|A cane toad. Photo courtesy of John Abramyan|
13 June 2012
Chemicals used by cane toad tadpoles to seek out and destroy their comrades are being employed by researchers from two Australian universities to help eradicate the species.
Professor Rick Shine from the University of Sydney and Professor Rob Capon from The University of Queensland’s IMB have developed a chemical trap that successfully caught most cane toad tadpoles in a population in laboratory and field trials.
“The rapid spread of cane toads through tropical Australia has been devastating for native predators that are poisoned when they attempt to eat these toxic newcomers,” Professor Shine said.
“But cane toads don’t just threaten native fauna. Intense competition in ponds has led to cane toad tadpoles eliminating rivals from their own species by locating and consuming newly-laid eggs.”
The team analysed the mixture of chemicals emitted by the toad eggs and found that the tadpoles were lured by a class of toxins called bufadienolides.
“Bufadienolides are used by the tadpole eggs to deter predators,” Professor Capon said.
“But by a strange quirk of fate, the toxins are also used by cane toad tadpoles to search out the eggs in order to eat them, so we came up with the idea of adopting bufadienolides as bait in traps for cane toad tadpole.”
In field trials in the Northern Territory, the bufadienolide traps successfully caught tens of thousands of cane toad tadpoles, with none being present in the ponds in the following fortnight.
Bufadienolides are ideal as a chemical attractant for cane toad tadpoles as they also deter other species, meaning that very few native animals were caught in the traps.
It is believed that targeting the cane toads at the tadpole stage of their development as opposed to targeting fully-grown cane toads will be more effective in the quest to control the species.
The team hopes to find a partner to manufacture the traps on a large scale for distribution to community ‘toad-busting’ groups.
The study was published in the international scientific journal Proceedings of the Royal Society B.
Professor Rob Capon - 07 3346 2979
IMB - 07 3346 2134