," he said.

Overshadowed by bird flu

But there are concerns bird flu is taking the community's attention and government resources away from shot-hole borer.

"One of the concerns we have at present is that we're facing a bird flu crisis, which is going to take up an awful lot of biosecurity resources, including people in government," Invasive Species Council policy director Carol Booth said.

"When we lose that focus that's potentially a really good opportunity for this beetle to really spread and start causing damage in other parts of Australia," Dr Booth said.

But the WA government insisted its surveillance and management programs of the borer had not changed.

"There has been no change to Western Australia's polyphagous shot-hole borer response as a result of the government's response to H5 bird flu," a government spokesperson said.

That included quarantine controls, surveillance, regulation, training and "capacity building to slow the spread and manage the impact of shot-hole borer".