Don’t worry about the leafcutter ants

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(clip from Ants- Nature’s Secret Power)

Leafcutters are the ant stars of many nature documentaries. Their most spectacular film appearances, including the nest excavation above, and the relocation of a full colony to a lab for the BBC’s upcoming Planet Ant, involve the destruction and removal of an established colony. Since leafcutters are such dominant players in tropical ecosystems, this practice of destructive filming raises the question of whether we ought be concerned about ant conservation when filming.

The short answer is: No.

Most Atta leafcutter species are not only not endangered, they may even be more numerous now than before our species intruded on their territory.

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Leafcutters, you see, are beneficiaries of human activity. They are a buggy, neotropical analog of North America’s ubiquitous whitetail deer, a species that thrives along forest edges, farm fields, and other places where weedy, disturbance-associated vegetative regrowth provides an abundance of their favorite foods. Cleared soil may also help leafcutters start new colonies. When humans make field from a forest, or build a road, they also make leafcutter habitat. The leafcutters thrive.

Don’t take my word for it, though. Have a look at these aerial images from rural Paraguay:

Atta_aerial1

[location]

Atta_aerial2

[location]

Atta vollenweideri nests- the white dots- are denser in old farm fields than in the undisturbed adjacent scrub. We humans have been good to leafcutters. They, in turn, have repaid us by becoming the most economically damaging pest insect in the region.

So enjoy your leafcutter ant documentaries, and don’t worry about the fate of the ants. Our environment is faced with far more serious troubles.


sources:
Wirth et al (2007) Increasing densities of leaf-cutting ants (Atta spp.) with proximity to the edge in a Brazilian Atlantic forest. Journal of Tropical Ecology 23: 501-505. DOI: http://dx.doi.org/10.1017/S0266467407004221

Vasconcelos et al (2006) Roads Alter the Colonization Dynamics of a Keystone Herbivore in Neotropical Savannas. Biotropica 38: 1744-7429. http://dx.doi.org/10.1111/j.1744-7429.2006.00180.x

18 thoughts on “Don’t worry about the leafcutter ants”

  1. Though the ants certainly weren’t endangered, people still left exasperated comments on a video of Walter Tschinkel making a nest mold out of molten metal, since it seemed that the procedure was unnecessarily cruel to the ants, and that there were other more ethical ways to study ant nest structure. To some people, it’s not that the species itself is being depleted that they’re uncomfortable with, but that the treatment kills healthy living animals (plants, fungi, etc. don’t get any attention). It is certainly unfortunate, but learning about life often means extinguishing it.

  2. Great post and great images as usual.
    I think Henry Walter Bates mentioned the destructive nature of leafcutters quite a bit in “A Naturalist on the River Amazons”.

  3. People that get upset about myrmecologists killing ant colonies will collectively kill more insects driving cars, having pest control companies spraying their homes, applying insecticides to their gardens, and having the land cleared for their homes, agriculture, football fields, soccer fields, and shopping malls (including such bastions of animal care as various dwellings used for PETA headquarters) in one year than all of the entomologists (non nozzle-heads, that is), in the world will kill in their scientific lifetimes.

  4. Every time I go by a clearing for a construction site, I can’t help but think of, and cringe a little, at the thought of all the life being destroyed to create habitat for our burgeoning species. I’m sure most people think it “just dirt” being moved.

    1. But they arent TRYING to exterminate millions of small animals, so its fine. But if you handnet,or worse, trap, them intentionally then its obviously much much worse… right? [/sarcasm]

      People dont care about the animals in themselves, its the notion of wanting to intentionally kill a lot of lives that upsets I think. That somehow makes it worse, for some reason, because you (entomologist) could have chosen not to, while the construction workers are unknowing and working towards a completely different goal.

      No one (well, some Buddhists might be) is in fact upset that lots of small animals die, which is not surprising as otherwise it would be common for people to have mental breakdowns after summer roadtrips, plowing fields, repotting indoor plants….

      Its some kind of illogical moral reflex of sorts.

  5. Great post Alex! After I read “The Leafcutter Ants: Civilization by Instinct” by Wilson & Holldobler, my interest in Ants and especially Atta reached a crescendo – The cover also features a great photo 😉

  6. This conversation seems to conflate conservation issues with the ethics of extermination. The former Alex addressed quite clearly, but the latter doesn’t get much attention by entomologists, not in public anyway (E. O. Wilson might be a noteworthy exception). I consider myself something of a secular Buddhist, and I do try to minimize the suffering I cause to others, human or not. I don’t freak out over what cannot be avoided, I just do what I can. I don’t know if anything new is learned by repeated casting of leaf-cutter colonies. If at this point it’s done for the sake of the cameras, then I think it’s unnecessary and should be discouraged. It reminds me a bit of high school vivisection and dissection labs that call for a yearly supply of worms and frogs to reveal anatomy that’s already well documented.

    Put another way, this is a case of the researcher being co-opted as exterminator, and I think there’s an ethical conflict there that should be addressed. I know biologists are not all veterinarians or doctors, they don’t take an oath to protect life, but that doesn’t mean there are no ethical aspects to their work. And if the public is developing an awareness and empathy for creatures beyond the warm and fuzzy types, I wouldn’t begrudge that.

  7. Joe,
    I don’t follow your logic: ” I don’t freak out over what cannot be avoided.” So, killing millions of insects is OK, I suppose because we all MUST drive, and build, but purposely killing ant colonies to study them must be examined carefully, lest we enter into an ethical danger zone? I assure you the killing of colonies for study is not entered into lightly by those of us that do it. We have a deep reverence for these organisms and these studies yield otherwise unattainable information about the lives of these mysterious creatures.

    1. Joshua,

      There does seem to be a difference between targeting and intentionally killing a living thing and unintentionally killing it, whether or not this difference is in fact real. The moral properties of the two actions are not necessarily identical (or at least not transparently). Many (most?) legal systems also consider intentional killing to be worse than unintentional, despite identical outcomes. However, I do agree with your point that claiming that killing by driving and construction as something which “cannot be avoid” is dubious.

    2. That line was triggered by AlexB’s earlier comment:

      “No one (well, some Buddhists might be) is in fact upset that lots of small animals die, which is not surprising as otherwise it would be common for people to have mental breakdowns after summer roadtrips, plowing fields, repotting indoor plants….”

      It sounded like he was talking about someone like me and I wanted to contest the idea that I might have mental breakdowns after such activities. But it doesn’t mean I don’t think about them. Sure I have to drive to my job, but along the way I find I can afford to look where I step on the pavement or watch for wildlife on the road. It’s never been a hassle except when I try to explain it to someone. I guess going back to my original point, I just wanted to see how entomologists felt about such things. Thanks for the reply.

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