insectessociaux

Hovering battles at the ant nest: the remarkable behavior of a rare ant parasitoid wasp

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By Satsuki Kajiwara

Satsuki is a PhD student in the Entomology Laboratory at Kyushu University, Japan, where she studies ant-associated parasitoid wasps. In this blog post, she shares her discovery of aerial fights between female Ogkosoma cremieri competing for access to ant larvae. Her lastest research in Insectes Sociaux can be read here.

Ant colonies, with their abundant resources and secure environments, are frequently exploited by various organisms that have evolved strategies to infiltrate and persist within them. These organisms, known as myrmecophiles, depend on ants for at least part of their life cycle.

The subfamily Hybrizontinae, which I am currently studying, represents a highly specialized group of parasitoid wasps that attack only ant larvae (Lachaud and Pérez- Lachaud 2012). Their known host ants belong to the genera Lasius (including the subgenera Lasius and Dendrolasius) and Myrmica. Notably, two species in the subgenus Dendrolasius exhibit unusual behavior: they transport their larvae between tree trunks and underground nests depending on the season (Kajiwara and Yamauchi 2023). Because Hybrizontinae wasps parasitize larvae during these transport events, the timing of larval movement is critical for their reproductive success (Komatsu and Konishi 2010).

Females of this subfamily oviposit by inserting their ovipositor into larvae being carried by worker ants—an opportunity that occurs only during the brief moments when larvae are exposed outside the nest.

Two basic host-searching strategies are known: (1) hovering near ant nest entrance and (2) ambushing along ant trails by clinging to vegetation.

Two host-searching strategies observed in the subfamily Hybrizontinae.

While surveying ant parasitoid wasps on my university campus in Japan, I was fortunate to discover a hovering female of Ogkosoma cremieri (Romand) near a nest of Lasius capitatus (Kuznetsov-Ugamsky). This unexpected encounter became the starting point for a more detailed behavioral study.

An adult female of Ogkosoma cremieri hovering in front of the nest of Lasius capitatus

Although earlier researchers reported hovering behavior in this species, they did not identify the specific time of day when it occurs. My observations revealed that females hover between 06:30 and 17:00, indicating sustained activity throughout the daytime.

One day I witnessed something remarkable. A female O. cremieri hovered at the nest entrance and approached larvae being carried by workers. When several females were present, they sometimes engaged in aerial jostling: the wasp positioned in front of the nest (red arrow in the image below) drove off an approaching female (yellow arrow) by pushing her while hovering. The displaced wasp was then attacked by ants and dragged into the nest, showing how dangerous it can be for wasps to approach ant brood. Aggressive competition between parasitoid females has been observed before in other ichneumonids, but usually on the ground or on plants — witnessing physical pushing while hovering appears to be a novel behaviour.

Aerial struggle between two female O. cremieri hovering at a Lasius capitatus nest entrance, where competition for host larvae can escalate into ant attacks. A, two females(yellow and red arrows) hovering in front of a Lasius capitatus nest; B, the female positioned in front of the nest (red arrow) attacked the approaching female (yellow arrow); C, the approaching female (yellow arrow) was pushed away by the female in front of the nest (red arrow), and the pushed-aside female (yellow arrow) was attacked by ants.

Interestingly, L. capitatus workers transport large numbers of larvae from tree trunks into underground nests at night. However, no oviposition behavior by O. cremieri toward these larvae was observed. This pattern suggests that nocturnal larval transport may serve as an adaptive strategy by ants to avoid parasitoid attacks. Consistent with this interpretation, my observations also suggest that O. cremieri is not a nocturnal species. Females became active at night only when the area was illuminated with a flashlight or headlamp—likely a response to artificial light rather than natural nocturnal activity.

Future comparative studies across genera may reveal how morphological traits and behavioral strategies have diversified within this intriguing group of parasitoids.


References:

Kajiwara S, Yamauchi T (2023) Larval transport by adults of Lasius morisitai (Hymenoptera: Formicidae): The season and the time of day. Nat Environ Sci Res 36:15–17 [in Japanese]. https://doi.org/10.32280/nesr.36.0_15

Kajiwara, S., Yamauchi, T. Parasitoidic strategy of Ogkosoma cremieri (Hymenoptera: Ichneumonidae: Hybrizontinae) against Lasius capitatus (Hymenoptera: Formicidae). Insectes Sociaux (2025). https://doi.org/10.1007/s00040-025-01072-8

Komatsu T, Konishi K (2010) Parasitic behaviors of two ant parasitoid wasps (Ichneumonidae: Hybrizontinae). Sociobiology 56(3):575–584

Lachaud J-P, Pérez-Lachaud G (2012) Diversity of species and behavior of hymenopteran parasitoids of ants: A review. Psyche2012:134746. https://doi.org/10.1155/2012/134746

Interview with a social insect scientist: Stefano Cavallo

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Stefano is a biologist specializing in animal behavior and currently works as a research fellow in behavioral ecology at the University of Florence. In this interview, he recalls moment he realized that even ants show individual personalities. His lastest research in Insectes Sociaux can be read here.

