Interview with a social insect scientist: Michael Breed

IS: Who are you and what do you do?

MB: My name is Michael Breed, and I am a professor at the University of Colorado, Boulder, where I have taught since 1977. My chief passions are my research on social insect behaviour and ecology, and teaching animal behaviour. I also direct a Residential Academic Program with about 400 first year college students in one of my University’s dormitories, Baker Hall.

IS: How did you end up researching social insects?

MB: By good fortune I landed in graduate school at the University of Kansas. As an undergraduate I’d developed an interest in insects and I applied to graduate programs in entomology, but I didn’t have much of an idea about how to go about applying for graduate schools so I just applied to entomology programs that were ranked in the top ten by the National Research Council. I was pretty clueless about differences among programs and the importance of choosing an advisor. I also had money limitations and couldn’t make more than a couple of visits to check out programs. By very happy coincidence KU was close to my parents’ home in Kansas City and I went over to Lawrence and met Professors Michener (Mich), Taylor and Bell. I must have made a positive impression on Mich because later they offered me admission and Mich offered me an assistantship working on sweat bees. At that point I didn’t even know what a sweat bee was, but I was glad to have the job and to get started. It only took a week or two of doing experiments on Lasioglossum zephyrum for me to hooked, both on bees and on the study of social behaviour.

My story is pretty much the opposite of how I would advise one of my undergraduates when they’re applying to graduate school. It also shows how being a little random in making life choices can work out well.

Before leaving this topic, I want to mention that as an undergraduate I majored in both English Literature and Biology and I was equally interested in the two areas. I made my decision to apply to graduate school before I chose between literature and biology, based on my desire to teach at the college level. My self-perception was that I wanted to do the actual creative process, rather than study the results of the creative process. In literature, to me this would have meant a career in creative writing and I didn’t feel confident in my ability to succeed as a novelist. In science, the creative process of identifying a big question, proposing specific hypotheses, designing experiments, and interpreting the results seemed much more accessible. I’ve been very glad that I made this choice but I have also maintained my lifelong interest in literature.

IS: What is your favourite social insect and why?


Paraponera clavata. Photo: bathyporeia/Flickr

MB: Paraponera clavata, also known as the bullet ant or the giant tropical ant. I was at La Selva Biological Station in Costa Rica in the early 1980s working on a cockroach project that wasn’t going well. I walked out to La Selva’s arboretum and sat on a log to think things through, and a Paraponera worker walked up close to where I was sitting. I had read about ponerines in Wilson’s Insect Societies and knew they were both fascinating and understudied and this Paraponera worker looked so studiable! And I would have to say cute in a puppy-like way! That one encounter started a super satisfying research thread that carried me back to La Selva nearly every year for two decades.

Ironically, Paraponera are no longer thought to be in the Ponerinae, but they hold their own little taxonomic niche and knowing about them still helps to inform understanding the evolution of social mechanisms in ants.

IS: What is the best moment/discovery in your research so far? What made it so memorable?

MB: I really like it when someone replicates a result I had or when I hit on the same result as a group working in parallel with me. This tells me that I’ve chosen a topic that other scientists think is interesting, and independent replication is rare in behaviour and ecology. The first instance I can think of this was when I was working on queen recognition in honeybees and it turned out that Rolf Boch and Roger Morse had been working along the same lines—I saw the two studies as mutually confirming and as together being more convincing than either would have been separately. Since then I’ve had this happen several other times, and each time I’ve thought it was very exciting to know that what I had thought/interpreted was more likely to be actually true.

IS: If teaching is part of your work, what courses do you teach? Has your work on social insects helped to shape your teaching?

MB: I teach animal behaviour to about 110 students each fall semester. Most of them are more interested in birds and mammals and I’ve had to adapt to addressing their interests but that doesn’t keep me from scattering in social insect examples along the way. Teaching remains exciting and challenging, in a good way, for me. The excitement comes from helping the students to understand concepts that have motivated me through my career. The challenge comes from the continuous change in the students. This year’s students are different in their needs and capabilities than last year’s, and over longer periods of time there is definitely major change—the gen-xers were so much different than the millennials and the post-millennials are yet different again. Nothing against the previous generations but I probably like the post-millennials the best—my current students are really delightful to work with. I hope that knowing about social behaviour on the level of insects helps me to be somewhat cognitive about the group personality of my students.

IS: What is the last book you read? Would you recommend it? Why or why not?

MB: I just finished Woman in White by Wilkie Collins. This is a classic, one of the progenitors of the genre of detective fiction, and I decided to re-read it as an escape from all the science stuff. I tend to have more than one book going at a time, so I’m also reading John Le Carre’s new George Smiley book, Call for the Dead, as well as Draft No. 4, On the Writing Process by John McPhee, and The Abundance, a collection of essays by Annie Dillard.

Of the four, I’d recommend reading Dillard to all biologists—there’s an essay in this book about viewing a solar eclipse that was originally published in Teaching a Stone to Talk that really resonated with me based on my experience seeing the eclipse this last August. McPhee’s take on the writing process is very unique, but I also think this book is a great read if you’re interested in the craft of writing. You have to have patience with Victorian prose and with a writer who apparently was paid by the word to read Collins, but there are real rewards in being immersed in such a well-crafted story.

IS: Did any one book have a major influence in shaping your career? What was the book and how did it affect you?

MB: When I was a new graduate student, my major advisor, Charles Michener, gave me a copy of the proof of his book, The Social Behavior of the Bees, to read. The fascinating stuff in this book about bee behaviour shaped my graduate work and ultimately my career. It was published in 1974 and I think it’s still a great place for any bee biologist to start.

IS: Outside of science, what are your favourite activities, hobbies or sports?

MB: Hiking, photography, attending theatre productions, and playing poker.

IS: How do you keep going when things get tough?

MB: I tend to use work to distract myself from distressing things, so if I have something difficult going on I’ll bury myself in work. Unfortunately, though, a career in science is a lot about rejection—journal submissions and grant proposals that are turned down—and it is key to be able to persist despite defeats. Like most people sometimes I have to fight self-doubt in the form of imposter syndrome. The sheer joys of discovery and of working with students serve as great counterbalances to occasional feelings of inadequacy. Having supportive family, good friends and positive social relationships really helps.

IS: If you were to go live on an uninhabited island and could only bring three things, what would you bring? Why?

MB: My wife, Cheryl, a dog (we’d have to get a new one as ours passed away last spring), and writing materials. If a person and a dog don’t count as “things” then I’d say writing materials, a computer chess game, and hiking shoes.

IS: Who do you think has had the greatest influence on your science career?

