The Food Search Box assay – where do we go from here?

A blog post highlighting the article by N. Tsvetkov, B. Madani, L. Krimus, S. E. MacDonald, and A. Zayed in Insectes Sociaux

By Armo Zayed

 

Assay for spatial learning and memory

Assay for spatial learning and memory.

 

As central place foragers, honey bees have an amazing ability to fly several kilometers away from their colony to forage and then beeline back to their home without getting lost. Honeybee foragers can perceive and communicate spatial information via the famous waggle dance. But how are these traits encoded in the honey bee genome?

When Nadia Tsvetkov joined my lab in 2012, she was keenly interested in studying the genetics of spatial learning and memory in bees. She spent several months training bees to fly through mazes. The maze experiments were fun but took too long, and our sample sizes were far fewer than the hundreds of bees needed to tease out the likely subtle genetic effects on learning and memory. What we needed was an assay that was as fast and as easy to standardize as the proboscis extension reflex assay – the workhorse of insect olfactory learning and memory studies. We tried some different approaches (one involved a very beautiful but unwieldy maze constructed out of Christmas balls) until colleague Dr. Suzanne MacDonald, a vertebrate biologist at York University’s Department of Psychology, suggested that we try the food search task paradigm. The paradigm is commonly used to study spatial learning and memory in primates and rodents. A common protocol entails hiding toys or food in boxes within a testing arena that animals are allowed to explore. Over time, the animals learn and can recall the location of boxes that contain rewards.

So we set out to try a similar assay on bees. For prototyping, we used some common and inexpensive items; we made the testing arena of clear Tupperware containers and we employed several artificial flowers made out of Q-tips. After a few pilot assays, we decided that a small arena containing four flowers was the best compromise between complexity and length of the experiment. Nadia worked out the testing protocol that involved placing bees into the arena where one of the artificial flowers had a sucrose reward. Once a bee found and fed from the rewarding flower, it was removed and tested again for a total of three training trials. Finally, the bee entered the arena where none of the flowers had a sugar reward. This time, the bee had to rely solely on its memory to find the focal flower. Our data analysis showed that bees subjected to this test exhibited two telltale signs of learning and memory: they improved their ability to find the rewarding flower during training, and they were able to recall the location of the rewarding flower after training. The Food Search Box (FSB) was born.

We carried out two more experiments to test the utility of the FSB for studying spatial learning and memory in bees. We first compared the performance of nurses (young honeybee workers that nurse the brood) and foragers (older workers that forage outside the colony) in the FSB paradigm. While both nurses and foragers did equally well in the training trials, foragers did substantially better than nurses in the memory test. So, is it age (young vs. old) or behavioral state (nurse vs. forager) that is influencing spatial memory in the FSB? To answer this question, we carried out another study on same-aged workers. We treated these workers with either cGMP, which causes precocious foraging, or cAMP, which does not alter behavioral state. The cGMP-treated bees performed similarly to foragers in the FSB, while cAMP and the control bees performed like nurses in the assay. Taken together, the results of these two experiments indicate that behavioural state (nurse vs. foragers) is primarily associated with differences in spatial memory in the FSB.

We are very excited by the results of the FSB; we were able to test bees quickly without much attrition. It is feasible to screen hundreds of bees within a short period, opening up the door for genetic and genomic studies of spatial learning and memory in honeybees. While it is certainly possible to improve on the design to enhance automation (i.e., RFID readers or tactile sensors to passively record visits to artificial flowers), the low-tech version presented in the paper is very easy to set up and perform. We are looking forward to feedback from the community on the test, and we hope it will provide a useful tool for studying spatial learning and memory in honeybees and other insects.

Interview with a social insect scientist: Luke Holman

Square Luke

IS: Who are you and what do you do?

Hi! I’m a Senior Lecturer working at the University of Melbourne. I did my undergrad and PhD in Sheffield, UK. My PhD was on sperm morphology in fruit flies, and I began working on social insects during my first postdoc at the University of Copenhagen with Prof. Patrizia d’Ettorre. Since discovering a bunch of ant, bee, and wasp queen pheromones in 2010-14, a lot of my research has focused on working out how queen pheromones evolve, how they work, and what they can tell us about the origins of eusociality. Currently, I also work a lot on sexual selection and ‘meta-science’ (including topics like p-hacking, research methods, and the gender gap in the science workforce), and I teach undergraduate genetics and evolution.

IS: How did you develop an interest in your research?

In short, I read most of The Selfish Gene during high school, and realised evolutionary biology was incredible! It was earthshattering to realise that we could make sense of nature’s astounding complexity and weirdness using simple, logical theory. Initially my research focused on puzzling traits that seem to defy conventional evolutionary logic: my PhD was on a group of flies that produce thousands of specialised, infertile sperm (apparently on purpose). Are these sterile sperm a worker caste that help the fertile sperm somehow? Or are they casualties of intragenomic conflict? We still don’t really know, but I was hooked.

IS: What is your favourite social insect and why?

Probably the black garden ant, Lasius niger, for changing my life by making my career in science possible. If it weren’t for their reliably massive mating flights in the parking lot outside my office in Copenhagen, I would not have had such a successful first postdoc. Each year I could collect up to 900 queens in a couple of hours, enough for a whole summer of experiments, simply by strolling around on summer evenings. A close second is the ant Lasius flavus, because they’re bright orange, very gentle, and have a nice simple cuticular hydrocarbon profile that’s easy to analyse by GC-MS.

