Australian meat ants eat cane toads


From EurekAlert!:

Aussie meat ants may be invasive cane toad‘s Achilles’ heel

Ecologists in Australia have discovered that cane toads are far more susceptible to being killed and eaten by meat ants than native frogs. Their research – published in the British Ecological Society’s journal Functional Ecology – reveals a chink in the cane toad‘s armour that could help control the spread of this alien invasive species in tropical Australia.

Professor Rick Shine and his colleagues Georgia Ward-Fear, Matt Greenlees and Greg Brown from the University of Sydney’s Team Bufo (from the Latin name for the toxic toad) compared habitat use and activity patterns in meat ants, metamorph cane toads and seven native Australian frog species. They found that, unlike the native frogs, cane toads are poorly equipped to escape the meat ants.

According to Shine: “The spread of cane toads through tropical Australia has created major ecological problems. The ideal way to control toad numbers would be to find a predator that kills and eats toads but leaves native frogs alone. However, bringing in a predator from overseas might have catastrophic consequences, like those that occurred when cane toads themselves were brought in. So we’ve explored an alternative approach – to see if we could use a native predator. Meat ants are abundant around tropical waterbodies, and we often see them eating small toads, so we suspected that there might be some kind of mismatch between the invader and its newly invaded range, for example something about the toads’ behaviour that makes them vulnerable to a predator that poses little danger to native frogs.”

Through a series of laboratory experiments, Team Bufo looked at when the ants, frogs and toads were most active, where they chose to live, and how good the frogs and toads were at escaping attacking meat ants. They found cane toads opt to live in open microhabitats and are active during the day, patterns that match those of meat ants. By contrast, native frogs are nocturnal and are safely ensconced in vegetation or other shelters during the day, when meat ants are on the hunt.

Cane toads are also less well equipped to escape attacking meat ants, Team Bufo found. Using a specially-built runway, they tested the frogs’ and toads’ sprint speed and endurance. They found that compared with the quick and nimble native frogs, cane toads’ hops are shorter and slower due to their shorter shin bones. Native frogs were also more vigilant for meat ants than cane toads, they discovered.

The results are interesting not only because they reveal the cane toad’s Achilles’ heel – a weakness that could be exploited to help control the spread of the toxic toad – but because the same “evolutionary trap” could be used to snare invasive species elsewhere.

“The end result of this mismatch between traits of metamorph cane toads, which evolved in the Americas, and the ecological interaction between metamorph toads and meat ants in tropical Australia, is an ‘evolutionary trap’. That is, characteristics that increased toad survival where they evolved in the Americas are now a disadvantage, because the toads are facing different challenges in Australia – challenges they have not evolved to deal with. Such evolutionary traps should be especially common for invasive species, because so many aspects of their environment differ from those in which the traits of that species evolved,” says Shine.

###

Georgia Ward-Fear et al (2009). Maladaptive traits in invasive species: in Australia, cane toads are more vulnerable to predatory ants than are native frogs, Functional Ecology, doi: 10.1111/j.1365-2435.2009.01556.x, is published online on 31 March 2009.

See also here.

Meat ants devour cane toads: here.

Cane toads approaching the last barriers to Western Australia: here.

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5 thoughts on “Australian meat ants eat cane toads

  1. Australia uses cat food in fight against cane toads

    Researchers have found that cat food attracts meat ants which attack baby cane toads in attempt to curb toxic amphibians

    Researchers in Sydney believe cat food is a powerful weapon in battling the cane toad problem. Photograph: Mark Baker/AP

    Forget cricket bats, golf clubs and carbon dioxide. Australia has found a new weapon in its war on the dreaded cane toad: cat food.

    Researchers with the University of Sydney found that a few tablespoons of cat food left next to ponds in the Northern Territory attract fierce Australian meat ants, which then attack baby cane toads as they emerge from the water. The results of the study were published in the British Ecological Society’s Journal of Applied Ecology this week.

    It is the latest idea in Australia’s seemingly endless battle against the cane toad, which was introduced from Hawaii in 1935 in an unsuccessful attempt to control beetles on sugarcane plantations. The toads bred rapidly, and with their population now in millions they threaten many species across Australia.

    Early cane toad killing methods included whacking the creatures with golf clubs or cricket bats. In recent years, most groups dedicated to fighting the pests have turned to freezing or gassing them with carbon dioxide. Still, the toads’ population continues to explode.

    Cane toads emit a poison that attacks the heart of would-be predators. But the University of Sydney researchers found that meat ants are impervious to the toads’ poison, said Rick Shine, a professor of evolutionary biology at the University of Sydney who supervised the research.

