Calls for Defence land audit as source of army base fire ant infestation confirmed (2024)

DNA testing has confirmed invasive fire ants found at a southern Queensland army base are linked to an existing Brisbane infestation, prompting calls for an audit of all Defence land.

Queensland Premier Steven Miles told Parliament compliance and tracing investigations were ongoing, but theinsects found at Oakey, west of Toowoomba, were from inside the existing biosecurity zone.

"It is highly likely, I am advised, that the ants arrived in the area from a turf farm within the south-east Queensland infestation zone," he said.

"Eradication activities will continue to occur up to five kilometres out from the detection site to protect the area and ensure no fire ants are remaining."

In a statement, a spokesman for Defence said the department was working with the National Fire Ant Eradication Program to support the incident response and to mitigate the spread.

"Defence applies stringent biosecurity protocols on Defence land, including restrictions to the movement of soil, pests and weeds," the spokesman said.

But he did not respond to questions about whether searches were being conducted on Defence land outside of the detection area that had received vehicles or aircraft from the base.

"The National Fire Ant Eradication Program is leading the treatment and monitoring of the Red Imported Fire Ant detection at Swartz Barracks, Oakey," he said.

Defence land of 'particular concern'

Fire ants have been found just south of Ballina in New South Wales, west to Oakey, and north to Morayfield north of Brisbane.

The Invasive Species Council, a not-for-profit organisation which advocates for the eradication of pest species, said an independent review of the fire ant program prepared for the Queensland government in 2021 had identified Defence land as a particular concern that could act as a "reservoir for reinfestation" if not included in suppression programs.

Advocacy manager Reece Pianta said he had written to the Defence and Agriculture ministers asking for an audit of all south-east Queensland and northern New South Wales defence land.

"And any properties that may have engaged contractors from this site or had shipments of freight and cargo from this site," he said.

"We think that it should be prioritised that some checking and an audit take place to make sure that there are no other fire ant infestations hidden away on defence land in other parts of Australia."

A spokesperson for the National Fire Ant Eradication Program, which is administered by the Queensland Department of Agriculture through Biosecurity Queensland, said 137 hectares of land at the site had been surveyed for fire ants, with a further 184 hectares treated as a precaution.

"We can confirm that all fire ant nests originally detected are contained to one infected property and have been treated," the spokesperson said.

"It is not unusual for remnant ants to re-establish nests before they die from the treatment.

"This does not mean the ants are spreading."

Mr Pianta said the nests on the base were found in two clusters, which was unusual for fire ants.

"There are 78 to about 120 nests, all tightly packed into a very small area on the property," he said.

"That's surprising because fire nests usually do spread out, particularly these type of single queen colonies that have been at the site."

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He said there were two types of fire-ant colonies— multi-queen colonies that spread by queens walking to new locations, and single-queen colonies that spread by flight.

"The furthest that a queen has ever been recorded flying is 32 kilometres, and that was in very favourable winds and it was a lightweight queen," Mr Pianta said.

"The average distance is actually a couple of hundred metres, but people in and around the area should keep their eye out up to a few kilometres away.

"There is a risk they could have flown quite some distance to establish a nest in a new location in the Oakey area."

Creek beds still being checked

Mr Pianta said it would take years of work before the pest was eradicated from the site, which sits about 60km west of the existing biosecurity zone.

"It's very encouraging because that they have now checked so many hectares around and not found any further nests," he said.

"It's probably a sign that they might not have spread, but it will take years of surveillance to make sure that the area is clear."

The spokesperson for the eradication program said it was confident infestation was contained, and that the origin and possible movement of the ants was being traced.

"Our program is conducting testing to determine genetics, social form, and prospect for spread, be that by flight, land, or waterway," they said.

Known for the ability to 'raft' on waterways, Mr Pianta said work had started to check nearby creek beds for signs of the ants to determine if they had travelled into the Murray Darling Basin through the Condamine-Ballone river system.

"One of the things that we'd like to see is the deployment of environmental DNA (EDNA) technology, where a screen is taken of topsoil and checked for fire ant DNA," he said.

"To make sure that fire ants haven't formed rafts because there have been recent flooding events in this community over the past few years."

"It's (EDNA) available and can be deployed relatively quickly and this would be a perfect test case to see it be used in the field."