Could a little beetle threaten Australia’s foodbowl?

Carrying around 14 trillion liters of water a year, the Murray River eventually empties into the Southern Ocean south of Adelaide through a vast network of estuaries and lagoons.

Two and a half thousand kilometers away, streams trickling from melted snow are modest enough to be flanked by hikers heading towards Australia’s highest peak.

Imagining a connection between the two seems almost as fanciful as chaos theory’s quotes about the butterfly flapping its wings to cause a distant disaster.

Yet it’s true.

The official source of the Murray River is located 40 km south of Mount Kosciuszko, Indi Springs, on the NSW-Victorian border.

But further upstream, along with dozens of smaller streams and streams, this normally unremarkable river is fed by the slow release of seasonally frozen groundwater that has been covered by snow for months.

Despite the uplands accounting for only one per cent of the river’s total catchment, more than a quarter of the Murray’s massive flow is thought to originate from this route.

Concerns are now growing that the mountains’ iconic snow gum population, guardians of this remarkable ecological contribution, is under constant siege.

Localized fallback eucalyptus pauciflora It was first discovered in Kosciuszko National Park in the 1990s.

However, more widespread damage – native wood-boring longhorn beetles, with the confirmed identity of the culprit – has only recently been recognized and there is evidence that climate change is worsening the problem.

Gums are currently in sharp decline across all subalpine habitats, from Mt Buffalo in Victoria to Kosciuszko and the ACT’s Brindabella Ranges.

The invasion is relentless and, according to experts, it is spreading rapidly.

Warmer winters and drier summers due to climate change, Phoracantha masters develop and spread.

Dieback is highly visible and poses a threat to all of Australia’s snow gum forests between 1600 and 1900 m above sea level.

Typically trees are devoured from top to bottom, with insect larvae penetrating their bark and feeding on the ‘veins’ and ‘arteries’ they use to transport water and nutrients to and from the soil.

When ringing scars appear, the gums are already dead or dying.

“This is not a minor problem at the local level,” according to Dr Matthew Brookhouse of the Australian National University.

He says few Australians are aware that snow gums play a huge role in retaining and supplying water to the Murray-Darling Basin.

“If you reduce the water-producing capacity of these areas by removing tree cover, you lose significant amounts of water.

“The beetles hit these trees over and over again until they die,” he adds.

“They are the only trees that can withstand harsh conditions at higher altitudes, endangering everything that depends on them.”

Consider sphagnum moss, a true sponge that can absorb 20 times its own weight in moisture; reed, known for its ability to filter and slow water movement downhill; and numerous mountain herbs and grasses that support infiltration.

Except for the troubles, each of these mechanisms is eliminated and the land is left wide open to indiscriminate currents.

Dr. Brookhouse says less water directed into the system could impact everything from food production to the abundance of wildlife in low-lying wetlands.

Like the fictional butterfly effect, flow is potentially disastrous.

Serving as the border between the country’s two most populous states for approximately 2000 km before crossing into South Australia, the Murray provides water to approximately 1.5 million households.

Established regional centers such as Albury-Wodonga, Echuca, Swan Hill, Mildura, Renmark and Murray Bridge all rely on the river to some extent for their livelihood.

Regulated by 35 dams, weirs and impoundments, the Murray-Darling Basin is managed by both the federal and state governments; its stakeholders include multiple industries and smaller communities.

Including interconnected lakes and rivers, the system covers one million square kilometres, the equivalent of 14 per cent of Australia’s total land mass.

It accounts for more than a third of the country’s food and fiber production.

The Murray is also home to countless wildlife, with significant populations of kangaroos, koalas, wallabies, turtles and platypuses along its route and 46 native fish species found along its shores.

Upstream, as the air in Australia’s highlands becomes warmer and drier, more moisture is withdrawn from the snowpack.

These are the conditions in which the voracious longhorned beetle thrives, according to the research led by ANU postdoctoral researcher Callum Bryant.

“Wood borer damage was first observed around 2017, following an extreme El Niño event in 2015/2016,” he and his colleagues say.

“However, the current study, conducted in 2022, also noted that 11 percent of trees examined showed evidence of recent borer damage.”

It is hoped that better-hydrated surviving trees will have a better chance of resisting insect populations in the future, while drier gums will allow the insect to proliferate.

But frequent periods of drought and fire are more likely to offset whatever recovery the gums can recover.

Using temperature-based models, Dr. Brookhouse determined that: Phoracantha masters He may actually be doubling down on his campaign.

“In the past, they usually emerged from their pupal chambers in the snow gum forest in late February,” he says.

“But in recent years this has happened as early as December.

“This means they now have a much longer period of time to mate, lay eggs and attack trees.”

The challenge will be to find a landscape-scale solution among the insect’s natural enemies.

Parasitoid wasps or other insects that tend to attack longhorn beetle eggs are prime candidates.

Dr Brookhouse and his team are already working to identify and trap the right pest controllers, but this is a huge task and not yet being carried out in enough places.

“This is our best chance, but we need to step up our efforts across large areas of Australia to find them,” he says.

“Achieving this will rely on ongoing partnerships between universities, parks and forest management agencies, as well as the private sector and the community.”

NSW Parks and Wildlife Service meanwhile Dr. He’s been watching the decline in snow gum as he awaits the results of Brookouse’s study and another project investigating pheromone-based trapping of male insects.

Significant progress was also made through the voluntary planting of 2,800 replacement snow gum saplings in multiple subalpine regions.