Australia’s cane toads evolved as cannibals with frightening speed

The list of ‘deadly animals in Australia’ just got a little weirder. The cane toad, a toxic, invasive species notorious for devouring anything it can fit in its mouth — household rubbish, small rodents and even birds — has become highly cannibalistic in the 86 years since it was introduced to the continent, according to a new study. Its counterpart in South America, where cane toads originated, is far less cannibalistic.

The discovery could help researchers to understand the evolutionary underpinnings of how this uncommon and extreme behaviour emerges. Scientists have seen cannibalism evolve in species before, says Volker Rudolf, a community ecologist at Rice University in Texas, who studies the phenomenon. But what’s exciting about this work, he says, is that the researchers are almost seeing it “develop in front of their eyes”, given that the behaviour arose in less than a hundred years — the blink of an eye by evolutionary standards.

“These toads have gotten to the point where their own worst enemy is themselves,” says Jayna DeVore, an invasive-species biologist at Tetiaroa Society, a non-profit organization in French Polynesia, and a co-author of the study, which was published on 23 August in Proceedings of the National Academy of Sciences of the United States of America1. Scientists estimate that there are well over 200 million of the amphibians in Australia. They have become so abundant, says DeVore, that they face more evolutionary pressure from each other, as they compete for resources, than from anything else in Australia.

Tadpole terror

Farmers first introduced about 100 cane toads (Rhinella marina) to Australia from their native range in South America in 1935 to control cane beetles (Dermolepida albohirtum), which were wreaking havoc on sugarcane plantations. The giant toads failed to knock down the beetle populations, but they succeeded in epically multiplying. Because of their highly poisonous skin, which is coated in bufotoxins, they had no natural predators and went on to invade large swaths of the northern and eastern parts of the country.

Although adult cane toads are fearsome — they grow up to 25 centimetres in length — it’s their tadpoles that are usually the cannibals. Multiple tadpoles together can gobble more than 99% of the hatchlings that emerge from the tens of thousands of eggs in a single clutch2.

DeVore and colleagues were curious to see whether the cannibalistic behaviour was common across all cane toads, or if it was due to how invasive the Australian ones are. So they collected cane toads from Australia and from French Guiana, and bred them to produce hatchlings and older tadpoles. The team then exposed a single tadpole to 10 hatchlings from its group — either from Australia or South America — hundreds of times and found that invasive Australian tadpoles were 2.6 times as likely to cannibalize hatchlings as native South American ones.

Researchers have long known that the Australian tadpoles are attracted to the hatchlings because of the scent of the younger animals’ toxic skin. “You’ll get this huge avalanche of thousands and thousands of tiny cane-toad tadpoles coming toward this chemical,” says Rick Shine, an evolutionary biologist at the University of Sydney in Australia, and a co-author of the study. DeVore, Shine and co-workers saw this play out in their experiments: the Australian tadpoles were nearly 30 times as likely to swim towards a trap containing hatchlings as an empty trap, and the South American tadpoles showed no preference for either.

Although the speed with which the toads evolved this behaviour is impressive, the team was even more surprised by how fast the animals evolved a defence to protect against it. The researchers found that when invasive Australian hatchlings shared a tank with caged, older tadpoles from the same group, the hatchlings were more likely to have a shorter developmental period than that of the South American hatchlings. Older tadpoles don’t tend to eat older tadpoles — so the toads might have evolved to speed up their hatchling phase, the researchers found. This would limit the amount of time they spend vulnerable to cannibalism, even if the adaptation eventually stunts their growth, says DeVore.

Roshan Vijendravarma, an evolutionary biologist at the Curie Institute in Paris, who has studied cannibalism in fruit flies, says the differences between the invasive and native toads’ behaviour probably have a genetic basis, given how extreme they are and how quickly they evolved over relatively few generations of toads.

Shine and his colleagues think this idea is worth exploring and are studying it now. Although there are still mysteries around the cane toads’ cannibalistic tendencies, one thing is for certain, says Shine: “The cane toads that are currently hopping across Australia are extraordinarily different animals from the ones that were first taken out of the native range.”

O’Connell River irrigation ban leaves Whitsunday farmers in lose-lose situation

A North Queensland farmer fears the state government’s snap decision to turn off the tap to a major river tributary will damage both his crop and the Great Barrier Reef. 

