A blog post highlighting the article written by Burchill and Moreau in Insectes Sociaux

Written by Andrew Burchill

Imagine that you’re a social insect scientist with musical aspirations. After many long years, you finally have enough free time to turn your persistent rock ‘n roll day-dreams into reality. But before you rock out as the most righteous post-hardcore, grungewave, electropunk band ever seen, you’ll need to recruit a few more members.

A social media shout-out to your colleagues garners more replies than you expected. Like ants at a spilled soft drink, the number of interested applicants begins to sky-rocket: it seems your entire department has been secretly harboring rock-star fantasies.

You are now faced with the problem of deciding how large the group should be. Traditionally, it seems that four members is the golden mean. For example, the Beatles followed the common pattern of two guitars, bass, and drums. (In your case this would be one accordion, a guitar, bass, and bongos.) But in a flashback from the late 60s, you remember that the successful psychedelic rock group Jefferson Airplane had seven members at one time.

Yet the options don’t stop there: a visiting researcher from Japan points out that AKB48—an all-girl pop group with 48 original members—is wildly popular overseas right now and has expanded to include more than 120 individuals. It’s clear that group size is an important consideration for any burgeoning rock band, but the question remains: what is the optimal size, and what factors determine this?

For biologists interested in social groups, this is not a new problem. Although there are many reasons that cause organisms to cooperate, it is still unclear what number of individuals works “best” in any given situation. Recent theory suggests that in complex environments, smaller groups should end up making better decisions (Kao and Couzin 2014), but Sasaki et al. (2013) found that when it comes to making difficult decisions like choosing the best nest, larger colonies of ants outperform smaller ones. With conflicting theories and little experimental data, we seem to be at an impasse. Where do we find the answer? If only we could run thousands and thousands of experiments, each with slightly varied environmental conditions…

All leading, rhetorical questions aside, we have arrived at our favorite subject: ants. As is oft-repeated by social insect enthusiasts, ants dominate the terrestrial biomass. Working and cooperating as a group is the key to their success; social cohesion between many individuals allows them to access and even create ecological niches that other species cannot. Naturally, the size of these groups (the colony) is a vitally important factor in social insect ecology—it affects traits such as foraging strategies, social organization, colony defense, and colony-wide immune responses. On one hand, we have species living in the leaf litter with colony sizes as small as the Fab Four from Liverpool. On the other hand, some species style themselves after the ever-growing AKB48, blurring the definition of what it even means to be “a” colony: the Argentine ant can form super-colonies that span thousands of kilometers. The 13,000+ living species of ants can thus be seen as a collection of “natural experiments,” with evolutionary forces “tweaking” colony sizes in response to changing environmental and ecological conditions.

But in order to understand the role of colony size in ant evolution, we first need to acquire a basic understanding of the patterns of colony size change over their 130 million year evolutionary history. Have average colony sizes gotten steadily larger over time? Do changes happen in little baby steps or in leaps and bounds? Once the average colony size gets very big, does it ever decrease in size?

A solid evolutionary study generally needs two things: data on lots of species (in our case, average colony sizes) and the evolutionary relationship between these species (the phylogenetic tree detailing which ants are most closely related to one another). Fortunately, Moreau & Bell (2013) had just published the most complete phylogeny of ant species ever seen, giving us the perfect foundation to begin our study. Unfortunately_, there was no way a single empirical study could gather enough data on the average colonysizes from hundreds of species. We were left with one option: combing through the previously published literature for size estimates.

This is where yours truly spent months slogging through data from controlled experiments, field measurements, and anecdotal observations, desperately trying to find estimates for as many species as possible. (We won’t directly describe such actions as ‘heroic,’ but we will leave the word for you to apply as you see fit.)

With an evolutionary tree in one hand and colony size estimates in the other, we decided to use Multiple State Speciation and Extinction (MuSSE) analysis to investigate our data. This analysis simultaneously estimates how frequently species with given traits—small, medium, or large colony sizes—transition from one trait to another and how frequently ants in such categories speciate into two daughter species. By constraining some of these transition rates, we can emulate popular hypotheses proposed in the literature and then compare these models.

We found that colony size change seems to undergo a kind of threshold event. After the colony grows large enough over evolutionary time, it seldom decreases backwards in size. In a somewhat tortured metaphor, imagine your hypothetical rock band from earlier. With only a few members, it’s relatively easy to add or lose new musicians. But suppose that you accept all those hopeful applicants from your department to form an AKB48-esque conglomeration. Now that you’ve been branded as a “mega-group,” it’s going to be almost impossible to eject enough members to play at the local drinking establishment. Reverting back to your typical four or five person band is not really an option anymore.

Additionally, our investigation suggests that changes are usually the result of incremental “tinkerings” with the number of workers in the colony. Large, exponential changes in average colony size were rare. Again, imagine our still-nameless rock band: musicians join or leave the group one at a time instead of in big cliques. Taken with the above-mentioned threshold-like activity, we suggest that as colony sizes grow larger, they may fall into a feedback loop. Workers may be able to specialize in certain tasks within a large colony, which could increase overall efficiency, allowing the colony to grow larger, etc., etc.

