The toad’s eyes seemed to glow red, its warty and poison-soaked skin – normally splodged in browns – instead a porridge of creamy whites. This albino toad was produced by a team of scientists with one foot in a Sydney university laboratory and the other in a research station on the vast tropical savannahs and wetlands far away to the north near Humpty Doo.
It was September 2023 and for the man who dreamed it into being, the toad was but an opening act in a radical new play against one of the world’s worst invasive species.
It was September 2023 and for the man who dreamed it into being, the toad was but an opening act in a radical new play against one of the world’s worst invasive species.
The molecular biologist Maciej Maselko was stunned by how quickly the team was able to successfully inject a cane toad egg with a mixture of proteins and RNA to knock out a gene needed for pigmentation.
“I was astonished,” the Macquarie University associate professor says.
“I mean, I knew it was technically feasible, but we got – within a few months – as far as I hoped we would get within, maybe, two years. Basically, one of our very first attempts at genetically engineering the cane toads worked.”
This, however, was just stage one in the plan put to Maselko – meant only to prove “the capabilities necessary” for stage two. Because the injected tadpoles, normally jet black, were instead pure white, it was immediately obvious that the scientists could, indeed, use Crispr-Cas9 gene-editing technology on cane toads.
Macquarie University’s Prof Rick Shine, an evolutionary biologist, ecologist and author of Cane Toad Wars, has dedicated much of his life to devising novel strategies in the ecological defence against the toads. In 2016, he won the prime minister’s prize for science for teaching quolls and goannas not to eat the invading amphibians by feeding them cane toad sausages.
That year he also won the New South Wales scientist of the year award for developing pheromone traps that lure cane toad tadpoles using the toad’s own poison.
“The Peter Pan approach is definitely [Shine’s] baby,” Maselko says.
By knocking out a single gene in toad eggs, the scientists produced hatchlings unable to metamorphose beyond tadpoles, hence their likening to the boy who wouldn’t grow up.
So how does this tale turn from fantasy to – for a cane toad at least – horror? The answer lies in its brief but storied Australian history.
The cane toad was introduced in 1935 in an effort to stop native beetles devastating sugar cane crops. An utter failure as a biological control, it was spectacularly successful as an invasive species.
The toads now number more than 200 million, having conquered the entire east coast of Queensland, swept across the tropical north, and are now marching down Australia’s west coast. Along the way they have devastated big predators naive to their deadly toxins, from lizards more than 1 metre long to freshwater crocodiles, marsupial carnivores to king brown snakes.
“The history of biocontrol is littered with failures,” Shine says. “But the introduction of cane toads to Australia is one of the classic examples of a truly stupid decision.” (...)
Shine has spent time in the toad’s native South American range. There, kept in check by parasites and co-evolved predators, and in competition with similar species, the cane toad can be “hard to find”.
Largely freed of these population checks in Australia, it thrives in such “fantastic abundance” that a cane toad’s greatest threat to its growing up is tens of thousands of other rival cane toads.
“If you are a cane toad tadpole and a female toad comes along and lays 20,000 eggs in your little pond, there are going to be 20,000 hungry mouths all trying to eat exactly the same stuff that you need,” Shine says.
Over years of observation and research, the ecologist and his team learned Australian tadpoles have responded by becoming irresistibly attracted to the scent of cane toad eggs, which they devour before the competition can hatch.
“We’ve discovered that the toads have evolved to be voracious cannibals in the course of their Australian invasion,” he says.
According to the team’s field studies, 99% of cane toad eggs are eaten in ponds that already have tadpoles – meaning eggs have next to no chance of survival until those tadpoles metamorphose and leave. (...)
by Joe Hinchliffe, The Guardian | Read more:
Image: Terri Shine; TerryJ/Getty Images/iStockphoto
[ed. Truly awful animals (they're also in Hawaii). Thankfully, in the last 60-70 years, the idiocy of introducing non-native species into new environments has been tempered by failure after spectacular failure. Mongoose are another Hawaiian example (nearly wiping out native bird populations because people thought they'd prefer rats). I remember a toad once jumping into our house through an open door and our dachshund immediately pouncing and throwing it back out. She started foaming at the mouth and nearly died from the toxins in its skin. Like I said, awful. Wipe 'em all out.]
