Image credit: Wikimedia Commons
The poisonous cane toad, which was introduced from Hawaii in 1935, has become a scourge in Australia. Native to South America, the toad was imported into the Pacific Islands and Australia as a means of pest control. Once there, however, the carnivorous and voracious toad preyed upon smaller native species and killed predators that fed upon it.
The Australian meat ant could devour the invasive toad problem. Image credit: dnatheist/Flickr
The new management technique is based on a discovery made in 2009 that the cane toad was more vulnerable to Australia's native meat ants than other species of frogs and toads. Cane toads, researchers found, share the same open habitats and are active during the same times of day as the carnivorous ants. Native frog and toad species, in comparison, are mostly nocturnal and hide in tall grass during the day.
Using a native predator to control the population of an invasive species is key, as it avoids the pitfalls inherent in introducing a foreign species—the very pitfalls that led to the cane toad outbreak in the first place. Once a native predator was identified, conservationists had to find a way to increase its interactions with the toads.
The solution, they have found, may be cat food. A small dollop of ordinary cat food placed in the middle of a toad habitat attracts ants into the area. These ants leave trails that attract others and, once the cat food has been consumed, they move on to nearby toads.
Rick Shine, the University of Sydney professor who led the study, explained:
The worker ants then leave trails back to the nest encouraging other ants to come out there and forage in that area, and within a very short period of time we got lots of ants in the same area as the toads are...even the ones that don't die immediately, die within a day or so of being attacked
By targeting areas in which baby toads emerge from a pond for the first time, researchers were able to kill 70 percent of the cane toads in a localized area with this technique.
This discovery could be an invaluable tool for conservationists trying to minimize the ecological destruction caused by the toads, but it also has implications for the control of other invasive species. Shine explained:
Such evolutionary traps should be especially common for invasive species, because so many aspects of their environment differ from those in which the traits of that species evolved.
Finding and exploiting such traits will be essential for conservationists working to control the invasive species in Australia and around the world.
Read more about invasive species:
The World's Most Lovable Invasive Species (Slideshow)
Destructive Impact of Invasive Species Measured In 57 Countries
Eating Aliens: Are Invasive Species Ethical Food?
The Iron Curtain Stopped Invasive Species