So what IS the optimal group size? We still don’t know. But now researchers have an empirical groundwork for further studying colony size evolution in ants. Do particular clades or groups of ants exhibit unusual changes in colony size? Before our work, myrmecologists wouldn’t have even been able to say what “unusual” was; now we can pinpoint clades that exhibit unique patterns, ideal of future investigation. Our results also corroborate previous theoretical (Bourke 1999) and mathematical models (Guatrais et al. 2002) of social insect evolution. Can we further refine these models or explore why the alternative models failed? We believe that the most promising route of inquiry should involve adding ecological data into this study: perhaps we can find how the number of queens a colony has, the type of food the ants eat, and/or the environment a species inhabits will affect the group size. Although the issue is by no means settled, we believe our work is a good first step in the right direction.

 

References:

Bourke AFG (1999) Colony size, social complexity and reproductive conflict in social insects. J Evol Biol 12:245–257. doi: 10.1046/j.1420-9101.1999.00028.x

Gautrais J, Theraulaz G, Deneubourg J-L, Anderson C (2002) Emergent polyethism as a consequence of increased colony size in insect societies. J Theor Biol 215:363–373. doi: 10.1006/jtbi.2001.2506

Kao AB, Couzin ID (2014) Decision accuracy in complex environments is often maximized by small group sizes. Proc Biol Sci 281:20133305. doi: 10.1098/rspb.2013.3305

Moreau CS, Bell CD (2013) Testing The Museum Versus Cradle Tropical Biological Diversity Hypothesis: Phylogeny, Diversification, And Ancestral Biogeographic Range Evolution Of The Ants. Evolution (N Y) 67:2240–2257. doi: 10.1111/evo.12105

Sasaki T, Granovskiy B, Mann RP, et al (2013) Ant colonies outperform individuals when a sensory discrimination task is difficult but not when it is easy. Proc Natl Acad Sci 110:13769–13773. doi: 10.1073/pnas.1304917110

IS: Who are you and what do you do?

JH: I am Joan Herbers, a Professor at Ohio State University. For about 30 years, I studied social organization within ant colonies, focusing on conflict resolution. About 8 years ago I closed my ant lab and developed a second career on gender issues in science. Now I study humans instead of ants! The shift has been fun and invigorating, and last year I published a book “Part time on the Tenure Track“.

 IS: How did you end up researching social insects?

JH: As a grad student in the 70s, I took a course on optimization theory. At that time, the only biological paper that used linear programming was E.O. Wilson’s work on caste ratios. I read that paper and was hooked on the problem of optimizing work forces within social groups.

IS: What is your favourite social insect and why?

JH: Hands-down, my favourite is Temnothorax longispinosus. Not only is it cute and incredibly interesting, but studying its social ecology earned me tenure.

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

JH: After starting my first academic job (at the University of Vermont), I spent the first summer (1980) at the Huyck Preserve in New York, collecting ants, watching their behaviour etc. During the first week, I cracked open a stick and watched little black ants run around in my collecting pan. There were 2 queens! I thought “wow, that’s not supposed to happen”. Shortly thereafter I cracked open another stick and saw 3 queens running around the pan. After finding about 5 polygynous colonies, I realized that this was a real phenomenon and completely unexplored from an evolutionary perspective. So I started working on why colonies of T. longispinosus were polygynous, a problem that consumed me for more than a decade.

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

JH: I teach courses in evolution, ecology, and women’s studies. There is no doubt that working on social insects has provided me with a broader perspective on biological problems because they inherently present levels-of-selection thinking. And, being female-dominated societies, they provide lots of fodder for my women’s studies courses!

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

JH: Ron Rash’s novel “One Foot in Eden”. Rash writes stories about the people of Appalachia and I find his use of language and sense of place incredibly moving. Highly recommended also are his short stories.

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

JH: “Caste and Ecology in the Social Insects“ by Oster and Wilson was deeply influential. Wilson sent me preprints of the book to help with my dissertation writing, which was extremely kind. I have had all my students read that book to find ideas for thesis topics, because it remains a gold mine.

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

JH: I am an avid amateur violinist, and play string quartets on weekends. I also plunk around on the piano and am addicted to New York Times crossword puzzles.

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

JH: I am an optimist, and have had occasion in the past years to reflect deeply on how many good breaks I have had in life. I grew up in a loving family, have been married happily for 32 years, and have two wonderful children. We have enough money and live in a great city. The hand I have been dealt may not be a royal flush, but it surely is a winner.

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

JH: A deck of cards, because I know about 50 ways to play solitaire; my violin, which brings me great joy; and a copy of “Anna Karenina“, perhaps the wisest and most compassionate novel ever written.

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

JH: In grad school I had a pretty serious case of the imposter syndrome. My department chair, Neena Schwartz, decided to meet weekly with the women grad students to discuss various issues about being a women in science. Learning from her that my insecurities were normal and gaining exposure to a powerful woman scientist helped me more than any other single experience.

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

JH: Study math and chemistry; they will keep doors open and give you tools to ask any questions about social insects that you can think of.