MB: Without a doubt, my major professor, Charles Michener. He was a kind and generous mentor. I wrote an essay for this same blog about him that talks about what a great mentor he was:

IS: What advice would you give to a young person hoping to be a social insect researcher in the future?

MB: Use your time effectively. I have an old New Yorker cartoon on my desk that shows deadlines arriving like waves rolling into a beach that I look at when I’m tempted to procrastinate. Keeping on top of what needs to be done next is so very important. Do the most important thing first, not the easiest thing. Don’t mistake answering emails for actually getting work done. But also keep in mind that to be effective in your work you need to eat well, sleep, exercise and have a social life.


Army imposters: the art of blending in

A blog post highlighting the article by S. Pérez-Espona, W.P. Goodall Copestake, S. M. Berghoff, K. J. Edwards, N.R. Franks in Insectes Sociaux

By Sílvia Pérez-Espona

Neotropical army ants of the genus Eciton represent one of the many fascinating examples of interaction between species, with hundreds of (vertebrate and invertebrate) species reported associated with Eciton burchellii, and many more yet to be described (Rettenmeyer et al., 2011). Among the plethora of species found with this army ant, are the staphylinid beetles belonging to the genera Ecitophya and Ecitomorpha. These beetles have evolved to mimic the appearance and colouration of the most abundant worker cast (medias) of different Eciton species. These army ‘imposters’ are considered hunting guests, as they are found in the conspicuous raiding (and emigrating) columns of Eciton colonies ants where they feed on dropped prey or at booty caches. The mimicry of these two genera of myrmecophiles can be explained as a combined strategy to avoid predators (Bayesian mimicry) and to integrate into colony life (Wasmannian mimicry).


Ecitophya simulans next to an Eciton burchellii foreli media worker. Photo: Taku Shimada.

This intriguing example of mimicry and adaptation of Ecitophya and Ecitomorpha with their Eciton host was first described by Erich Wassmann in the late 19th century. Since then, studies of these two myrmecophile genera have mainly focused on resolving their challenging taxonomy as well studies of their behaviour in the field (e.g Akre and Rettenmeyer, 1966; Kistner and Jacobson, 1990; Reichensperger, 1935, 1933). We took a genetic approach to assess the evolutionary relationships between Ecitophya and Ecitomorpha with their Eciton hosts, with a special emphasis on the association of these myrmecophiles with E. burchellii, the only Eciton species known to harbour both beetle genera. To this end, we sequenced the same mitochondrial marker, cytochrome oxidase subunit I (COI, cox1), for ants and beetles collected from colonies located in west (Bosque Protector de Palo Seco, Reserva Forestal Fortuna) and central Panama (Área Protegida de San Lorenzo National Park and its buffer zone). COI is a maternally-inherited genetic marker widely used for studies assessing phylogenetic relationships between closely related taxa, as well as phylogeographic and population-level studies such as the ones we conducted in our study. Phylogenetic, molecular clock and population genetics analyses were conducted in order to determine the degree of specialization of species of Ecitophya and Ecitomorpha to their Eciton host. If there was a high specialization of the myrmecophiles with one particular host, molecular signatures would support earlier taxonomical classifications of Ecitophya and Ecitomorpha by Reichensperger (1933, 1935), based on the assumption that each myrmecophile species evolved to adapt to colony life of a particular Eciton species.


Raiding column of Eciton burchellii foreli. Photo: Silvia Perez-Espona

Indeed, our analyses revealed that Ecitophya and Ecitomorpha are truly host-specific and thus support the earlier taxonomic classifications by Reichensperger. Therefore, current taxonomic classifications that considered a lack of consistent morphological characters to support Reichensperger’s views need to be revised. Phylogenetic relationships between species of Ecitophya (found with different species of Eciton, in contrast to Ecitomorpha which is only found with E. burchellii), however, did not mirror those of their host; indicating that at this more specific level, the evolutionary path of this myrmecophile differed from that of its Eciton hosts. These analyses also provided further insights into the taxonomy of Eciton burchellii, indicating that the genetic divergence between the subspecies E. b. foreli and E. b. parvispinum was higher than between other recognised Eciton species, and that therefore E. burchellii ‘s taxonomy also warrants further taxonomical revision. Our molecular clock analyses indicated that the diversification of Eciton is likely to pre-date the diversification of the myrmecophiles and that Ecitophya’s species diversification (and therefore potential association with Eciton) might be older than that of Ecitomorpha. This possible earlier association of Ecitophya with Eciton, and therefore longer time-frame to adapt with the host, could explain why beetles from this genus are found with a larger number of Eciton species.

Population-level analyses of the Ecitophya and Ecitomorpha associates of Eciton burchellii showed strong patterns of population structure between colonies at broad geographical scales (west versus central Panama). In contrast, higher gene flow was observed at small geographical scales, with Ecitophya and Ecitomorpha lineages not being Eciton lineage- or colony-specific. Gene flow within each species of myrmecophile was also detected across the Chagres River, a landscape feature that acts as dispersal barrier for E. burchellii females (Pérez-Espona et al., 2012). This, therefore, confirms a higher dispersal ability of female Ecitophya and Ecitomorpha than their Eciton hosts. Morphological studies have described fully developed wings in both myrmecophiles (Kistner and Jacobson, 1990); however, flight ability in these beetles has only been reported anecdotally as observations of hovering during disturbance of colonies (Mann, 1921; Pérez-Espona pers.obs.). Considering the strong specialization to their host, and the likely dependence of these myrmecophiles to colony life, it is possible that the main dispersal events between colonies might take place by the beetles riding on alate Eciton males when they leave their natal colonies in search of a mate.

Ecological and evolutionary studies of Ecitophya and Ecitomorpha with Eciton army ant colonies are still in their infancy. This study demonstrates the usefulness of genetic approaches to provide insights into the biology and evolutionary history of these myrmecophiles with their Eciton hosts, as well as to help resolve the taxonomic challenges they present. We hope that our study will serve as a platform for the many further investigations that are still needed to fully understand this captivating manifestation of Darwin’s ‘entangled bank’.


Akre, R.D., Rettenmeyer, C.W., 1966. Behavior of Staphylinidae associated with army ants (Formicidae: Ecitonini). J. Kansas Entomol. Soc. 39(4), 745–782.

Kistner, D.H., Jacobson, H.R., 1990. Cladistic analysis and taxonomic revision of the ecitophilous tribe Ecitocharini with studies of their behavior and evolution (Coleoptera, Staphylinidae, Aleocharinae). Sociobiology 17, 333–480.

Mann, W.M., 1921. Three new myrmecophilous beetles. Proc. United States Natl. Museum 59, 547–552.