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

I’m Stefano Cavallo, a passionate biologist specialized in animal behaviour. I’m living in Pisa and currently work at the University of Florence as a research fellow in behavioural ecology. My interests range from communication and cognitive aspects of animal behaviour in invertebrates and beyond. At the moment, my project focuses on exploring phenotypic plasticity—particularly behavioural plasticity—in marine decapods.

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

Since I was a child, I’ve always been passionate about animals. Although I grew up in a city, I had the chance to keep and observe a variety of species—fish, amphibians, reptiles, birds, mammals, and of course, insects. Among them, social insects, and especially ants, have always fascinated me. Their remarkable social organization combined with apparent simplicity sparked both curiosity and deep biological admiration in me. As my studies in biology progressed, I developed a strong interest in behavioral biology. What I find most stimulating is the possibility of identifying similar behavioral patterns in evolutionarily distant species, both human and non-human.

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

It’s hard to choose just one. I’m fascinated by social insects for very different reasons: for instance, the interspecific relationships of Atta ants, the communicative flight and cognitive abilities of Apis mellifera, and the complex social structure of Polistes dominula all capture my interest. What I find most stimulating is not a single species, but rather those organisms capable of challenging the “dogmas” of biology. For example, the recent discovery by Juvé et al. (2025) on Messor ibericus which destroy species definitions.

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

One of the best moments in my research was when I first realized that even ants—creatures we often think of as identical and mechanical—show individual personalities. That realization was unforgettable: it felt like discovering a hidden layer of complexity within a familiar world. From that moment on, I stopped seeing colonies as uniform units and started seeing them as societies of individuals.

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

No, at the moment I don’t deal with these aspects but in the future I hope it can become part of my job as a scientist. I think it is important to disseminate scientific advances to a wide audience and shorten the distances between laboratories, research and the general public.

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

As we know, the environment today is subject to strong anthropogenic pressures and global warming is shaping habitats very quickly. The effects on social insects are still poorly understood. I believe it is essential to focus on these aspects and understand how changing conditions act on the biology and behavior of social insects.

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

I love being in nature, trekking in the mountains, climbing, swimming and snorkelling

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

The last book I read was Entangled Life: How Fungi Make Our Worlds, Change Our Minds and Shape Our Futures by Merlin Sheldrake. I would definitely recommend it—it’s a fascinating and beautifully written synthesis of what we know about fungi. These organisms are extraordinary in the way they challenge traditional paradigms of biology and reveal how deeply interconnected life really is.

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

I practice tai-chi and mindfulness techniques to stay in the present moment and focus on beautiful things.

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

I would bring a knife, a tinderbox and a book on edible plants. These three things would help me get food, be able to cook and warm up and not die of intoxication haha!

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

I believe that the most important role was played by two high school teachers. My chemistry professor and biology professor taught me scientific rigor and wonder at the living world

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

If I had to advise someone to hop to be a social insect researcher, I would tell them to follow the thirst for knowledge and not stop at appearances. I would ask him to always look with a critical eye at those who claim to have absolute certainties in biology.

IS: Has learning from a mistake ever led you to success?

I couldn’t point to a specific mistake, but I believe that in private life and at work we often learn by falling and making mistakes. Trying by trial and error: this is generally just how we manage to grow.

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

My favourite place where science took me is Paris, in the experimental and comparative ethology laboratory of the Sorbonne University in northern Paris. I was lucky enough to work in the group led by Professor Patrizia d’Ettore who with dedicated passion dedicates herself to research in the myrmecological field.

How does a caterpillar use its tentacles to get the attention of ants?

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By Amalia Ceballos-González

In this blog, Amalia from the University of São Paulo tells the story of how she and her colleagues studied a strange functional behaviour in a myrmecophilous riodinid caterpillar. Read her latest article in Insectes Sociaux here.

Caterpillars that establish close interactions with ants have developed various adaptations to maintain the ants’ attention. These adaptations involves specialized organs that produce nutritional rewards or chemical signals to attract ants. The butterfly families Lycaenidae and Riodinidae provide many examples of myrmecophilous caterpillars, including species with these organs. In our recent study, published in Insectes Sociaux, we explored the impact of these specialized organs on ants by focusing on a species from the less-studied family Riodinidae, Synargis calyce, which interacts with various ant species. In our study area, the most frequent interaction involved the ant species Camponotus crassus.

Caterpillars of Synargis calyce interacting with different ant species. (a) With Camponotus crassus, (b) with Camponotus renggeri, (c) with Wasmannia auropunctata, and (d) with Paratrechina longicornis. ©Amalia V. Ceballos-González.

Caterpillars of this species possess two pairs of tentacular organs. The first pair, known as ATOs (Anterior Tentacle Organs), likely release volatiles that influence ant behavior, although there is insufficient evidence to confirm this. The second pair, known as TNOs (Tentacle Nectary Organs), secrete a nutritive substance (primarily composed by sugars and amino acids) that ants consume. Whether these organs work synergically or if one is more relevant than the other was still unclear for our study species and it is also the case for many other species of the family Riodinidae.

