Ant science: Thieving ants know how to be sneaky

Ectatomma ruidum. Image by Alex Wild

Ectatomma ruidum. Image by Alex Wild

The most recent paper from my lab is a fun one. We show that thieving ants have a suite of sneaky behaviors, to help them avoid being caught in the possession of stolen goods. These differences are dramatic enough to classify thieves as a distinct and new caste of ant.

In thieving ants (Ectatomma ruidum), each colony has workers that specialize on stealing food from neighboring colonies of the same species. This isn’t really like anything other ants do, and it was described in detail more than twenty years ago, by my doctoral advisor Mike Breed, and his students. They found that the thieves are able to steal because their odors are intermediate between the colony that they’re stealing from and the colony that they are stealing to. So, thieves can only specialize on stealing from one colony, because they need to acquire that colony’s odor. And they produce fewer odors, which helps them fly under the radar.

Stealing food from other colonies of same species is a rare evolutionary waypoint, and a curiosity of natural history. What I find fascinating is how this isn’t a widely known phenomenon among the people who study ants and social behavior. Whenever I get to show this to other scientists when we visit the rainforest, they’re mighty amazed, and wonder why this isn’t a bigger story. I’d have thought the paper describing thievery would be a citation classic.  It’s done okay, but seems to have only picked up 38 citations since it came out. It’s done a lot better than Mendel did in his first twenty years, I guess.

There are still way more questions than answers about how thievery happens, and why it’s evolved in this species and yet (as far as we have detected) in no other ants (kinda sorta in one other species).

To leap into this question, I wanted to ask: are these thieves truly behaving in a manner different than other ants, or are they just foragers collecting food in a creative manner? Aside from the act of stealing, do they have other behaviors that facilitate their thieving habit? In other words, are they sneaky?

We observed thieves in the field very carefully. We challenged them with encounters from foreign ants. And we looked at their tissue to see if they were eating different things. Though they eat the same food, they are a lot more sneaky. They avoid bumping into other individuals. They turn around and walk the other way when perturbed, and if you grab them, they’ll guiltily drop their food while regular ants defiantly hang onto their food knowing that they rightfully acquired it.

We conclude that the thieves are a distinct caste, characterized by a clear and distinct set of behaviors that make them different from non-thieving ants. This is an important step in the process of identifying the mechanism that turn ants into thieves.

It’s nice to see that this paper has has gotten a little coverage, including New Scientist and a local paper near my university. (I won’t link to the IFLScience story, considering this media empire was built on content theft.)

Here’s the paper, by the way:

McGlynn, T.P., R. Graham, J. Wilson, J. Emerson, J.M. Jandt. 2015. Distinct types of foragers in the ant Ectatomma ruidum: typical foragers and furtive thieves. Animal Behaviour 109: 243-247.

I should add that when writing the manuscript, I put in an effort to write it for public consumption as much as possible. I worked to avoid jargon (except in a few places in the methods when the jargon probably was necessary to satisfy some reviewers), and to state things as plainly as possible. I’m curious if you think I had any success.

How this paper happened in a teaching-focused institution

The bulk of the fieldwork was done by two undergraduates in my lab (Russell Graham and Jeremy Emerson) and a middle-school teacher (Jane Wilson). (These people were able to work with me in Costa Rica thanks to support from the National Science Foundation. Thanks, NSF!).

I went down to the rainforest with Russell, Jeremy, and other students who were doing other things. Then Jane joined us once she was done teaching. Then I went home and they worked on it for the rest of the summer, and we emailed once in a while. And we developed and ran the experiments described in this paper. After we got back to the States, after talking with the team, I was identified as the guy to write the paper.

Joining this project are Jenny Jandt and Hope Jahren. Jenny is an animal behaviorist, and has worked with me on other questions involving thieving ants and bullet ants, and she was important for mentorship, experimental design, and writing. Hope is a geochemist who (among other things) uses isotopes to understand plants in the present and the past, and she worked with us to compare ant diets. She also did a helluva job in editing the manuscript, which is no surprise because Hope Jahren Sure Can Write. (Which is why you should pre-order her forthcoming book, which is compelling, fun, and a good story.) Nowadays it’s rare for me to get a paper out only a year after the fieldwork is done, and one reason this happened was because of great collaborators.

A cute little story related to this paper

About a dozen years ago, I got a review request from Animal Behaviour. Not only did I not have the time, it was mighty far outside my wheelhouse. After I did the courteous thing and clicked on the ‘decline’ box, a new window asked me, “Why did you decline to review this manuscript?” I wrote something like, “First, this paper falls outside my expertise. Two, I’m overcommitted and have a couple other reviews due. Third, I’m less likely to review a paper for an Elsevier journal when publishers with more ethical practices also need reviews too.” I definitely didn’t say I wouldn’t review for the journal, I just said it was a lower priority.

A week later, I got a ranting email — two long paragraphs from one of the Executive Editors at that time. It explained that I don’t understand the publishing industry, that I should be grateful for services provided by Elsevier, and that I won’t ever publish an article in Animal Behaviour again!

The funny thing is, I’m not primarily a behavior person, and I hadn’t yet published in the journal (though if I recall correctly at that point I got rejected once or twice). I hadn’t done anything that would fit the journal since then, until this paper, and I’m glad to see it in print in Animal Behaviour. I’m also glad because this was the first paper we submitted to so I didn’t have bother with the journal dance.

2 thoughts on “Ant science: Thieving ants know how to be sneaky

  1. very very interesting, do you suppose that the sneakyness they exhibit is the result of learned behavior (from others in the same caste) or instinctual resulting from evolvutionary processes!???

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