'Last resort' fire ant rafting behaviour raises alarms as wet season begins

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Experts are urging caution as Queensland's wet season ramps up, with fears unique rafting behaviour could assist the spread of fire ants.

Marni Manning from the National Fire Ant Eradication Program says eradication efforts are "on track" and warned people to keep a distance if discovering a nest or raft of ants.

The National Fire Ant Eradication Program has urged the community to work with them to stay on top of fire ant containment.

Experts are warning Queenslanders to be vigilant during the wet season, with fears fire ants could raft up and spread through waterways.

Invasive fire ants have infested about 850,000 hectares across south-east Queensland and northern New South Wales in recent years.

With Queensland's wet season ramping up for another year, National Fire Ant Eradication Program (NFAEP) general manager of operations Marni Manning said now is the time to keep an eye out for the pests.

She said heavy rains and swollen waterways can see the ants "join together" in a rafting configuration for survival.

"The raft is designed to do things like share oxygen, protect the queen and any young, and move themselves to a safer spot," Ms Manning said.

Cassidy Winter is a PhD candidate at Griffith University and said the unique nature of fire ant nests made the rafting behaviour particularly threatening.

"One of the more unique things about fire ants is they will quite frequently have multiple queens in a single colony," Mr Winter said.

He said rafting was not entirely unique to fire ants but the additional queens posed challenges to containment.

"Because of the multi-queen colony thing that they have, they're very easily able to split off and form multiple colonies from the one colony if they raft away," he said.

Ms Manning said fire ants are particularly dangerous in the "last resort" raft configuration.

"Because it is a last resort and therefore it is completely in colony-survival mode, they also increase their toxicity at this time," she said.

"It is very dangerous for people to handle a fire ant nest in water or to handle it when [a raft] has hit the side of a riverbank, because they will latch onto anything they possible can to actually get out of that rafting and the weather and the water."

She urged anyone coming across a nest or raft to exercise caution.

"We ask people if they do disturb a nest, stay well back from it because they can come out at such a rate and they will continue to attack whatever has threatened or disturbed the nest," she said.

Ms Manning said fire ants are "a stand-out in a dirty group of alien invasive species".

"Part of the reason they are considered so bad is their ability to reproduce so quickly, spread quickly across different — including human — systems of movement," she said.

The NFAEP biosecurity zone map covers Brisbane, Logan, and Ipswich, and reaches as far north as the Sunshine Coast and into northern New South Wales, with isolated hotspots across the south-east.

"We have contained it to the south-east corner, and that is an absolute precursor for successful eradication," Ms Manning said.

She urged Queenslanders to work with the program.

"We thank our community and we thank our partners like local governments and industry, but we need you to still continue to work with us," she said.

"We really need your help. We do not want this in Australia."

Mr Winter said various metrics supported the Queensland government's claims eradication was working.

"Even just holding steady for the fire ant containment zone is a massive accomplishment," he said.

"It's going to be very, very difficult to eradicate each of those colonies and stop other groups of fire ants from moving into those now unoccupied areas," he said.