Cane toad advance (2002)
The cane toad was introduced into Queensland in 1935 to combat the sugar cane beetle It has since spread far and wide and is now a pest. Scientists are using gene technology to interfere at the metamorphic stage of the frog’s life cycle and to stop it becoming an adult.
[Music plays and the words “sci files” flashes around the screen]
[An aerial image of Canberra City appears on screen and the camera pans over and stops at Parliament House. The sound of a rowdy parliamentary session can be heard]
Narrator Australia’s political capital is used to insults about the types it attracts, but there’s one new arrival in Canberra who aptly fits the description of fat bellied and slimy.
[Image changes to show a group of cane toads]
It’s the cane toad!
Brought into Queensland in 1935 to combat the sugar cane beetle, cane toads have now spread far and wide, even invading Kakadu National Park in the Northern Territory.
They have no known natural predators and viruses from their native Venezuela are lethal to some of our native frogs. So CSIRO researchers have brought them to Canberra to try and stop their spread with gene technology.
[Image changes to show John Bray holding a cane toad]
John Bray: Environmentally they’re bad, but they do grow on you.
Narrator: The toads are well looked after, in a home heated to 27 degrees and they receive a weekly bath.
[Image changes to show John placing the cane toads into a container of water]
John Bray: I generally leave them in there for an hour or an hour and a half. This gives them plenty of time to shed the old skin and clean up the new area. They certainly appreciate it.
Narrator: Then after the bath comes the romance. The toads are injected with hormones to get them in the mood, then left overnight to mate.
[Image changes to show a cane toad being injected and then to two frogs mating]
John Bray: We just put one male and one female in each tank and you come in the next morning and there’s thousands of eggs just wrapped in nice concentric circles around the rock. Then we transfer them into smaller tanks and the next day the tadpoles start hatching.
[Image changes to show lots of tadpoles swimming around]
Narrator: So far the team has just been assisting nature, but now the real science begins.
[Image changes to show the tadpole being injected]
This tadpole is being injected with an adult toad protein called Betaglobin, in the hope that its antibodies will reject it. If that happens then its antibodies should also reject the tadpole’s natural Betablobin when it occurs, stopping it from turning into an adult.
[Image changes to Suze Tarmo]
Suze Tarmo: We’re injecting them with a possible protein that could be used in halting the metamorph of the tadpole into the toadlet.
[Image has changed back to the cane toads]
Narrator: Once the method is perfected, the gene that stops the maturing of the toad will be isolated and introduced into the toad population, before they get to Canberra by themselves.
[Music plays and the words “sci files” appears on the screen]