The winner takes it all, the loser standing small!

A blog post highlighting the article written by Bang and Gadagkar in Insectes Sociaux

Written by Alok Bang

Remember the song by ABBA, ‘The winner takes it all’? In a nutshell, the fate of the dejected lover ABBA portrays can be extended to any conflict. Winners keep winning, and monopolise resources and opportunities. Losers keep losing and forego everything. Or, do they really?

But before coming to that, let’s discuss conflict in animal societies. Why is conflict of utmost interest and importance? For the simple reason, that it is omnipresent. Think of societies most harmonious and in unison, such as those of paper wasps, honey bees, ants and termites – where tens to hundreds and sometimes millions of individuals live and work together – are strewn with conflict. Individuals in these seemingly cooperative societies fight with each other often, over food, mates, territories and other opportunities. Who wins and who loses, thus, has a direct impact on an individual’s survival and reproduction, thereby affecting its evolutionary fitness.

Classically, researchers have focussed on role of individual characteristics such as age, size, weight, hormones and genes, in making winners and losers. While this approach has been important, it has excluded the role an individual’s social environment might play. Environment may influence fighting behaviour, fighting abilities, strength, and finally self-assessment of one’s strength, but this has been largely ignored.

Take the case of self-assessment of one’s fighting ability. When individuals fight, are they winning or losing merely based on their strengths, or does self-assessment of strength influence the outcome of a contest? Human history is laden with examples of an underdog, who is physically average or even weak, defeating a stronger opponent, because of a heightened perception of her strength. Similarly, a strong individual is known to lose a contest if she has a diminished self-assessment of her strength. Self-assessment can thus be influential – as much if not more – than the actual strength, in deciding the outcome of a fight.

In the past two decades, the phenomenon of winner-loser effects have come to the forefront of such enquiries into external determinants of fighting abilities and contest outcome. Simply put, they refer to an increased probability of winning or losing a contest based on prior experience of winning or losing, respectively, even if everything else is randomised. A prior experience of winning may enhance and a prior experience of losing may diminish an individual’s perception of its own fighting ability; thereby, affecting the contest outcome. Such studies have been mostly performed in vertebrates and research on the role the environment plays in conflict outcome in invertebrates is severely lacking.

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A typical Ropalidia marginata colony. R. marginata is found abundantly in peninsular India. Photo credit: Thresiamma Varghese.

In the first study of its kind that investigated the role of prior experience on current contest outcome in a eusocial species, we chose the primitively eusocial Indian paper wasp, Ropalidia marginata as the model system. To control for a wasp’s environmental experience, the focal individuals to be included in the experiments had to be devoid of any prior fighting related experience. This was achieved by bringing adult-less colonies of R. marginata into a controlled environment, keeping thorough census records of all individuals being born on a colony, and isolating these individuals as soon as they were born.

The other important step was the method of choosing focal individuals for winner and loser effect experiments. We achieved random-selection by giving pre-decided contest outcomes to random focal individuals in the first contest, independent of their intrinsic strengths. We chose this method because these experiments aim to investigate the effect of experience, and not strength, on the contest outcome.

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A lone R. marginata female. R. marginata females, like in many other paper wasp societies, can found new colonies individually as well as in a group. Photo credit: Alok Bang

In experiments performed to investigate winner effects, a pre-decided winning experience was given to a random focal individual by pairing it with an extremely weak individual (termed habitual loser) of the population. This ensured that the pool of focal individuals used for testing winner effects did not include only strong individuals, but included individuals with a wide range of intrinsic strengths. Similarly, in experiments to investigate loser effects, a pre-decided losing experience was given to a random focal individual by pairing it with an extremely strong individual (termed habitual winner) of the population. This, in turn, ensured that the pool of focal individuals used for testing loser effects did not have only weak individuals, but included individuals with a wide range of intrinsic strengths. The focal individuals with such pre-decided contests were then paired with a random naive individual in the second contest.

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R. marginata females engaged in a dominance-subordinate interaction. The behaviour displayed here is called ‘sit over’, where the dominant individual sits over the subordinate individual and renders her immobile. Fights such as these are quite common in R. marginata. This helps to establish a dominance hierarchy between individuals, and has important implication on survival and reproduction of individuals, and work regulation in the colony. Photo credit: Alok Bang.

Each experiment thus consisted of a first contest between a focal individual and a habitual loser/winner, giving it a pre-decided contest that occurred for one hour, followed by a 45-minute gap, which then was followed by a second contest of one-hour between the focal individual with a random naïve opponent. In such an experimental set-up, a second successive win (or loss), in significantly more than half the cases, would indicate that the individuals’ self-perception was impacted due to their prior experience. During all these contests, dominance-subordinate interactions between individuals were observed, and winners and losers of the contests were declared. All experiments were carried out  blind.

We indeed found that there was a significantly high number of pairs in which a win was followed by a second win, and a significantly high number of pairs in which a loss was followed by a second loss, indicating that both winner and loser effects are present in the Indian paper wasp, R. marginata.

Winner effects may evolve due to advantages associated with winning, but why would a species evolve loser effects? Moreover, how do two such apparently opposing phenomena concurrently exist in a species? Winner and loser effects are most likely independent or even interdependent effects. If self-assessment of winners and losers are independently advantageous, these effects would exert independent feedback loops on individuals and co-exist. For example, winning a contest may allow winners a higher access to resources and mates, thus developing and reinforcing winner effects. Losing a contest on the other hand, though seemingly disadvantageous, may allow individuals to forego costs associated with fighting such as injuries, exhaustion and death. If the benefits of avoiding these costs are much higher than the benefits acquired from winning, loser effects will simultaneously develop in the population.