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

Probably the day I isolated the queen pheromone of Lasius niger. I moved to Denmark in summer 2008, and on Patrizia’s advice I began my first experiment with synthetic pheromones, on boxes of ants kept in my living room (they needed to be treated twice daily with pheromones for a month). At the same time I was working day and night on a Marie Curie fellowship application, and exploring the new city. I ran the whole experiment blind, so for ~2 months I had no idea if the putative pheromones were doing anything. After collecting all the blind-coded data and making the graphs and statistics, I took them to Patrizia’s office for decoding, and we realised that we had isolated arguably the first ant queen pheromone. That felt great! As well as being a significant discovery, it was a lucky break that set the stage for a productive postdoc.

IS: Do you teach or do outreach/science communication? How do you incorporate your research into these areas?

I have written a little for The Conversation, which is a great website – for those that don’t know it, it hosts science journalism explained in plain English by actual researchers. I’d encourage your readers to contribute to it: it’s a non-profit enterprise with a large readership that provides a good antidote to mainstream science journalism, which is hit-and-miss. In my lecturing, I certainly touch on my own research interests, but I have also been surprised by how much my teaching has helped my science. Many times, I have been writing lectures and realised that I didn’t properly understand something, or I have noticed papers or knowledge gaps that lead me to a new research project (particularly when I have been asked to teach something outside my comfort zone).

IS: What do you think are some of the important current questions in social insect research and what’s important for future research?

The question that springs to mind is “Does methylation matter?” There are many review papers arguing that social insects use DNA methylation to regulate caste polyphenism, but precious little data, and most of the data that we do have is non-experimental and uninformative (e.g. “We looked at the methylome of one queen and one worker, and found some differences”). There’s a widely-cited 2008 Science paper showing that experimental manipulation of DNA methylation causes larvae to develop into queens, and we could settle the question by replicating or expanding this approach.

More broadly, I think social insect research would benefit by incorporating recommendations from the ongoing “Reproducible Research” movement: open data, good experimental design, transparent statistical analysis, etc. In a recent meta-analysis, I showed that 70% of queen pheromone experiments were not conducted blind, and that non-blind experiments had hugely inflated effect sizes (presumably due to observer bias). Sample sizes were very often strikingly small (e.g. n=6, barely enough to analyse), making these studies almost entirely uninformative. Given that social insects are known for being numerous, I don’t think it’s unreasonable to insist on large, blind, well-designed experiments. I have also found that many flat-out social insect scientists refuse to share or archive their raw data, hindering research synthesis and ensuring that their results are unavailable for re-use or fact checking.

IS: What research questions generate the biggest debate in social insect research at the moment?

Unfortunately, the answer is probably still the continuing fallout over the 2010 Nature paper by Nowak, Tarnita and Wilson! For my part, I am baffled by both sides. The original paper made various obviously untenable claims, e.g. that kin selection theory has made only a “meagre” contribution. However I also find it odd how much effort has been invested in rebutting this paper: there are dozens of papers replying to it, and I have sat through multiple angry conference talks. At some point I think we just need to shrug and get on with it. An uncomfortable truth is that all science is somewhat wrong, and I’m not convinced that doing science “at” a particular person/group is a useful way to advance knowledge.

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

I Contain Multitudes by Ed Yong, about the microbiome. Absolutely fascinating read with Ed’s characteristically playful, funny style. A sample factoid: some researchers think that humans and bacteriophages have co-evolved. Our gut is lined with mucus that just so happens to be a great habitat for phages to lurk and take out bacteria that try to get through the gut lining. I never thought that I was involved in a mutualism with a virus!

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

I like travel, hiking, rock climbing, yoga, and meditation. In the past I was cripplingly addicted to juggling, and spent many hours a day throwing small sacks of seeds in the air; my record was 8 balls for about a second, or 5 balls for about a minute. I also spend plenty of time reading the news and fretting, though I’m trying to cut down.

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

The last 2-3 years have been very stressful, as I made the transition from postdoc to lecturer. Instead of doing less science to make room for my new responsibilities, I just worked harder, which was a bad idea as I ended up burning out. I now try to leave work on time and keep active, but years on fixed-term contracts has left me with a loud inner voice that shouts, “You should be publishing!”. I’ve been lucky to have lots of supportive friends and family to lean on, but I think the best way to manage in tough times is to make sure you’re not already exhausted by your normal work. Maybe the answer is to sit down and plan for your mental health and well-being, just as you would plan for a field season.

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

Swiss army knife, water purifier, and a boat to get off the island.

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

Probably WD Hamilton. Reading his 1964 papers, it’s amazing how many future branches of evolutionary ecology he foreshadows in throwaway sentences. Also, I likely wouldn’t have become a scientist if his work wasn’t evangelised so well in The Selfish Gene. As for people I’ve actually met, I pick my second postdoc advisor, Prof. Hanna Kokko. I try to emulate her incisive way of thinking, her efficient work practices, her skill in balancing work and life, and her kindly enthusiasm for everything.

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

I’d recommend keeping up with research outside as well as inside the social insect world! To its detriment, a lot of social insect research is focused on narrow, taxon-specific issues, and only uses methods that have previously been applied to social insects. This slows down the pace of development in social insect science, and reduces its appeal to researchers from other fields. Some of my best papers involve applying a widely-used concept or method to social insects in a novel way. For example, dozens of non-social insect people work on ‘intralocus sexual conflict’, the concept that there is antagonistic pleiotropy for male and female fitness, leading to maladaptation in both sexes. I pointed out that the same thing applies to queens and workers: basically, it’s hard to make a perfect worker and a perfect queen using the same genome, so each caste ends up a little bit maladapted. Another example involves the analysis of gene expression data. Most social insect transcriptomics studies test each gene for differential expression one at a time, but in other fields it has long been commonplace to also test for differential expression in ‘modules’ of strongly co-expressed genes.

