Australia’s new ally in war on toads: Meat-eating ants
Australian scientists believe they have discovered a secret weapon in the country’s war on toxic toads with new research suggesting the poisonous amphibians are highly vulnerable to attack by meat ants.
Cane toads were introduced to Australia from South America in the 1930s in a misguided effort to control beetles on sugarcane farms.
But the toads, who are estimated to number more 200 million, pose a growing threat to indigenous wildlife, spreading diseases and eating insects, birds and small reptiles and mammals. Even crocodiles have died after eating the toads, poisoned by their highly toxic venom. The toads are also prodigious breeders with each adult female capable of laying 20,000 eggs.
On Sunday hundreds of Queenslanders took part in the annual “Toad Day Out” ritual, when thousands of the toads are caught and killed with prizes awarded to the most successful toad hunters.
The creatures have to be caught alive and are put to death humanely in an initiative backed by the RSPCA.
But now scientists hope the toads may finally have met their match. Rick Shine of the University of Sydney has discovered that cane toads are far more vulnerable to meat ants than Australian amphibians.
In laboratory experiments, the cane toads were discovered to be less nimble than their native rivals, less vigilant for ant attacks and more likely to freeze if bitten. Australian toads are also nocturnal, whereas meat ants prefer to hunt in the day when cane toads are at their most active.
Worker meat ants are about one centimetre long with powerful jaws. “They’re formidable predators if you’re a little toad,” Shine told the Sydney Morning Herald.
He said the apparent mismatch between the meat ants and the toads could make the little insects an ideal first line of defence – particularly as the ants seem to prey particularly on young toadlets as they emerge from rivers and ponds.
“The ideal way to control toad numbers would be to find a predator that kills and eats toads but leaves native frogs alone. However, bringing in a predator from overseas might have catastrophic consequences, like those that occurred when cane toads themselves were brought in,” Shine said.
“So we’ve explored an alternative approach — to see if we could use a native predator. Meat ants are abundant around tropical waterbodies, and we often see them eating small toads, so we suspected that there might be some kind of mismatch between the invader and its newly invaded range.”