A video and blog post highlighting the article by O’Fallon, Suarez and Smith in Insectes Sociaux

Written by Adrian Smith and Andy Suarez

Our new study describing rapid antennation behavior in Odonotmachus trap-jaw ants relied on high-speed videography. To the human eye, this behavior is an unintelligible blurry burst of action. Video is the only means of making any sense out of it. So, when we thought about how to publically communicate this piece of science, making a video seemed the most appropriate medium.

Hopefully, the video above gives you a sense of what the main goal of this research was: to describe how rapid, rapid antennation is in four species of ants. We thought this question was worthy of asking for a few reasons. First and foremost we thought: how cool would it be if we recorded a bunch of slow-motion videos of ants punching each other with their antennae? Then we also came up with some more scientifically-oriented reasons.

Research from Sainath Suryanarayanan and colleagues on wasp antennal drumming behavior showed that antennal drumming evokes physiological responses only when it’s performed at a particular rate. Rapid antennal striking behavior, similar to rapid antennal drumming, is common in many Ponerine ants. Previous research on one of our study species Odontomachus brunneus by Scott Powell and Walter Tschinkel showed that dominance behavior in the form of rapid antennation between workers is responsible for creating a division of labor between nest workers and foragers. However, to our knowledge, no one had quantified the frequency of rapid antennation behavior for any ant species. So, we thought doing a small comparative study of the rates of rapid antennation in trap-jaw ants would be particularly informative. If we found that four species of ants all performed rapid antennation at the same rate, this might be evidence of selection for an evolutionarily conserved direct link between frequency and physiological response like what is seen in wasps. We also thought that it would be interesting to see if antennal rates differed when they are delivered to nestmates rather than non-nestmates.

We didn’t end up finding evidence for conserved rapid antennation rates in these species. Average rates of rapid antennation per species ranged from 19.5 to 41.5 strikes per second. Next, for O. brunneus we found that rapid antennation behavior is quantitatively similar when the interactions involve nestmates or non-nestmates. Finally, and perhaps most importantly, we ended up answering our first research question: yes, it’s pretty cool to be able to make a lot of slow motion videos of ants fighting.

Note from blog editor: if you want to see more amazing videos about ants and science, check out Adrian Smith’s YouTube channel here.

Highlighting the article by Leppänen, Seppä, Vepsäläinen and Savolainen in Insectes Sociaux

Written by Insectes Sociaux Editor in Chief, Michael Breed

How a species comes to exploit another species’ social advantages for survival is a rich and highly textured area of inquiry. Perhaps the most well known example of socially parasitic species are the slave-making ants, which steal the brood of other ant species and effectively make them ‘slaves’ working for the benefit of the slave-makers. Other types of social parasites exist only as queens, which live within the colony of a host species. How one species evolves to take advantage of another’s social system is an intriguing evolutionary question.

Intense discussion has focused on two very different models for how social parasites evolved. The first model proposes that social parasites evolve as sister species to their host. The social parasite is then initially similar to its host in communication and life history traits. This model is called Emery’s rule; the main difficulty with this route to social parasitism is that when it is strictly applied speciation occurs within a population, without geographic isolation.

It is easier to accept a relaxed interpretation of Emery’s rule, in which host and parasite are on the same very limited branch of a cladogram (evolutionary tree), but not necessarily sister species. Most supporting cases for Emery’s rule involve the relaxed interpretation, as it may not require speciation originating in the same geographical area. Genetic and morphological studies suggest that at least the relaxed version of Emery’s rule applies to many species of socially parasitic ants.

The second model invokes a common evolutionary ancestry, or clade that evolves with characteristics typical of certain kinds of social parasites, such as large size, a lack of foraging structures, a thick exoskeleton for protection against attack, and no worker caste. Members of this clade exploit other clades of the same general type of social insect. Species of the parasitic bee subgenus Psithyrus, which cladistically lies within the genus of their hosts, the bumblebees (Bombus), are good examples of this evolutionary model, as are members of the halictid bee subgenus Paralictus within Dialictus.

In this issue, Leppänen et al. (2016) present interesting data on mating isolation between macrogyne and microgyne populations of Myrmica rubra. The microgyne ants are workerless inquilines (social parasites) within the macrogyne colonies. Previous studies had suggested incomplete reproductive isolation between these sister populations of M. rubra.

However, it has been unclear how the mating system of Myrmica creates the opportunity for reproductive isolation between such sympatric populations of host and parasites. In a nicely designed set of genetic and mating compatibility tests, Leppänen and colleagues show that some ants prefer mate within their population, but that a small amount of cross-population gene flow likely occurs.

Leppänen et al. (2016) collected two kinds of data. First, they genotyped the gynes, worker, and males in colonies to determine the source of the males. In seven of the eleven nests studied, all males were produced by microgynes. In the remaining four colonies, males were produced either by macrogynes or by workers. Second, data on mating success of males were collected. Macrogyne (host) males mated more often with their own morphological type, whereas microgyne males seemed to succeed more evenly between the types/morphs.