Tony Jeppesen said while a closure of the O’Connell River was expected, the move was made weeks earlier than in other years, blindsiding growers and leaving them unable to water newly planted crops.

The Bloomsbury-based farmer said this could put he and others in violation of laws requiring them to prevent environmental run-off. 

“I’ve already contacted the Department of Environment and told them I’ll be in breach,” he said.

“I can’t do anything about it because of the conditions the local [department] office has placed on us.  

“It could cost jobs, it’s going to cost the environment, it’s a stupid decision.”  

A department spokesperson, however, said irrigators should have foreseen the ban and were given reasonable notice to stop taking water from the river and its tributaries in the Whitsundays.

Communication breakdown

Mr Jeppesen grows sugar cane and broadacre crops across four properties that use water from the O’Connell tributary and employs about 12 people. 

“It takes months to plan our cropping programs; we try to get a couple of cover crops in, it’s great for our soil biology and soil structure, and in one week they’ve destroyed that,” he said.

“I’ve just planted 46 hectares of cover crops … finished Friday afternoon, [and now] we can’t actually water them, so they’ll die.”

The government spokesperson said irrigators were notified of limitations on August 6 by letter and notification on its website. 

Mr Jeppesen said his letter did not arrive until August 18. 

a rocky creek with some water in it
Mr Jeppesen says restrictions on irrigation have come earlier than ever before.(Supplied: Tony Jeppersen)

Under the restrictions, he is permitted to water three nights a week — Mondays, Wednesdays and Fridays. 

He finalised planting on Friday, fertilised and set up irrigation systems over the weekend with plans to water Monday evening as per restrictions, but received a call on Monday from his local Canegrowers branch informing him that all irrigation was now banned. 

On Tuesday, Mr Jeppesen received a text from the department confirming the ban. 

It was not the first time Mr Jeppesen had issues with not knowing when allocations had changed, and said the website was not a reliable way to get information to farmers.  

“It’s like them putting in a stupid website somewhere that no-one can see and saying there’s now a 50-kilometre speed limit on the Bruce Highway and charging everyone the next day a big fine,” he said. 

Between a rock and a hard place

The effort to protect the health of the O’Connell River system is not what frustrates Mr Jeppesen.

“We’re not saying we shouldn’t be on restrictions, we’re saying they have to be incorporated in a way that doesn’t do environmental damage to the system,” he said.

“They have to be incorporated in a way that works with landholders. 

“[Now the crops are planted], there’s legislative requirements in the sugar industry we have to comply with, so I must water some products in so there’s less chance of [soil and fertiliser] moving.” 

Mr Jeppesen said that in previous years when more warning was given, restrictions increased incrementally from nights only to five and then three nights a week, before a week’s warning was issued ahead of a total water ban. 

Amanda Camm, the LNP member for the Whitsundays, said she had written to Water Minister Glenn Butcher requesting an urgent audit of the system. 

“Information that the department makes decisions on should always be transparent,” she said.

“Growers pay for these allocations, they pay for water licensing; I think it’s upon the department to always be upfront and share information as soon as it comes to hand.” 

Ms Camm also said she was concerned for the lose-lose position growers now faced. 

“The challenge the state government has delivered to farmers is what decision do they make?

“Do they take water they’re not meant to take to make sure they comply with legislation around run-off, around reef regulations, or do they plough it into the ground also risking that they may not comply with legislation?” 

Mr Butcher’s office declined to comment.

Regional industry: How Wide Bay Burnett loses and wins

The Wide Bay Burnett region about three hours’ drive north of Brisbane has mastered the art of keeping skilled workers after industries shut by gaining new employers. It is also trying to recruit people, including students and grey nomads, to help industry and farmers deal with shortages due to Covid border closures.

Its city of Maryborough has lost its MSF Sugar mill and about 75 jobs this year after 126 years of operation but it is keeping its Downer train manufacturer and gaining a defence artillery-shell factory being built by a partnership between Germany’s Rheinmetall and Brisbane small-arms company NIOA.

MSF Sugar was forced to shut its mill at Maryborough by a broad decline in the sugar industry and falling cane supply in that region – but one reason for that was Rural Funds Management’s purchase of 5409 ha of MSF Sugar’s cane land for planting with lucrative macadamia nuts.