Pérez-Espona, S., McLeod, J.E., Franks, N.R., 2012. Landscape genetics of a top neotropical predator. Mol. Ecol. 21, 5969–5985. doi:10.1111/mec.12088

Reichensperger, A., 1935. Beitrag zur Kenntnis der Myrmecophilenfauna Brasiliens und Costa Ricas III. (Col. Staphyl. Hist.). Arb. iiber Morphol. Taxon. Entomol. aus Berlin-Dahlem 2, 188–218.

Reichensperger, A., 1933. Ecitophilen aus Costa Rica (II), Brasilien und Peru (Staph. Hist. Clavig.). Rev. Entomol. 3, 179–194.

Rettenmeyer, C.W., Rettenmeyer, M.E., Joseph, J., Berghoff, S.M., 2011. The largest animal association centered on one species: The army ant Eciton burchellii and its more than 300 associates. Insectes Soc. 58, 281–292. doi:10.1007/s00040-010-0128-8


Dr Sílvia Pérez-Espona during collection of specimens in a forest fragmented area in the Área protegida de San Lorenzo’s buffer zone.

The curious case of antennating ants telling each other where to go


A blog post highlighting the article by S. Popp, P. Buckham-Bonnett, S.E.F. Evison, E.J.H. Robinson and T.J. Czaczkes in Insectes Sociaux

Written by Tomer Czaczkes and Sophie Evison

Anyone who has spent a few minutes watching ants running along a trail will have noticed that when two ants meet, they often interact for a second or two. It seems obvious to anyone watching that some sort of information transfer is occurring. But what could they be communicating? One of the most tempting hypotheses is that the returning ant is telling the outgoing ant where to go: “take the next left to a great patch of aphids!” in the way that the honey bee waggle dance conveys information about the location of food patches to other workers. However, as inviting as this hypothesis is, multiple investigations over the centuries have found no evidence to support an antennal language in ants. The widely accepted view is summed up by Hölldobler and Wilson in their bible of myrmecology (1990): “‘ants antennate nestmates in order to smell them, not to inform them’’.

However, from the mid 1990s, a Russian scientist named Zhanna Reznikova has been researching the communication skills and numerical competency of wood ants (family: Formicidae). Reznikova and colleagues report finding astounding physical communication abilities: not only could ants communicate a complex series of turns to nestmates by physical contact, they could also encode numbers (i.e. take the 27th turn to the food”) (Reznikova and Ryabko 1994). Sophie Evison first heard about this during her doctoral studies from Reznikova herself, at a Central European Workshop on Myrmecology. Of course, she had to try this herself, so using the ants Evison had available at the time – Lasius niger – she carried out a (fairly rudimentary) replication of Reznikova’s experiment. Evison’s experiment simply tested whether returning L. niger foragers could tell outgoing foragers the correct direction to go at an upcoming T-maze. Amazingly, initial experiments appeared to show that these ants were communicating a form of directional information about a T shaped maze simply via antennation, with no other cues. However, to be candid, these results had similar impact to those of Reznikova’s, and the findings only ever appeared in Evison’s doctoral thesis.

Reznikova’s discoveries are incredible. Why were they not picked up? Simply put, no one believed them. However, incredulity is not a basis for scientific discourse. Many incredible scientific findings – in both the current and original meaning of the word – have gone on to be proven right, and changed the face of science forever. It seems incredible that we live on a spherical ball of rock, but it is true. Although before it was widely accepted, this fact had to be independently verified by repeated observations. The appropriate response from a modern but incredulous scientific community should be replication, not dismissal.

Why then did no one try to replicate these results? Why didn’t we, in our recent Insectes Sociaux study, try to replicate it exactly? The answer is simple: No incentives. Replication – the backbone of the scientific method – has no career rewards – especially for low traction ideas. We all remember the STAP cell fiasco, but do you remember who tried to replicate it and failed? Indeed, when we take into account the time lost performing such replications, they can reasonably be considered harmful to a career. This is especially true in the specific Reznikova case, as their method requires weeks of patient observation to define stable working ‘teams’ before tests can even begin.

Our recent study in Insectes Sociaux has convinced us that, at least in two Lasius species, on-trail physical interactions do not communicate direction, but these are only two species. This increases the burden of proof for such physical communication, but does not rule it out. Of course, even though we set out to find evidence for such communication, we also find the results of Reznikova incredible. And while incredulity alone is not a basis for scientific discourse, it is far from meaningless. The collective intuition of our research community should not be ignored. Perhaps we should be taking a Bayesian approach, adjusting our demands for evidence by our level of incredulity. There an important part of this story that helped to keep our collective investigation going all these years: during a Royal Society event, the artificial intelligence expert Donald Michie mentioned to Elva Robinson that he had spent some time with Reznikova, and was very interested by her results. He had planned to investigate the claims further, but tragically lost his life in a car accident. Donald’s perspective on the work of Reznikova was important; it provided an externally driven impetus to resolve our contrasting findings.

So what would it take to convince us of the Reznikova findings? We propose replication by an unaffiliated research team, with meticulous video documentation. But let’s face it – for the reasons stated above, we don’t think this is going to happen. We hope to be proven wrong.



Staying close to home

Highlighting the article written by A. Friedel, R. J. Paxton, A. Soro (2017) in Insectes Sociaux

Written by Insectes Sociaux Editor-in-Chief, Michael Breed (

In this issue of Insectes Sociaux, Friedel et al. (2017) report on their investigations of population structure of a eusocial sweat bee, Lasioglossum malachurum. Their fascinating study exemplifies the complex choices that dispersing animals face. An animal that moves far from its birth location encounters unknown arrays of predators, uncertainty in finding a suitable destination habitat, and the possibility that all of the good habitat space in their path is already occupied. On the other hand, staying close to home raises the likelihood of competing with close relatives as well as inheriting any diseases or parasites that beset the previous generation.

For animals living in aggregations some challenges may be amplified. In addition to high potential for competition with close relatives, disease and parasite problems are compounded, as many possible hosts live in close proximity to one another. Aggregations may form via philopatry, in which animals establish nests close to their natal nest, which creates potential questions about social evolution. If more than one individual lives in a nest, as is the case in the closely related Lasioglossum zephyrum, Then the mechanisms of social recognition that maintain high levels of familial relationship within each nest may break down. High genetic similarity among nearby colonies, as in Lasioglossum malachurum, may blur kin distinctions, setting up possible difficulties for kin-selection explanations of the evolution of a worker caste. Given these intriguing contradictions between advantages in settling near the natal location and dispersing further, this investigation (Friedel et al. 2017) of genetic structure is particularly interesting and timely.