Here we show that wasp behaviour is not only governed by their own internal constitution, but to a considerable extent by their surroundings. The role of external and social determinants of behaviour balances the hitherto unduly skewed importance given to individual characteristics.

Finally, is the Indian paper wasp R. marginata a unique and only eusocial species that displays winner-loser effects? It is definitely the first eusocial species, but we believe it will not be the last. The uniqueness of R. marginata in this regard may have less to do with ecology of the species, and more due to lack of such investigations in other social insects. This study should steer efforts towards finding the presence, extent and longevity of winner-loser effects in other social species. A comparative approach to studying proximate and ultimate factors governing winner and loser effects in social species will be key to understanding sociobiology of group living animals.

Facultative slave-making ants tolerate alien slaves but not their masters

A blog post highlighting the article written by Włodarczyk in Insectes Sociaux

Written by Tomasz Włodarczyk

Many ant species in nature are closely associated with other ant species. The closest form of such an association is called a mixed colony where ants of both species inhabit common nest, share food and raise their brood side by side. Mixed colonies arise as a result of social parasitism when one species exploits the labor of the other, such as in slave-making ant species. Slave-maker ants raid the nests of the host species, steal the pupae and bring them back to their home nests. Newly-emerged individuals integrate into the parasite’s society and perform all domestic duties.

In the lab, we can also create mixed colonies using species that would never form such an association in nature. The species don’t even have to co-exist geographically. This is because ants learn (imprint) colony odor after eclosion from pupae and use it as a template for subsequent nestmate recognition. Thus, by putting together callow ants of different species we can create a mixed colony of individuals that have imprinted on the odor of each other.

As a part of my PhD project I investigated the recognition behavior of ants using a colony of the facultative slave-making ant species, Formica sanguinea. By supplying them with pupae of Formica polyctena or F. rufa -which soon emerged- I formed mixed colonies (Włodarczyk 2012, Włodarczyk and Szczepaniak 2014). These experiments were inspired by the studies conducted by Wojciech Czechowski (1994) whose results suggested that F. sanguinea ants acquire their recognition signature form their slaves, as in the obligate slave-making species Polyergus samurai (Yamaoka 1990).

Excavation

Formica sanguinea is a facultative slave-making species enslaving ants from the subgenus Serviformica. Here, a colony with black F. fusca slaves has been excavated.

Later I became curious about how things look in the case of F. sanguinea colonies containing the most frequently used slave species, F. fusca. Results of chemical studies revealed that odor of F. sanguinea ants is quite different from that of its host species (Martin et al. 2008, Włodarczyk and Szczepaniak in prep.). Moreover, we found that enslaved F. fusca ants develop a chemical recognition signature which is intermediate between that of their parasite and ants from free-living colonies (Włodarczyk and Szczepaniak in prep.). This raised the question about how recognition cue diversity in F. sanguinea colonies affect the recognition abilities of ants. Even more interesting was whether there are differences in the recognition abilities between F. sanguinea and F. fusca ants given that the parasite is the only party to be under selective pressure to live in such a condition.

I collected eight queenright F. sanguinea colonies containing F. fusca slaves and maintained in the the laboratory. The slave-making F. sanguinea ants and their slaves were exposed on a Petri dish to anesthetized ants from alien colonies. I measured the number of aggressive behaviors in various encounter combinations. I showed that F. sanguinea ants are able to discriminate other individuals from the same species from alien colonies towards which they exhibit aggressive behavior. However, slaves from alien colonies were generally tolerated. This result supports the hypothesis that F. sanguinea ants are intrinsically tolerant to individuals whose odor indicates that they are slaves. Otherwise slave-making ants might accidentally attack their own slaves, which possess a recognition signature that deviates from that of the other slaves. This situation would arise when slaves from new source colony appear in the slave-maker’s society.

The other result was that slaves (F. fusca) are poor at discriminating slave-making ants and slaves from alien colonies and do not exhibit an overt aggression toward them. This could be explained by the high within-colony recognition cue diversity that hampers formation of an accurate template during colony’s odor learning phase. This is intuitive explanation since it might be hard to recognize an object of a given class when this class is relatively heterogeneous. Thus, there is no recognition barrier for F. sanguinea ants to take over slaves from alien colonies. However, such a phenomenon has not been recorded for F. sanguinea ants. Therefore we can hypothesize that intraspecific raids play at best very limited role as a way of slave gaining.

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Formica fusca slaves showing aggressive behavior towards an anesthetized conspecific ant.

Moreover, I conducted an experiment in which slaves and slave-makers were reared separately. After about 2-month period, ex-slaves elicited aggression in ants from stock colonies (both in slave-makers and in slaves). Conversely, slave-makers separated from slaves were still treated as nestmates. This result suggests that F. sanguinea exert a strong impact on the odor of F. fusca ants, possibly by the transfer of recognition cues during food exchange.

The results of my study highlight that selective pressures associated with different life histories can lead to differences in recognition systems between social insect species.

 

References

Czechowski W (1994) Impact of atypical slaves on intraspecific relations in Formica sanguinea Latr. (Hymenoptera, Formicidae). Bull Pol Acad Sci 42(4):345–350

Martin SJ, Helantera H, Drijfhout FP (2008) Evolution of species-specific cuticular hydrocarbon patterns in Formica ants. Biol J Linn Soc 95:131–140

Włodarczyk, T (2012) Recognition of individuals from mixed colony by Formica sanguinea and Formica polyctena ants. J Insect Behav 25: 105–113

Włodarczyk T, Szczepaniak L (2014) Incomplete homogenization of chemical recognition labels between Formica sanguinea and Formica rufa ants living in a mixed colony. J Insect Sci 14:214

Yamaoka R (1990) Chemical approach to understanding interactions among organisms. Physiol Ecol Japan 27:31–52

Interview with a social insect scientist: Mark Brown

IS: Who are you and what do you do?