Ants colonise bird nests and raise broods in them

A blog post highlighting the article by M. Maziarz, R. K. Broughton, G. Hebda, and T. Wesołowski in Insectes Sociaux

By Marta Maziarz

As an ornithologist, I have focused on the reproduction of birds but often overlooked the fact that bird nests can also be home to many invertebrates that find shelter, food or a suitable microclimate within them. When we discovered ant workers and their larvae inside nests of the wood warbler Phylloscopus sibilatrix, curiosity drove us to study this phenomenon.

An initial literature review revealed just a handful of published records of ant broods found inside bird nests, including blue tits Cyanistes caeruleus breeding in nest-boxes in Corsica (Lambrechts et al. 2008), and great tits Parus major and marsh tits Poecile palustris occupying tree cavities in primeval stands of the Białowieża Forest, Poland (Mitrus et al. 2015). Blem and Blem (1994) reported ant colonies on the side of nests in nest-boxes used by prothonotary warblers Protonotaria citre but gave no further details. This surprising scarcity of observations of ants in songbird nests suggested that this phenomenon may be exceptional and occur only among cavity-nesting species.

Our discovery of ant workers and their larvae in wood warbler nests, which are domed structures composed of dry grass, moss, and leaves and situated on the forest floor, challenged this view. We made the original finding during long-term studies of wood warbler ecology in 2004-2015 in Białowieża Forest (Eastern Poland), which prompted us to document this phenomenon systematically during 2016-2017. In 2017, we also contacted researchers in Switzerland and the UK to ask them to inspect nests for the presence of ants and their broods. We wanted to find the frequency of ants colonising wood warbler nests, and whether ants are present in wood warbler nests elsewhere in the species’ breeding range.

During our systematic observations in 2016-2017, we found adult ants in 43% of warbler nests, and one-third of nests also contained ant larvae or pupae. These ant broods were situated within the sidewalls of the nests, at or just above ground level. The most frequent species were Myrmica ruginodisor M. rubra, and occasionally Lasius niger, L. platythoraxor L. brunneus. These numbers, compared to 30% of nests containing adult ants and 20% containing broods during the earlier (2004-2015) period, indicated a long-term association between the ants and the birds. The findings from Białowieża Forest contrasted with those from Switzerland and the UK, where we only found single cases of adult ants and their broods. The different frequencies of ant presence between regions could be due to varying densities of bird or ant nests between woodlands transformed by humans to a different degree, but further studies would be necessary to confirm this.

These first records of adult ants and their broods in wood warbler nests showed that occupation of bird nests by ants can be a locally common phenomenon, which may have been overlooked previously in this and other songbirds. Systematic examination of nests belonging to different bird species would be valuable in understanding this further.

Furthermore, the occurrence of ant broods in the walls of wood warbler nests showed that ants colonised these structures following their construction by birds. Why they do this remains unclear; are the ants attracted to the nests by their structure, the presence of other invertebrates as a source of protein, or by heat generated by the birds? More work is underway to answer these questions, but it seems that these potential ant-bird interactions could be much more widespread than has been suspected.

Picture1

Wood warbler nests are dome-shaped and constructed of leaves, grass, and moss. They are usually hidden among low herb vegetation, under a tussock of grass or sedge, or wedged under fallen branches or logs. Such structure and locations could promote their occupation by ants, for example, Myrmicaspp., which raise their broods in similar places.

Picture1

Numerous ant Myrmicaspp. larvae and two larger, well-grown blowfly Protocalliphoraspp. larvae (centre-right) in the wall material of a wood warbler nest

References

Blem CR, Blem LB (1994) Composition and microclimate of Prothonotary warbler nests. Auk 111:197–200.

Lambrechts MM, Schatz B, Bourgault P (2008) Interactions between ants and breeding Paridae in two distinct Corsican oak habitats. Folia Zool 57:264–268.

Mitrus S, Hebda G, Wesołowski T (2015) Cohabitation of tree holes by ants and breeding birds in a temperate deciduous forest. Scand J For Res 31:135–139.

Microbiomes and worker tasks

Highlighting the article written by J. C. Jones et al. in Insectes Sociaux

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

Molecular techniques for identifying microbial community composition have created a
true biological revolution. Recent discoveries lead us to understand the bacteria as an
evolutionarily complex and diverse domain, and this in turn has sparked interest in
characterizing microbiota from a large number of contexts. Of particular significance has been the exploration of gut microbiomes, which vary dramatically among species, and developmentally within species. Gut microbiomes interact strongly with diet and health, giving added interest to studies focusing on this subset of communities (Dunn 2011, DeSalle and Perkins 2016).

We have long understood the importance of the gut microbiome in social insect species. In termites, some components of the microbiota reduce cellulose to usable sugars while in other species, members of the microbiota fix nitrogen. More recent studies of ant and bee gut microbiomes have shown some level of intraspecific consistency even over broad geographic ranges, but also variation associated with diet and to a certain extent differences among colonies.

In this issue of Insectes Sociaux, Jones and her colleagues (Jones et al 2018) focus on
differences in the gut microbiota based on task group in honeybee (Apis mellifera) colonies. This is a question previously addressed by Kapheim et al (2015) but Jones and colleagues add critical dimensions by age-matching the worker bees in their study and collecting gut samples from bees observed performing specific tasks.

Each of five experimental colonies consisted of 1500 workers of the same age and from
the same source colony (400 of which Jones and colleagues individually marked). They
observed worker behavior in ten to fourteen-day old bees. Nurses, food receivers/handlers and foragers were noted and collected. This approach allowed assessment of diet and task-related differences in microbiomes independent of age-related developmental effects.

Jones et al (2018) found that Firm-4 (Lactobacillus mellis), one of the characteristic
bacteria of the honeybee microbiome, was more prevalent in nurse and food handling bees than in foragers. This pattern was also seen with quite a few other bacteria species, which had higher presences in nurses and/or food handlers than in foragers. One species, Lactobacillus kunkeei, was more common in forager guts, although they found it less commonly there, so this result is more provisional. Of particular note in the guts of food processing bees was Bartonella apis, as this species expresses genes that may be involved in the degradation of secondary plant metabolites.