Illustration showing the position of the tentacular organs (TNOs and ATOs)  in a caterpillar of the Riodinidae family. Below, a photograph of Synargis calyce indicates the two pairs of tentacular organs with arrows (Yellow = ATOs, Blue = TNOs). Drawing adapted from DeVries (1991). ©Amalia V. Ceballos-González.

To uncover those aspects, we aimed to explore this pair of tentacular organs by checking ants’ reaction. Our research was conducted at the University of São Paulo, Ribeirão Preto campus. Our first objective was to create an ethogram documenting the behavioral interactions between caterpillars and ants. During these observations, we identified a striking behavior. The ethogram revealed that after the eversion of ATOs, ants exhibited stereotyped “jumping” behavior. This behavior involved ants rapidly lifting their legs and jumping towards the caterpillar’s head.

 Synargis calyce caterpillar interacting with a Camponotus ant.

Next, we conducted experiments in which we experimentally manipulated – by allowing or preventing them to evert – the two types of caterpillar organs (TNOs and ATOs), to determine their role in maintaining ant attendance. Our findings demonstrated that TNOs are more effective in maintaining the attention of attendant ants, likely due to the rewards these organs provide. However, we also found that caterpillars with only functional ATOs received more attention compared to those with neither organ functioning. This indicates that TNOs play a central role in sustaining ant-caterpillar interactions, while ATOs serve a complementary function.

Three caterpillars (possibly third instar) interacting with Camponotus ants.

In conclusion, the interactions between S. calyce caterpillars and attendant ants are primarily driven by the rewards produced by TNOs, with ATOs playing a smaller, supportive role. These findings are consistent with observations in Lycaenidae species, which exhibit similar mutually beneficial relationships with ants. The evolution of these organs may represent a case of convergent adaptation to environmental pressures experienced by caterpillars in both families.

Viruses of eusocial insects: high and underestimated diversity

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By Anna Zueva

In this blog, Anna Zueva, researcher at the A.N. Severtsov Institute of Ecology and Evolution (Moscow), reveals the hidden world of viruses in eusocial insects. Read her latest article in Insectes Sociaux here.

Eusocial insects are a kind of human society in miniature. Each part of the community has its own functions and features. The system of social insects’ family works as a coherent and well-coordinated mechanism, and the life of each individual strongly depends on the life of the whole complex.

The functioning of even a fine-tuned system can be disrupted. For example, in the history of mankind there are known episodes when whole civilizations suffered from local epidemics and even pandemics caused by microscopic entities – viruses. But is that the case for social insects?

Our work started from our interest in viruses of invertebrates. Tropics are especially promising for us, as this region is known for its great biodiversity and has lots of still unknown biological species, including of course microorganisms and viruses.

We started our investigation with the research on viruses of termites of Cát Tiên National Park – a part of the Đồng Nai Biosphere Reserve (Fig. 1). We are grateful to the South branch of the Joint Russian-Vietnamese Tropical Research and Technological Center for invaluable help in our studies.

Figure 1. A gap in the tropical monsoon forest of Cát Tiên National Park (Vietnam). ©Anna Zueva

We took samples of termites of three different species feeding on different substrates – lichens and fungi – as we expected that food resource can affect the composition of viruses associated with insects (Fig. 2, 3).

Figure 2. One of the studied species of termites, Hospitalitermes bicolor (Haviland) feeding on lichens. ©Alexei Tiunov
Figure 3. A small termitarium. ©Andrey Zuev

Thought we did not observed any visible symptoms of infection, we detected four new viruses related to viruses previously discovered in termites. We also found the evidence of presence of virus probably belonging to termites’ food substrate (Litov et al. 2022), which partly support our suggestion about the effect of feeding type on the insect virome.

Potentially, eusocial insects can be a model for studying the spread of viruses via social interactions. In the recently published review (Zueva et al 2024), we aimed to actualize the information on the diversity of viruses associated with termites and ants, which are among the most functionally important soil invertebrates. In our review we analyzed 93 articles dedicated to viral findings in both groups of insects. To date, viruses were detected in 54 ant species and in 28 species of termites. We have pointed out 270 viruses and viral genetic variants detected in soil-dwelling social insects, and less than one third of them were associated with termites (Fig. 4). It is obvious that the virome of termites is still mostly undescribed. In addition, both for ants and termites, the information on symptoms or on replication of viruses in their insect hosts remains strongly limited. More studies of the virome of soil-dwelling eusocial organisms with more attention to viral replication and infection symptoms are needed (Zueva et al. 2024).

The most amazing is, that despite the presence of numerous potentially harmful viruses and intense interactions between individuals within a colony, evidences of massive viral epidemics in termites are virtually unknown. We found the information only about one possible virus-caused termite family extinction (Chouvenc et al. 2013). This is especially surprising since termites are important pests of human structures and agriculture, and the search for viruses that infect them has been ongoing for a long time.

Figure 4. Visualization of the presence of viruses in ants and termites (based on Zueva et al. 2024).

There are numerous other unsolved questions on the virome of social insects. How many more viruses of eusocial insects we still don’t know about? Are they able to cause acute dangerous infections or are they just present in the insect tissues and do not manifest themselves until the immune system of host is critically compromised?

