Ants can learn lots, fast

by Tomer Czaczkes

Based on research for the paper “T.J. Czaczkes and P. Kumar. In press. Very rapid multi-odour discrimination learning in the ant Lasius niger. Insectes Sociaux.”

Most people are shocked to hear that ants can learn. While the readers of this blog are probably not surprised by this, quite how good they are might come as a surprise – it certainly surprised me! In our recent study, Pragya Kumar and I found that Black Garden ants (Lasius niger) can learn at least two (most likely three) odour-sugar associations, having only experienced each combination twice. They can learn one association in just one visit.

A curious Lasius niger forager sporting a stylish blue gaster mark. Painting ants helps us follow our trained ant over multiple training visits.

The joys of comparative psychology:

Let’s unpack that: we were exploring discrimination learning, where the ant has to learn that one odour (e.g. rose) means very sweet sugar water, another (e.g. lemon) quite sweet, another (e.g. lavender) slightly sweet, and another (e.g. blackberry) just a teeny bit sweet. If the ant learns successfully, she should prefer rose to lemon, and lemon to lavender. They should never prefer blackberry when one of the other options is available. So, we let individually-marked ants up a bridge to find a drop of flavoured sugar, then let her go back to the nest, and when she came back for a second visit she found another drop with a different taste and a different sweetness. After she’s experienced each combination once or twice, we give her a choice on a Y-maze: for example, does she follow the arm which smells like lemon, or the arm which smells like lavender? By the way, the methods are all published in another Insectes Sociaux paper (Czaczkes, 2018). And if you have a 3D printer, you can print your own mazes too.

The 3D printer Y-maze we used, with added walls (not used in this experiment). Why not print yourself one?

Ants made mostly correct decisions, even if they only experienced each taste/quality combination once. Clever ants! So… why did I say that ants can learn “at least two” combinations? Well, we simply can’t be sure of more.

Consider our situation: Rose > lemon >  lavender >  blackberry. Firstly, they didn’t prefer lavender to blackberry. So, we’re down to three. Now, imagine that the ants never learned the second worst smell (lavender). What would her decisions look like? It would still prefer lemon > lavender, because lemon is better than nothing. So, we’re down to two we can be sure of. Now, we’re pretty sure they learned lavender, but we just couldn’t prove it in this setup!

This, to me, is the joy of comparative psychology – every experiment is like a logical puzzle, where evidence builds up, ruling out alternative explanations, until you run out of alternatives (or evidence). I admit, it’s hard work – or, at least, I find it hard. Sometimes I feel my brain creaking under the pressure. But it’s also very rewarding, when you’ve lined up your evidence, and can knock the alternatives out. Even finding the logical holes is fun, as happened in this experiment!

A lucky marked L. niger forager enjoying a drop of high quality sucrose solution. Yum!

Back to the ants   

So, L. niger ants can learn quite a lot, and fast. Why is that interesting? Firstly, it’s perhaps surprising, given how small their brains are. But enough e-ink has been spilled on this topic. More practically, this opens the door to performing complex training regimes and tests. A lot of psychological research involves asking the question: “which option do you prefer, A or B? How about C or D?”. Because we cannot simply ask animals, we have to train them to associate each option with a cue, and then see which they prefer. So, for example, we can ask if ants like to gamble by teaching them that lemon is a risky smell, but rose is a safe smell. Being able to quickly train ants to complex option sets can open the door to a much deeper understanding of how ants think, what they like, and how they make decisions.

References

Czaczkes T.J. 2018. Using T- and Y-mazes in myrmecology and elsewhere: a practival guide. Insectes Sociaux 65, 213-224

Simple behaviors – collective outcomes. How individuals affect group decisions.

By Stamatios Nicolis

Based on research for the paper “Nicolis, Pin, Calvo Martín, Planas-Sitjà and Deneubourg. In press. Sexual group composition and shelter geometry affect collective decision-making: the case of Periplaneta americana. Insectes Sociaux

Gregarious arthropods such as cockroaches, constitute the most widespread social species in the animal kingdom. Yet, as far as collective decision-making is concerned, most of the literature is focused on eusocial insects such as ants or termites, which are complex societies. In comparison, cockroaches of the species Periplaneta americana have (as far as we know) no division of labor. During the night, each individual of this species searches for food and during the day, the individuals are at rest. While the first activity is solitary, the second one is collective and implies interactions between individuals. Moreover, resting often happens in shelters that provide protection against predators and whose selection depends on their shape and/or their physical characteristics such as the level of darkness or the temperature.