Globally, the microbiomes of nurses and food handlers were more diverse than the
microbiome of foragers. Jones et al (2018) suggest that the needs for carbohydrate metabolism are higher for nurses and food handlers and that perhaps this drives functional differences in the gut microbiome between these task groups and foragers.

Concerns over bee health, responses of bees to diseases or parasites, and the impact on bees of the agricultural use of antimicrobials have generated much of attention given to bee microbiomes (Napflin and Schmid-Hempel 2018, Raymann and Moran 2018). While these topics are important, the microbiomes of social insects existed long before humans started to impact social species, and social insect microbiomes must have evolved alongside sociality. How might gut microbiomes facilitate worker task performance? Do they determine workers’ roles within colonies? The cause and effect relationship between task group and microbiome could go in either direction, with task environment driving the microbiota or the nature of the microbiological community feeding back into the task choice of bees. This study presents these alternatives as tantalizing avenues to pursue in future research.

References

DeSalle R, Perkins SL (2016) Welcome to the microbiome: Getting to know the trillions of bacteria and other microbes in, on, and around you. Yale University Press 264pp.

Dunn R (2011) The wild life of our bodies: Predators, parasites, and partners that shape who we are today. Harper 304pp

Jones JC, Fruciano C, Marchant J, Hildebrand F, Forslund S, Bork P, Engel P, Hughes WOH (2018) The gut microbiome is associated with behavioural task in honey bees. Insect Soc https://doi.org/10.1007/s00040-018-0624-9

Kapheim, KM, Rao VD, Yeoman CJ, Wilson BA, White BA, Goldenfeld N, Robinson GE (2015) Caste-specific differences in hindgut microbial communities of honey bees (Apis mellifera). PLoS ONE 10: e0123911

Napflin K, Schmid-Hempel P (2018) Host effects on microbiota community assembly. J Anim Ecol 87: 331-340

Raymann K, Moran NA (2018) The role of the gut microbiome in health and disease of adult honey bee workers. Current Opinion in Insect Science 26: 97-104

Does size matter when using celestial cues to navigate towards home?

A blog post highlighting the article by R. Palavalli-Nettimi and A. Narendra in Insectes Sociaux

By Ravindra Palavalli-Nettimi and Ajay Narendra

Imagine finding a location in a new city without any map. How would you navigate toward your destination?

If you were an ant, you could use celestial cues such as the position of the sun or the polarised skylight pattern (Wehner and Strasser 1985; Zeil et al. 2014) as a compass to navigate in the direction of your destination (e.g., nest). The compound eye of an ant has a few special ommatidia that are sensitive to polarised skylight (light waves oscillating in one orientation). However, the eye size and also the total number of ommatidia in the ants’ eyes decrease with their body size. Some ants have close to 4,100 ommatidia (Gigantiops destructor) in their eyes while a miniature ant has a mere 20 ommatidia (Pheidole sp.). However, it is not clear how this variation affects their ability to navigate.

 

Picture1

Size variation in ant heads.

 

In this study, we investigated how size variation affects ants’ ability to use celestial cues to navigate towards their nest.

To test this, we captured ants on their way to their nest and displaced them to a circular platform. The displacement site was at least 500-1,000 m from the ants’ nest and was surrounded by a creek. Thus, the ants had never foraged there and could not use landmark cues to navigate, but instead, they had to rely on celestial compass cues to walk towards their nest. We filmed the paths taken by the ants using a video camera and later digitized their head position frame by frame.

We found that having fewer ommatidia does not affect the ants’ ability to use celestial cues. The ants’ heading direction on the platform did not significantly differ from the fictive next direction. Since larger ants have greater strides and thus travel more distance for the same number of strides, we also analyzed their heading direction at a distance on the platform scaled to the body size of the ants.

We also found that the smaller ants were slower and had less-straight paths than the larger ants, even after controlling for differences in leg size (correlated with body size and head width) and stride length. This finding means that a reduced ability of the smaller ants to access celestial compass information results in a less straight path and reduced walking speed. However, the overall ability to initially orient towards the nest using a celestial compass is retained in miniature ants. Thus, while miniaturization in ants can affect their behavioral precision, it may not always lead to a loss of vital behavioral capability such as using celestial cues to navigate.

 

Picture1

Paths and heading directions of various ants that differed in head width and ommatidia count.

 

In conclusion, finding a destination in a new city might be a lot easier if we were ants—of any size—and could use celestial cues!

References

Wehner R, Strasser S (1985) The POL area of the honey bee’s eye: behavioural evidence. Physiol Entomol10:337–349.

Zeil J, Ribi WA, Narendra A (2014) Polarisation vision in ants, bees, and wasps. In: G Horváth (ed) Polarized light and polarization vision in animal sciences, Springer, Heidelberg, pp 41–60.

Welcome to the new Insectes Sociaux social media team

Hello social insect fans,

It is my pleasure to introduce the new social media editing duo for Insectes Sociaux, Bernadette Wittwer and Madison Sankovitz, coming to you from Australia and the United States respectively. Having worked with them over the last month to hand over the reins to the Insectes Sociaux social media accounts, I can tell you that they have lots of exciting things planned for you, including an Instagram account (@insectessociaux)!