We are planning to continue our work in tropics, both on social insects and beyond them. We are sure that this region is a great source of new virological investigations, both on social and solitary invertebrates. By the way, a recent research of our team revealed at least eight new viruses in millipedes collected in the Cat Tien National Park (Litov et al. 2024).

References:

Chouvenc T, Mullins AJ, Efstathion CA, Su NY (2013) Virus-like symptoms in a termite (Isoptera: Kalotermitidae) field colony. Florida Entomologist 96(4):1612–1614. https://doi.org/10.1653/024.096.0450

Litov A.G., Semenyuk I.I., Belova O.A., Polienko A.E., Thinh N.V., Karganova G.G., Tiunov A.V. (2024) Extensive diversity of viruses in millipedes collected in the Dong Nai Biosphere Reserve (Vietnam). Viruses, 16: 1486. https://doi.org/10.3390/v16091486.

Litov AG, Zueva AI, Tiunov AV, Van Thinh N, Belyaeva NV, Karganova GG (2022) Virome of Three Termite Species from Southern Vietnam. Viruses 14(5):860. https://doi.org/10.3390/v14050860

Zueva AI, Zuev AG, Litov AG, Karganova GG, Tiunov AV (2024). Viruses of ants and termites: a review. Insectes Sociaux, 1-12. https://doi.org/10.1007/s00040-024-01008-8

Interview with a social insect scientist: Tom Ratz

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Tom Ratz is a researcher at the University of Zurich, studying social interactions in arthropods like Drosophila and beetles. One of his most surprising discoveries came during his PhD while observing burying beetle mothers. Check out his latest work in Insectes Sociaux here!

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

I am an SNSF Ambizione Fellow based at the Department of Evolutionary biology and Environmental Studies, University of Zurich, Switzerland. My research broadly explores social interactions in arthropods and their role in evolution. My current focus is on agonistic interactions in the highly aggressive species of fruit fly Drosophila prolongata. My group uses a combination of behavioural experiments, quantitative genetic tools, and experimental evolution to test how the competitive environment shapes the evolution of social and non-social traits. 

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

My fascination with the insect world began early, around the age of eight, when I started collecting beetles in the backyard of my house. I was captivated by the hidden, bustling world of insects happening all around us, often unnoticed. I wanted to pursue a career in entomology and enrolled in a biology degree. During my studies, I found myself particularly drawn to ethology and behavioural ecology. Applying these fields to insects felt like an exciting way to maintain a connection to entomology while exploring broader scientific questions about behaviour and ecology.

Aggressive encounter between two male Drosophila prolongata. In the first image (left), one male chases the other, leading to an escalation into a fight involving leg fencing (right).

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

Burying beetles are my favourite social insects. I studied them during my PhD and still find their social behaviour incredibly enigmatic–most of which takes place on or inside the decaying carcass of a vertebrate! In a sense, what is a crypt to some is a cradle for burying beetles. Aside from their important ecological role as efficient buriers of small rodent and bird corpses, the complexity of their social interactions within family is, to me, unparalleled in the arthropod world. These behaviours include larvae begging for food and parents regurgitating a “soup” of pre-digested carcass flesh to feed them. Conveniently, burying beetles are mostly undisturbed by experimental conditions, making their behaviour relatively easy to observe and study in the lab.

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

A memorable discovery was analysing the data of my first PhD experiment and finding that they absolutely defied our initial predictions. Contrary to expectations, burying beetle mothers didn’t reduce care when experimentally handicapped by a led weight attached to them –instead, they provided more care. At first, this result was puzzling to me, but it became a revelation about the importance of understanding a species’ natural history. It makes sense for a parent to increase investment towards the current brood when prospects for future reproduction are low, which is the case with handicapping, even if the cost of care is higher. This insight highlighted a crucial lesson: while theoretical predictions are valuable, they must be contextualised within the specific biology of the study system.

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

In both teaching and science communication I try to incorporate my own research as case studies to illustrate key concepts and bring scientific research to life. I find that people are more engaged when they can interact directly with the researchers behind the studies.

Lab stock and experimental populations of the fruit fly Drosophila prolongata

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

In my opinion, some critical questions in the field include clarifying the role of social behaviour in shaping population dynamics and evolutionary responses. It is increasingly clear that social interactions within a group can drastically influence the population growth, survival, and how animals respond and adapt to environmental changes. However, what remains less understood is when and to what extend behavioural dynamics taking place among interacting individuals can impact group fitness and drive long-term phenotypic evolution.

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

One of my top hobbies is spending time outdoors. I’ve been fortunate to live near beautiful natural landscapes and mountains, which has allowed me to enjoy hiking throughout the year. It’s a great way to clear the mind and recharge. I’m also a regular at the bouldering gym. And of course, entomology remains an important hobby of mine.

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

The book “In search of us: adventures in anthropology” by Lucy Moore, and I highly recommend it. It’s a fascinating account of the origins of anthropology, told through the stories of people who helped found the discipline. It’s rich in field work and historical anecdotes. The author does a nice job of highlighting the complexities of the influential figures in the field–acknowledging both their biases as Westerners and their progressive ideas ahead of their time.

