An unlikely combination of sausage and dogs is being used to combat one of the world’s most invasive ant species that has established a stronghold in Far North Queensland.
Electric ants, native to Central and South America, were first detected in Cairns in 2006 and have since caused problems for humans, pets and the far north’s native flora and fauna.
Dr Lori Lach, who studies biological invasions and insect ecology, said the electric ant was considered one of the world’s five most invasive ant species.
“It’s really small, even for an ant, and therefore it’s really hard to detect,” Dr Lach said.
What the electric ant lacks in size, it makes up with its venomous sting – in large groups, the ants are capable of incapacitating animals much larger than themselves.
“They eat anything,” said Gary Morton, principal project officer for the National Electric Ant Eradication Program (NEAEP).
“They’ll eat other ants, other insects, small vertebrates like skinks and geckos, and newly hatched animals.
“So where we find them in large densities, we don’t really find many other [living] things.”
Electric ants can cause problems for humans too.
Dr Lach, who was willingly stung by electric ants when she found them on her property north of Cairns, said large infestations of the species in agricultural areas can prevent manual harvesting of crops, as workers fear being bitten by swarms of the ants.
“It’s like a really intense sharp burn for a little bit, then a tingling sensation for a while afterwards,” she said.
“At least on me, the sting was much more potent than what a red, imported fire ant is capable of.”
And for people allergic to bees, wasps and other insects, electric ant stings can trigger anaphylaxis, causing symptoms that range from swelling to shortness of breath and can lead to death.
Sausages attract ants, dogs clean up the scraps
To locate infestations of the ants, the NEAEP relies on a particular brand and style of sausage.
“They have a real taste for Don Skinless Footy Franks,” Mr Morton said.
To gauge whether a property or area is infested with electric ants, slices of sausage are skewered on wooden sticks with brightly coloured flags, which are then planted in the ground.
In residential areas, that means sticking skewered sausage on roadside verges and nature strips.
“Generally, if there are ants in people’s yards, then they’ll be out the front along the verge, so it’s a very quick and easy way for us to do surveillance without needing access to people’s properties,” Mr Morton said.
When ants are discovered, teams move outwards from the area, repeating the skewered-sausage process until they establish the perimeter of the infestation.
“We’ll then put a buffer around those properties and treat the area up to three times before we start our post-treatment surveillance,” Mr Morton said.
The NEAEP employs the world’s only known electric-ant-detection dogs – four of them – reportedly capable of sniffing out even a single ant.
“We send the dogs in to the area up to three times after the treatment, and when they tell us that there’s nothing there, then we do one more round of [sausage] trapping,” Mr Morton said.
“If there’s still nothing there after that, then we declare the area free.”
Consistent funding key to eradication
The battle against the invasive species itself is not the only one the NEAEP has fought since it was established in 2006.
Receiving consistent and adequate funding has also been a struggle.
The NEAEP was jointly funded by the Commonwealth and Queensland governments in the 11 years after its inception, but when federal funding dried up in 2017, it was left to the state to run the program.
Dr Lach said the program had whittled down Far North Queensland’s electric ant population to just a few small infestations when the Commonwealth funding ran out.
“And that’s the pattern we see over and over with eradications,” Dr Lach said.
“There’s a problem, eventually funding is provided, people get on top of it and therefore the complaints stop and then everybody moves on to the next thing.
The electric ant was named in the Commonwealth’s National Invasive Ant Biosecurity Plan 2018-2028 and federal funding has since been reinstated to the NEAEP.
But Dr Lach said if the funding had been consistent since the species’ discovery, the battle against it may have already been won.
“When teams go back out after being cut to a skeleton crew just doing what it can, they go back out to find that they [the ants] have spread again and that’s what needs to be avoided,” she said.
“This is one species where we have the right treatment regime that can knock them out … we’ve got something that works, so it just becomes a resource game.”