MB: Mark Brown. I’m a Professor at Royal Holloway University of London, where I lead a research group that seeks to understand host-pathogen interactions in bumblebees, as well as aiding in the conservation of bumblebees. We also enjoy investigating other aspects of social insect biology.

IS: How did you end up researching social insects?

MB: In my 2nd year at university, I was lucky to have Deborah Gordon – ant biologist – as one of my tutors. After teaching me for a term, she asked me if I’d like to come and work for her as a field assistant in the desert in Arizona for the summer. I said yes, to a large degree because I thought it was an opportunity to combine biology with travel. But then I met the ants and fell in love (with the ants, I should add!), and since then it’s been social insects all the way!

IS: What is your favourite social insect and why?

MB: Can I ask for two? The first – Messor andrei – was the subject of my PhD research. They’re beautiful black ants, who make a habit of carrying seeds like parasols back to their nest. The second – Bombus lapidarius – I have yet to work on, but they’re a beautifully smart bumblebee that make the most elegant nests.

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Bombus lapidarius, one of Mark’s favourite species. Photo credit: Jürgen Mangelsdorf / flickr

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

MB: That’s a tough one. Discovering that the parasite Crithidia bombi had a major impact on bumblebee fitness has to be up there, as before then it was seemingly a parasite without virulence. However, I think that work with Matthias Fürst, Dino McMahon, Juliet Osborne, and Robert Paxton, where we showed that honey bee pathogens spill over into wild bumblebee populations, is at the top. Understanding the dynamics of viral diseases in the field has important practical implications, as well as being exciting from a pure research perspective, and so our finding has had a real impact on the field.

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 courses in invertebrate biology, conservation biology, and a field course in ecology and conservation on the island of Samos, Greece. It’s surprising how often my examples involve social insects of one kind or another. 😉

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

MB: ‘A Place of Greater Safety’ by Hilary Mantel. A character-focused history of the firestorm that was the French Revolution, this is definitely worth reading! Mantel writes incredibly incisively about people and their motivations, and how this shapes history. For anyone who wants to understand the politics of science, and how this can impact careers and the trajectory of science itself, this is a great primer.

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

MB: I read ‘The Trouble with Lichen’ by John Wyndham when I was a teenager. This inspired me to become a research scientist (in particular, a biochemist, which lasted only until I realised that the ‘bio’ aspect was rather limited), and also to recognise that gender has a significant impact on recognition and career advancement in science (this was long before I’d heard of Rosalind Franklin). We still have a long way to go to make science a level-playing field for all genders and orientations, but it’s a goal we have to reach.

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

MB: Reading fantasy novels, and spending time with my nieces. It would be walking safaris through the Zambian bush, but I can’t afford to do it often enough to call it a hobby!

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

MB: I remember that I’m a very lucky man – I have a family, friends, and a job I love – and try to focus on the day-to-day until I get my perspective back.

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

MB: My husband, good Swiss chocolate, and an endless supply of paperback books (none of these need explanation!).

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

MB: My PhD supervisor, Deborah Gordon, taught me how to look at ants, and how to think and write like a scientist. Paul Schmid-Hempel, my post-doc boss, introduced me to the intriguing world of host-parasite interactions, and also taught me how to play the scientific game. I owe them both a huge debt.

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

MB: Get outside and watch the animals. If you can spend hours watching ants or bees (apologies to my termite and wasp colleagues!), and still come away fascinated, then you’ve got a good foundation to build on. If you decide it’s not for you, get another job, earn loads of money, and set up a charitable foundation to fund the research you’d like to see done.

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Messor andrei, Mark’s first ant love. Photo credit: photographer (unknown) and http://www.antweb.org / Wikimedia commons

 

Two views on invasive ants

Highlighting the articles written by Calcaterra et al. and Santos in Insectes Sociaux

Written by Insectes Sociaux Editor in Chief, Michael Breed

Species ranges are often defined by natural barriers such as lakes, rivers oceans or mountains. Human actions can break down natural barriers or transport species across those barriers- creating biological invasions with serious consequences. Social insects play a large role in the overall picture of biological invasions, with many species of ant, including fire ants, Solenopsis invicta, and Argentine ants, Linipithema humile, wreaking havoc on ecosystems. Wasps, such as Polistes dominula and Vespa velutina, have gained serious footholds in non-native habitats. The Formosan termite, Coptotermes formosanus, is equally a scourge. Even the honey bee, Apis mellifera, whose introduction into the New World is often seen as a benign event and whose current presence is valued for its role as a pollinator, has had dramatic effects on native bees and possibly on plants that rely on native bees for pollination.

In this issue two papers highlight different aspects of social insect invasion biology. Calcaterra and colleagues (2016) take on the original community roles of ants that become invaders by comparing ecological dominance among ants in both native and introduced communities. They take advantage of the natural occurrence in Argentinian ecosystems of several prominent invasive ant species, including two of particular note, Solenopsis richteri and L. humile. These two species are ecologically co-dominant in the Otamendi Natural Reserve, near Buenos Aires, Argentina, with S. richteri being numerically the most abundant ant and L. humile being the best at recruiting colony mates to new food sources. However, these ants co-exist in this reserve with 47 other species of ant, including several that are also invasive, suggesting that ecological resistance to the qualities that favor invasive success have evolved among ants in these communities. Competition may not be the primary factor in structuring these communities, reducing the impact of species with high competitive abilities. These two invasive species were abundant across several habitat types, suggesting that they are ecologically flexible. Three non-invasive species were also dominant in the habitats, meaning that the characteristics that lead to invasiveness are not the sole qualities that lead to dominance in a native habitat, although the invasive potential of these other species is unknown.