The genetic differentiation between the two populations suggests speciation. Spatial separation of mating, with microgynes mating inside the nest and macrogynes mating in swarms, may explain the differentiation. The ability, however, of males to mate with either morphotype and the observation that microgyne males sometimes fly with swarms show that the evolutionary process that leads to mating isolation is incomplete in this system. To complete this story, a more thorough knowledge of the mating behavior of this species in the field will be required. Surprisingly little is known about the mating biology of many common species of ants, and gaining this knowledge will be difficult in examples like the microgynes of M. rubra, which mate within the nest.

Our understanding of the evolutionary processes that yield social parasites hinge on studies like this, which focus on species that are in an evolutionary dynamic state. Emery’s rule acknowledges that sister species have ‘‘the keys to the kingdom’’ in terms of shared communicatory mechanisms but the rule has a major weakness in requiring genetic isolation of sympatric populations.

Generally, the relaxation of Emery’s rule to incorporate species that have evolved in geographic isolation, and then come together, with one as host and the other as a parasite maintains the idea that commonality of social mechanism opens the door to parasitism, but that this can overlaid on a more plausible route to speciation. This study shows how genetic and behavioral data can be combined to help to shed light on these intriguing systems and that at least in some cases sympatric reproductive isolation should be considered as a mechanism.

Leppänen J, Seppä P, Vepsäläinen K, Savolainen R (2016) Mating isolation between the ant Myrmica rubra and its microgynous social parasite. Insect Soc 63:79–86. doi:10.1007/s00040-015- 0438-y

Happy New Year social insect fans! I hope you enjoy this interview with Patrizia d’Ettorre. I definitely did.

IS:  Who are you and what do you do?

PD: I am an evolutionary biologist interested in the evolution of chemical communication and recognition of identity in social insects, mainly ants but also bees and wasps. I try to understand how they tell friends and enemies apart, how they make the difference between the smell of a queen and that of a worker and why some particular chemical compounds have been selected to play a significant role in communication. I am also interested in how ants perceive and process key chemical compounds.

 IS: How did you end up researching social insects?

PD: It was by chance. I wanted to study mammals, in particular Mustelidae, which are mostly solitary and nocturnal. However, at the end of my Master’s, I did an internship in the ant group of Professor Le Moli, at University of Parma, Italy and I became fascinated by these little social creatures.

 IS: What is your favourite social insect and why?

PD: It the socially parasitic ant, Polyergus rufescens, the species I studied during my PhD. They are obligatory so-called ‘slave-makers’, meaning that they cannot live in absence of their host, which belongs to a different species of the genus Formica. The Polyergus queen is not able to found a new colony independently; she must enter a host nest and kill the resident queen. Therefore, the stock of host workers needs to be renewed. This is the job of the parasite workers, which go pillage the brood of neighbouring colonies of the host species. Being in the field and observing a Polyergus slave-raid is an impressive and amazing experience.

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

PD: There are several very nice moments, I am not sure I can say which was the best. One is when I discovered that Pachycondyla ant queens, which associate to found a new colony and aggressively establish dominance order, recognize each other individually. It was memorable since it was the last experiment I did myself, hands on, as a post doc. Another nice moment was when one of my post docs and a PhD student discovered the first ant queen pheromone regulating worker reproduction (in Lasius niger). However, since we always work ‘blind’, these great moments are typically coming at the end of the experiments, when we look at the graphs and do the statistics, which is usually not very poetic as a moment. A different kind of hurrah! moment was when one of my post-docs showed me the video of a harnessed Camponotus ant learning to associate an odour to a sugar reward. This was the establishment of the maxilla-labium extension response protocol, and we now can study perception, learning and memory in ants using a controlled procedure similar to the one used with honey bees.

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

 PD: Yes, I teach and I like teaching. I teach principally human ethology, cognitive ethology and ontogeny of behaviour. Yes, I use examples from social insects in my teaching, even in human ethology when I talk about collective behaviour.

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

PD: I am reading “Darm mit Charme” by Giulia Enders (the French version). It is a journey along our digestive system; it is instructive, funny and nicely illustrated. I would recommend it because it is an entertaining way to know something new about our body and it is a vey nice example of science communication to the general public.

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

PD: I was a young teenager when I read “King Solomon’s Ring” by Konrad Lorenz, and I loved it. This book probably influenced my choice of studying animal behavior.

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

PD: Outside science? Is there anything? 🙂
I like cooking for my friends, going to a nice restaurant, going for a walk in a park with my dogs, going to the cinema, concerts, and so on. Recently, I developed an interest for rugby, it took me a while to understand the rules though.

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

PD: A little chocolate now and then.

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

PD: Two are not really ‘things’ but they are my two dogs, Livio and Gioia. I would bring them because they are fun. Then, I would probably bring a towel, you should never travel without a towel.

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

PD: This is a difficult question. I had several excellent mentors. They all had a great influence on my career, and at different stages, from Master’s student to senior post doc. I became a truly independent researcher in Koos Boomsma’s lab. I believe Koos contributed significantly to my intellectual independence. My students have a substantial influence on the direction I will take next; I had the most inspiring and enjoyable discussions with Jelle van Zweden, Volker Nehring and Nick Bos when they were PhD students.