The director of regional development for Wide Bay Burnett, Scott Rowe, says the mill closure “could have knocked the confidence out of the region. But the munitions facility, the venture with Rheinmetall, has been a really positive thing and gained national and international interest.’’

Rowe, who manages the local agency of Regional Development Australia, says the majority of mill workers were picked up not only by local manufacturers but also the munitions facility.

“Our region also has three major meatworks, and the Swickers Kingaroy Bacon Factory is the largest pork-processing facility in the southern hemisphere.’’

Maryborough currently has the lowest rental vacancies in Queensland, and our meatworks are having to buy up houses to try to attract and retain workers, he says.

“We are also the largest softwood producer in Queensland and our timber workers are putting in 24/7 just to keep up.’’

The region, which includes Bundaberg, Kingaroy and Hervey Bay, already has a diverse economy with health care and social assistance the highest employer so in a way Covid helped keep jobs, Rowe says.

“Agriculture, food and beverage manufacturing have really held on. But tourism, hospitality, retail – like everywhere else – have been knocked around,” he says.

“Water will always be the greatest issue for regional Queensland, but workforce is probably No.2 at the moment.

“Our citrus crops have only been picked once instead of twice this season due to the shortage; workforce is a real problem.

“An aircraft manufacturer in Hervey Bay is trying to get people in from overseas. The Kingfisher Bay Resort on Fraser Island is operating at 70 per cent capacity due to an inability to attract workforce.

“We’re trying to close the gap by putting in regional jobs committees that are working with industry, and helping forecast what they’re going to require in skilled labour. TAFEs and training centres and universities are collaborating to try to close that gap.

“We’re even trying to get school kids to get friends together in holidays and pick fruit, and getting grey nomads up and into caravan parks and put a bit of jingle in their pocket to help with the [farm] pick. They’re trying everything they can but we need those overseas workers and tourists back.’’

Terrain NRM soil health coaching workshop success for Tully producers

Growers in the Tully region welcomed the opportunity to participate in a soil health coaching workshop to improve their mentorship skills in regenerative farming practices.

The one day workshop held in May, was coordinated by Terrain Natural Resource Management group, and delivered by agro-ecologist and soil health expert, David Hardwick from Soil Land Food.

Sharing his passion for regenerative farming practices, Mr Hardwick’s workshop focused on equipping northern producers with the tools necessary to provide confident extension to their peers and facilitate behavior change to promote healthy landscapes.

Terrain NRM Tully Basin coordinator Fiona George said the workshop attracted the attention of eight growers and four extension staff.

“It was useful to have both growers and extension professionals in the same forum, as essentially we were teaching the growers how to improve their extension skills,” she said.

Soil health was one of the many topics covered on the day, with growers also receiving training in areas to improve their extension and communication skills.

Mr. Hardwick said the growers who attended the workshop were already great communicators, regularly bouncing ideas, and openly sharing knowledge with their peers.

“These guys are already getting a number of calls a month from other farmers wanting to talk through ideas and results, or get a feel for how regenerative practices might fit into their farming system,” he said.

“This workshop was about equipping those guys with tools to better support their peers through change.”

Growing confidence - Tully farmers gather to discuss soil health and regenerative farming practices.
 Growing confidence – Tully farmers gather to discuss soil health and regenerative farming practices.

With more producers converting to regenerative farming practices, it was felt the importance of maintaining peer to peer networks would be integral for positive growth.

“Implementing regenerative practices that improve soil health makes absolute sense for improving long-term productivity and profitability, but change isn’t without challenges,” said Mr Hardwick.

“Soil health is a really important topic. Knowing how to communicate soil messages, and understanding the process of change that people go through when they learn new things, helps support people through that.”

Ingham cane grower Michael Waring attended the Tully workshop and said through Mr Hardwick’s teachings he was able to improve his interpersonal skills to enable him to communicate in a way that was relatable and relevant.

“There’s no point rabbiting on to your neighbor about specific species of cover crop to use, if all they’re wanting to find out about are the benefits of cover cropping, he said.”

“Everyone’s at different stages, sharing relatable information is as much about listening as it is talking.”