Santos (2016) reviews the roles of ants in urban ecosystems. In a meta-analysis based on over 100 papers published about ants found in urban environments, Santos found that many known invasive ants, including S. invicta and L. linipethema are also prominent in the literature on urban ants. Other invasive ants occurring in urban environments include the pharaoh’s ant, Monomorium pharonis, and Tapinoma sessile. The majority of the studies of urban ants came from the United States (with a bias towards southern and northeastern states) and Brazil (with a bias to southeastern Brazil). While urban ants are more often aesthetic pests rather than vectors of disease or destroyers of food supplies, some species present public health problems by stinging or being incidental purveyors of bacteria and fungi. Their presence in urban environments is thus a concern due to public demand for control and in some cases public health concerns.

For those of us whose interest lies in the beauty of social insects’ complex systems of communication and division of labor, as well as their major significance in terrestrial ecosystems rather than in applied entomology, reading these two papers is a dark reminder that introduced social insects can have significant negative impacts on both humans and natural communities. By the translocation of ants across geographic barriers that would be otherwise impassable for ants, humans have created real problems of immediate importance. Transfers of social wasps, social bees, and termites have happened in much the same ways as for ants. These movements have largely resulted from inadvertent actions or carelessness with shipment sanitation and quarantine. We cannot unreel these past actions; in fact, more than half a century of futility in trying to control fire ants and the “Africanized” version of the honey bee suggest the irreversibility of these introductions. Biologists who work on social insects should have much to bring to discussions of how to ameliorate the impacts of social insect populations as they become established in natural communities and in urban environments.

References

Calcaterra L, Cabrera S, Briano J (2016) Local co-occurrence of several highly invasive ants in their native range: are they all ecologically dominant species? Insect Soc 63:**-** DOI 10.1007/s00040-016-0481-3

Santos MN (2016) Research on urban ants: approaches and gaps. Insect Soc 63:**-** DOI 10.1007/s00040-016-0483-1

 

Editor’s note: If you are interested in Luis Calcaterra’s explanations of how invasive ants are like tango dancers, please click here for his blog on his work.

Montane ants use their bodies to make warm homes for themselves (and others)

A blog post highlighting the article written by Baudier and O’Donnell in Insectes Sociaux

Written by Kaitlin Baudier

Army ants are predatory and nomadic. To find food, the army ant Labidus praedator marches in carpet-like swarms both on the forest floor and underground, very different from most ants that you likely imagine walking in neat rows. Army ants have temporary nests that they can move around called bivouacs. Bivouacs are constructed from clustered, interlocking bodies of worker ants that are not foraging for insect prey. Bivouacs can either be free hanging aboveground or within a cavity or series of cavities belowground. In fact, other arthropod species live within the bivouacs. Army ants are important ecological keystones in the tropics, largely because of the other arthropods that rely on them for food and shelter while living within army ant bivouacs.

Bivouacs allow the ants to thermoregulate- warming and reducing temperature variation to accommodate the specific thermal needs of the colony’s maturing brood (eggs, larvae, and pupae) suspended within the bivouac. However, of the approximately 1,000 species of army ant in the world, all of our understanding of bivouac thermoregulation comes from only two species that form aboveground bivouacs. Research has shown that aboveground army ant bivouacs at low elevations can actively warm brood, but until now underground and high-elevation bivouacs were poorly understood.

Excavated soil bivouac

Figure 1: Excavated soil mounded atop an underground bivouac of Labidus praedator (Photo credit: Sean O’Donnell)

Montane bivouacs of L. praedator have a different structure than lowland bivouacs. Though lowland L. praedator have historically been observed nesting in preexisting cavities, often with other species of army ant, these high-elevation ants construct largely self-excavated bivouac chambers at the base of trees, seemingly independent of other army ant species (Figure 1).

In our study, we examined underground, lower montane L. praedator bivouacs to ask:

  1. Do below-ground army ants warm their bivouacs?
  2. How do thermal tolerances of ants and inquilines (other arthropods that reside in the bivouacs) compare to bivouac temperatures?
  3. Are high elevation bivouacs challenged by cold?

In order to find out, we placed temperature and humidity loggers at different depths in an underground bivouac of Labidus praedator and also in adjacent soil. After five days of recording we excavated the bivouac, keeping careful notes on depths at which we found brood, young adult workers, mature adult workers, and inquilines.

 

Next, we collected worker ants and inquiline millipedes as subjects of thermal tolerance assays to estimate the range of temperatures tolerable by each group. We exposed the ants and millipedes to either a range of increasing or decreasing temperatures. The most extreme temperature for which individuals were able to move was considered either its maximum thermal tolerance, or minimum, depending on the test each individual received. We then compared these thermal tolerances to environmental temperatures to see if any of the colony members were “thermally challenged” in these high elevation underground bivouacs.

Samples

Figure 2: Subjects compared for thermal tolerance (A-B) bivouac-dwelling millipede (Calymmodesmus sp.), (C) host adult Labidus praedator worker (mature), (D) a ‘callow’ or recently-molted young adult L. praedator worker

 

We found that L. praedator bivouacs were significantly warmer than reference soil. Temperatures within the bivouac were on average 6.2°C warmer than soil at similar depths, and more than 8°C warmer than average nighttime surface lows. Both reference soil temperature and bivouac temperature varied little at depths of 40cm below the forest floor. Together these two findings suggest that army ants may passively use soil to buffer against diel fluctuations in temperature, while actively warming the nest with their collective metabolic heat. Below-ground bivouacking species of army ant are able to survive at both higher latitudes and elevations than their highly-studied aboveground relatives. The thermal buffering effects of soil are likely key to creating a homeostatic and warmed brood environment despite seasonal and daily low temperatures.