Burying beetles parents feeding their larvae.

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

Talking things through with colleagues, friend, or family often helps. While it may not directly solve the problem, verbalising it can normalise the issue and make it feel less dramatic (which it often is). Sometimes, simply going for a walk works wonders–a change of scenery can help put things into perspective.

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

If it can count as one item, I’d bring my partner with me. She’s incredibly resourceful and crafty, and would surely be a great survival companion (as she is in life!). I’d make sure she brings her Swiss army knife, so that’s item number two covered. And obviously a tube to collect beetles as my third item.

Tom, collecting beetles in Greece

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

My PhD supervisor, Per Smiseth, has been a major influence on my scientific career. He’s a mentor with exceptional work ethics. Another key figure was Sylvain Pincebourde, who took me as an intern in his lab when I just a first-year undergraduate. That was my very first  real research experience, and was incredibly formative. I also owe a great deal to many other mentors and colleagues who have had an important role in shaping my interest and career in Science, including Joël Meunier, Pierre-Olivier Montiglio, Niels Dingemanse, Cristina Tuni, Stefan Lüpold, and Wolf Blanckenhorn.

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

A general piece of advice, not just for someone interested in social insects, is to focus on work you’re passionate about and truly enjoy. With genuine interest and motivation, nearly everything seems to become achievable.

IS: Has learning from a mistake ever led you to success?

Yes! And, sadly, the most painful mistakes are often the ones that teach us the most.

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

The tropical forests of Panama are a favourite of mine. I also have a soft spot for Mediterranean ecosystems. Despite their dryness, I’m always surprised by their abundance and diversity of plants and animals.

Ants and their commensals: The intriguing presence of other groups in ant nests

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By Mariane Dias-Soares and Cléa S. F. Mariano

In this blog, Mariane Dias-Soares and Cléa Mariano explore the diverse organisms cohabiting ant nests in the Neotropics, from gastropods to myriapods. They explain how do these guests interact with ants, sharing resources and space within the nest environment. Discover more about these intriguing interactions in their latest work for Insectes Sociaux, here.

What attracts these other groups? What are these groups? Are there really gastropods inside ant nests? What are commensals? Do ants benefit from their presence? Why aren’t they expelled? These are some of the most frequent questions when the topic of conversation is our research and our article. Let’s now address each of these questions, the work done so far, and the next steps toward the discoveries that researching an ant nest provides us…

The ant nests provide a protected environment for the workers, the queen, and all of their immatures, as well as storing food and maintaining stable temperature and humidity. When studying these nests, the presence of other groups was observed, which, attracted by these resources, coexist with the ants. These groups may spend part of their life cycle inside the nests or even their entire existence.

Gastropod near the immatures of N. verenae. Photo: Laís Bomfim

Our research aims to identify which groups are associated with different ant species in a Neotropical region. In my master’s studies, I focused on the species Neoponera verenae, an ant from the subfamily Ponerinae that nests in various substrates such as dry cocoa pods, soil, and decomposing logs. In our study, we found a variety of groups, including Myriapoda, Isopoda, Araneae, Lepidoptera, Pseudoscorpiones, Collembola, Acari, Coleoptera, Diptera, Dermaptera, and Gastropoda, among others. This highlights the great diversity of organisms that coexist within these ant nests.

Caterpillar in a N. verenae nest near workers and immatures. Photo: Mariane Dias-Soares]
Researchers during new field collections in the Neotropical Region of Brazil. Photo: Mariane Dias-Soares

Noticing the high number of groups within the ant nests sparked in us the need not only to identify which groups inhabit them but also to understand the interactions that occur in these environments. In our article, we studied the facultative commensalism of gastropods in N. verenae nests, presenting novel records and proposing hypotheses about this type of interaction.

There are different types of interactions between ants and gastropods. In the case of facultative commensalism, the gastropods coexist peacefully with the ants, benefiting from the protection provided by the colony, the available food, and the environmental stability, while also being found outside the nests. For the ants, however, we did not observe any apparent benefit or loss. Further research will delve deeper into these issues.

Gastropods recorded inside N. verenae ant nests. (yellow arrows indicate immatures, and orange arrows indicate snails). Photos from the article by Dias-Soares et al. (2024)

Through various observations and records made in the field and laboratory, we found the presence of several gastropod species inside the ant nests. Among the gastropods found, the family Achatinidae was the most abundant. These gastropods coexisted harmoniously with the workers and the young individuals in the nest (larvae, pupae, and eggs), moving freely without being disturbed by the ants. We also observed that the gastropods produced a foam, which generated a pacifying effect that prevented their expulsion from the nests. This is one of the strategies used by these organisms to inhabit ant nests.

