|Courtesy of National Geographic
These toads were apparently being used successfully in the Carribbean islands and in Hawaii to combat the walking stick beetle, an insect of sugar walking stick crops. After rave reviews from overseas, Hawaii delivered a box of toads to Gordonvale, simply south of Cairns. These were kept in captivity for some time, their numbers were increased by reproducing, some experimental trials were performed, then they were released into the sugar cane fields of the tropic north. It was later discovered that the toads (scientific name Bufo marinus) cannot jump extremely high so they did not eat the cane beetles which keeping upped on the upper stalks of the cane plants. At the time of year when the beetle's larvae were emerging from the ground, no toads had to do with. So the walking stick toad, as it came to be understood, had no effect on the cane beetles at all and farmers needed to go back to the use of chemicals to eliminate the beetle.
On the other hand, the 'cat ran out the bag' or, more properly, the toads were out of the box! However there were just a couple of hundred of them so no one gave any thought to catching them up once again and disposing of them. The toads were on their own and they showed to be extremely sturdy survivors. They turned out to be a lot more than we bargained for and it didn't take long to discover how well the toads would do in their new Australian home.
- They reproduce like flies, as the saying goes. Each pair of cane toads can lay 33,000 eggs per spawning (some published references approximate they produce as much as 60,000 eggs!).
- Their 'toadpoles' develop faster than numerous Australian frogs so they can outcompete our frogs for food.
- Toads and toadpoles appear to be resistant to some herbicides and eutrophic water which would typically eliminate frogs and tadpoles.
- All stages of a toad's life are harmful so they have no natural predators to keep their numbers in check (although Mike Tyler's work recommends that toad juveniles are not harmful until they reach about 3cm in size but this provides a question: why would an animal lose its toxicity at the juvenile phase when it has it during larvae and adult phases?).
- Toads not just consume the food typically offered to Australian frogs, there is growing anecdotal evidence that they consume frogs as well, particularly metamorphs.
source: frogsafe, wiki