Madison Sankoviz

I am an entomology Ph.D. student in the Purcell Lab at the University of California Riverside. My research interests are the ecological interactions and biogeography of ants. With a passion for insects and understanding the dynamics of changing ecosystems, I am interested in answering questions of what social and behavioral traits allow survival in the extremes of latitudinal and elevational gradients in Formica ants. I also explore ant-mediated soil manipulation. Passionate about teaching and communicating science to the public, I am the graduate student coordinator for our department’s outreach program. I received a B.A. in ecology and evolutionary biology from University of Colorado Boulder, where I studied the effects of Formica podzolica ant colonies on soil moisture, nitrogen, and plant communities. Not only am I constantly inspired by the research of other social insect scientists, but I admire their enthusiasm for the natural world. I look forward to highlighting future publications and investigating the stories behind them as a social media editor for Insectes Sociaux!

Bernadette Wittwer

I am an evolutionary biologist with research interests in broad evolutionary transitions. I competed undergrad and honours at the University of Queensland. My honours research examined the evolution of feeding behaviour in crocodilians, with a focus on Isisfordia duncani, a 90-million-year old crocodile from western Queensland, Australia. After honours I moved to the University of Melbourne and undertook my Ph.D. looking at the evolution of communication in bees. Bees have an extraordinary depth of behavioural diversity and it is through them that I was introduced to the wonderful complexities of insects that live in groups. My research has particularly focussed on antennal structures and how bee species have adjusted their investment in communication as they have evolved different social behaviours. Through my research I’ve been grateful to work with and meet so many enthusiastic social insect researchers and I look forward to exposing more wonderful social insect research through Insectes Sociaux’s social media channels.

The best part of this role has been working with all the contributors to the blog and our interviewees. Thank you again to all of you that have participated.

If you are interested in blogging or interviewing, do not hesitate to contact Bernie and Madison via Twitter (@InsSociaux), Facebook, or via email at bernie.inssoc@gmail.com and madisoninsectessociaux@gmail.com.

Interview with a social insect scientist: Roberto Keller

RobertoKeller-2016-04-Lisboa

IS: Who are you and what do you do?

RK: My name is Roberto Keller. I grew up in Mexico City where I majored in Biology, later pursuing a PhD in Entomology up north in the USA, and since the past decade I live in Lisbon, Portugal, currently working at the Nacional Museum of Natural History. I’m a comparative anatomist that specializes in ants.

IS: How did you end up researching social insects?

RK: Back at the University in Mexico the people in our group of insect enthusiasts was choosing which taxon to specialize on. Most of my peers were drawn to shiny scarab beetles, some into colourful butterflies, but I loathed those clichés so I placed my attention into all those little brownish ants running around. Once I looked at them under the stereoscope I was surprised at how elegant and varied ants can be. I was instantly hooked. Oh, that and the fact that I never liked to mount insects with wings because getting them to look right is just a pain.

IS: What is your favourite social insect and why?

RK: Neoponera apicalis. This is an ant species that lives in the tropical forests from Mexico to South America. The workers are large, matte black, with the tip of their antennae light yellow. Workers forage alone on the shaded damp forest floor, so you only see a pair of yellow antennal tips dancing around. The first time I saw one I was so excited that I grabbed with my bare hand. Their sting feels like a painful electroshock.

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

RK: I was once reading a short paper comparing the external morphology of queens versus workers in an ant species. The whole discussion was off because the authors had wrongly assumed that the largest thoracic segment in workers was the fusion of the first and second segments when compared to queens. My first reaction was to rail against the authors for making what I consider an obvious mistake. It later hit me that not only was their error quite understandable, but that it pointed to a remarkable difference between those two castes that had been in front of me for years but I had been blind about until that moment.

That turned into a productive research project and taught me to keep a keen eye and question the obvious. I learned a lot from that short paper even with its errors, and I think that this is how science keeps moving forward— we built upon the work of others and hope that the next person who comes will be able to solve the things we were too short sighted to see.

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

RK: I teach courses in general Entomology and, once in a while, on ant morphology. I can’t think of a way in which studying social insects has influence my teaching. I often forget that ants are social, it’s bad. That is why I have collaborators: to remind me.

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

RK: I’m finishing Steven Pinker’s latest book Enlightenment Now: The Case for Reason, Science, Humanism, and Progress. It is appalling to me seeing that we live in a very modern society, and yet we have political extremes converging on pure irrationally. This is a good book to remind people how much science has benefit humankind as a whole, but I’m afraid the people who will read it already know this.

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

RK: Once I was hooked learning about ants during college I got myself a copy of Hölldobler and Wilson’s The Ants, which had been recently published. The dedication reads “For the next generation of myrmecologists.” I felt they were talking directly to me and that dispelled any doubts I still had about following a career in social insects. So at the end I am that cliché I was trying to avoid.

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

RK: I’m a portrait photographer. I’m intrigued about people, and portraiture allows me to sit down for a brief face to face conversation and try to capture that interaction through an image.

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

RK: I like to follow the advice of philosopher Paul Feyerabend:

“If you want to achieve something, if you want to write a book, paint a picture, be sure that the center of your existence is somewhere else and that it’s solidly grounded; only then will you be able to keep your cool and laugh at the attacks that are bound to come.”

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

RK: Hmm, can’t think of any objects that will make sense with the prospect of solitude other than hemlock.

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

RK: My parents. Both chemists, they created a growing environment for my siblings and me in which science was a natural part of life.

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

RK: Don’t grab large social insects with your bare hands. Unless they are termites. Termites are always safe to grab.

 

Interview with a social insect scientist: Hollis Woodard

thumb_UCR S. Hollis Woodard 2016 64 copy_1024IS: Who are you and what do you do?

HW: My name is Hollis Woodard and I’m a bumble bee biologist and an Assistant Professor in the Department of Entomology at UC Riverside. My lab group works on all sorts of things to do with bumble bees, including their nutritional biology, social organization, foraging ecology, and more.

IS: How did you end up researching social insects?

