Scientists identify the cane toad’s deadly enemies

A scientific breakthrough could finally curb the explosive numbers of Australia’s cane toads, the feral pest that has spread across the continent.

After years of work, the cane toad genome has been sequenced, leading to the discovery of three cane toad-specific viruses that have the bio-control potential to halt the seemingly unstoppable spread of the toxic amphibians.

Originally from South America, cane toads have so successfully adapted to the Australian environment that they now number in the hundreds of millions across the nation. They are a threat to native animals, fatally poisoning the northern quoll, freshwater crocodiles and several species of lizards and snakes.

Peter White, the project leader and a professor in microbiology and molecular biology at the University of NSW, said the viruses were potentially useful in controlling the toad spread, just as viruses helped suppress rabbit plagues in the 1950s and 90s.

“I’m a virologist, so I was interested in finding viruses to control the cane toad population,” he said. “One way of doing that is to look through the genome, so I went to get the ­genome, but the genome wasn’t there. When I looked around, I saw a West Australian team had a go at doing it in about 2007.

“They got sequences but they couldn’t put them together again — they weren’t able to assemble the jigsaw puzzle. But we succeeded because we are using more modern, third-­generation technology, and we assembled a very good team to do each of the steps of the genome.”

He said number-crunching bio-mathematicians used supercomputers over two years to complete the research, and the findings, freely available to all scientists, were published in academic journal GigaScience today.

The cane toad’s genetic sequencing helped scientists pinpoint the cane-toad specific viruses, detailed in research published in an earlier paper in the Journal of Virology.

Now scientists from the University of Sydney, Deakin University, Portugal and Brazil have the blueprint of the cane toad and further cane toad sequences will be a fraction of the cost.

Professor White said the breakthrough would permit scientists to sequence cane toads from the beginning of their journey in French Guiana in South America through Puerto Rico and Hawaii to the introduction of 101 toads in Queensland in 1935 to control the cane beetle, and then the toad’s westward and southward spread.

Along the way, the cane toad evolved to cope with local conditions. Mapping its genome will help scientists understand this remarkable adaptation, he said.