Thermal tolerances of bivouac-resident millipedes and ants varied, and this variation corresponded to placement within the bivouac. More cold-sensitive individuals were located deeper in the bivouac where they experienced hotter and less variable temperatures. Callow and mature L. praedator workers had the same heat tolerance, but callow workers were more susceptible to immobility at low temperatures. The most cold-sensitive, however, were the millipedes, many of which had minimum tolerable temperatures at or above temperatures occurring on the bivouac surface. This suggests that warmth within army ant bivouacs may be an added benefit for arthropods that live in bivouacs at high elevations, enabling some bivouac-dwelling species to occupy geographic ranges that they would not be able inhabit without the ants and their bivouacs.

Editor’s note: You can find the video above and many other ant videos on Kaitlin Baudier’s YouTube channel AntGirl

Interview with a social insect scientist: Miriam Richards

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Moonshine, Miriam and Blueberry. Photo credit: Michele du Moulin

IS: Who are you and what do you do?

MR: Miriam Richards – I am a professor at Brock University, in the Niagara Region of southern Ontario, Canada. I teach courses in Animal Behaviour, Ecology, and Evolution. I do research on the social behaviour, ecology and evolution of carpenter and sweat bees, and on restoration of local bee communities. I also spend a lot of time gardening and communing with farm animals – this fits right in as applied ecology and animal behaviour.

 IS: How did you end up researching social insects?

 MR: I’ve always been interested in animals and as far back as I can remember thinking about what I would be when I grew up, it was related to animals. By grade 8 I wanted to study animal behaviour and ecology, but I was completely focussed on vertebrates. I first thought about comparative social behaviour in bees in my third year Animal Behaviour course (the same one I teach now!) when I wrote an essay on the evolution of sociality in bees. That was about 1982, and I must have read Michener’s work, but I don’t have the essay any more to check it out. And besides, I was fully occupied studying common tern behaviour (my undergrad thesis and first publication) and then snow goose demography (my MSc thesis). And I really wanted to be a zookeeper and breed endangered species.

My MSc experience was traumatic and nearly the end of my career in science. We decided to have a baby during grad school, because in the mid-1980s, being a pregnant post-doc or new faculty member was clearly a stressful thing. Unfortunately, being a pregnant grad student also turned out to be stressful – such a thing was practically unheard of then. When my supervisor learned I was pregnant, he told the lab technician that this proved I wasn’t serious about research. A member of my committee informed me (and several other members of the lab) that women with small children really couldn’t do science. I managed to finish my MSc, but decided to abandon research as a career.

Over the next couple years, I worked at a pet store, as a secretary for my husband’s PhD supervisor at York University in Toronto, then as a zookeeper at the Metro Zoo in Toronto, thought about various options, like medical school and environmental law, and realized they were not for me. While I was a secretary, I heard about a new professor who had just been hired at York, who studied bees and was interested in doing molecular ecology (although it was not called that yet). This was Laurence Packer, and after I realized that being a zookeeper meant feeding and cleaning, not saving animals from extinction, I finally made my mind up to do a PhD. I joined Laurence’s lab as his first grad student. That was a fateful decision – I got to know bees, and I adore the science of social evolution. And after a few more years of fateful twists and turns, I got really lucky and landed a job at Brock. And here I am!

IS: What is your favourite social insect and why?

MR: My favourite social insect is Xylocopa virginica. Talk about charismatic microfauna! It has everything going for it: it’s big enough to see and readily identifiable. It lives in social groups that are organized in ways that are very different from eusocial bees, even from the primitively eusocial bees that we still love to study. It is becoming very common in southern Ontario, so it is easy to find. The males also have interesting social behaviour. And the males’ antics as they guard territories are hilarious.

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Xylocopa virginica at her nest entrance. Photo credit: Lyndon Duff

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

MR: That’s a hard question, because we have lots of great moments, and I don’t look back on great moments and compare them to now. I really like when we find some new behaviour, especially something that is unusual or contradicts a major theoretical paradigm, but I am not sure what I’ve done that is more important. I think the best moments are when students confidently and authoritatively describe their work, or when they stand up to my arguments and bring me over to their point of view. Then I see that they have become scientists, and I feel like I’ve done my job.

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

 MR: I’m in a very small department, so I teach all sorts of general topics, from introductory ecology and evolution, to animal behaviour, molecular ecology, behaviour genetics, etc. I use social insect examples in my teaching all the time, including analysing data sets that we’ve already published (or not). More importantly, my teaching has shaped my research. For instance, there are major differences in the way scientists think about insect versus animal sociality, and sometimes I think that insect sociobiologists need to broaden their definitions a bit. Our entire line of research monitoring bee communities in restored landfill sites was largely inspired by my teaching community and ecosystem ecology, fields way outside my research comfort zone.

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

MR: I mostly read murder mysteries, for their escapist value. Every so often I read a science book, but only in the summer when I can focus. I am about to read Clutton-Brock’s new book on mammal societies.

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

MR: Michener’s 1974 book is one of my favourites – I still use it when I need a quick synopsis of the social behaviour of some group that I don’t really know much about. In the last few years, I’ve begun to realize that it is getting out of date, but it is 40 years old, after all. I still recommend it to new students, though.

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

MR: The absolute joy of our lives is our 2-year old granddaughter, but it’s a long distance relationship that is maintained by Skype and visits every few months. I love being outside tending my garden and my animals. Recently, I bought a mule named Moonshine. He’s so much fun to ride through the woods. I am also training one of my donkeys to become a saddle and cart donkey for my grand-daughter.