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

 PD: Be passionate, be enthusiastic, be reliable, be rigorous, be curious … and be stubborn.

A personal reflection by Michael Breed, Insectes Sociaux Editor-in-Chief

I was one of the 42 students who received PhD’s under Charles Michener’s tutelage. Mich was quiet, unassuming, and never sought to publicize or self-promote his work. He thought deeply about science, the art of mentoring, and how he got his start in entomology. Fortunately he recorded his own history, including a very thoughtful section on mentoring, in a memoire published in 2007 in the Annual Review of Entomology.   His memoire obviates much of the need for a formal scientific obituary, as Mich recorded the details of his career with far more precision than anyone could achieve from the perspective of looking at his career from the outside, but I think it’s valuable to reflect on the immensity of Mich’s less tangible contributions to science and to the study of social insects.

This summer I was privileged to visit Mich at his house in Lawrence, and he talked about getting his start in science doing watercolors of flowers as a child. Bees visiting the flowers intrigued him, and that was the start of a lifetime passion for bees. He published a note on his observations of bees while in high school. He corresponded with T.D.A. Cockerell, curator of entomology at the University of Colorado. Cockerell encouraged him by inviting Mich to join him and P. H. Timberlake in collecting trips in California. In the summer before Mich’s senior year in high school Mich was invited to spend several weeks in Boulder with the Cockerells, studying bees. In my opinion the kindness that Cockerell and Timberlake showed Mich, as a high school student, fed forward through Mich’s own commitment to mentoring students.

For me, Mich was the perfect mentor. Always supportive, but also demanding, you never wanted to meet Mich in the hallway without having progress to report, as he unfailingly knew exactly where you had been with a project the last time you talked and he always remembered what you had promised to do, and by when. I’m not sure what happened if you didn’t meet his expectation for progress, it was just understood that it would be best not to have to report falling short. This may give the impression that he was an unkind taskmaster, but far from it; he was gentle and supportive, but he also knew what was needed to succeed and he knew how to keep his students on track.

Mich liked going to professional meetings, particularly those of the Entomological Society of America and the IUSSI, and only stopped going when problems with his hips made flying too uncomfortable. He didn’t attend many talks, but could always be found within sight of the room where the social insect talks were being held, always engaged in conversations with current and former students as well as colleagues who shared his interests.   He served as a catalyst for keeping the IUSSI going in North America and while I don’t think he thought about networking in the mundane sense, he actively worked to introduce his students to scientists with similar interests and to promote the intersection of social and scientific relationships among colleagues.

He also liked going to lunch, either at the Kansas Union or in later years at a restaurant near the west end of main campus. I was first invited to go with him to the Kansas Union the day I had a bad experience taking the comprehensive exam for my master’s degree and, when I reached for my wallet to pay for my lunch, he said “your money’s no good here”, and paid for my lunch. This was a kindness that created for me the principle of always paying for my own students’ lunches. According to students who went through the program after I left, he developed a deep fondness for nachos. I don’t recall that nachos existed in eastern Kansas in the mid-1970’s when I was there but I can easily imagine Mich embracing them when they became a part of the cuisine of Kansas.

Another important part of Mich’s abilities as a mentor was that in addition to his mastery of the study of bees, he was surprisingly up to date on topics distant from bee systematics. He was always fully aware of the leading edges of scientific progress and he encouraged his students to explore new ideas and to incorporate new tools into their scientific toolboxes.

Mich was an outstanding friend, companion, and fellow voyager for students of bees and of social insects. His academic legacy consists of massive contributions to our understanding of bee systematics and behavior, his academic ‘children’ and ‘grandchildren’, and his encouragement of a much larger scientific community to pay attention to the behavior of bees.

 

Michener, C. D. 2007. The professional development of an entomologist. Annu. Rev. Entomol. 2007. 52:1–15

Note: Mich’s academic genealogy is at:

http://academictree.org/evolution/tree.php?pid=37249

Check it out if you’re interested and add to it if you have information that currently isn’t in the tree.

 

 

IS: Who are you and what do you do?

TL: My name is Tanya Latty and I am a lecturer/researcher in the Faculty of Agriculture and Environment at Sydney Uni. My research is focused mostly on collective and group behaviours in social insects like ants and bees, although I am also interested in integrated pest management and the management of pollinators in agricultural systems.

 IS: How did you end up researching social insects?

TL: I did my PhD on bark beetles which attack and kill live trees. The only way they can do this without being killed by the tree’s resin defences is to attack in enormous groups. Working with them got me really interested in understanding how insect groups are coordinated.

 IS: What is your favourite social insect and why?

TL: That’s a hard one- there are so many to choose from! Today, I’d have to say bull ants (Myrmecia sp) because they are so over-the-top aggressive. I love the way they charge at you as if they haven’t realized how much smaller they are- that, or they don’t care. Research-wise, my current favourites are Australian meat ants (Iridomyrmex purpureus). They build efficient transportation networks, farm hemipterans, and have beautiful nest mounds decorated with sticks and rocks.