HW: I fell in love with social insects during college when I took an evolutionary biology class. We had a lecture on sociobiology and talked about insect societies and division of labor and I remember thinking it was the most interesting thing I’d ever thought about. I already had an incipient interest in social behaviour because I’d spent some time working at primate sanctuaries, and was thinking about going into primatology, but around the time I took this class I was also becoming interested in experimental biology and realized that insects would be a better way to go for taking that sort of approach in my research.

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Photo: H. Woodard

IS: What is your favourite social insect and why?

HW: Bumble bees! The group has it all: they live in some unusual places (like the Arctic), they have solitary and social stages to their life cycle, socially parasitic lineages, unique thermoregulatory capabilities, they’re dominant pollinators in a lot of systems, they buzz pollinate, and so on. I’ll never get bored working on bumble bees. Lately I’ve gotten particularly interested in queen bumble bees, which are just so special because they undergo so many changes (behavioural and physiological) across their life cycle and face so many challenges, like having to survive through the winter and start new nests on their own in the spring before their workers emerge.

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

HW: One of the highlights of my career thus far was going to Alaska for the first time, in summer 2016, to start working with arctic bumble bees. I became fascinated with them when I read Bernd Heinrich’s book Bumblebee Economics as a graduate student and had been wanting to work in that system ever since, so it was gratifying to make that a reality. There is nothing like watching giant Alpinobombus queens fly around open tundra!

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Searching for Arctic bumblebees.

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

HW: I teach an insect behaviour course for more senior undergraduates and I’m currently developing a new social insects course that I’ll teach for the first time next year, which I’m super excited about. We’re going to talk about theory in the class but I’m also going to heavily emphasize all of the insights we’ve gained through molecular work, especially in the last decade. There’s an awful lot to talk about.

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

HW: The last book I read was Bernd Heinrich’s The Thermal Warriors, which is all about how insects deal with thermoregulatory challenges. It’s a fun read; it takes a complex subject in comparative physiology and makes it very accessible. I highly recommend it, and all of the other books Heinrich has written.

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

HW: E.O. Wilson’s autobiography, Naturalist. I read it the first time in one sitting. Reading it inspired me to go to graduate school and pursue a career in studying social insects. It includes such an interesting treatment of the history of the division between molecular and ecological research, and the idea that that division doesn’t really exist (which Wilson talks about a lot more in Consilience) was exciting to me, given that I was thinking a lot at the time about how to use approaches from molecular biology to study social evolution. Wilson’s passion for ants also really shines through in the book and it’s clear that he appreciates them both for their own sake and because they’re a lens through which you can understand life on Earth, in the broadest sense. That influences how I think about bumble bees: I’m enamoured with them but I also think they contain the answer to every fundamental question in biology.

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

HW: To be perfectly honest I don’t have too many hobbies outside of work, but I have been learning Taekwondo and I’m really liking it. I also love to go hiking and I have three Australian cattle dogs that keep me busy.

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

HW: I experienced burnout at the end of PhD and since then I’ve tried to take it a bit easy on myself and pace myself, when I can. I’ve incorporated more fieldwork into my research program, which gets me out of the lab and office, broadens my perspective, and helps keep me more physically active. I’ve also worked hard to cultivate a buoyant mindset; academia is full of crushing blows to the ego and you have to digest and move on quickly or you’ll get overwhelmed. I also have a lot of wonderful friends in my department who are also new professors and we support each other and celebrate when good things happen.

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

HW: That’s easy, I would bring my dogs, who aren’t ‘things’ to me but I hope would be fair game. They help keep me happy. Hopefully there would also be bumble bees on this island.

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

HW: My PhD advisor, Gene Robinson, has definitely had the greatest influence on my career. When I started graduate school I had a lot of enthusiasm but I didn’t have much research experience and I hadn’t learned how to think like a scientist yet. Gene taught me to think critically, think things through, and think big. I feel so fortunate to have been given the opportunity to learn with and from him.

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

HW: My advice would be to start by picking an organism and learning it well, then the specific research questions will follow. I floundered a bit at first with my bumble bee research because I didn’t really understand them at all – I hadn’t spent time getting to know them, so to speak. Things really picked up for me after I went to Israel to work in Guy Bloch’s lab, where I took a lot of time to sit and watch them, try different things out, and hang out and talk with other bumble bee biologists. The better you know your organism, the better you’re able to formulate solid questions and effectively answer them. All of the best experiments are designed in the context of the organism, in my opinion.

Interview with a social insect scientist: Maggie Couvillon

IS: Who are you and what do you do?

MC: My name is Dr. Maggie Couvillon. I started in 2017 as an Assistant Professor of Pollinator Biology and Ecology at Virginia Tech. I consider myself a broadly trained bee biologist, with experience in stingless bees, bumble bees, and of course honey bees.

In my lab, I focus on basic and applied aspects of bee foraging. At the moment, I am developing honey bees, in particular their waggle dance communications, as bioindicators to give biologically-relevant data on the ability of landscapes to feed flower-visiting insects.  Our project will hopefully generate useful recommendations on how to improve bee nutrition by pinpointing when and where human intervention is useful.

IS: How did you end up researching social insects?

MC: I actually started out in birds. My undergrad had been from a small, liberal arts university, and I simply didn’t have the vocabulary when I graduated to describe my interests. I ended as a dissatisfied graduate student of neurobiology looking at songbird vocal learning. Then, for a class assignment in 2004, I stumbled upon a paper by Ben-Shahar and Robinson that investigated the effect of an increase in gene expression on a honey bee behavior. The data were really cool, but it was the authors’ background description of honey bee division of labor that blew my mind.

I’m really lucky. Just when I was realizing that I didn’t belong in neuro, I simultaneously fell in love with honey bee behavior and was able to find an opportunity for me to swap from the birds to the bees.