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

MR: One of my great discoveries in life is that my outlook is actually quite independent of my circumstances. For instance, I am often tired, cranky and depressed in February. It’s easy to find reasons to explain this to myself, so I try to remember that I am one of the luckiest people on the planet. I have a great job, I live in a great house on a fabulous little hobby farm, we’re all healthy and busy, my graduate students generally have been successful and done interesting work, my undergraduates sometimes tell me I inspire them, and every so often somebody is appreciative for the work I do. Of course I have low moments, but very few of them are “real”, just irritating foibles of brain chemistry, I think.

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

MR: I need to bring my husband, my camera, and a guidebook. I need the guidebook so I don’t miss anything great, the camera to record it because I look at things more carefully when I take pictures, and my husband, because it’s always more fun when he’s along, too.

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

MR: Laurence Packer, my PhD supervisor, set me on my current path. He also helped me stay on that path, and has helped me to new opportunities over the years. And my husband, Adonis Skandalis, who is a molecular biologist and my chief scientific advisor, collaborator, and sounding board, even though we work on completely different topics.

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

MR: I encourage them not to put all their eggs in the academic basket. Research jobs are hard to come by and social insect jobs are harder still. Academic positions are the most obvious path into research, but not the only path. I think the incredible growth of citizen science will present a lot of opportunities for people with scientific training to do science, even if they don’t get to call themselves scientists on their tax returns. Science is a way of knowing – and a way of life, too. Let’s go back to a time when scientists were people who made discoveries using scientific method, even if you earn a living doing something else.

 

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Xylocopa virginica female foraging. Photo credit: Lyndon Duff

Doing it for the cool kids: honey bees fanning for the larvae

A blog post highlighting the article written by Cook, Durzi, Scheckel and Breed in Insectes Sociaux

Written by Chelsea Cook

My best friend Kika is about to have her first child. She is eating nothing but organic food, staying away from alcohol & caffeine, and lightly exercising. One thing she doesn’t have to worry about is the temperature at which her baby is developing. Humans are endotherms – we regulate our own body temperature right around 98.6°F, and with even just a degree off we feel terrible.

Honeybees are individually ectothermic, which means they use their environment to regulate their body temperature. As a hive, however, honey bees work together to maintain a narrow range of temperatures, between 96°-97°F. One of the main reasons why the bees do this is to maintain the optimal temperature range for the developing larvae. If the temperature inside the hive gets hotter than 97°F, the developing larvae inside become malformed (Himmer 1932) or will have altered behavior as adults (Groh et al. 2004).

Honey bees actively work to keep their hive cool. Honey bees will collect water to spread over the developing larvae for evaporative cooling (Kühnholz & Seeley 1997), spread themselves out inside and outside of the hive to allow for airflow (Bonoan et al. 2014), and will fan their wings to circulate cool air. All of these jobs are performed by groups of bees, who actively cooperate to maintain stable temperatures for the delicate developing larvae.

 But how do honey bees know when it’s too hot for the larvae?

We placed single fanners (honey bees observed fanning) into a cage, and they we either 1) added a larva from the same colony directly into the cage with them, 2) added a larva but into a separate compartment where the fanner could not touch the larva, or 3) kept the fanner alone. We then heated the bee with the larva if there was one present, and recorded their fanning behavior.

When honey bees are alone, they rarely begin to fan. This makes sense: fanning is a very energetically expensive behavior, so it doesn’t make sense to do if there is no one around to fan. When a larva is present, however, a honey bee worker is more likely to fan, but only when they are able to have physical contact with the larva. If the larva is less than a centimeter away, but the worker is unable to touch it, the worker behaves as if there is no larva and rarely fans.

What could be the cue that larvae are giving off? Brood pheromone is a well known pheromone that honey bee larvae produce (Pankiw et al. 1998). It tells the workers whether the larvae are hungry or not, so it may tell the workers if the larvae are too hot. We found that being heated in the presence of brood pheromone did not increase fanning behavior. There are many other pheromones that could be telling the workers the larvae are overheating, but it does not seem to be brood pheromone. While we know that workers know when larvae are hot, most likely from having physical contact with them, we don’t know what the larvae are doing to let the workers know they are too hot.

Honey bees must actively monitor nutrition, infection, and temperature when rearing their babies. Workers manage their colonies very well, as thousands of workers care for the queen and hundreds of babies. For all of my friends having children, I am glad thermoregulation is one less thing they have to worry about.

References

Himmer, A (1932) Die Temperaturverhaltnisse bei den sozialen Hymenopteren. Biological Reviews, 7(3), 224-253.

Groh, C, Tautz, J, & Rössler, W (2004). Synaptic organization in the adult honey beebrain is influenced by brood-temperature control during pupal development. Proceedings of the National Academy of Sciences of the United States of America, 101, 4268-4273.

Kühnholz, S & Seeley, TD (1997). The control of water collection in honey bee colonies. Behavioral Ecology and Sociobiology, 41, 407-422.

Bonoan RE, Goldman RR, Wong PY, Starks PT (2014) Vasculature of the hive: Heat dissipation in the honey bee (Apis mellifera) hive. Naturwissenschaften 101:459–465.

Pankiw T, Page RE, Fondrk MK (1998) Brood pheromone stimulates pollen foraging in honey bees (Apis mellifera). Behavioral Ecology and Sociobiology 44:193–198.

 

 

Interview with a social insect scientist: Franne Kamhi

IS: Who are you and what do you do?