The aim of the study was to look at the influence of the shape of the shelters and of the sexual composition of groups of individual cockroachesin the decision-making outcome, and to highlight the interactions at work. Despite their less sophisticated modes of communication, our objective was to demonstrate that some combinations of environmental and group-related factors could lead to different collective behaviors that are reminiscent to those observed in eusocial insects.

To do so, we performed lab experiments in which three different group compositions were faced with three different environments. Groups either constituted of 16 males, of 16 females or of 8 males and 8 females. As for the environments, the three different groups had to choose between two identical horizontal shelters where individuals can only settle on the floor of the shelters, two identical vertical ones where cockroaches can settle on the walls and the floor, or one vertical and one horizontal shelter.

Experimental set-up consisting of an arena and two dark shelters (a) along with an example of organization within a vertical (b) and a horizontal (c) shelter.

For the nine conditions we showed that the sheltering behavior implies different levels of interactions between individuals and therefore different levels of collective choices depending on the different group compositions tested. In particular, for the symmetrical geometrical conditions (two vertical and two horizontal shelters), the social inter-attraction between individuals in homogenous groups of males are weaker than the ones in homogenous groups of females or in heterogenous groups of males and females. Formulated differently, males have difficulty reaching consensus (all individuals within the same shelter), which is not the case for the groups of females or mixed-groups.

While it is known that these insects prefer to stand vertically, we expected to observe different collective choices between the two symmetrical (two horizontal or two vertical shelters) conditions, but we didn’t. Yet, in the asymmetrical case (one horizontal vs one vertical shelter), the choice towards the vertical shelter was clear for the three group compositions, although the homogenous groups of males and of females had a weaker selection than the mixed groups of males and females. This result may sound puzzling considering the results obtained for the symmetrical conditions, but could be explained by the fact that homogenous populations of males, while having weaker social interattractions between them (as compared to females), are counterbalanced by a higher preference for the vertical shelter. Conversely, females have stronger interattractions between them and a lower individual preference for the vertical shelter. As for the mixed groups, the strong male-female interattractions coupled with the vertical position preference for the males led to a stronger selection of the vertical shelter as compared to the homogenous groups.

Finally, in terms of internal organization within the vertical shelters, no sexual segregation was found to be at work. But we showed that the tendency to stand in the vertical part of the shelter is amplified with the sheltered population for groups of females and for mixed groups but is independent for groups of males.

The results obtained thanks to experiments in a simple device show that the coupling between individual responses to the environmental heterogeneities and the network of interactions between individuals can lead to a diversity of responses. While they contribute also to our understanding of how individuals of Periplaneta americana are interacting and how they collectively choose their resting place, the genericity of the mechanisms implied lead to the conviction that the phenomena presented are likely to be present in species presenting the same modes of organization.

Interview with a social insect scientist: Katja Kwaku

You can read Katja’s recent research article about leaf transfer behaviour in Atta cephalotes here.

IS: Who are you, and what do you do?

My name is Katja Kwaku and I am a Master’s student in the Biology department of Tufts University. I’m an ecologist; I’ve worked on a variety of projects, but I’m generally interested in behavioral ecology and global change biology.

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

I’ve been fascinated by animals and their behavior since I was little, but I only really became interested in social insects and leafcutter ants in particular in 2019 when I worked as an educator at the Montshire Museum of Science in Vermont. The Montshire has a colony of honey bees and a colony of leafcutter ants. The leafcutter ants constituted one of the museum’s most popular exhibits and visitors of all ages always asked great questions. Sometimes, I didn’t know the answer to a question, and moments like these inspired me to delve into the primary literature and start researching leafcutter ants.

Social insect researcher Katja Kwaku.

IS: What is your favorite social insect, and why?