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

 TL: My favourite moment has little to do with my actual research. I was finishing my first day of field work in the Canadian Rocky Mountains in an isolated patch of forest along a fire road. Just as I reached my car, I turned around in time to see an ENORMOUS cougar follow me out of the bush! Cougars are elusive and you really only see them if they are stalking you, which this one clearly was. I jumped in my car and watched in terrified awe as this pony-sized cat walked around my car a few times before getting bored and wandering back into the forest to stalk some other hapless PhD student. It was an amazing moment because almost no one ever sees cougars in the wild. I felt lucky because a) I hadn’t been eaten but also because b) I had a job that let me spend the whole summer in one of the most wild and beautiful places on earth.

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

TL: I teach Introduction to Entomology, Integrated Pest Management, and Insect Taxonomy and Systematics. I use a lot of social insect examples in all three courses.

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

TL: The last book I read was ‘The Martian’. I loved it because all the heroes are scientists. I’m currently re-reading ‘American Gods’ by Neil Gaimen. It’s awesome because it’s Neil Gaimen.

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

TL: I went through a phase of wanting to be an astronaut, so I was in love with the book ‘Moon Shot: The Inside Story of America’s Race to the Moon’ written by Apollo astronaut Alan Shepherd. It actually had the opposite effect as I worked out the mortality rate of astronauts and decided it was too risky a career choice.

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

TL: I enjoy bushwalking, minding (and typically killing) plants in my veggie patch and hanging out with my family.

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

TL: I go and play with my three year old daughter. She thinks I’m a super hero.

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

TL: Food, a desalinisation device and a fully fuelled/equipped yacht. Because my goal would be to get off that island as fast as possible.

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

TL: My mum and dad. My mum let me keep all sorts of creepy crawly things in the house, even though she was terrified of them and they had an annoying tendency to escape. They are both scientists so I was very lucky to be exposed to lots of interesting things from a very early age.

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

 TL: That’s a tricky question. It’s a tough job market at the moment. I know firsthand how discouraging it can be when you are chasing down funding/jobs and worrying about whether or not you can continue as a researcher. That part sucks. But the flip side is that we get to study the things that we love and we get to surround ourselves with lovely, nerdy, passionate people who share our interests. It is not a guaranteed job, it’s not necessarily a stable job, but it IS a great job. I’d tell young researchers to stay positive and enjoy the ride. Even if it doesn’t work out in the end, you will have enjoyed yourself doing a job you loved- few people get that opportunity.

 

Highlighting the article by da Silva, Stevens and Schwarz in Insectes Sociaux

Written by Insectes Sociaux Associate Editor Miriam Richards

My favourite social bee is generally the one that I am writing a paper on, which at the moment is the Eastern Carpenter Bee, Xylocopa virginica. The more we study this bee, the more complex and interesting its social behaviour gets, which is mildly ironic, because recently a reviewer suggested that despite complicated behavioural interactions among co-nesting females, these carpenter bees are not “truly social”. The still rather widespread presumption that caste-based eusociality is the only “true” form of sociality certainly influences how we think about social evolution in insects. [1] The recent publication in Insectes Sociaux of a paper entitled “Casteless sociality in an allodapine bee and evolutionary losses of social hierarchies” by da Silva, Stevens and Schwarz (2015), provides a timely reminder of the enormous breadth of social behaviour in bees, which includes both caste-based and casteless forms.

Allodapine bees are the best studied of four tribes in the carpenter bee clade (Xylocopinae), thanks to years of research by Mike Schwarz and his colleagues at Flinders University in Australia.   Allodapine bees exhibit several distinctive characteristics, including progressive provisioning of their offspring, which are raised in chambers excavated in plant stalks and branches. They also exhibit a wide range of colony types, from mostly subsocial species to eusocial, including a highly eusocial species whose morphologically distinct castes represent an independent transition to this form of obligate eusociality (Dew et al., 2012). Da Silva and colleagues studied Braunsapis puangensis nesting at several locations in Fiji (!), collecting nests and examining their contents. These bees live in small groups of up to five females, with the modal group size being one, suggesting that females can nest either solitarily or socially. By comparing the number of brood in a nest to the number of adult females, da Silva et al. estimated the per capita rate of brood production in nests with differing numbers of females. Two main trends emerged. First, social nests almost invariably contain brood whereas solitary nests often do not. This is consistent with a general pattern in allodapine bees in which sociality protects against total brood loss. Second, in social nests with brood, the main predictor of per capita brood productivity was the length of the nest cavity, with per capita brood productivity declining as group size increased. This is a surprising conclusion because in previous studies of allodapines, Schwarz’s group has found a positive relationship between group size and per capita productivity. The study thus provides “a clear benefit to social nesting in terms of preventing brood loss”, but no advantage (indeed, a detriment) when group size increases above two females.