FK: I am a post doc in Ajay Narendra’s lab at Macquarie University. I am interested in the neural mechanisms underlying ecologically relevant behaviour in an evolutionary context, focusing on ants. I am currently studying the neurobiological basis of visual navigation in Australian bull ants (Myrmecia) active in different temporal niches.

IS: How did you end up researching social insects?

FK: My background is in neuroscience and I worked in several neuroscience labs during college. While studying electrosensory systems in fish in my final year of college and adult neurogenesis in mice after I graduated I realized that I wanted to focus on the neural underpinnings of ecologically relevant behaviors. And I wanted to do field work in addition to working in a lab. For graduate school, I looked into several neuroethology labs and became fascinated by the questions about the neurobiology of ant social behaviour and colony organization that James Traniello and his lab group focused on.

IS: What is your favourite social insect and why?

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Oecophylla smaragdina Photo credit: F. Kamhi

FK: I have to say the Australasian weaver ant (Oecophylla smaragdina), also known as the green tree ant, the species I studied during my PhD. They are incredibly charismatic – they wave their antennae at me when I approach the nest and put up quite a fight when I collect them. They’re renowned for being one of the most socially complex species of ant and I could spout off all the reasons why, but one of the most impressive things I saw (and what solidified them as my favourite) was a nest that they built around the light fixture above the table on my porch. When the light was on, it inevitably attracted a lot of insects and the weaver ants would attack them and drag their prey into their perfectly positioned home.

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

FK: One exciting moment was when I finally got the weaver ants to eat a drug that I was trying to feed them to decrease octopamine, a neurotransmitter. I had spent a long time trying to get the concentration of honey water to drug just right so that it did not taste foul to the ants. Once I figured that out, it took only a couple weeks to test them and find that, as I hypothesized, it actually did reduce their level of aggression.

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

FK: I am not currently teaching, but hope to have the opportunity to do more in the future.

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

FK: I just moved to Sydney and have been on an Australian literature kick to familiarize myself with my new country of residence. The last book I read was Kate Grenville’s “Sarah Thornhill,” the sequel to “The Secret River” (which I read previously). Both are very well written, moving novels about a British convict and his family settling in what is now Sydney.

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

FK: I think several books influenced my research interests, but one that comes to mind is Georg Striedter’s “Principles of Brain Evolution,” which I read in a seminar in college.

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

FK: I enjoy spending time with my friends, whether having dinner parties or seeing live music. I also try to get out of the city as much as possible to go hiking and camping.

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

FK: I take a step back and go for a walk. Ice cream and chocolate are good. Also, I have a great support system of friends and family.

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

FK: I always hate these types of questions. Probably a good book, a blanket (can double as a towel), and sunscreen.

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

FK: I have had a lot of fantastic mentors, I don’t know how to choose just one! Chris Cain was my first research mentor. I decided to study neuroscience while working with him, and he’s the first person who ever suggested that I go to graduate school. Mark Braford was my honor’s supervisor and taught me a great deal about evolutionary neuroscience –working in his lab gave me the idea that I could combine fieldwork with neuroscience. And James Traniello, my PhD adviser, has been a fantastic mentor and is continuing to help me develop into an independent researcher.

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

FK: Find someone whose research interests you, contact them, and try it out!

 

 

The nastiest ants dance the tango at home and abroad

A blog post highlighting the article written by Calcaterra, Cabrera and Briano in Insectes Sociaux

Written by Luis Calcaterra

The world’s worst invasive ants originated in the same place as the tango- the River Plate basin in Argentina. Step by step, naturally, helped by humans and/or global warming, these ants then proceeded to move from their native range in all directions over the last 150 years. Finally conquering the world, they have changed human life on Earth irreversibly. But why are invasive ants, as the tango, more notorious abroad than in their homeland?

Of the approximately 14,000 ant species on earth, only a handful are invasive and threatening to the planet. Like tango dancers, these species gained fame abroad, but not for positive reasons. These ants cause billions of dollars in losses by affecting agriculture, human health and wildlife, replacing and reducing native species, and even pushing some species to the edge of extinction.

Main source of global invaders

Like the tango dancers, these versatile ants have evolutionary adaptions to move freely around the world to establish and dominate successfully in new places, with devastating consequences. Most of their invasions originated in the basin of the River Plate, as in the case of the invasive red and black fire ant (Solenopsis invicta and S. richteri), the Argentine ant (Linepithema humile), the little fire ant (Wasmannia auropunctata), and the South American big-headed ant Pheidole obscurithorax, whose source populations have been recently discovered in Argentina.

But are these evil invaders as dominant and problematic in their homeland as they are in the invaded regions? Little is known about the performance of invasive ants in their native land or how they interact with other native ants. Previously, we thought that invaders were not dominant in their homeland, but studies conducted during the last decade revealed that some of them can be just as ecologically dominant in their home as in their introduced range. Such is the case of the aggressive red fire ant (Calcaterra et al. 2008), now spread in North America, Australia, China, Hong Kong, Taiwan, the Philippines and some Pacific and Caribbean islands (Ascunce et al. 2011).

Local coexistence of several highly invasive ants

In our study, we investigated how different invasive ants fare against other native ant species as part of an effort to learn more about the behavior of invaders in their homeland. We studied interactions between several of the most highly invasive ants and other native aboveground foraging ants that locally co-occur in four habitats of a protected area (Otamendi Natural Reserve) next to the city of Buenos Aires. We used a combination of pitfall traps and baits to study day-to-day activity in ant communities to determine ant abundance at the sites, and this showed the ability each species had to discover and dominate food resources.