Clearly, I am biased, but I have to go with leafcutter ants. There are so many strong interspecific interactions at play! Leafcutter ants have a mutualistic symbiotic relationship with the fungus they cultivate in their underground nests, they rely on bacteria in many ways to mediate this ant-fungus interaction, and they are voracious herbivores of many tree species. Also, they’re just so adorable when they’re carrying leaf fragments.

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

I’m relatively new to research, but I would say the best moment so far was witnessing leafcutter ants transfer leaf fragments to one another for the first time. My classmates and I had spent several months reading articles about leaf transfer and had finally travelled from Boston to Costa Rica to do a project about it, so it was such a relief seeing leaf transfer with my own eyes and knowing that the entire basis of our project wouldn’t fall through. It was also really exciting to see leafcutter ants transfer fragments directly to one another on tree trunks because leaf transfer in that context, to my knowledge, has not been explicitly documented before.

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

Yes! I am currently a teaching assistant and have served as an educator at various science museums in the past. I love highlighting the connections between my research and the material I’m teaching, even if they’re not directly related, because it shows how everything in science is connected and relays why I’m excited to teach the material and why I think it’s important.

Leafcutter ants on their foraging trail. Photo: Katja Kwaku

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

Some important research questions involve understanding how insects use specific cues to drive foraging decisions and communication. Understanding the mechanisms behind fundamental behaviors will give insight into how to best conserve insect species and associated ecosystem services such as pollination and decomposition.

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

One topic of debate relevant to social insect research is whether or not global insect decline or the “insect apocalypse” is actually happening. There is evidence of insect population declines in many areas, but there are so few insect monitoring programs around the world that we run into the issue of having insufficient data to make a generalized conclusive statement about it.

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

The last book I read was Silent Sparks: The Wonderous World of Fireflies by Tufts professor Sara Lewis. I would recommend it because it’s scientific in content but written like a novel, so it’s an interesting and easy read!

Katja Kwaku and her co-author Elena Gonick observing leafcutter ants in Costa Rica.

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

I love dancing and doing yoga. I also enjoy making videos with my family and friends.

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

Things often don’t go as planned in ecology, so I like to laugh about all the unexpected field work mishaps; they make great stories for later. I also like to reach out to and talk with friends and get exercise when things get tough.

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

I’m the cautious type, so my immediate instinct would be to bring first aid supplies! Otherwise, I would bring a hammock to relax in, binoculars to better enjoy the landscape and wildlife, and a notebook to document my experiences.

Leafcutter ant on an artificial foraging trail. Photo: Katja Kwaku

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

Dr. Colin Orians has been an excellent mentor and professor during my time as a Master’s student. He was always happy to spend lots of time with me discussing science, but ultimately encouraged me to make my own research decisions and let me think for myself.

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

Be patient, since insects don’t always cooperate with experiments right away. Also, if possible, try to send time outdoors observing wildlife outside of dedicated research hours. Your observations will remind you of insects’ magnificence and might inspire your next research question!

IS: What is your favorite place science has taken you?

This is such a hard question since every place is different and has its own positives. One of my favorite places is Long Point, Ontario, where I helped study the endangered Fowler’s toad population. The auditory experience of several frog species chorusing in addition to the sounds of birds and insects at night was enchanting.

Interview with a social insect scientist: Robin Southon

You can read Robin’s recent research article about female reproductive skew in Polistes wasps here.

Who are you, and what do you do?

Robin Southon, I did my PhD at the University of Bristol and was most recently a postdoc at University College London in the Sumner Lab. I’m an ethologist at heart, and a little bit fanatical about wasps. My current research focuses on the social evolution of wasps and their potential use in integrated pest management.

How did you develop an interest in your research?

Quite by luck. I was finishing a job in the US and about to return back to the UK but saw an urgent ad for an internship in Panama on Polistes paper wasps – a slight detour. The study site was an abandoned cold war era US military communications station. A surreal setting with nature slowly reclaiming dilapidated concrete structures, but a haven for wasps with hundreds of nests dotted between different rooms. It’s impossible not to fall in love with Polistes, watching a nest is like a soap opera, from the fall of a dominant queen and the ensuing chaos as sisters battle for power. I was hooked and had too many questions, so ended up doing a PhD to try and answer at least some of them.

What is your favorite social insect, and why?

