Carol Booth: Foreign invaders in Australian trees on the march as government quits after $60m investment

I met a Moreton Bay fig the other day — a true elder of this land. It began life before Europeans colonised, when the western reaches of Brisbane were still bushland. Now it stands alone in a pocket-sized suburban park, scarred by lightning and a survivor of several near misses with a chainsaw. But it might not survive much longer. Over the past four years in Perth, many grand old figs as well as paperbarks, banksias, bloodwoods and sheoaks have fallen victim to a beetle whose name on this page — polyphagous shot-hole borer — is some 20 times longer than it is. Now that Australia’s governments have quit funding an eradication attempt, it will likely make its way east. Unable to fly more than a few dozen metres, this Southeast Asian beetle seems an unlikely invader. But over the past 25 years, it has hitched around the world and is now colonising four more continents. It takes just one borer to found a population. An unmated female can tunnel into a tree or shrub, cultivate an edible fungus and lay eggs that hatch sons for her to mate with. If her branch or tree is removed, she can survive, perhaps for months, ensconced in a bit of wood as small as a woodchip. In some trees, the fungus she farms to feed her young spreads and blocks the flow of water and nutrients. In just four years in Perth, more than 40 urban species have proven highly to extremely susceptible, including at least 15 Australian natives. In South Africa, invaded a decade earlier, trees are dying in native forests and up to 65 million urban trees are said to be at risk. So, it was momentous when Australia’s governments recently decided to give up on the Perth eradication after investing almost $60 million and removing more than 4000 trees. Was this teeny beetle too fecund a foe? Or were opportunities missed during the eradication? Could it have been kept out of Australia in the first place? And is the rest of the country now prepared, with plans ready to activate and people on the look out? The Invasive Species Council is calling for an independent inquiry to probe these matters. We applaud Australia’s governments for attempting to eradicate the borer — the investment was trivial compared to the likely cost of managing it in perpetuity — but we need to get better at both preventing and eradicating new invaders and learning from failures. Another new tree-killer, myrtle rust, is already pushing plants to extinction after a fumbled stop-start eradication attempt failed in 2010. And if the eradication of red fire ants in south east Queensland fails, we and our domestic and native animals face a painful future — animals stung to death, wildlife in decline, hundreds of thousands of people requiring medical attention each year, and costs of up to $2 billion a year. What will cross our borders tomorrow? Rock snot, a stream-suffocating alga? The deadly crayfish plague, recently detected in Indonesia? A new eucalypt-killing strain of myrtle rust? The disease killing off stony corals in the Caribbean? The fungus killing millions of bats in North America? The voracious predatory rosy wolfsnails? H5 bird flu, the killer of millions of wild birds and mammals? Australia has an excellent national cost-sharing system for eradication programs and has achieved some outstanding successes. We lead the world on ant eradications. But years of underfunding the south east Queensland fire ant eradication is leading to outbreaks in NSW, the Sunshine Coast and Central Queensland, adding to the costs and risks of failure. Some governments may want to back away from this and other eradications. They seem expensive and success is not guaranteed. But the in-perpetuity costs of not trying, or not trying hard enough, are much greater. The answer is not to retreat from eradications but to be willing to learn from failures. An independent inquiry can show us how to do better in future. Dr Carol Booth is the policy director at the Invasive Species Council