Of the 49 ant species that locally coexisted in the reserve, five were well-known global invaders: the black fire ant S. richteri, the Argentine ant L. humile, the little fire ant W. auropunctata, the tawny crazy ant Nylanderia fulva, and the rover ant Brachymyrmex gaucho. But only two of them, the black fire ant and the Argentine ant were ecologically dominant, though their supremacy was much lower than in the invaded regions, likely due to the presence of much more skilled competitor ants in their homeland. It´s as if local acceptably good dancers were treated as demigods abroad, something that in fact often happens in the tango world.

Factors promoting ant coexistence

Coexistence among so many invasive ants and other co-dominant native, but non-invasive, ants was apparently helped by niche and competitive differences, different habitat preferences, different abilities to scout and discover the baits, and in the ability to immediately recruit enough workers to monopolize them. But the high ant species diversity and the fact that invasive ants are mostly randomly distributed in space (not segregated) suggest that competition only played a secondary role in organizing the ant communities.

The other invasive ants were not dominant in the reserve- much like the tango dancers that appear mediocre in their very competitive local environment. Thus, it is possible that their dominance in native and introduced regions of the world is more associated with their high colonization capacity to harsh environments (mostly anthropic) rather than to their superior competitive abilities. For example, the little fire ant is able to monopolize bait only when a large number of workers are recruited to it, which can rarely be achieved owing to its slow performance in scouting and recruiting workers to defend it from better contenders (unless the bait is within its nesting territory). The little fire ant is mostly problematic in places where there are very few competitor ants, such as islands (e.g. Hawaii) or anthropic sites (e.g. cities, where the weather is also more extreme).

Pheidole workers removing little fire ant workers from a bait. 
Video credit: Lucila Chifflet

 

As for the ant tango, a question remains without answer: what factors enable the appearance in the River Plate basin of so many successful invaders? To our knowledge, this region represents the main exit door of known and potential invasive ants. As global trading expands, the spread of the nastiest ants from this region of the planet will continue threatening life on Earth.

 

References

Calcaterra, L. A., Livore, J. P., Delgado, A., & Briano, J. A. (2008). Ecological dominance of the red imported fire ant, Solenopsis invicta, in its native range. Oecologia, 156(2), 411-421.

Ascunce, M. S., Yang, C. C., Oakey, J., Calcaterra, L., Wu, W. J., Shih, C. J., Goudet, J., Ross, K.G. & Shoemaker, D. (2011). Global invasion history of the fire ant Solenopsis invicta. Science, 331(6020), 1066-1068.

Colony size evolution in ants

Highlighting the article by Burchill and Moreau in Insectes Sociaux

Written by Insectes Sociaux Editor in Chief, Michael Breed

How animals transitioned from simply living together to forming eusocial societies is a fascinating question for social insect researchers. As a result, much of the current science on eusocial animals focuses on the cusp between presocial and eusocial life. A lot of interesting evolution happens, though, after eusociality is firmly established in a group like the ants. In this issue Burchill and Moreau (2016) assemble the available data on colony size for ants and overlay this information on the current consensus evolutionary tree for ants. Doing this allowed them to develop an understanding of dynamics of how colony size evolved and to propose hypotheses that will lead to very interesting subsequent studies.

Casual observers of ants probably have the impression that most or all ants live in large colonies, like those of pavement ants, leafcutters, and army ants. Researchers of ants will appreciate that the majority of ant species have colonies of a few dozen to a few hundred workers. Burchill and Moreau’s study is an excellent invitation to consider that very large colony size has many independent origins in ants. What are the evolutionary steps between the basal state of small colony size to colonies of tens or hundreds of thousands of workers? Is colony size evolutionarily fluid, with movement from large to small as possible as small to large?

Burchill and Moreau provide at least suggestive answers to these questions. Evolutionary trends show gradual transitions to larger colony sizes. This may support a view that there were few unique innovations that allowed sudden jumps in colony size. They found no strong evidence for reversal of colony size evolution when considering large to medium shifts, at least if the evolution of obligate social parasites is set aside.

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Photo credit: Dzipi/Flickr

An impact of Burchill and Moreau’s discussion is a renewed call for publication of more extensive sociometric data (Tschinkel 1991). Characterizations of colony proper- ties, such as the number of workers, have extreme importance in facilitating deeper studies of evolutionary processes. Unfortunately, there are few published high quality sociometric studies of eusocial insects. Such studies would have sample sizes that are large enough to establish the certainty of estimates for measures like colony size. They would also allow assessment of within- and between- population variances. Important surveys like Burchill and Moreau’s would be greatly facilitated by sociometric data banks.

As Burchill and Moreau point out, it is likely that ant species with small colonies are under-represented in the sociometric literature. This means that in their analysis the transition from medium to large colonies is better repre- sented than small to medium transitions. Nevertheless their results strongly support the hypothesis that colony size evolution in ants is gradual rather than saltatory, with trends for increasing colony size in some groups. Among the many interesting questions suggested by this study are whether modifications of colony reproductive structure, such as movement from monogyny to polygyny (Hölldobler and Wilson 1977), facilitate colony size evolution. Similarly, are modifications of social mechanisms like division of labor important in these evolutionary shifts? Much remains to be answered about the fascinating trends highlighted by Burchill and Moreau.

 

Editor’s note: If you want to know how ant colonies are like rock bands, check out Andrew Burchill’s post about his article here.

 

References:

Burchill AT, Moreau CS (2016) Colony size evolution in ants: macroevolutionary trends. Insect Soc doi:10.1007/s00040- 016-0465-3

Hölldobler B, Wilson EO (1977) The number of queens: an important trait in ant evolution. Naturwissenschaften 64:8–15

Tschinkel WR (1991) Insect sociometry, a field in search of data. Insect Soc 38:77–82