Fire ant eradication attempts may be helping the invaders, study finds

Current attempts to eradicate invasive fire ants are wasting money and might actually help them spread, according to a new study.

Large-scale pesticides called insect growth regulators (IGR), which are usually dropped from helicopters or drones, are the backbone of the National Fire Ant Eradication Program’s (NFAEP) plan to stop the ants from spreading in south-east Queensland and northern NSW.

The ants are known for their painful stings and their ability to ruin crops, agriculture and wildlife.

But their presence and extermination are contentious, and the national body behind the program has accused its opponents of spreading “downright dangerous ... misinformation and disinformation” about its activities.

Governments have spent hundreds of millions of dollars fighting the ants’ spread, with Queensland boosting its contribution by $24 million last year for a taskforce that works alongside the NFAEP.

In a paper to be published in the journal Austral Ecology, Southern Cross University professor Nigel Andrew questioned whether the program’s current mass pesticide tactic is effective.

The paper, which has already drawn criticism from the Invasive Species Council and the NFAEP, argues that insect growth regulators can be successful, but have usually been used in much smaller areas.

“The biggest eradication using IGR has been around 10,000 hectares, which was at the Port of Brisbane,” Andrew told this masthead.

That 2001 infestation was the first official sighting of the ants in Australia. Now, the NFAEP is battling ants from Tweed Heads to the Sunshine Coast, and as far inland as Toowoomba.

A respected and award-winning entomologist, Andrew has appeared in videos produced by conspiracy theorists, who take issue with the government’s methods.

Andrew worked with Professor Joshua King from the University of Central Florida, where fire ants run rampant. He said his study showed IGR also wiped out many of the fire ants’ competitors and predators, such as beetles.

“If we don’t move towards adaptive, ecologically sensitive management that respects the role of biodiversity in urban backyards, industrial parks and rural properties, we risk spending billions of dollars only to help the fire ants win,” he said.

“We are essentially clearing the neighbourhood for the fire ant invader when we mass release IGRs into the environment over large areas,” he said.

Up to 2000 queens can fly from every nest each year to establish their own nests, Andrew said. Each one will then stay underground for up to a month, meaning it evades any baits put in the area during that period.

But the director of advocacy at the Invasive Species Council, Reece Pianta, rejected Andrew’s characterisation of IGR as clearing the way for fire ants.

“On-ground observations and monitoring in Australia’s fire ant eradication area show local ant colonies are thriving where fire ant treatments have been used,” he said after reading the study.

“Australia’s co-ordinated eradication effort has tools that weren’t available to the United States government during its failed eradication effort decades ago.”

A NFAEP spokesperson said their plan was backed by science, and the only proven way to eliminate fire ants in Australia,

“Our current broadscale treatment prevents fire ant queens from producing viable offspring, leading to colony collapse. It remains the only proven eradication method effective at the scale required in Australia,” they said.

“The 2021 independent strategic review confirmed eradication of fire ants in Australia by 2032 is possible.”

The program already used direct nest injection in high-risk areas like parks and schools, they said.

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