“I was astonished,” the Macquarie University associate professor says.
“I mean, I knew it was technically feasible, but we got – within a few months – as far as I hoped we would get within, maybe, two years. Basically, one of our very first attempts at genetically engineering the cane toads worked.”
This, however, was just stage one in the plan put to Maselko – meant only to prove “the capabilities necessary” for stage two. Because the injected tadpoles, normally jet black, were instead pure white, it was immediately obvious that the scientists could, indeed, use Crispr-Cas9 gene-editing technology on cane toads.
What they would produce next was a tadpole that – should eggs dream – would belong to a cane toad’s most diabolical of nightmares. They called it Peter Pan – and it was a “super cannibal”.
But while Maselko and the likes of post-doctoral researcher Michael Clark brought the genetic engineering expertise needed to execute the plan, it was not one of which they had conceived.
But while Maselko and the likes of post-doctoral researcher Michael Clark brought the genetic engineering expertise needed to execute the plan, it was not one of which they had conceived.
That year he also won the New South Wales scientist of the year award for developing pheromone traps that lure cane toad tadpoles using the toad’s own poison.
“The Peter Pan approach is definitely [Shine’s] baby,” Maselko says.
By knocking out a single gene in toad eggs, the scientists produced hatchlings unable to metamorphose beyond tadpoles, hence their likening to the boy who wouldn’t grow up.
So how does this tale turn from fantasy to – for a cane toad at least – horror? The answer lies in its brief but storied Australian history.
The cane toad was introduced in 1935 in an effort to stop native beetles devastating sugar cane crops. An utter failure as a biological control, it was spectacularly successful as an invasive species.
The toads now number more than 200 million, having conquered the entire east coast of Queensland, swept across the tropical north, and are now marching down Australia’s west coast. Along the way they have devastated big predators naive to their deadly toxins, from lizards more than 1 metre long to freshwater crocodiles, marsupial carnivores to king brown snakes.
“The history of biocontrol is littered with failures,” Shine says. “But the introduction of cane toads to Australia is one of the classic examples of a truly stupid decision.” (...)
Shine has spent time in the toad’s native South American range. There, kept in check by parasites and co-evolved predators, and in competition with similar species, the cane toad can be “hard to find”.
Largely freed of these population checks in Australia, it thrives in such “fantastic abundance” that a cane toad’s greatest threat to its growing up is tens of thousands of other rival cane toads.
“If you are a cane toad tadpole and a female toad comes along and lays 20,000 eggs in your little pond, there are going to be 20,000 hungry mouths all trying to eat exactly the same stuff that you need,” Shine says.
Over years of observation and research, the ecologist and his team learned Australian tadpoles have responded by becoming irresistibly attracted to the scent of cane toad eggs, which they devour before the competition can hatch.
“We’ve discovered that the toads have evolved to be voracious cannibals in the course of their Australian invasion,” he says.
According to the team’s field studies, 99% of cane toad eggs are eaten in ponds that already have tadpoles – meaning eggs have next to no chance of survival until those tadpoles metamorphose and leave. (...)
Shine says that unable to transform into toads, his Peter Pans grow larger and exist as tadpoles for as long as three months, as opposed to – under ideal conditions – fewer than three weeks.
Which means that if Peter Pans were put into a pond, they might eat just about every single egg laid in it for an entire breeding season. Then, unable to metamorphose, they too would die.
Which means that if Peter Pans were put into a pond, they might eat just about every single egg laid in it for an entire breeding season. Then, unable to metamorphose, they too would die.
by Joe Hinchliffe, The Guardian | Read more:
Image: Terri Shine; TerryJ/Getty Images/iStockphoto
[ed. Truly awful animals (they're also in Hawaii). Thankfully, in the last 60-70 years, the idiocy of introducing non-native species into new environments has been tempered by failure after spectacular failure. Mongoose are another Hawaiian example (nearly wiping out native bird populations because people thought they'd prefer rats). I remember a toad once jumping into our house through an open door and our dachshund immediately pouncing and throwing it back out. She started foaming at the mouth and nearly died from the toxins in its skin. Like I said, awful. Wipe 'em all out.]
