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Can using an introduced animal to control another animal actually work on a large scale?

I have seen on the Internet the devastation being caused by cane toads and I was wondering if this is just a one off occurrence. If so, should this technique be used more often? Surely this biological control will actually work well if the research on the chosen animal is done properly. Also if it goes wrong surely the animals can be removed quickly so why didn't they do that for the came toad? Obviously it would be better if the animal didn't have to be introduced but it would be much more friendly way of controlling animals. No killing would be involved so it would also suit animal activists and if it works then one could focus less on controlling the actual pests population meaning it would also be cheaper. - This is a link which explains some of the effects that pheasants have caused in the uk. They have not effected the natural environment very badly even though no research was done on to the effects. Surely this shows that if we are carefully then it is possible.

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    May 22 2013: The introduction of any species into a foreign environment always has unforeseeable complications, especially when it is considered that all species of flora and fauna carry their own microbial ecosystems. It's been said that about 3 pounds of adult human weight is hosted microbes (primarily beneficial). Quarantine for the microbes, let alone the introduced species that host them, is next to impossible. The movie "Rabbit-Proof Fence" circles the issue of containment of rabbits in Australia.

    Synergies are essential to bolstering ecosystems; but, introducing species almost always eventually leads to the loss of multiple native species due to lack of competition favoring the introduced species.

    I think the essential flaw in your premise is the idea that humans are outside of the global ecosystem and therefore capable of mastering it. Such thinking has led to many calamities that are well documented on the internet if you look around: kudzu, anacondas and killer bees in the US will give you plenty of places to start on wikipedia alone.
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      May 22 2013: However if you predicted these (ironically) "unforeseeable complications" then surely it would work?
      Considering basic biology tells you using animals to control animals is a lot safer than using chemicals (like pesticides). Yet I don't know enough about this topic to give a proper opinion.
      Surely you must admit it is better to try, than not to try at all?
      (Or have I misunderstood your argument?) :-)
      I'm not sure whether he is arguing "humans are outside of the global ecosystem and therefore capable of mastering it". I believe he is arguing that if we manipulated the ecosystem we are in, then it may produce more well-being (for humans that is).
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        May 22 2013: Thanks for your thoughts Bernard.

        A simple Wikipedia search for "introduced species" yields a lot of answers. Check out this page:
        and a quote therefrom: "The effect of introduced species on natural environments is a controversial subject, and one that has gained much scrutiny by scientists, governments, farmers and others. Not all introduced species are problematic. Those species that spread widely and create significant problems are known as invasive species."

        To summarize: humans can not predict the behavior or effects of a given species on a foreign environment because we do not have the required knowledge to address all of the factors involved therefore it is reckless to introduce any new species into an established biome.

        Granted, we introduce foreign matter constantly, simply by moving around the planet, conducting trade and establishing monocultures that we use as foodstuffs. Although it is true that these activities have not made the world unlivable, it is also true that they have reduced global biodiversity significantly. For example, the common rat was introduced to New Zealand by infested ships and the creatures might seem to do no more harm there than they do in their native lands; but, the truth is they decimated insect, small mammal and bird populations that many New Zealand ecosystems relied upon, causing eventual failure of those systems and extinction for some species.

        The idea that people know enough about any ecosystem on the planet to intelligently select the best or optimal species for a given environment follows naturally from a logic that ignores how much we don't know about the world we live in. We still can't classify much of the life in the Amazon's dwindling rainforest, for example. Surely, you agree that a computer model can not take into account migratory patterns, parasitic behavior, synergistic organisms and human impacts sufficiently to avoid error.
    • May 23 2013: Thank you for replying. I understand what you are saying but if we can control the animal in a particular area and the pest is decreased in population without any major effects then surely they then can steal to be released from these areas slowly? Then we would not have to predict the outcomes but see the result ourselves. However I do believe that if the area does contain other more fragile species then I would not encourage this idea, especially as you say, the amazon rainforest as it could be catastrophic there. Though I do believe the idea could be used to contain other introduced species like rabbits and cane toads. I suppose the movie that you mentioned is about how bacteria is being spread to rabbits to destroy a large percentage of them. I strongly disagree with this idea as it is very unethical way of doing it.
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    May 31 2013: I think it's just sweeping the mess under the rug, replacing one thing for another seems like bad math to me if you're trying to subtract and get zero, it's best not to add anything extra unless it's going to equal zero.

    Animals are variable driven beings, they need many variables to thrive, cause many variables to happen where they live and determine the variables of other beings that live in the same area.

    With those facts I'd think, using animals to rid other animals is a bad choice.
  • May 25 2013: This has happened many times, the cane toad in Australia is just one such case, the introduction of rabbits in the early 1900's in Australia was another. They multiplied to the millions and were only stopped by introducing mixametosis, the disease specific to rabbits which wiped out the population to managable levels. In that case two introductions worked to cancel each. This worked because the disease was so specific. It failed with the cane toads because they could not be eaten ny predators (they are poisonous), had a vast area to expand into so food was not lacking and lastly they chose to eat food which was easier to obtain than the beetle they were sent to destroy. This happens when people think in a piecewise fashion so that they forget about the environmental interactions that constantly take place. To succeed you need in depth research and trials over maybe several years to be sure of what will happen and even then you could have missed something. This is the main weakness with GM food, the environmental effect of which has not been thoroughly studied.
  • May 23 2013: Oh my gosh, I hope it works unlike how it often doesn't.
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    May 23 2013: There have been some successful introductions but it needs to be a very specific introduction. Cane toads didn't work because they are prepared to eat anything and found a whole bunch of things they like better then cane beetles. Cactoblastis was better because it is a very choosey feeder.
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      May 23 2013: The "success" of the moth introduction to contain the failure of the cactus introduction has an irony to it don't you think?

      If you take a peek at the Wikipedia page about the Cactoblastis moth you will find that its Caribbean introduction has resulted in it invading America, decimating the native cacti there, especially in Florida.

      Perhaps the Australian "success" is more attributable to the absence of similar native succulents and the grace that allowed the moth to not find a native species to exploit, rather than any particular genius of the practice of introducing species.
      • May 23 2013: This is the area that I am quite interested in as somehow we need to reach an equilibrium between the 2 species population size. Surely when these moths were being introduced, the scientists were in control and were able to see the effects. If the scientists wited for the equilibrium to occur then surely this would not be a problem.
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        May 27 2013: Perhaps the Australian "success" is more attributable to the absence of similar native succulents and the grace that allowed the moth to not find a native species to exploit, rather than any particular genius of the practice of introducing species.
        Agreed. Cactoblastis only worked here because we don't have a whole lot of native cacti. Specificity is the key.