Friedel et al. (2017) specifically test the hypothesis that when gynes (potential queens) search for a new nesting site they are likely to choose a location near their natal nest. By using microsatellite markers to investigate genetic similarity they were able to determine that bees in neighboring nests have higher degrees of genetic similarity than bees from more distant nests within the same aggregation. They found in three of four aggregations studied that bees from very close nests were more genetically similar than expected if random dispersal had taken place. In other words, very short range dispersal seems to have resulted in the formation of aggregations of individuals or nests in small pockets within larger expanses of seemingly suitable habitat. Colonies located further apart within each aggregation showed random degrees of genetic similarity. The aggregation in which no population substructure was observed is very large and perhaps older, leading the authors to suggest that founder effects account for small scale genetic similarity within aggregations and that over time immigration of unrelated bees in the aggregation dilutes these effects. This study sets the stage for assessing how population genetic substructure affects social evolution and disease-host relationships.

The halictid bee studied by Friedel et al. (2017) is typical of many eusocial insects, which establish their nests in aggregations of tens, hundreds or even thousands of individual colonies. Aggregated nests are common in many species of halictid sweat bee, in some species of Apidae, such as Apis dorsata, and in some species of the social wasps Polistes, Mischocyttarus, and Ropalidia. We can also look beyond insects to find many interesting behavioral and evolutionary analogies that can be seen in the aggregated nesting of birds, such as oropendolas, Psarocolius spp., and various swallows Hirundo spp., and in mammals such as prairie dogs, Cynomys spp.

The repeated appearance of aggregated nesting across this wide range of taxa raises many interesting evolutionary and behavioral questions. On the surface, if aggregated nests result from limited dispersal from natal sites, this could have major effects on population genetic structure, leading to high levels of genetic similarity among individuals within small sampling areas in the aggregation. As Friedel et al. (2017) point out, this may represent a transitory phase in the development of aggregations across generational time, as long-term movement of unrelated animals into the aggregation may counterbalance the short-term effects of an aggregation having been initiated by a single female and her immediate offspring.


A. Friedel, R. J. Paxton, A. Soro (2017) Spatial patterns of relatedness within nesting aggregations of the primitively eusocial sweat bee Lasioglossum malachurum. Insectes Sociaux DOI: 10.1007/s00040-017-0559-6




Do fungus-farming leaf cutter ants smell like fungus?

Figure 1

Superficial view of an Atta bisphaerica leaf-cutting ant nest, in the Brazilian savannah. Photo: Lohan Valadares

A blog post highlighting the article by L. Valaderes and F.S. do Nascimento in Insectes Sociaux

By Lohan Valadares  (@valadareslohan, @lo.han.792)

About 30 million years ago, in the South American savannahs, ants that cultivate fungus have over evolutionary time become the leaf-cutting ants (genera Atta and Acromyrmex). These ants reside in large subterranean nests of the Neotropical region, with galleries and fungus chambers that shelter thousands to millions of individuals, where they farm the fungus Leucoagaricus gongylophorus. The fungus has never been found free-living without the ants, and it is generally accepted that both organisms have co-evolved into an obligate mutualism, which means that one organism cannot live without the other. For the ants, the fungus is priceless as it serves as a rearing site and unique nutritional substrate for brood development. In exchange, the ants protect the fungus against parasites and forage for fresh vegetation, which is used as substrate for fungal growth. Recently, chemical analyses of the fungus gardens of Acromyrmex species have revealed the presence of hydrocarbons, a class of chemical compound found commonly on the cuticle of insects (Viana et al., 2001, Richard et al., 2007). These two species are so intertwined, however, that whether it is the ants or the fungus which are the ultimate producers of these hydrocarbons is not yet clear.

Cuticular hydrocarbons (CHCs) are of particular importance for social insects, and decades of studies have demonstrated that they are important as nestmate recognition cues. Consequently, variations in these substances have been associated with caste, age, dominance hierarchy, worker subcastes, and developmental stages. Furthermore, the leaves used as the fungus substrate seem to be an important source of CHCs for leaf-cutting ants (Richard et al., 2004, Valadares et al., 2015). This leads us to hypothesise that the intermediate organism in this process – the symbiotic fungus – is actually the one promoting the transference of these substances, or may actually be involved in the synthesis of hydrocarbons itself.

To explore the resemblance between the chemical compounds of both organisms involved in this symbiotic association, we studied the resemblance between the CHC profile of fungal cultivars with those of the ants, focusing on the changes in the CHC composition during the ants’ larval-to-adult moulting in the leaf-cutting ant Atta sexdens and its associated fungus. Our main question was: how do the changes in the CHC profile associated with the moulting cycle correlate with the hydrocarbon profile of the fungus cultivated by the ant Atta sexdens? To assess it, we collected pieces of fungal mycelium, and ant larvae, pupae and adult workers from laboratory populations, and soaked them in a solvent to extract their hydrocarbons, which later on were injected into a gas chromatography–mass spectrometry (GC–MS) for separation and identification of hydrocarbons.

Figure 2

An excavated fungus chamber of an Acromyrmex subterraneus leaf-cutting ant nest, in the Brazilian savannah. Photo: Lohan Valadares

Our analyses demonstrated that ant and fungus shared 58% of hydrocarbons, and the rest were all ant-specific hydrocarbons that were absent from the symbiotic fungus. Our comparative analyses revealed a great similarity between the hydrocarbon profiles of larva and fungus, due to the fact that both groups shared mainly highly concentrated linear hydrocarbons. As individuals progressed through developmental stages, the chemical profiles between ant and fungus became increasingly different. As the moulting cycle progressed, the hydrocarbon profile was characterised by a great shift from the ‘less pronounced’ state of the brood’s chemical profile towards a more diverse chemical profile of adult workers comprised of highly concentrated branched hydrocarbons.

Our findings coincide with the observations made for Acromyrmex leaf-cutting ants (Vianna et al. 2001, Richard et al. 2007), strengthening the evidence for the intimate relationship between brood and fungus as a variable shaping the hydrocarbon profile of both species. However, because we don’t know in detail how the hydrocarbons are biologically synthesised and transferred between these organisms, it is difficult to interpret whether the ants or the fungus (or even both organisms) are the ones actually synthesising hydrocarbons. However, we believe that our descriptive and comparative analyses indicating such strong resemblances has suggested new exciting opportunities of research tha­t will help us to understand how this co-evolutionary relationship has shaped the chemical profile of both organisms. If we consider the optimistic scenario where the fungus is actually the one to be transferring these compounds to the ants, how does this transference impact colony odour? Do these substances play a role in nestmate recognition? Several questions remain to be answered and hopefully our work has contributed to the journey towards the understanding of the chemo-ecology between leaf-cutting ants and their fungal cultivars.