IS: What is your favourite social insect and why?

MC: The honey bee will always be my first love.

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Maggie’s favourite social insect, the honey bee.       Photo: Jill Bazeley/flickr

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

MC: During my postdoc at the University of Sussex in Brighton, I had the chance to conduct some experiments involving training honey bees to forage at feeders while we examined their waggle dance communications. At this stage, I had been decoding waggle dances for a few years to learn where and when bees are foraging in the landscape, but I hadn’t yet had the chance to do a feeder experiment.

Seeing the dances of foragers for a known location – the feeder – was just amazing. I knew of course that bees could communicate a direction and a distance, but actually seeing it in real-time was super exciting.

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

MC: I’m new faculty, so at the moment, I’m teaching a seminar course where I’m trying to train new graduate students to summarize and critique (constructively) research seminars. I hope that the students get from the course some basic tips for how to be a valuable peer-reviewer. I’m also contributing to several existing courses (Bees and Beekeeping, Insect Physiology, and Urban Greenspaces), where all my guest lectures possess a strong bee theme. Over the next year, my plan is to develop a course called The Behavioural Ecology of Pollinating Insects, where we will cover some of the major themes from a usual Behavioural Ecology course, but using flower-visiting insects as model organisms.

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

MC: I just finished Station Eleven by Emily St. John Mandel. I’ve been going through a post-apocalyptic reading binge for a few years, and Station Eleven, while fulfilling the niche of a story set in a dystopian future, takes a different focus on how civilization goes about preserving or rebuilding not just sustenance, but culture. The book is set in a near future where 99.9% of the world’s population is decimated by a pandemic called the Georgia flu. People remain in small, scattered settlements. One of the main characters, Kirsten, is a member of 20 or so actors and musicians that travel in horse-drawn wagons from settlement to settlement to perform Shakespeare, taking as a motto “Survival is insufficient”. It’s a neat idea for a book – what is important enough to you that you’d want to recreate it if it were taken away, even if that took 20 years.

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

MC: I’d say the combination of Niko Tinbergen’s “The Study of Instinct” and his 1963 paper “On aims and methods of Ethology” were both pretty influential to me, partly because they came at just the right time when I was leaving neurobiology for honey bee behavioral ecology. I was entranced by the idea that there are four different ways to study the same behavior (i.e., how does it work, how did it develop, what is it for, and how did it evolve). My early training heavily focused on the physiological aspects of behavior (or the “how does it work”), which felt unsatisfying to me. And so it was really exciting to learn that there are other approaches.

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

MC: I enjoy reading, swimming, cycling, cooking (and therefore eating), and traveling. The best times are the experiences that bring it all together. We have a 10 month old baby, so the cycling holidays that my husband and I enjoy are on hold, but we can’t wait until he’s old enough that he can join us cycling between beautiful places with delicious food.

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

MC: I mostly feel extremely grateful that I’m able to have the career that I do. There are times that I feel overwhelmed, that I’m not doing enough, and that I’m not nearly smart enough to pull off this career, but with a little one at home that I want to spend time with after work and on weekends, there is simply a limit to how much work I can do and how much worrying I can handle. So life and career keep each other in check, whether I like it or not!

Probably one recent challenging time was when we moved to Switzerland for 2 years and I found out just how abysmal I am at learning new languages. And without German AND French AND English, I was virtually unemployable in Bern. I had months of struggling with “who am I” if I am not a bee researcher. Eventually I found ways to stay active in science as an advisor to EFSA (European Food Safety Authority) on bee health across EU-member states. I also worked on analyzing human health data, looking at the non-compliance in HIV treatment in sub-Saharan Africa. Both of these felt like jobs, not careers, which was tough at first, but it allowed me to enjoy other things for a few years. And then, in 2016, I thought I’d try myself on the job market for one final season, and lo, I got my present position.

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

MC: Well of course top pick would be my family, especially as my husband has a Swiss army knife! But otherwise, I’d say my kindle to keep my brain active, some bubble wrap because it has been shown that keeping one’s hands busy reduces stress and the perception of wait time, and some sunscreen because I burn and freckle easily.

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

MC: I’d say it was my advisor Professor Francis Ratnieks. When I started in his lab, fresh from leaving a bird neurobiology program, I had no experience with honey bee research in any incarnation – from experimental design, to field work, to analysis, and writing. Francis is a very clear thinker and an exceptional scientist, able to turn small observations of “something interesting” into research projects. He also is good at bringing together a great team of people to work in his lab. This team always provided me with equal parts scientific inspiration, hilarity, and some excellent pranks.

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

MC: It’s just as important to know what you don’t find interesting as it is to know what you do. And be open to different opportunities in different places.

Digging in the deep: how does carbon dioxide affect communal nest building in ants?

A blog post highlighting the article by D. Römer, F. Halboth, M. Bollazzi and F. Roces in Insectes Sociaux

By Daniela Römer

Watch a nature documentary of the South American tropics and it’s almost a given you will see some columns of leaf-cutting ants, busily carrying leaves back to their nest. Aside from their photogenic foraging behaviour these ants are also known for having developed the ability of farming, a feat only humans and some termite species have achieved. Perhaps less well known to the public, but equally as impressive, are their underground nests. The ants use the freshly cut plant material as a substrate to grow a symbiotic fungus, which is very voluminous and therefore needs a lot of space. Adding to the space demands of their nests are the high number of ‘citizens’ a single leaf-cutting ant colony can have, sometimes reaching millions (Moreira et al. 2004a, b). When scientists want to make casts of the nests to discover the intricate network of their nest chambers and connecting tunnels, they need tons and tons of cement to fill the complete structure (Forti et al. 2017). And yet, the tiny single workers measure less than a centimetre and weigh only 5-25 mg. How do these little, autonomous units coordinate their digging effort with thousands of other small units so that these huge functional nest structures are created?