Perhaps the most interesting finding in this paper is that referred to in the title: multi-female groups comprise casteless societies. In most social insects, the familiar queen and worker castes exhibit a negative association between reproduction and work. An idiosyncracy of social carpenter bees is that the reproductive castes can be based on a positive association between reproduction and work (Hogendoorn and Velthuis, 1999). However, in Braunsapis puangensis, there is no evidence of either type of caste division – co-nesting females are no more different in wing wear (which measures foraging activity) and ovarian development (which measures reproductive potential) than randomly selected pairs of solitary females. Although Schwarz’s group prefer the term “casteless sociality”, the more traditional term “communal” would also appear to be an apt descriptor of colony social organization in B. puangensis. Phylogenetically, B. puangensis seems to represent an evolutionary transition from a hierarchical, caste-based form of sociality to an egalitarian, casteless form of sociality. Although it was once predicted that communal and eusocial behaviour were mutually exclusive and not to be found in the same clade, but it would appear that B. puangensis provides us with a rare piece of evidence refuting this hypothesis.

How rare is communal behaviour in bees, and is the almost complete absence of communal behaviour in eusocial lineages real? It’s difficult to tell, because current approaches emphasize caste-biased sociality, relegating other forms to the “not truly social” category. For instance, in a recent phylogenetic study investigating evolutionary transitions between solitary and social behaviour in halictine bees, communal species were classified as solitary while species with caste-based societies were classified as social (Gibbs et al., 2012). [2] In another recent contribution to Insectes Sociaux, Dew, Tierney and Schwarz (2015) emphasize that our ability to identify egalitarian, casteless societies in bees depends on how we define communal, egalitarian behaviour and the observational methods used to distinguish it from hierarchical forms of colony social organization. I would not be surprised to find out that in bees, at least, casteless and other types of non-eusocial societies, are a lot more common than we currently think.

Author’s footnotes:

[1] Of course, I disagreed with the reviewer and included the word “social” in the title – not once, but twice! (Richards, 2011)

[2] Some of the authors of this paper have been forced to endure considerable haranguing from me about behavioural differences between solitary and communal bees, which they did with great good humour.

References

da Silva, C.R.B., Stevens, M.I., and Schwarz, M.P. 2015. Casteless sociality in an allodapine bee and evolutionary losses of social hierarchies. Insectes Soc. http://link.springer.com/10.1007/s00040-015-0436-0

Dew, R.M., Rehan, S.M., Tierney, S.M., Chenoweth, L.B., and Schwarz, M.P. 2012. A single origin of large colony size in allodapine bees suggests a threshold event among 50 million years of evolutionary tinkering. Insectes Soc. 59: 207–214

Dew, R.M., Tierney, S.M., and Schwarz, M.P. 2015. Social evolution and casteless societies: needs for new terminology and a new evolutionary focus. Insectes Soc.

Gibbs, J., Brady, S.G., Kanda, K., and Danforth, B.N. 2012. Phylogeny of halictine bees supports a shared origin of eusociality for Halictus and Lasioglossum (Apoidea: Anthophila: Halictidae). Mol. Phylogenet. Evol. 65: 926–939

Hogendoorn, K., and Velthuis, H.H.W. 1999. Task allocation and reproductive skew in social mass provisioning carpenter bees in relation to age and size. Insectes Soc. 46: 198–207

Richards, M.H. 2011. Colony social organisation and alternative social strategies in the eastern carpenter bee, Xylocopa virginica. J. Insect Behav. 24: 399–411

da Silva, C.R.B., Stevens, M.I., and Schwarz, M.P. 2015. Casteless sociality in an allodapine bee and evolutionary losses of social hierarchies. Insectes Soc.

IS: Who are you and what do you do?

BB: I am a researcher at the Centre for Integrative Bee Research (CIBER) at the University of Western Australia using honey bees and leaf cutting ants as my preferred research pets. I was trained as a classical behavioural ecologist but now try to use tools from systems biology such as proteomics to understand how life history traits related to reproduction or immunity are determined through the complex interactions of protein and metabolite networks.

IS: How did you end up researching social insects?

BB: I always had a crush for insects, but regarded that more as a hobby while doing research on “real animals”. In my case that was a small monkey that I chased through South American rainforests as part of my Honours thesis. As I had spectacularly little success with the monkeys, I became increasingly drawn to social insects, especially after I saw the amazing diversity of orchid- and stingless bees, and my first encounters with fully grown colonies of army- and leaf-cutter ants.

IS: What is your favourite social insect and why?

BB: I don’t have a specific species that I would call my preferred pet. The most amazing thing for me is not so much that these insects are social, but the amazing variation we see between species. Having said this, bees just give me a tiny little extra kick.

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

BB: I conducted the field research of my Honours thesis on a field station in French Guiana, located a two-day trip by car, boat and foot away from the next human settlement in the jungle. To observe our study animals in their habitat, we installed ropes and wooden platforms into some of these giant rainforest trees. Climbing up there into the canopy for the first time a good 30+ meters gave me the ultimate kick. Hanging on a small rope 30 meters above ground was the scariest thing in my life and turned me into an endorphin junky. However, sitting up there and seeing this carpet of green, completely unspoiled rainforest to the horizon was a key event that lead me to continue a career in science.

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

BB: I am teaching in Biology and Agriculture. Using social insects for my research makes teaching so much easier, because it is easy to get students interested in a topic.

