SUNDAY TIMES (Perth, Australia) 09 April 08 Worm attacks cane toad menace (Narelle Towie)
A worm that feeds on blood may reduce the westward march of the dreaded cane toad to a stumble before the pest reaches WA, scientists believe.
The parasitic worm, which weakens amphibians by attacking their lungs, has been discovered in cane toads near the WA border.
The breakthrough gives environmentalists hope that the worm may wipe out the toads, one of the world’s most invasive species, before they cross the border, or at least cut their numbers sharply.
Cane toads were introduced to Australia 73 years ago from South America, in a failed attempt to rid Queensland sugar cane from leaf-destroying beetles.
The toads are prolific breeders and their poison glands kill native animals.
The pests took quickly to their new home, colonising Queensland, NSW and the Northern Territory, and have spread to within 25km of the WA border.
Researchers have known for some time that the toad may have an Achilles heel.
They hoped its vulnerability to the lung-worm, believed to be passed on by native frogs, may represent a biological tool for wiping out the wildlife menace.
However, hopes were dashed when the toads arrived in the Northern Territory and became less infected by the parasite, which kills small and immature cane toads and metamorphs.
Scientists concluded the cane toads had outrun the parasite, moving too quickly to become infected.
“When you look at toads on the front line, they didn’t seem to be picking up the parasite until that parasite has become established in the toad population - which could take up to 10 years,” frog parasitologist Dr Diane Barton said.
Now Jordy Groffen, a researcher from the Netherlands’ Delft University who is working with toad buster volunteers in the Kimberley, has discovered lung-worm in cane toads near the WA border even though toads have been there for only two or three years.
Researchers think the much dryer Kimberley landscape may be giving the parasite the upper hand.
Lung-worm fares poorly in wetter areas such as those found in the marshy Northern Territory.
“Across the Northern Territory, where you have lots of marshy wet areas, the parasite is there but it’s not easy for it to infect the host, because its such a massive area of flooded wet plain and there is limited chance that they would be able to find the toad,” Dr Barton said.
“Whereas the Kimberley are more like Queensland and it is a little bit dryer, so the parasite is able to cycle a lot more effectively.”
Volunteer group the Kimberley Toad Busters have called on the Department of Environment and Conservation to allow Dr Barton and Mr Groffen to conduct research on native frogs close to WA, to study the lung-worm parasite more closely.
Worm attacks cane toad menace