The answer to this question is a process known as ‘self-organization’. The tiny workers with their very limited view of the nest structure react to very simply cues of their immediate environment and so decide where and when to excavate (Deneubourg and Franks 1995).

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Worker of Acromyrmex lundii leaving a digging arena.       Photo: James Waters

Having encountered an underground environment to their liking, the workers dig with their mandibles into the earth and, as if it would be a piece of vegetation to harvest, ‘cut’ out little bits of soil, which they then discard outside of the nest. Digging is a strenuous process and a colony spends considerable energy excavating their nest. What the ants gain from such a herculean effort is a structure that offers the colony, and in the case of leaf-cutting ants, their symbiotic fungus (on whose survival colony success depends) an environment suitable for both.

Underground, the three main environmental factors are temperature, humidity and carbon dioxide. The latter is quite frequently mentioned in the media in connection with global warming, where even seemingly small increases in CO2 levels can lead to dramatic environmental changes. Subterranean ants are confronted with CO2 concentrations vastly exceeding atmospheric levels (currently ~0.04%), even very close to the soil surface. These levels increase even more with depth so that 5-6 meters underground ants encounter an environment with 6-7% CO2 (Kleineidam and Roces 2000; Bollazzi et al. 2012). At these high levels, the growth of the farmed fungus seems to be compromised (Kleineidam and Roces 2000), so that leaf-cutting ants should try to control carbon dioxide levels to ensure the best possible fungus harvest. A recent study showed that when given the choice, the leaf-cutting ant Acromyrmex lundii indeed avoids such high CO2 levels for fungus farming and, surprisingly, also atmospheric levels (Römer et al. 2017). Instead, it chose levels associated with soil strata close to the surface.

We therefore asked ourselves whether the ants also use the carbon dioxide concentration underground as a cue when they excavate their nests and examined this question by performing different experiments. In the first, we tested whether the ants’ digging activity and soil pellet transport was affected with increasing CO2 concentrations (from atmospheric values to 11%). In the second experiment, we evaluated what CO2 concentration workers prefer for nest digging, using a binary setup, offering atmospheric, shallow soil (1%) and deep soil (4%) CO2 concentrations.

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Digging arenas at end of  experiment 1. CO2 levels L to R: atmospheric, 4%, 11%.           Photo: Daniela Römer

Acromyrmex lundii is a species whose nest is usually characterized by having only superficial nest chambers. This is apparently not due to the inability of the ants to excavate under higher CO2 concentrations, as digging activity was comparable whether the ants excavated under atmospheric CO2 concentrations or levels of deeper nesting leaf-cutting ants. Only at 11%, a level so high that it was never measured around any leaf-cutting ant nest (Nielsen et al. 2003), the ants reduced their digging activity. Therefore, a negative effect of CO2 on digging activity does not seem to be the reason why this ant species only excavates superficial chambers. Soil pellet transport away from the digging site, on the other hand, increased when CO2 concentration underground increased. We do not know whether this was because ants were physically unable to excavate and therefore switched to soil carrying (masked at most CO2 levels by replacement workers) or whether ants ‘aimed’ to increase ventilation at the site by creating more open space. When creating a situation where workers could choose where they wanted to dig, they preferred superficial-soil CO2 levels and avoided levels of deeper soil strata. These choices help to explain the ants’ nesting biology.

One might therefore ask ‘Then why do other leaf-cutting ants excavate deep nests if the high CO2 concentrations there hinder the growth of their food source?’ The answer to this question might be a competition between the different environmental factors in the soil. Leaf-cutting ants should trade-off their microclimatic preferences to ensure the excavation of a suitable nest, but that is an experiment for another day

References

Bollazzi M, Forti LC, Roces F (2012) Ventilation of the giant nests of Atta leaf-cutting ants: Does underground circulating air enter the fungus chambers? Insectes Soc 59:487–498. doi: 10.1007/s00040-012-0243-9

Deneubourg JL, Franks NR (1995) Collective control without explicit coding: The case of communal nest excavation. J Insect Behav 8:417–432. doi: 10.1007/BF01995316

Forti LC, Protti de Andrade AP, Camargo R da S, et al (2017) Discovering the giant nest architecture of grass-cutting ants, Atta capiguara (Hymenoptera , Formicidae). Insects 8:39. doi: 10.20944/preprints201702.0027.v1

Kleineidam C, Roces F (2000) Carbon dioxide concentrations and nest ventilation in nests of the leaf-cutting ant Atta vollenweideri. Insectes Soc 47:241–248. doi: 10.1007/PL00001710

Moreira AA, Forti LC, Andrade APP, et al (2004a) Nest architecture of Atta laevigata (F . Smith , 1858) (Hymenoptera : Formicidae). Stud Neotrop Fauna Environ 39:109–116.

Moreira A, Forti L, Boaretto M, et al (2004b) External and internal structure of Atta bisphaerica Forel (Hymenoptera: Formicidae) nests. J Appl Entomol 128:204–211. doi: 10.1111/j.1439-0418.2004.00839.x

Nielsen MG, Christian K, Birkmose D (2003) Carbon dioxide concentrations in the nests of the mud-dwelling mangrove ant Polyrhachis sokolova Forel (Hymenoptera: Formicidae). Aust J Entomol 42:357–362. doi: 10.1046/j.1440-6055.2003.00372.x

Römer D, Bollazzi M, Roces F (2017) Carbon dioxide sensing in an obligate insect-fungus symbiosis: CO2 preferences of leaf-cutting ants to rear their mutualistic fungus. PLoS One 12:e0174597. doi: 10.1371/journal.pone.0174597