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

BB: The Beekeeper’s Pupil by Sara George, which might read a bit nerdy, because it is a book about honeybees. The book is based on a true story, that took place in the 17^th century and describes the research that revealed the first insights into the life history of honey bees and their sex life. The most fascinating bit of the book is that the main character of the book doing the research is blind. He therefore needed to train a man servant to do the practical work and describes his observations to him. It is therefore not only a book about bees, but also about science and how to progress it.

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

BB: I was still a boy when I got the book Man Meets Dog by Konrad Lorenz. I was instantly fascinated by animal behaviour and as it was the high days of Ethology, I decided to become an ethologist. This had interesting side effects as I turned our dog into a scientific experiment and my parents had to protect the poor creature every now and then from being overused as a laboratory animal.

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

BB: I like to go sailing, which is a wonderful opportunity to get unplugged from work. The boats used can easily tip over in high winds so I need to concentrate on the wind and water, so it is also a perfect way to escape daily life.

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

BB: A tent, a magnifying glass and my wife. The tent is obvious; the magnifying glass is good to have a look around and apparently also gets a fire going. Based on my life experience so far, I see the presence of my wife as the best warrant to keep me alive.

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

BB: This must be clear by now from my answers above: First go sailing and if that does not help go and have a whinge* chat with my wife.

*IS note: in Australian English, ‘whinge’ means to whine or complain.

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

BB: My grandmother. She was fascinated by the natural sciences and her flat was something between a science library and a museum. She had a large collection of books on geology, astronomy or biology but her shelves also displayed all sorts of things such as rocks and bones, including a telescope that we used during summer nights to look at Mars. If she would have been born in modern times, there is no doubt that she would have become a scientist, but as a girls born 1901 into a family of bankers, there was no way for her to pursue such a career. I guess her way deal with this was to get her grandchildren fascinated in science. It worked.

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

BB: There is still so much we don’t know about these animals and we have so breathtakingly new methods and technologies available now to study and understand them, so if you have the slightest interest, then go for it! Unfortunately, we also live in a time where scientists need to constantly justify their existence and performance. My advice is to not let paper numbers, impact factors and key performance indicators dictate your career. Play that game but use the remaining academic freedom you have left to explore where your interests are and don’t be afraid to pursue the impossible.

Highlighting the article by Leniaud et al in the November 2015 issue of Insectes Sociaux

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

In this issue Leniaud et al. (2015) consider the impacts of genes and environment on caste in the silver ant, Cataglyphis bombycina. The topic of genes, environment and caste continues to be a fascinating and complex arena in the study of eusocial insects, and Leniaud et al. present a fascinating contribution to this discussion.

Caste is a fundamental concept in the study of eusocial insects. Differences between the reproductive and the worker caste often extend to morphological specializations that preclude each caste from performing the other’s work. Queens can lack the tools needed for successful foraging but have numerous ovarioles and metabolic capacity to produce large numbers of eggs. Workers of the same species then have reduced or vestigial ovaries, are missing the physical structures needed for mating, and have the morphological tools to allow them to fill the defensive and foraging needs peculiar to their species.

How are such different individuals derived in the course of development? Genes and environment, which are the two major drivers of phenotype, should explain the differences, but what is the relative role of each in caste determination? Thousands of studies of caste determination over the last century have yielded the consensus that caste is largely determined by environment. The precept is that all eggs of the appropriate sex, when laid, are totipotent. This means they have equal potential to yield reproductive or worker adults. When there is more than one worker phenotype then totipotency extends to those differences as well.

But in the last two decades we have come to appreciate that individual response thresholds to tasks can drive worker behavioral choices. These thresholds often reflect genetic differences among workers; this knowledge has brought genetics back into play in conversations about caste and task performance in eusocial insects.

Leniaud et al. take on a much different, but equally exciting, aspect of the overall question of gene/environment interactions in caste in eusocial insects. In Cataglyphis bombycina there are two distinct worker castes. One of these fits the norm for most ants—workers which are, within the caste, morphologically uniform but variable in size. This size variance is associated with task performance.

The other worker caste in Cataglyphis bombycina, though, is unusual. Soldiers are relatively invariant in size and stand as a morphologically distinct group from the workers. This contrasts with many ants in which “soldiers” are workers from the large end of the size spectrum. Soldier distinctiveness as a caste is also known in some types of termites and a few other ant species.

Leniaud et al (2015) found that environment likely is the preponderant influence on caste determination in Cataglyphis bombycina. This fits well with the consensus model of totipotency. In a few colonies, though, they found evidence for a genetic influence on soldier determination based on patrilineal effects. These results are highly important because they suggest that if we backtrack in our thinking about gene X environment interactions in caste determination we may find other examples in which genetic influences, while smaller than environmental influences, are nonetheless present and important in the development of workers during caste differentiation. The results in this paper are well worth considering in the continuing search for the mechanisms of caste differentiation.

Leniaud L, Pearcy M, Taheri A, Aron S (2015) Testing the genetic determination of the soldier caste in the silver ant. Ins. Soc. 62:517-524