A wasp I’ve not worked with yet and only seen museum specimens of, Polistes gigas. The males are remarkably larger than females and possess enormous mandibles for fighting. Males likely defend a territory around a nest from rivals. It’s rather unique morphology and behaviour in comparison to the leks and aggregations observed in males of other wasps. A hopeful future study.

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

The crux of my PhD was whether newly emerged males in the wasp Polistes lanio would help on their natal nests. Male helping behaviour in the Hymenoptera hadn’t received much attention in the literature, so it was a risk to base an entire thesis on. Arriving in Trinidad and locating my first nest with males, I fed one and he chewed up the food and shared it out to his siblings, which was a big relief. Looking back, I was also very lucky to have fed a young male first, as it turned out older males stop feeding nestmates. Repetition is key even in preliminary experiments.

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

In the past I’ve volunteered for two great organisations: Soapbox Science which promotes women in science and highlights STEM as a career path; Pint of Science in which researchers present a talk about their subject at a local pub or cafe to the general public, quite hectic but fun.

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

There’s an increasing number of publications that demonstrate the effectiveness of ants and social wasps as biocontrol agents. At the moment, discovering methods that promote existing natural populations to target pest species seems an achievable goal. But to unlock the full potential of these agents, in comparison to the domestication of the honeybee, we are a few thousand years behind. We are missing basic questions to advance this goal, such as knowledge on how to successfully maintain and breed such species in captivity.

Another cold war relic home to wasps – Trinidad

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

There has been a clawback on what we should describe as eusocial or a superorganism, and the same applies for terms such as primitively eusocial. In structure, how much difference is there between a Polistes paper wasp colony and a group of cooperatively breeding meerkats? Testing the limits of subordinate to reproductive transitions/successions within tropical totipotent species may be insightful, given that reproduction is not as strictly dictated by seasonality and mate availability in such environments.

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

Forest and Jungle by PT Barnum from 1900; found in an antiques shop. I would not recommend as it’s both very archaic in its scientific and cultural view of the natural world. A window into the past and thankful reminder of changes made.

Outside of science, what are your favorite activities, hobbies, or sports?

I’m a typical naturalist: travelling, hiking, and filling up my home freezer with more insect samples that I promise myself to one day pin.

How do you keep going when things get tough?

Misery loves company – grabbing a coffee with equally frustrated colleagues and listening to and hashing out ideas together has always helped.

If you were to go live on an uninhabited island and could only bring three things, what would you bring? Why? A machete and fire striker for survival, eppendorf tubes with RNAlater/ethanol for when my boss complains about where I’ve disappeared to.

Polybia nest – Trinidad

Who do you think has had the most considerable influence on your science career?

The ‘spark’ happened back in my childhood thanks to my grandfather. He lived out in the countryside and was a bit of an amateur zookeeper: horses, fish, owls, peacocks, attack geese, etc. When I visited, I would sit inside enclosures thinking about why animals behaved in certain ways and the interactions between them. Some things haven’t changed.

What advice would you give to someone hoping to be a social insect researcher in the future?

For undergraduates, reach out to labs that align with your interests. Research assistantships provide opportunities to get valuable experience, which can give you a head start in future postgrad studies. Also, a bee-suit is not necessarily a wasp-suit, Vespula are incredibly good at finding vulnerabilities.

What is your favorite place science has taken you?

Trinidad – astounding nature, excellent food, and an abundance of wasps. I met many people with the attitude of “if it doesn’t bother me, I don’t bother it” when it comes to wasps, and you can find all sorts of different species around the eaves of houses. I don’t know if it truly was an old motto or someone trying to amuse me, but I was once told having wasps around your house is a sign of good fortune, the symbolism being between wasps bringing back forage and people bringing back money to the home.

If you had unlimited funds to conduct whatever research you wanted, where would you go and what would you investigate?

My fantasy answer would be to use a large artificial self-contained biosphere to study the impact of environment on sociality. Actual tests of inclusive fitness are complex, but this would allow genetic and demographic data for each subsequent generation to be sampled for the entire population, whilst manipulating the climate, predation risk, and resource availability. I would hope funding also covers a control-biosphere…

Interview with a social insect scientist: Omar Urquizo

You can read Omar’s recent research article about reproductive and brood-rearing strategies in tree hoppers here.