Our study presents novel records of the interaction between ants and gastropods, leading us to explore various unresolved questions. One of these questions is the degree of interaction between immature ants and gastropods, as we found individuals in the chambers that contained the immatures. Additionally, we are investigating the chemical nature of the mucus involved in these interactions and identifying the new species of gastropods found in the nests, in collaboration with Dr. Sthefane D’ávila. Ongoing studies focus on analyzing the chemical strategies used, the morphological adaptations and behaviors exhibited, and the existence of mimicry within these nests. There is still much to be discovered in the vast world that is an ant nest…

Some members of the research team currently conducting collections for the new phase of the Project. from left to right: Fred da Silva, Mariane Dias-Soares and Jossiane Dias
Part of the research group led by Cléa Mariano and Jacques Delabie, focusing on studies of various ant species and other groups present in ant nests

Interview with a social insect scientist: Tomer Czaczkes

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Tommy is a researcher at the University of Regensburg, where he leads the ACElab since 2016. He study value perception and decision-making in invertebrates (mostly ants). His latest work in Insectes Sociaux can be found here.

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

My name is Tomer (Tommy, please) Czaczkes, and I study the behaviour of mostly ants, sometimes bees, and very occasionally other arthropods. My current focus is on comparative psychology – understanding how animals think, learn, and make decisions. I’m trying to apply our hard-earned knowledge of behavioural ecology to controlling invasive ants. I also dabble in collective behaviour.

Tommy Czaczkes thinking about Lasius fuliginosus.

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

Ah, well. During my undergraduate the average grades for different modules were available, and I noted that while cell biology and microbiology had pretty low average grades, behaviour and ecology had quite high ones. I know which side of the bread is buttered, and, honestly, I never expected to stay in research. Then, during my undergraduate project, I realized that while the miserable vertebrate ecology people would have to trek for hours through the forest to sight their animal, I, as an experimental behavioural ecologist working on ants, could collect 50 datapoints in half a day, while drinking rum.

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

Oooh, a tough question! I’m torn between two ant species: Lasius niger and Pheidole oxyops. L. niger is perhaps the most common ant in Europe, and as my PhD supervisor Francis Ratnieks always says “it’s the common animals that are most interesting. They’re clearly doing something right.”. L. niger are extremely smart, polite, helpful, and make excellent colleagues. P. oxyops, however, do wonderful cooperative transport – the collective carrying of loads. They have an amazing, explosive recruitment behaviour, and love cheese. They’re also extremely common, but alas, in Brazil and not in Germany, where I’m based.

Pheidole oxyops carrying a 10x10mm square of choose by the corners (published in Insectes Sociaux).

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

Seeing ants being visibly disappointed when they received food which was poorer than what they were expecting – poor things! It was clear from the moment I did the first pilot on that project that we would have a clear and strong effect. It was memorable because it was simply so easy to relate to: the disappointed ants would check the food, break away, try again to make sure, and circle around looking for the good stuff they were sure was there before. It was simply so cute and relatable.

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

I enjoy going into schools and kindergartens, to talk to kids about ants and insects in general. It’s always fun to bring an ant colony or two, and show the “mama ant” and her babies. For the bigger kids, it’s fun to do a pheromone following assay – makes me feel like an ant whisperer, who can use my super science powers to talk to insects.

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

This is showing my own biases here, but I think the question of insect sentience and intelligence is a huge question, and social insects are central to the experimental examination of these topics. We’ve had a slew of high impact work reporting all sorts of impressive cognitive abilities, with a big swing from behaviourism to cognition. I expect that very soon the swing will move the other way again, with people starting to push for simpler explanations, or attempting replication studies. Animal behaviour as a subject is overdue a big replication study, the likes of which shook up the worlds of experimental psychology and cancer research (amongst others) recently. I have attempted to replicate some of my own work, with some things replicating wonderfully, and others simply not there next time I looked. And yes, I publish the failed replications too.

Lasius niger worker who is very satisfied with her drop of sucrose solution.

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

I really enjoy hiking in the mountains, when I can get out. When not, I’m a big fan of sci-fi books and computer games. My mind is still somewhat blown by my VR set.

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

I’m almost through “Delusions of Gender” by Cordelia Fine. The book speaks against the supposed ‘evidence’ for a simplistic biological basis for gender roles. Would I recommend it? It’s convincing and helpful, but sometimes feels like being bludgeoned with an endless series of (reasonable) criticisms of studies. It’s well researched and useful, but perhaps not the page turner it could have been.

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

Give up! No, really. On days where I can’t focus, I simply stop working. If an experiment runs into wall after wall, I’ll drop it. But for things like rejections, failures, etc – I take the long view, and remind myself that this is normal, and this too shall pass. Oh, and moaning. Moaning helps.

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

Assuming my basic survival needs were met? My ebook stuffed with books (for entertainment), a solar charger to charge it, and a Swiss army knife to bootstrap other tools from. I think I’ve played too much Minecraft.

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

Certainly my Doctoral supervisor, Prof. Francis Ratnieks. He has an absolutely excellent eye for interesting biology. Moreover, I admire (and have tried to emulate) his quick, cheap, and cheerful approach to research projects – avoiding the huge, long term, ultra-high tech projects, and preferring short, fun, and simple projects which require only some ants, a few strips of paper, and some drops of sucrose. And a good idea, of course.

In this experiment, Tommy’s team was testing whether ants prefer food they have worked harder for (they do). A good example of their experimental designs. Note the Lego, paper runways, and complete lack of high tech gubbins.