The soil health coaching workshops were made possible by the Wet Tropics Major Integrated Project, funded through the Queensland government’s Reef Water Quality Program, and coordinated by Terrain NRM as part of its leadership training offered to farmers.

Farmers wanting more information on regenerative farming:

The Lower Wet Tropics Soil Care Group: Alan Lynn on 0419 722 101 or Michael Waring on 0428 771 361.

The Wet Tropics Soil Care Group:Mal Everett on 0439 829 159.

The Regenerative Cane Network: Michael Waring on 0428 771 361.

Bundaberg farmers forced to irrigate like it’s the 1999’s after 22pc allocations announced

Irrigators on the Bundaberg water supply scheme are coming to terms with their recently announced allocations (AA) for the 2021-22 water year.

With recent rainfall recorded across the Wide Bay region over the weekend, some growers were rewarded with widespread falls and inflows into their on-farm dams.

The rain arrived just after Sunwater released a statement on Friday July 2, announcing medium priority allocations for the Burnett sub-scheme, other wise known as Paradise Dam, are 22 per cent.

Medium priority allocations for the Kolan sub-scheme (Fred Haigh Dam) are 98pc, while high priority allocations for both sub-schemes are 100pc.

The AA for Bundaberg growers is slightly higher than the 14 and 17pc prediction Sunwater released back in June.

A spokesperson for Sunwater said the 2021-22 water year allocations cannot decrease as dam capacity levels reduce.

“It is important to note that should inflows occur allocations can increase to a maximum of 100 per cent, as they did during the 2020-21 water year,” the spokesperson said.

“We understand the significant pressure drought conditions are having.

“Over the last 24 months the Burnett has seen some of the lowest rainfall on record for the region. Across the catchment, prevailing dry conditions have impacted all Sunwater water storages.

“Sunwater is hopeful the rainfall forecast in coming days delivers inflows to water storages in the Bundaberg region, and provides a boost to the announced allocations.”

Sunwater said it will continue to work with customers to ensure there is as much water available as possible for irrigators and the community.

Bundaberg businesses feel impact  

Irrigators and business owners in the Bundaberg region fear the district will be plunged back into the economic stagnation of the 1990s and early 2000s after the formal release of the announced allocations.

Local business owner, Tony Denton, Adds Up Engineering, has operated an engineering business in the Bundaberg region for 23 years and employs almost 20 staff.

Mr Denton said he remembers how tough it was in this area before Paradise Dam was built back in 2005.

“In the 1990s and early 2000s, in particular, things got really tough due to low water allocations for local farmers,” Mr Denton said.

“To learn that in 2021 farmers have been given an AA of 22pc, it’s like a bad dream”.

“My business relies on building equipment for farmers. If farmers are struggling it puts a lot of pressure on my business to keep my 20 staff in a job.”

Mr Denton paid $1.4 million in wages last year including pay roll tax, but if things continue to slow down he fears jobs will be lost.

“People may not realise it yet, but Bundaberg is about to go through another tough time because the low water allocation farmers are receiving from Paradise Dam will have a big impact on local jobs and local spending,” he said.

“To be brutally honest, jobs will be lost in my business if farmers stop ordering new equipment.”

AA HISTORY: This graph showcases the historically low announced allocations which Bundaberg growers from 1995-2003 faced.
 AA HISTORY: This graph showcases the historically low announced allocations which Bundaberg growers from 1995-2003 faced.

Back to the future for farmers

Local agribusiness lawyer, Tom Marland, is running the class action against the state government over the mismanagement of Paradise Dam.

Mr Marland said the AA from Sunwater feels like a scene from ‘Back to the Future’.

“Sadly, local farmers will be forced to irrigate like they did in 1999, when the AA in July was just 20pc,” Mr Marland said.

“Local records show that from 1995 to 2002 the AA in July were between 5 and 35pc, with the exception of 1996 when the AA in July was 50pc.

“Growers are going to experience major income losses on a 22pc AA and those are the kinds of losses we will be seeking to claim in the class action”.

Destructive coconut rhinoceros beetle a ‘stone’s throw’ from Australia as it spreads through Pacific

Australia’s sugar, pineapple, mango, and coconut oil industries are facing a major threat from a destructive pest beetle sitting on the nation’s doorstep.