Branstetter, M.G., Jesovnik, Aa, Sosa-Calvo, J., Lloyd, M.W., Faircloth, B.G., Brady, S.G., Schultz, T.R. (2017). Dry habitats were crucibles of domestication in the evolution of agriculture. Proceedings Royal Society B. 284: 20170095.

Richard, F.J., Heftz, A., Christides, J.P., Errard, C. (2004) Food influence on colonial recognition and chemical signature between nestmates in the fungus-growing ant Acromyrmex subterraneus subterraneus. J Chem Ecol 14: 9–16

Richard, F.J., Poulsen, M., Hefetz, E.C., Nash, D.R., Boomsma, J.J. (2007). The origin of the chemical profiles of fungal symbionts and their significance for nestmate recognition in Acromyrmex leaf-cutting ants. Behav Ecol Sociobiol 61(11):1637-1649

Valadares, L., Nascimento, D., Nascimento, F.S. (2015) Foliar substrate affects cuticular hydrocarbon profiles and intraspecific aggression in the leafcutter ant Atta sexdens. Insects 6: 141-151

Viana, A.M., Frézard, A., Malosse, C., Della Lucia, T.M., Errard, C., Lenoir, A. (2001) Colonial recognition of fungus in the fungus-growing ant Acromyrmex subterraneus subterraneus (Hymenoptera: Formicidae). Chemoecol 11(1): 29-36

Interview with a social insect scientist: Mary Jane West-Eberhard


Polistes fuscatus, a representative of Mary Jane West-Eberhard’s favourite genus. Photo: John Brandauer/flickr

IS: Who are you and what do you do?

MJWE: Mary Jane West-Eberhard, retired research scientist, Smithsonian Tropical Research Institute. Retired = working as usual for less pay.

IS: How did you end up researching social insects?

MJWE: The answer started when I was a little kid. My first pet (or so I thought) was a beautiful sweat bee that looked like a jewel. It landed on my arm when I was about nine years old. I thought it liked me. But then it stung me and flew away! That did it for the solitary Hymenoptera. But I liked wasps – they are perky and beautiful. I first paid attention to them when making an insect collection for a 4-H entomology project. Then, in college I wanted to do something on insect behaviour for my honors thesis at the University of Michigan. Henry Townes, a taxonomist of parasitoid Hymenoptera, suggested that I do it on Polistes. It was the dead of winter but I found some hibernating females and put them in a terrarium. They woke up immediately and immediately started to antennate each other and fight. I figured I couldn’t go wrong with those.

IS: What is your favourite social insect and why?

MJWE: My favourite is still Polistes. Every Polistes species has distinctive visible social displays, and they are always active. Seeing a new species always rewards you with something new and interesting. They never disappoint. I have worked on MANY species of wasps. Some, like Mischocyttarus, are very common in the tropics where I have lived, and they have open nests like Polistes. There are many species and I have tried looking at lots of them but they are unbearably dull compared to Polistes.

IS: What is the best moment/discovery in your research so far? What made it so memorable?

MJWE: I guess there are two kinds of excitement – discoveries during fieldwork, and making new connections (having new ideas). Maybe I can get away with giving more than one example, one for each decade of my fieldwork on social insects:

  • [as an undergrad] Seeing a mother cricket, who was caring for her nymphs, lay a tiny egg and then feed it to one of her nymphs! A trophic egg, like those of ants, but never before seen in a cricket.
  • [As a grad student] Seeing some marked Polistes females return to their single-queen natal nest site after hibernation, and start building nests together (the first direct field confirmation of the relatedness aspect of kin selection theory).
  • Discovering the complex dominance displays of Metabolybia queens toward each other, and the displays of workers toward them that indicated worker choice of queens – they actually dominated some of the queens into becoming workers!
  • Finding a nest of Zethus miniatus the very species studied long ago by Ducke in Brazil, famously a group living eumenine wasp used by Wheeler as a model transitional species.
  • Realizing (in the 1980s) that most alternative states considered “genetic polymorphisms” are actually condition-dependent polyphenisms and other kinds of non-genetically determined alternative forms – just like workers and queens. This undermined some assumptions of genetics and, within behaviour studies, ESS game theory, that predominated at the time.

IS: If teaching is part of your work, what courses do you teach? Has your work on social insects helped to shape your teaching?

MJWE: As a grad student I planned to become a college professor. But my job with the Smithsonian Tropical Research Institute has been a research job; and my husband Bill has taught the courses I might have taught in the places we have lived. But I like to think that the general-scope writing I have done is a kind of teaching – “courses” on the evolution of insect societies, sexual and social selection, and development (including of behaviour) in relation to genetic evolution. I like to think that it helps researchers working on real organisms to see the general significance of their work.

IS: What is the last book you read? Would you recommend it? Why or why not?

MJWE: “Hillbilly Elegy,” by J.D. Vance. I recommend it because it describes some truly forgotten, especially by academics and politicians, elements of US society – their deep problems and why ignorance (including bigotry) is entrenched and difficult to deal with, for those (victims and idealists) who would try to find a way out of it.

IS: Did any one book have a major influence in shaping your career? What was the book and how did it affect you?

MJWE: Mayr 1963, “Animal Species and Evolution.” A grad-student seminar (led by R.D. Alexander) read that book and we critically examined every page – every sentence. The book was mainly about speciation, but it was a summary of organismic evolutionary biology at that time. I still use it for history and references – as a marker of what was understood when I was a student, and what was not.

IS: Outside of science, what are your favourite activities, hobbies or sports?

MJWE: My favourite activity is good conversation. “Good” means intelligent and entertaining (this does not necessarily mean intellectual and can be with small children or people without earphones on airplanes). It means open as well as considerate. Travel. Watching behaviour including of people, and trying to figure out what is going on in different settings, and why. My work and my family have always been my hobbies. Aerobics 3 times a week.


IS: If you were on an island and could only bring three things, what would you bring? Why?

MJWE: A flashlight, a bottle of water, and a helicopter. The “why” seems self explanatory.

IS: Who do you think has had the greatest influence on your science career?

MJWE: Richard Alexander, my professor at the University of Michigan. He encouraged critical thinking and independence, and encouraged thinking about the general importance of my discoveries. He didn’t expect his students to work on aspects of his own research. He was bursting with original ideas and always talked about them. He didn’t worry about getting ripped off because he was publishing as fast as he talked.

IS: What advice would you give to a young person hoping to be a social insect researcher in the future?

MJWE: Choose a species or a taxon and resolve to become the world expert on it – to learn everything that is known about it, including classification, physiology, behaviour, evolutionary history. Then do whatever you have the greatest patience for. For example, I have no patience for making apparatus work in a lab. But I can watch animal behaviour for hours and hours without getting bored. Whatever you do, whether it is ecology, or library work, or laboratory experiments, or microscopic studies of morphology, be sure to spend SOME time observing behaviour, because that will give you clues about whatever you are trying to understand.