IS: Who are you, and what do you do?

OU: My name is Omar N. Urquizo. I do research at the Chemical Ecology Laboratory of Universidad San Francisco Xavier in Chuquisaca, Bolivia in the field of the evolution of social insects in contexts of behavioral ecology and their interactions with plants, other insects, or arthropods.

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

OU: I felt much curiosity about arthropods in 2013 when I participated in a conference where two investigators presented their work on morphological diversity in bees and treehopper behaviouOU: So, I wanted to investigate and learn more about insect–plant interactions, and I decided to request admission as a student of the Chemical Ecology Laboratory. There, I started supporting research on treehopper vibrational communication in a mating context. I was really surprised because we could listen to signals (substrate-borne signals) that usually are not easy to perceive, thanks to bioacoustic tools. So, I learned about the phenomena of this group; one of them, brood parasitism, was reported in my first study. In treehoppers, there are different social levels during which we can observe awesome behaviours. I believe that we must get to know what we have around us, from the smallest and mimetic individual to the biggest and remarkable individual.

IS: What is your favorite social insect, and why?

OU: My favourite social insects are treehoppers, because within the Membracidae family the species display different strange forms and colours in their pronotum, being cryptic or aposematic depending on the species. But also, this group has peculiar behaviours during vibrational communication during mating, maternal care, and feeding search, which depend on the level of social organization of each species.

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

OU: I think that the best moment in my research was data collection because I learned several things about the natural history of Alchisme grossa; however, there are several biggest moments, like when we finally saw genetic results that allow us to open a discussion about intraspecific brood parasitism in treehoppers.

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

OU: I do not teach nor do outreach formally; however, I always share my knowledge with other students and researchers. I think that science communication is very important for displaying our work at different levels, be it a school, university, or simply individuals who enjoy and are surprised to know new things about nature. I am eager to incorporate my research into an educational video in an entertaining way.

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

OU: I think that an important question is: What are the mechanisms that lead to different levels of social organization, from community levels, through evolutionary or/and ecological contexts, to individual levels, such as physiological processes? I think that if we can understand all social interactions, we can make the best decisions when we face different problems with conservation, pest control, or natural resources.

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

OU: I feel that the research that has generated more intense debate is the evolutionary processes leading to social behaviours. In this area, it is not uncommon to discover new findings that change a way of thinking and strengthens or renews a postulate.

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

OU: In science,I am reading Evolutionary Analysis by F. Scott F, but the last book I read was Communities’ Ecology by F. Jaksic. But also, I was reading Moby Dick by Herman Melville, as recreational reading. I recommend these books because the former contain concepts and research explained in very practical ways, and the last book because it is an interesting study of character within an adventure of pirates and whales.

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

OU: My favourite activities outside of science are photography and music. I think they are both ways to capture and express beauty and to demonstrate and communicate your feelings in an artistic way. I also love skating.

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

OU: I am a religious person, and my faith and family are my principal support in difficult times; they provide me moments of calm and peace. But also, when things get tough, I tend to remain calm and maintain clarity to act or make the best decision. I also like to go out to the city to attract good vibes.

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

OU: I would take my family (is the most important to me), but if I only have to carry objects, I would carry a radio to communicate with them, a guitar, and a camera.

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

OU: Carlos Pinto, who has been an extraordinary mentor to me. He has taught me that science can be made anywhere – that you just need to believe you can do it.

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

OU: All research is valid, but it is best to work on a problem that really motivates you. And, of course, to put body and soul into your endeavours. In ecological research, observe each trait or behaviour mindfully with utmost patience. The insect world is small, but that makes it more fascinating, since we can analyse many processes. For example, studying large group behaviors is easier with insects than with big animals.

IS: What is your favorite place science has taken you?

OU: Outside Bolivia,I have only travelled to Santiago, Chile through science. There, I met very interesting researchers in many fields of science. Within Bolivia, several study trips have taken me to spectacular places.

IS: If you had unlimited funds to conduct whatever research you wanted, where would you go and what would you investigate?

OU: If I had unlimited funds, I would create a strong research university department in Sucre, Bolivia working in different areas of ecology. Within it, I would like to work in molecular ecology and evolution with native bees to describe interactions between species and other social behaviours.