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

Read “The Ants” by Hölldobler and Wilson. Yes, it’s almost 35 years old, but it’s a wonderful primer to most of the major topics in social insect biology. I read it cover to cover to prepare for my PhD, and that knowledge has stood me in good stead since then.

IS: Has learning from a mistake ever led you to success?

Not nearly as much as I would have hoped. I seem doomed to making the same mistakes over and over again. However, at least by now I recognise them with absolute clarity in hindsight.

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

The La Selva biological field station in Costa Rica, where I did my Bachelors project (on leaf cutter ants). Being surrounded by researchers for the first time, in a beautiful jungle, with amazing animals, was life changing. I also met my future wife there, so that was a nice bonus.

Networks and ants: how do ants maintain connections?

/ Damien Gergonne / Leave a comment

By Balint Kovács

In this blog, Balint Kovács, who is an assistant Research Fellow at the HUN-REN-PE Evolutionary Ecology Research Group, explains how social networks in ant colonies are structured and influenced by different castes. His latest work in Social Insects can be read here.

How do the animals maintain connections? What do these connections look like? What shapes them? These are the basic questions posed by a generalist network scientist. When we talk about social animals, sooner or later, we arrive at the ant colonies. Ants are famously and extremely social, and many tales and stories highlight their industriousness and diligence. But what are the real facts? How can we describe these communities scientifically? My passion for social animals led me to investigate this question during my research work and PhD studies. I researched multiple animal species in the context of social networks, and of course, ants had to be one of them. Let’s see what we found in our observations.

In human societies, different jobs and workplaces create different microcultures and behavior patterns. But what about ants? Do different work tasks (castes) create different roles for individuals? If we look closely at these castes, what will we find?

Our research used a previously published paper (Mersch et al., 2013) about carpenter ants (Camponotus fellah). In this research, three main castes were defined:

Nurses: individuals who spend most of their time near the core of the nest. These workers guard and take care of the eggs.

Foragers: these individuals are responsible for gathering food. Most of the time, they search for resources for the colony.

Cleaners: their responsibility is to clean the nest and maintain tunnels. So, we have castes and queens. Now, we need to examine their connections. Mersch et al. tagged and tracked all individuals for approximately a month in six colonies of these ants to detect interactions among individuals. More specifically, they observed when two individuals touched each other with their antennas. We used these interactions to create networks. In these networks, or graphs, the nodes were the individuals, and the edges represented the interactions. So, we have nodes (ant individuals) and edges (interactions between them). With this information for each day, we can model networks for each day as well. A whole network for six colonies in one day looks like this:

Too many edges, too many nodes. Quite chaotic. Our idea was to model networks only for castes.

Nurses:

Foragers:

Cleaners:

Okay. Now we had networks for each colony, each day, and each caste. Almost done. But we had another idea as well: What about the queens? What if the individuals’ networks looked different when they interacted directly with the queen? To investigate this question, we modeled another two types of networks: Queen-related and No Queen-related networks. To distinguish these additional “castes” of individuals, we called the subnetworks.

Queen-related:

No Queen-related:

Now we had all that we wanted: interactions, castes, and subnetworks. The last step was to compare these networks to each other to see the basic differences between networks and, therefore, the differences in behavior among these worker groups.

But how is this possible? Visually, we can see some differences, but we need to prove it. In network studies, we use network indices to describe network properties. Every index tells something about the group we modeled. Multiple indices are available in the literature; here we used three basic indices: Network Centralization Index (NCI), Clustering Coefficient (CC), Average Path Length (APL), and Small-World Index (SW). NCI gives the hierarchical properties of a group, CC is an indicator of the rates of cliques within the group, APL calculates the average “step” (network edges) between all individuals, and SW represents how many “neighbors” are required to reach everyone within the group. In other words, NCI represents the hierarchy rate, CC shows how easily information can flow through the group, APL calculates the “speed” of this information flow within the group, and SW shows how “closed” the group is.

We used a statistical method (Linear Mixed Models, LMM) to compare these indices between castes and subnetworks. The results showed that Cleaners are less hierarchical (low NCI), with fewer cliques (low CC) than Foragers and Nurses, with slower information flow (high APL).

The presence of the queen surprisingly influenced only the information flow. Those individuals who were connected with the queen established “faster” networks than individuals with no queen connections.

In summary, our results revealed new information about castes and individuals through their networks. It seems like the tasks of nursing and foraging require a more centralized, denser, and faster information flow than the cleaning task. Moreover, the presence of the queen makes information flow faster within the group. So, the role of the queen seems essential not only for producing offspring but also for “controlling” the castes as well.

Cited article:

Mersch, Danielle P., Alessandro Crespi, and Laurent Keller. “Tracking individuals shows spatial fidelity is a key regulator of ant social organization.” Science 340.6136 (2013): 1090-1093.

Interview with a Social Insect Scientist: Riley Shultz

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Riley works in the Department of Entomology at Purdue University and is interested in honey bee health. Her recent research published in Insectes Sociaux can be viewed here.