Interview with a social insect scientist: Corrie Moreau


IS: Who are you and what do you do?

CSM: I am Dr. Corrie Moreau (@CorrieMoreau), Associate Curator/Professor at the Field Museum of Natural History. I oversee a very large scientific collection and run an active research program using molecular and genomic tools to study the evolution of social insects.

IS: How did you end up researching social insects?

CSM: Since a young age I have always wanted to study ants. Growing up in New Orleans, Louisiana, there were always ants everywhere and they completely fascinated me.

IS: What is your favourite social insect and why?

CSM: Ants! There are so many closely related species that look and behave differently and even distantly related species that have converged on their morphology and behaviors. These differences and similarities provide an excellent system to understand how and why these traits evolve.

IS: What is the best moment/discovery in your research so far? What made it so memorable?

CSM: For me there are two moments in my research so far that have stood out. One came when I inferred the first large-scale molecular phylogeny of the ants and found striking diversification that corresponded to the rise of the flowering plants. The second came when I started to realize the key role that host-associated bacteria can have on the ecology and evolution of social insects. For me what made these both so memorable is they helped explain the ecological and evolutionary success of the group of organisms I had been studying so intimately.

IS: If teaching is part of your work, what courses do you teach? Has your work on social insects helped to shape your teaching?

CSM: Being at a large natural history museum, I have the opportunity to share my research and educate a very diverse audience on a daily basis. This is really rewarding. Since everyone has at least seen an ant, this opens the door to be able to talk about cutting-edge research and how this informs other aspects of science. I have also taught a phylogenetics course at the University of Chicago and enjoy being in the more formal classroom setting too. Being able to share the theoretical framework and analytical skills that allow students to address their own research questions is very gratifying.

IS: What is the last book you read? Would you recommend it? Why or why not?

CSM: I am currently reading “Time, Love, Memory: A Great Biologist and His Quest for the Origins of Behavior” by Jonathan Weiner. It was sent to me as a gift from Dr. Hopi Hoekstra, behavioural geneticists at Harvard University. The book follows the research career of Dr. Seymour Benzer to tell the history of behavioral genetics. The book is very well written and provides insights into not only the scientific highlights of this field, but the opportunity to learn a little about the lives of several scientists that helped develop this field.

IS: Did any one book have a major influence in shaping your career? What was the book and how did it affect you?

CSM: One book that I consistently return to is “Ants: Their Structure, Development, and Behavior” by William Morton Wheeler. This book was published in 1910 and is still one of the most insightful and complete books on ants. Of course, many things we know about ants has changed in the last 100 years, but this book still has so many inspiring insights into ant biology. And the figures and diagrams on ant internal and external anatomy are excellent!

IS: Outside of science, what are your favourite activities, hobbies or sports?

CSM: Reading, running, yoga, hiking, and traveling the world for research and fun with my husband, Dr. Christophe Duplais.

IS: How do you keep going when things get tough?

CSM: I wish I had some words of wisdom here since I know everyone has difficult times or obstacles to overcome. For me I try to return to what excites me, which is often enough to help push me through the tough times.

IS: If you were to go live on an uninhabited island and could only bring three things, what would you bring? Why?

CSM: This is a tough question. I would bring an avocado seed to grow lots of avocados to eat. A hand lens to be able to try to identify all the cool insects I find. And, lastly, a field notebook (and lots of pencils – I know that is more than one thing, but you need pencils if you have a notebook) to record all my observations.

IS: Who do you think has had the greatest influence on your science career?

CSM: I don’t think any scientist can attribute their careers to one person and that is certainly true for me. My advisors and mentors from undergraduate, master’s, Ph.D. and postdoc all deserve very special thanks. In addition there are a myriad of teachers and scientists that have had a big impact on the way I think and try to solve problems. I thank them all.

IS: What advice would you give to a young person hoping to be a social insect researcher in the future?

CSM: Follow your passions. Working in science is really rewarding, and I believe it is important to do what you love everyday. So if you are passionate about some aspect of social insect science then you should absolutely go for it! There are more questions and species than people on the planet so we need all the social insect scientists we can get.



Interview with a social insect scientist: Elizabeth Tibbetts

E TibbetsIS: Who are you and what do you do?

ET: My name is Elizabeth Tibbetts and I am a professor in Ecology and Evolutionary Biology at the University of Michigan.

IS: How did you end up researching social insects?

ET: I’m not one of the those people who always loved insects. In fact, I was pretty scared of them as a child. I decided to study social insects in graduate school because they seemed more tractable than vertebrates. I’m glad I did. I fell in love with wasps and haven’t looked back.

IS: What is your favourite social insect and why?

ET: My favourite social insects are Polistes paper wasps. I’ve become quite attached to them over the years. I love the way their social organization combines cooperation and conflict. Polistes form stable societies, but each wasp also has its own agenda. Sometimes individuals fight for supremacy within their group or leave their natal nest to reproduce independently. Polistes are also a great group to study my favourite topics: communication and cognition.

IS: What is the best moment/discovery in your research so far? What made it so memorable?

ET: My best moment of scientific discovery happened in graduate school when I figured out that Polistes fuscatus use their facial patterns for individual recognition. In my second year of graduate school, I noticed that Polistes fuscatus wasps have highly variable facial patterns. I followed up the observation with a few behavioural experiments. I still remember the thrill of analysing the data and realizing my experiment worked. Wasps really are capable of individual face recognition.

As a new graduate student, I wondered whether I could ever discover something new. People have been studying social insects for hundreds of years, so how could I hope to contribute anything? Over time, I’ve learned that there is no lack of exciting research questions in even the most common organism.

P fuscatus individual recognition

The distinctive facial markings of Polistes fuscatus. Photo: E. Tibbetts

IS: If teaching is part of your work, what courses do you teach? Has your work on social insects helped to shape your teaching?

ET: I teach animal behaviour classes at introductory and advanced levels. I’m sure I include more insect examples than many animal behaviour instructors. However, I try to limit myself. For some reason, introductory students tend to be more interested in whales than bees.

IS: What is the last book you read? Would you recommend it? Why or why not?

ET: I recommend “Lab Girl” by Hope Jahren. It’s a beautifully written memoir about her life as a plant geobiologist . The book does a great job of describing the ups and downs of life as a research scientist.

IS: Did any one book have a major influence in shaping your career? What was the book and how did it affect you?

