Finally, a Predator to Control the Notorious Cane Toad: Meat Ants?

By Rachel Cernansky | March 30, 2009 6:06 pm

canetoad.jpgResearchers in Australia think they have found a solution to the country’s toxic cane toad problem: make Australian meat ants eat them. Cane toads—which can grow up to 8 inches (20 centimeters) in length—were imported from South America to Queensland [in northeast Australia] in 1935 in a failed attempt to control beetles on sugarcane plantations. Trouble was, the toads couldn’t jump high enough to eat the beetles, which live on top of cane stalks [AP]. Since their introduction… cane toads have spread through most of tropical Australia, eating and poisoning native animals [New Scientist]. No one has been able to get their population growth under control, and past suggestions to do so by introducing exotic diseases have only raised concerns about causing as much harm as the toads have themselves.

But a research team led by ecologist Rick Shine found that cane toads are more vulnerable to being eaten by Australia’s predatory meat ants than are native frogs, which may allow the ants to be used as a “safe” biocontrol agent that would not interfere with native frog species. Shine said the team plans to try ways of encouraging meat ants to build colonies near toad breeding ponds. One way would be to plant trees the ants favour [The Australian]. He is hopeful the strategy will work because unlike native frogs, cane toads are active during the day, when meat ants roam about scavenging for food. Toads also tend to breed in ponds that are out in the open sun, which results in their young emerging onto bare, baked mud areas, a habitat where meat ants like to forage [Sydney Morning Herald]. The toad is also more vulnerable because it lays its eggs in the dry season when water is low and there’s little protective vegetation at the pond’s edge [The Australian].

Until its adult life, when it grows to be quite large, the toad is smaller than native amphibians, and sticks around longer when the ants attack—it takes about five seconds to move away, compared with the natives’ one second average: it doesn’t have the leg-power to leap quickly away from attacking ants. Worse, it doesn’t watch for the ant as do local species. The final kiss of death for baby Bufo [cane toads] is that its potent toxin doesn’t faze ants. The compound attacks the heart of vertebrate predators and ants, of course, are heartless [The Australian]. Meanwhile, meat ants are fierce fighters with powerful bites, and a band of the insects can easily take down a small toad.

The study, published in Functional Ecology, coincidentally follows the weekend’s “Toad Day Out” event, a mass capture and killing of the cane toads, with many of the creatures’ corpses being turned into fertilizer for the very farmers they’ve plagued for years [AP]. But according to Shine, the Queensland event will likely reduce numbers, but only in the short term. “There’s been a tremendous community effort,” he says, but “with females laying up to 30,000 eggs in a single clutch, it’s not a long-term strategy” [New Scientist].

The meat ant proposal is not quite shovel-ready, of course. Ecologist Ross Alford said that while the proposal is interesting, people should “try it cautiously. Ants are generalist predators, so if you increased their numbers, you may see an effect on native animals apart from frogs” [New Scientist].

Related Content:
80beats: Attempt to Control Invasive Species Backfires Spectacularly on an Antarctic Island
80beats: Contaminated Australian River Spawns Millions of Two-Headed Fish
80beats: Worsening Drought Threatens Australia’s “Food Bowl”

Image: Wikimedia

CATEGORIZED UNDER: Environment, Living World
  • NoAstronomer

    Not a bad idea. Also what might eat toad eggs? Or are they poisonous too?

  • Sally

    When a biocontrol agent is used, whether it’s truly safe of course needs to be very carefully tested, otherwise, it’s just an replay of history.

  • Sally

    When a biocontrol agent is used, whether it’s truly safe of course needs to be very carefully tested, otherwise, it’s just a replay of history. They already have been too many failure examples, though this time the meat ant it a native species.

  • Stacy L Mason

    I’ve wondered whether it be possible to train Australian crows and ravens the trick of flipping the toads over and pecking out their livers like the crows from Germany and Denmark? Per the “exploding toad” phenomena a few years ago…unless their bellies are toxin laced as well.

  • jed

    I would like to know how crows eat cane toads
    please reply and I will thank you very much

  • Stacy L Mason

    I didn’t say they had to eat the toads, just the toads livers. Which would kill the toads.

  • Luís Lopes-da-Fonseca

    Their bellies are toxin free and the crows in East-Timor learned that and are eating adult Bufo.

  • Koen

    Hello ,Great article, very entertaining stuff. Thank you for posting…wanna go check out your other posts now….I think it’s hard to make a blog stand out on the web, because it’s so huge, but yours is really cool. Thanks.

  • Leigh

    In theory it could work, but wouldn’t meat ant populations then take over? It’s scientists who started the problem in the first place, same with killer bees. People need to stop messing with nature. There are several listed predators in central america that eat cane toads. Why not entertain a controlled or trained group of one of those predators to eat the cane toad.

    IF the scientists had collected the 102 original toads this issue would be non-existent, but once again scientists were too busy not thinking long term and just let the toads roam free. Man must think long term before trying any of these theories, esp in Australia where many rare and isolated species exist. Don’t bring anything in, don’t bring anything out.

    If the citizens banded together they could kill the toads in massive numbers, or add a natural chemical to standing water, during breeding season to make all their eggs infertile. OR as alligators, or toads the hotter the conditions the more production of females over males, making all the toads one sex, thus no mating can occur. Or poisoned foods source for the toad, ie bugs, or etc. All must be tested in order to find out if those solutions would cause more problems.

    Like with killer bees, this issue could have been avoided if man did not interfere with nature. Just to control a sugar cane crop, Australia now must battle a toad crop! Everyone must think, before ever messing with nature.


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