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

I am a PhD student researcher in the Department of Entomology at Purdue University. I work in the Harpur Lab investigating honey bee health with a focus on honey bee drones. The Harpur lab strives to bridge the gaps in our knowledge about genomics, the evolution of eusocial species, and their adaptive traits. My specific research interests include mutation and molecular mechanisms of repair.

A frame of drone bees with nurse bees tending to the newly emerging adults.

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

I have always had a fascination with honey bees and medicine. When I was in high school my dad brought home a nuc of bees and invited me to join in the hobby with him. Spending summers doing mite washes, observing colony behaviors, and of course harvesting honey sparked my fascination with social insects. I ended up joining a bee lab during my undergraduate at Washington State University and developed further research interests in honey bee health. Now during my MS and PhD at Purdue University I am able to foster my interests in mutation using the unique haplodiploid honey bee.

Riley’s dad checking hobby beehives in 2018.

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

Honey bees from day one have captured my full attention. There are so many unique behaviors in these eusocial insects that make them a fascinating study subject. While my research interests lie more on the pathways within the insect itself, the colony structure of honey bees make them highly complex.

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

This past summer I worked with a mutant honey bee colony, where drones in the colony had either white or dark eyes. We ran a series of experiments to learn more about the sight deterioration in the white-eyed males. While we presumed that the white eye drones would go blind at some point, it was really exciting to perform some simple tests on this. I spent hours outside a colony observing drones leaving and returning to the colony. This was memorable partly due to the sheer amount of time I spent observing the mutants’ behaviors, but it was also fun to observe bee behaviors more generally.

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

The Harpur lab works to spend a lot of time doing various outreach activities. I really enjoy connecting with the local community to talk about honey bees and pollinators more generally. I’ve done outreach with the local library as well as with scout troops in the area. My favorite moment is always when young children overcome their fear of an insect. It is a fun puzzle to teach children about honey bee genetics, and we all look forward to helping children ‘build-a-bee’ as a simple way to learn about the inner workings of a colony.

Honey bees swarming to find a new location to establish a colony. Honey bees were collected from the fruit tree and put in a new hive.

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

Insects play an integral role in human lives. They provide a powerful model for medical research, pollination to our agricultural systems, vital roles in our ecosystems, and so much more. I think we still lack fundamental knowledge on many social insect systems and discoveries within these systems will be key to innovative studies. Conducting comprehensive studies on the genotypes and associated phenotypes is crucial as it lays the essential groundwork for future practical research endeavors.

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

I am an avid reader of fiction. When I’m not pouring over journal articles, you’ll find my nose in a book. Reading is a really nice way to escape and embrace your creative side. I enjoy hiking and kayaking. Spending summers on Idaho’s whitewater was the perfect way to cool off after beekeeping.

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

The book I am currently reading for my insect genomics course is “A Primer of Population Genetics and Genomics” by Daniel L Hartl. This book has helped further my understanding of population genetics for someone whose background is more molecular biology. For my personal enjoyment, I recently read “Six of Crows” by Leigh Bardugo. I am a huge fan of books that describe things outside of our reality. While this book is more realistic than some, I really enjoyed how well-developed the character’s backstories were. There is a real art to developing a story where the reader can get inside the character’s head and understand the forces that drive them.

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

I am fortunate to have a supportive family and partner, as well as friends and colleagues. The going may get tough in the winter time for someone researching bees, but holding out till the next summer is well worth the wait.

Riley’s co-workers and her harvesting honey and collecting drones in 2023.

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

I would bring a really large book, some sunscreen, and some semipermeable membranes to filter seawater. I am well known as the coworker who advises sunscreen even when wearing a bee suit as well as the one who carries around a comically large water bottle.

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

This is a hard question to answer. My first research experience as an undergraduate was not very rewarding. I switched my path to work in an entomology lab and was met with immense support from my co-advisors Dr. Nicholas Naeger and Dr. Jennifer Han. I found a renewed passion for research and was able to grow my interest in honey bees with an independent project under their advisory. I attribute my current career trajectory to the experiences created by these mentors. I would also name my current advisor Dr. Brock Harpur for his enthusiasm in studying social insects as well as his continued support for all of the students in his lab. He has helped me to refine my skills in designing robust experiments as well as writing grants.

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

My advice would be to pursue your passion and not stress over the small things. Working with social insects can be labor intensive as well as unreliable. I cannot count the number of rainy days in the summer that have added new challenges to working with honey bees. I think learning to adapt to these new challenges and to frame your mindset as each stress being a little ‘puzzle’ will help in the long term.

IS: Has learning from a mistake ever led you to success?

Absolutely. I have made many mistakes in my short career, but those are the moments that allow me to remember and adapt. When something works the very first time I do it, it’s often forgettable. If something went wrong, I was bound to learn from that experience as well as gain new skills along the way.

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

I haven’t had too much need for travel in my career at this point, but my favorite place thus far is probably traveling to the Plant and Animal Genome conference in San Diego. There I was not only able to attend a wonderful conference and do a bit of sightseeing, but I was also able to connect with my advisor’s colleagues. I always look forward to making connections with people who share the same interests in insects!