ET: In high school, I read all the books in the ‘Nature’ section of our public library. Some were great (“The Selfish Gene”, “Gorillas in the Mist”), while others were not so great (“The Naked Ape”). That section of the library is probably responsible for my decision to study biology as an undergrad and animal behaviour as a grad student.

IS: Outside of science, what are your favourite activities, hobbies or sports?

ET: Most of my time outside of work is spent with my two kids (4 and 7 years old). We spend a lot of time playing Legos, pretending to be superheros, reading, and swimming.

IS: How do you keep going when things get tough?

ET: I remind myself that a scientific career is a marathon rather than a sprint, so there is no need to panic about a failed experiment or a rejected grant. There is usually lots of time to overcome challenges and turn things around.

IS:  If you were to go live on an uninhabited island and could only bring three things, what would you bring? Why?

ET: I would bring a satellite phone to call for help, fresh water, and a book to read while I wait.

IS: Who do you think has had the greatest influence on your science career?

ET: I’m grateful to my dad for instilling an early love of science. My graduate experience at Cornell was also very influential. There was a large, enthusiastic group of graduate students who had a big effect on my scientific development. My advisor, Kern Reeve, and committee, Tom Seeley, Elizabeth Adkins-Regan, and Cole Gilbert were also wonderful.

IS: What advice would you give to a young person hoping to be a social insect researcher in the future?

ET: Having a life outside work (hobbies, family) is compatible with being a successful scientist. Don’t let anyone convince you otherwise.

Get in the habit of writing every day. You need to get your ideas into the world and effective writing is the best way to do it.


Interview with a social insect scientist: Juliana Rangel


IS: Who are you and what do you do?

JR: My name is Juliana Rangel, Assistant Professor of Apiculture at Texas A&M University in College Station, TX, USA. I run a research and teaching program focusing on the health and biology of managed and feral Apis mellifera colonies.

IS: How did you end up researching social insects?

JR: When I was an undergraduate student at the University of California, San Diego, I emailed Dr. James Nieh, who had just started his position as Assistant Professor in the unit of Ecology, Behavior and Evolution, which was also my major. Coming from Colombia, I wanted to get experience with research, especially in projects that were being conducted in the tropics. Coincidentally Dr Nieh had a research project in Brazil studying communication mechanisms in stingless Melipona bees. I worked for a semester analysing sound pulses produced by Melipona mandaçaia foragers upon being trained to feeders… I really liked what I was doing! Then Dr. Nieh invited me to be his research assistant in Brazil working with actual colonies… the rest is history. I worked with stingless honey bees for the rest of my undergraduate years, and in 2004 I started a doctoral degree in the department of Neurobiology and Behavior at Cornell University still working with stingless bees. My project wasn’t going fast enough so a couple of years into it my Ph. D. advisor, Dr. Tom Seeley, suggested that I switched to working with Apis mellifera. I have worked on several research projects exploring various aspects of reproductive biology of queens and drones ever since, and I love it.

drone with varroa

Left: a male honey bee (drone) with a varroa mite on its back. Right: a queen honey bee.

IS: What is your favourite social insect and why?

JR: Of course Apis mellifera. Despite being widely studied, there are still so many fascinating discoveries about its biology that never stop to amaze me… the way that colony organization is decentralized and yet so meticulously timed and executed is a feat difficult to top by any other organism… and the rules applied in decision-making processes are just as captivating. I am particularly amazed at how sperm storage is maintained for so long in honey bee queens after mating… overall there are just too many factoids about honey bee biology that make it the ideal organism to study and love.

IS: What is the best moment/discovery in your research so far? What made it so memorable?

swarm 2

A honey bee swarm taking off.

JR: I have had many great moments of discovery, but my favorite one happened in 2009. I was on Appledore Island, Maine, studying with Tom Seeley the signals (and signallers) that initiate a swarm’s departure from the parental nest. We set up glass walled observation colonies and artificial boxes that nest-site scouts soon discovered and started recruiting nest mates to. Upon arrival to the boxes our assistant Sean Griffin (who still also studies pollinators) would label scouts with paint on their thorax so that we could identify their arrival back at the observation colony. We soon discovered that indeed, nest-site scouts start the house hunting process days before a swarm leaves the parental nest, a great discovery of its own. Even though Sean had labelled a few hundred bees from one colony that was preparing to issue a swarm in a couple of days, we did not find that many labelled bees back in the colony. Something was off… when the swarm left a couple of days later, we suspected something weird and opened the nest box, only to find hundreds of labelled bees “guarding” it by staying inside until the swarm movedinto the box. This exciting discovery led us to conduct a follow up study the next summer in which we set up pairs of swarms on stands (we could distinguish the two form the color of their cuticle) and video taped what happened inside nest boxes. Indeed swarms compete for high quality nest sites by keeping guard inside the coveted boxes, and engage in overt aggression ranging from behavioural escalation of intent, to direct stinging and lethal combat. Really cool stuff…

IS: If teaching is part of your work, what courses do you teach? Has your work on social insects helped to shape your teaching?

JR: I teach three courses. Two undergraduate courses are focused on honey bees: Honey Bee Biology which is a course for juniors and is solely lecture-based. And my favorite, Introduction to Beekeeping, which is a field, hands-on ‘laboratory’ course that teaches students how to start their own colonies and how to manage them throughout the year. I also teach a graduate-level course on “Professional Contract and Grant Writing” which helps students understand the “art” of grant writing and award management.

IS: What is the last book you read? Would you recommend it? Why or why not?

JR: I am currently reading “Bee Genetics and Breeding” by Tom Rinderer. It’s a very thorough book on all aspects of honey bee breeding. I would highly recommend it to people studying honey bee reproductive biology. Although it was written in the late 80s, it still has a lot of pertinent information about queen and drone biology, some of which has not been advanced much since the book was written.

IS: Did any one book have a major influence in shaping your career? What was the book and how did it affect you?

JR: Yes, “The Wisdom of the Hive” by my Ph.D. advisor Tom Seeley. I had to read it for my oral exams, and it gave me a lot of insights into what we knew and didn’t know (then) about colony organization. Oh, and of course “Honey Bee Biology” by Mark Winston, because even though it has not been updated since 1987, it shows how much we still don’t know about honey bee biology. The are “must reads” by anyone studying Apis mellifera.

IS: Outsisde of science, what are your favourite activities, hobbies or sports?

JR: I love to travel and to go camping. Now that I am a new mother of a six-month old baby, I love spending time with my husband and kid just walking and traveling with them… and with our red heeler dog, Max. I also love to cook and to entertain friends and family at our home… and I play the guitar and sing Latin American folk songs, especially during gatherings.

IS: How do you keep going when things get tough?

