The fairytale Little Red Riding Hood has inspired Australian scientists to invent a new weapon in the fight to save endangered native marsupials from being poisoned by cane toads.
Cane toads have driven the northern quoll to extinction in many parts of northern Australia and they are threatening to invade Western Australia's Kimberley region, one of the quoll's last strongholds.
But scientists from the University of Sydney have trained a group of 62 young quolls to associate cane toads with feeling sick - a process called "conditioned taste aversion".
Before releasing the quolls into the wild, Professor Rick Shine, Stephanie O'Donnell and Dr Jonathan Webb fed each marsupial a small dead cane toad.
The toads were not large enough to kill the quolls, but they were laced with a chemical that made the quolls feel nauseous.
Webb says the quolls quickly learned to avoid eating toads.
"When we offered them a live cane toad they wanted to eat it. You could see them looking at it," he says.
"The toad was hopping around. It looked like something good to eat, but once they sniffed it they got that signal saying, 'Hey, we're not good to eat' and they ignored it."
Webb says aversion remained when the quolls were released into the wild, wearing radio collars to monitor their survival.
"The quolls that had been trained to avoid toads had a much higher survival [rate] than the untrained quoll," he says.
Webb says the idea for the research came to him while he was reading a modern version of Little Red Riding Hood to his children.
"In that story Grandma sews raw onions into the wolf's stomach, so when the wolf wakes up he feels sick and refuses to eat another Grandma again," he says.
"It dawned on me that if we could teach northern quolls to associate sickness with cane toads, we might have a way of conserving them."
The team is hoping to adapt the same training to other predators under threat.
"The next challenge is to see if we can scale up our results to really make a difference to wild populations of endangered predators like quolls, goannas and bluetongue lizards," says Shine in a statement.
"First, we have to check that the aversion we create to cane toads is long-lasting.
"If it is, the next step is to refine our delivery methods - for example, perhaps wildlife agencies could aerially deploy 'toad baits' ahead of the cane toad invasion front to educate quolls to avoid attacking cane toads before the toads invade."