    “A single toad can have 30,000 eggs in a clutch, so there’s a heck of a lot of tadpoles turning into toads along the edge of a billabong,” he said. “You can literally have tens of thousands of toads emerging at pretty much the same time. They are vulnerable to meat ants if the colony discovers there is a source of free food.”

    Between July and September 2008, researchers studied tens of thousands of cane toads emerging from cat food-lined ponds and found that 98% of them were attacked by meat ants within two minutes. Of the toads that escaped, 80% died within a day from ant-inflicted injuries.

    The baby toads are around 1cm in size, about the same as a meat ant. The aggressive ants have strong jaws and can kill even larger animals by sheer numbers.

    “It’s a pretty unequal fight,” Shine said. “The toads have this terribly stupid response to attack – which is just to freeze and do nothing.”

    Not all think the study is valuable. Graeme Sawyer, an official with Frogwatch, an environmental group dedicated to wiping out the toxic amphibian, said the cat food technique just isn’t powerful enough.

    “The impact of meat ants on cane toads can be significant with a small number of cane toads, but when you get areas where there are large number of cane toads it doesn’t seem to make any difference at all,” he said.

    Australia’s Royal Society for the Prevention of Cruelty to Animals said encouraging ants to attack cane toads is inhumane.

    “RSPCA Australia recognises that cane toads must be controlled, but urges researchers to concentrate on identifying effective methods that do not cause unnecessary pain or distress,” the group said in an email.

    Shine acknowledged the study doesn’t have all the answers.

    “You’d have to be a desperate optimist to think that we’ll ever see the end of cane toads in Australia,” he said.

  2. Radio-savvy snakes used to spy on cane toads

    STAFF REPORTER
    March 18, 2010

    An olive python fitted with a radio transmitter. Supplied by: DEC

    The cane toad’s impact on native snakes will be tracked by radio-transmitters surgically implanted in 20 wild pythons.

    The Department of Environment and Conservation has fitted devices in 10 olive pythons, 10 water pythons, four black-headed pythons and one king brown snake in the East Kimberley.

    The department’s principal research scientist, David Pearson, said the aim was to see if large snakes would be killed by cane toads, as they make their descent towards Perth.

    Laboratory trials had already demonstrated that various reptile species were susceptible to cane toads, he said.

    “We don’t know how wild snakes will react when they encounter their first toad,” Dr Pearson said.

    “Using radio transmitters, we can closely follow individual snakes during the arrival of toads to see if they will ignore the toads or if they will be tempted to try one.

    “Cane toads are toxic to most native predators so if they attempt to eat a large toad, death is likely.”

    Mammals, lizards, snakes and threatened land snails have shown to be at risk of population declines due to toads.

    Already scientists are tracking several snakes near Lake Argyle.

    “Toads arrived in our Lake Argyle study area several weeks ago and we are locating the snakes regularly,” Dr Pearson said.

    “So far, none of the snakes has been lost to toads, but the temptation to try a toad will no doubt increase as toad numbers grow.”

    Dr Pearson, DEC technical officer Bill Stewart and University of Sydney researchers plan to “teach” wild blue tongue lizards and two species of goannas to avoid toads.

    “Using a bait of toad pieces with a nausea-inducing chemical, it is hoped that the first experience of a native predator with something tasting like a toad will be unpleasant but not lethal,” Dr Pearson said.

    “This could then teach them not to be tempted by the toads, allowing various native species to survive and build up populations after the toad invasion.”

    http://www.watoday.com.au/wa-news/radiosavvy-snakes-used-to-spy-on-cane-toads-20100318-qh9j.html

  3. Pingback: Australian termites used for finding gold | Dear Kitty. Some blog

  4. On Wed. 21 May 2013 Derrick Rowe posted in Asclepidaceae – Dischidia imbricate (in Iron Range National Park, Australia).

    Dischidia major alongside an ant-house tuber of a Myrmecodia tuberosa. Iron Range National Park.

    This is probably Dischidia imbricata. Kokopo, Gazelle Peninsula. Here the ants nest under the imbricating domed leaves and the plant sends its root therein to obtain nutrients from ant rubbish..

    (Derrick Rowe) Ant plant groups:

    https://www.facebook.com/groups/152984704767011/

    Publications:

    “ Australian ant-plants: amazing relationships with insects.

    http://www.andrewisles.com/all-stock/publication/australian-ant-plants-amazing-relationships-with-insects

    “Talking plants.”

    http://talkingplants.blogspot.nl/2012/07/never-enough-ant-plants.html

    “Ant plants”

    http://australiansucculents.com/articles-news/ant-plants

  5. Pingback: Wildlife discoveries on Western Australian islands | Dear Kitty. Some blog

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