JR: I rely on my family for support, and try to communicate with colleagues and mentors who have always supported me. I have always found that talking about what is going on, regardless of how difficult the situation might be, is very positive for resolution. As my wise mother always says, “no two days are alike” and “each day comes with its own rush,” both of which are true. Taking life one day at a time but with a good plan for the future has worked well for me.

IS: If you were to go live on an uninhabited island and could only bring three things, what would you bring? Why?

JR: This one is very tough. Would I be alone or with my family? If I was alone I would bring my baby, my husband, and my mother… but what about the rest of my family? And Max? Oh this question is tough. If it had to be things, not people… tools to seek and cook food and/or to make a shelter. That’s all. Maybe a pen and paper.

IS: Who do you think has had the greatest influence on your science career?

JR: Of course it has to be my PhD advisor, Tom Seeley. I am just so lucky to have been accepted in his lab and to have worked so closely with him during my years at Cornell. I could not have asked for a better advisor. I still keep in touch with Tom and ask for advise on life-changing opportunities… his words are always wise and accurate. He also finds joy in seeing me progress in my academic and personal life, which is always a plus.

IS: What advice would you give to a young person hoping to be a social insect researcher in the future?

JR: I would say go for it. You know that if you’re in an academic life, you will never be rich. We don’t do this for the money. As the late Dr Tom Eisner said, we do it “for love of insects.” I would encourage students to explore questions that have a basic biology aspect to their research… too much of the current research focuses on next-generation “-omics” work that often overlooks past the importance of knowing basic biology: behaviour, ecology… which are the studies that I find most fascinating still to date. Learn a wide set of experimental tools to be competitive in the current job market, be flexible with your job expectations, and do good, ethical work, always. Oh, and have fun while doing it!


Do persistent ants work better together?

A blog post highlighting the article by H.F. McCreery in Insectes Sociaux

By Helen McCreery (@HelenMcCreery)

Ants are famous for their ability to carry heavy things. But some food items are too large and heavy for an ant to carry alone. In some species, ants that come across these large food items will return to the nest to recruit help to carry it home.

Ant species differ dramatically in how effective groups are at cooperatively transporting these items. A small number of species – such as weaver ants and crazy ants – can rapidly carry extremely heavy objects many thousands of times the mass of each individual. On the other hand, most ant species are relatively uncoordinated, and may not succeed at all.

What makes some ant species excel at cooperative transport? One major challenge of cooperative transport is that the group must agree on a travel direction. I hypothesized a behavioral trait possessed by individual ants – persistence – affects groups’ ability to coordinate their efforts in a particular travel direction, and thus, to succeed.

Persistence is a measure of how likely an individual is to change the direction she’s trying to move an object – or even to give up – if she’s unsuccessful. Highly persistent ants will keep pulling in the same direction for a long time, even if it’s not working. If a group is full of highly persistent individuals, they may fail because they pull in opposing directions for a long time. On the other hand, if a group is full of low-persistence individuals, they may change direction too frequently or simply not try for long enough to get going. Some previous work (McCreery et al. 2016) showed that in most cases high persistence improves coordination, at least in a theoretical context. I tested this hypothesis experimentally, by comparing cooperative transport ability in species that differ in persistence, and by manipulating persistence in groups of one species.

For the first part of this project, I worked with four ant species that ranged from impressively successful at cooperative transport (crazy ants: Paratrechina longicornis) to poor cooperative transporters (Formica pallidefulva), with Formica podzolica and Formica obscuripes making up the middle ground – groups in these two species seem to be moderately effective at carrying objects together (see video below). I measured persistence for dozens of individuals in each of these species by watching them complete an impossible task – trying to move a dead cricket I pinned to the ground. Separately, I measured the degree of coordination of groups in each of these species by recording groups engaged in cooperative transport. I measured two aspects of their coordination: success fraction (in what proportion of attempts did groups move at least 10 cm?) and path directness (did they move in a straight line or did they change direction frequently?). If species with highly persistent individuals were also more successful, it would support my hypothesis.


Video: H. McCreery

In the four species that I compared, I found just that pattern. Importantly, I found that there was substantial variation among species in both persistence and in coordination. P. longicornis individuals were the most persistent by far, and formed groups that were the most coordinated, succeeding in over 97% of attempts. On the other hand, F. pallidefulva individuals had dramatically lower persistence and were the least coordinated – F. pallidefulva groups only succeeded in about a quarter of attempts. The two other species, F. podzolica and F. obscuripes, both had individuals that were moderately persistent, and formed groups that were moderately coordinated – these groups succeeded most of the time, but with relatively indirect paths, they tended to travel about twice the distance they needed to because they frequently changed direction. High individual persistence is correlated with high group coordination in these four species.

ant pulleyIn the second part of this project, I wanted to test whether coordination could be improved by increasing persistence so I manipulated persistence in groups of F. podzolica. I did this by measuring the path-directness of groups, and then adding one or two infinitely persistent “fake ants,” and measuring path-directness again. I added fake ants by mimicking the pulling force that such ants would apply on an object. I gave groups of ants heavy baits attached to string. Using a pulley system, I could add a pulling force on the baits by adding weight on the end of the string (see above figure). Check out the video below to see how I measured the pulling force of these ants.


I measured the pulling force of F. podzolica workers by recording them pulling on coiled chains. They enthusiastically pulled on these chains without bait!
Video: H. McCreery

The fake ants that I added to these transport groups were infinitely persistent, because the string would never stop pulling and never change direction. While the force of one ant made no difference, adding the pulling force of two ants going the same direction seemed to moderately improve coordination. These groups tended to move with more direct paths after I added the fake ants. I was surprised to see even a moderate effect, given that I only mimicked a single possible cue (the pulling force); my fake ants did not mimic anything else about real ants. Together with the results from the first part of this project (species comparison), these results suggest an important role of individual persistence in coordination during cooperative transport.

I found that species with more persistent individuals formed more coordinated transport groups, and that artificially increasing persistence moderately improved coordination. It can be difficult to draw strong conclusions when comparing across species, and indeed, the four species I evaluated differ in many more traits than just persistence. It is possible that another difference among these species, instead of persistence, has a more important effect on coordination. Despite this difficulty, comparing cooperative transport across species that dramatically differ is an important step in understanding the mechanisms of coordination. I would be interested to see if other species, beyond these four, fit a similar pattern with respect to persistence and coordination. The results of this study further suggest additional, targeted experiments that could get at the specifics a causal relationship between persistence and coordination.


McCreery HF, Correll N, Breed MD, Flaxman S (2016) Consensus or Deadlock? Consequences of Simple Behavioral Rules for Coordination in Group Decisions. PLOS ONE 11:e0162768. DOI: 10.1371/journal.pone.0162768