A new invasive insect that has caused the felling of hundreds of trees in Perth could attack popular species such as Moreton Bay figs if it escapes quarantine zones, conservationists say.
While the East Coast responded to the incursion of the varroa mite in bees, Western Australia dealt with another invasive insect known as the polyphagous shot-hole borer (PSHB).
The little beetlewhich is native to Southeast Asia, is a “mushroom cultivator” – it burrows into trees and spreads a fungus that can kill the host.
It was first detected in a tree in Perth in September last year and has since spread to 200 locations in the western suburbs of Perth.
The WA government has contained the spread with quarantine areas in 21 local government areas in Perth, restricting the movement of any wood or green waste that may harbor the borer.
Because there is no treatment for infested trees, the Department of Primary Industries has removed over 370 trees to reduce the risk of spread.
The Invasive Species Council says the incursion underscores the need for a well-funded biosecurity system to tackle the continued threat of harmful pests arriving in Australia.
Council conservation manager James Trezise said although the borers were small they were capable of taking down large trees and it would be a ‘disaster’ if the beetles started to affect environments and habitats. parks across the country.
“At the moment it is having an effect on heavily urbanized areas, but if it escapes from the current quarantine areas into nearby forests or reaches the east coast, it could be a major problem,” he said. declared.
“To put it into perspective, it could potentially mean that you lose some of these huge old trees in places like [Sydney’s] Hyde Park.
The beetle is considered an environmental and agricultural pest. It cultivates a fungus to feed its young, and some host trees may die within two years of infestation.
The beetle is unable to establish the fungus in all species and it is unclear how many types of trees in Australia – native and introduced species – could become targets. Overseas, more than 400 host species have been identified.
In WA, the main host identified was the elderberry box maple. Other trees monitored include oak, plane, avocado and fig.
Trezise said the beetles were known to target ficus species, of which there are 45 in Australia, including the Moreton Bay fig – a feature of towns and parks on the east coast and an essential part of many ecosystems from the east coast.
He said the lack of understanding of the trees the beetle might strike underscores the need for more investment in environmental biosecurity research to better understand the risks to native ecosystems and what is needed to combat them.
“The shothole borer is known to prefer ornamental and fruit trees, but we don’t have a full understanding of their potential impacts on our native forests, which is part of the problem,” Trezise said.
It is not known how the beetle got to WA. Authorities considered several possibilities, including that he “hitchhiked” over untreated wooden items and packaging.
Sonya Broughton, Plant Biosecurity Officer for the Department of Primary Industries, said the beetle’s natural spread was limited because only females could fly and only for short distances. This meant that the greatest risk came from human transport.
“Early detection and prompt removal or pruning of infested trees are essential to contain the spread of PSHB and minimize further impact on nearby host trees,” she said.
Broughton said managing the pest has involved the largest monitoring program in the department’s history, with staff inspecting more than a million trees on more than 25,000 properties over the past 12 months.
“Between the combined efforts of surveillance, trapping, tree management and quarantine restrictions, as well as public education, every effort is being made to contain the spread of PSHB in WA,” she said. .
Federal Agriculture Minister Murray Watt said the WA government was managing the response and his department was “keeping me informed of response activities”.