The coconut rhinoceros beetle has bulldozed its way across the Pacific in just a few years and is now in Papua New Guinea, University of Queensland researcher Dr Kayvan Etebari warned.

“If it gets into Australia, coconut oil palms and many other palms found in the forest and in home gardens will be at risk,” Dr Etebari said.

“If it gets into Australia, coconut oil palms and many other palms found in the forest and in home gardens will be at risk,” Dr Etebari said.

It has been a year since another invasive pest, the fall armyworm, was first detected at Bamaga at the tip of far north Queensland and has since devoured crops across most states and territories.

Dr Etebari said the fall armyworm came down the island chain from PNG. 

“Last week it got into Tasmania,” he said.

The coconut rhinoceros beetle, a native of South-East Asia, has been in Samoa, Fiji, and Tonga for a century, but was successfully controlled by a virus for the past 50 years.

However, that biological control is now failing.

Stone’s throw away

Central Queensland horticulturalist Neil Fisher has been watching with growing concern the beetle’s rapid march from the South Pacific across to Guam and Hawaii to Vanuatu, New Caledonia, and Solomon Islands.

“The move through Papua New Guinea has been quite swift and we’ve seen large-scale coconut plantations and oil palm plantations being destroyed,” he said.

“Our border security is the Torres Strait and it’s only a matter of kilometres, just a stone’s throw from Papua New Guinea into north Queensland.”

A coconut rhinoceros beetle with a number on its back perches on a blue-gloved finger.
The coconut rhinoceros beetle was stopped in its tracks by a virus introduced 50 years ago, and it stayed put — until now.(Supplied: Forest and Kim Starr)

Councillor Fisher, who is also the deputy mayor of the Rockhampton Regional Council, said it was a concern shared with council colleagues in Cairns.

“There are miles of coconut-lined beaches to the north of Cairns and to lose those would see erosion coming back. You could lose two or three kilometres of actual shoreline,” Cr Fisher said.

The beetle causes damage by boring into the plant’s stem and feeding on the sap, damaging the developing leaves.

The plant will then be defoliated and will die during a heavy infestation.

The beetle lays eggs in decaying matter and then moves on.

“We knew it was a risk, but it wasn’t until it got into large horticulture and agriculture areas in Hawaii that suddenly the red flags went up,” Cr Fisher said.

He said Hawaii had similar horticulture and plant culture to Australia.

On top of the obvious economic threat to the country’s $2 billion sugar industry and $53 million pineapple industry, Cr Fisher said the beetle could pose a threat to other plants.

“If it’s in pineapples, what about bromeliads? It’s an up-and-coming collector choice for gardeners. And if it can get into sugar cane, what is the risk to other canes and bamboos?” he said.

Cr Fisher said it was important to work with universities to find a new biological control to keep the insect at bay.

COVID-19 similarities 

Dr Etebari and his team at UQ are studying why the virus is no longer controlling the beetle and their findings would be critical to managing the pest if it got a foothold in Australia.

“The question is how do we stop it? And what’s gone wrong with the control that’s been effective for the past five decades?” Dr Etebari said.

The researchers discovered that there have been several new waves of beetle invasions, not one as previously thought, as well as different types of beetles.

They also found there were variations to the beetle virus which was originally sourced from Malaysia.

“It’s similar to how other scientists spot different strains of COVID-19. We are detecting variations in the beetle virus in the Pacific,” Dr Etebari said.

“In our case the problem is more complicated because there are different types of beetles and different strains of the beetle virus.”

Their next step was finding out how the virus variations behaved in the different beetles and how that could be used to control them.

Dr Etebari said it was important for Australia to help its Pacific neighbours to tackle the pest, not just for economic reasons, but also humanitarian.

“It’s a serious threat to livelihoods across the Pacific islands as the coconut tree provides essential resources like food, copra, building material, and the coastal protection for more than five million vulnerable people,” he said.

A Department of Agriculture, Water and the Environment spokesperson said it was working with biosecurity counterparts in PNG and Solomon Islands to track and monitor the spread of the new beetle strain.

The department was also actively monitoring the spread of the beetle strains through PNG, particularly in the Western Province and PNG Treaty Village areas bordering Australia’s northern Torres Strait Islands. 

The spokesperson said the department was also supporting regional initiatives that were dealing with the coconut rhinoceros beetle.