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 2^nd 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.

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.

 

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.

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.

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.

 

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