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
In this blog post, the authors of the Insectes Sociaux article title “High environmental temperatures put nest excavation by ants on fast forward: they dig the same nests, faster” (Rathery et al. 2025) talk about their research on the effects of environmental temperature on ant digging activity.
Imagine watching a video of someone doing normal everyday activities. First, at normal speed, then, at double speed: suddenly everyone moves like olympic sprinters, but still appear calm and relaxed. Now slow down the video: every step and gesture becomes painfully sluggish.
Imagine if that could also happen in real life: one day, it’s only noon and you have already wrapped up all the work for the day; the next day, you have barely had breakfast and the day is already getting to an end!
These situations look unrealistic to us, but ants experience them all the time!
Ants are ectotherms – animals that don’t maintain a constant body temperature. As a result, their physiology and behaviour depends heavily on the temperature of the environment. In warmer weather, ants move faster, they likely forage more quickly, and probably they also age faster. In our study, for instance, the walking speed of Lasius flavus ants doubled when the temperature rose by about 12 °C.
Of course, the sped-up video analogy only goes so far. For example, gravity does not change with temperature, so winged ants need to flap their wings at least at a minimum speed in order to fly, and this might become completely impossible in cold weather. At high-temperature, when ants are moving too fast, they might struggle to take in enough oxygen to keep up with their energy consumption. So, while some behaviours might simply speed up with increasing temperature, other behaviours are likely to hit a physical or physiological limit, and could change in unexpected ways. In all cases, the changes of behaviour induced by temperature are likely to be important for colony survival, and may play a role in future adaptations of ants to the changing climate.
IS: How did you choose this research topic, and to explore it with Lasius flavus?
“It was a combination of love for the topic, but also of practical circumstances”, says Alann Rathery, lead author of the study. Originally planning to study termite nests in Australia, his plans were upended by the Covid-19 pandemic. “I had to pivot quickly, soon abandoned the idea of travelling to Australia I began collecting ants from my backyard in London. At some point, I even ran some preliminary experiments in my room!“
The image is just a frame grab from the video linked: laboratory in Alann Rathery’s room where preliminary experiment leading to the present study were conducted during the Covid19 pandemic.
“Luckily, the yellow meadow ants (Lasius flavus), which are one of the most abundant ant species in the meadows of South-West London, are very interesting ants. They are important ecological engineers, that shape the local landscape with their mounds, creating ecological niches for many other plant and animal species.”
IS: Can you tell us a bit about the experiments that you did?
“We have long been curious about how environmental factors – like temperature and humidity – affect the behaviour of social insects” – says Andrea Perna, senior author of the study. – “These environmental cuesmay help ants and termites figure out things that they cannot measure directly, like how deep inside the nest they are. One of the key functions of nests is to provide the colony with a suitable environment in terms of temperature and humidity: it makes sense that insects respond to these cues. In a related study (Facchini et al. 2024), for instance we found that termites may use water evaporating from damp soil as a signal to coordinate how and where to build their nests.
When it comes to ants, previous studies had indicated that they likely respond to temperature gradients – differences in temperature across space – during nest building. But it wasn’t clear whether temperature alone, without a gradient, could influence how ants dig or build. So we set out to test two things: first, how ant digging speed changes depending on temperature, and second, whether the shape of the nests that they excavated was different at different temperatures.
We followed a somewhat classical approach for the experiments, letting ants excavate in-between two glass plates, so that we could image the growth of the pattern over time while the experimental colonies were housed inside temperature-controlled incubators”.
“The experiments were technically a bit challenging – adds Alann Rathery – we had to image ant colonies continuously over multiple days, and the space inside the incubators was a bit tight, so I had to build a custom imaging system with Raspberry Pi computers and cameras – one inside each incubator. I connected them all to a router outside, and through that I could control the cameras remotely to automatically record photos and videos.” Analyzing the footage wasn’t simple either. “The ant tunnels grow into very complex shapes, and it takes a solid analysis pipeline to automatically extract and quantify the structures. But some of the patterns they create are really beautiful!”
Do you want to see these structures grow? Here is a time-lapse video of the growing galleries.
Screen shots from the time-lapse video of the growing galleries.
IS: What’s next for this type of research?
“There’s still a lot we don’t know about what happens at the individual level when ants dig these intricate underground networks. In our study, we didn’t focus on the detailed behavior of individual ants as they carve out tunnels in the soil. But what they do, how they decide where to dig, how new branches start, are all incredibly interesting questions. Some of this behavior can be seen in action in a real-time video clip from our experiments. Analysing in detail this type of footage is fascinating, but could easily become an heavy research task.
Another promising direction for this research would be looking at the internal structure of natural nests in the wild: how do galleries inside the mound differ, depending if the mound was built in a sunlit area compared to a shady one?Are there shape differences between the northern exposed and the southern side of the mound?
The nests built by social insects are more than just shelters: they are the physical records of the life and activity of a colony. If we learn to better read the information written in these structures, we might uncover new insights into the hidden lives of these wonderful insects”.
References:
Rathery, A., Facchini, G., Halsey, L.G., Perna, A. High environmental temperatures put nest excavation by ants on fast forward: they dig the same nests, faster. Insect. Soc. (2025). https://doi.org/10.1007/s00040-025-01049-7
Facchini, G., Rathery, A., Douady, S., Sillam-Dussès, D., Perna, A. (2024). Substrate evaporation drives collective construction in termites. Elife, 12, RP86843. https://doi.org/10.7554/eLife.86843.4
Peter recently completed his Ph.D. at Charles University in Prague. During his doctoral study, he focused on the formation of sunning clusters, the phenomenon in red wood ants as a part of their nest thermoregulation. Currently, he is looking for a research position on ants. Read his latest article in Insectes Sociaux here.
While walking in the European coniferous forest during early spring, some large hills are covered by needles; these are the anthills. If you get closer and look at one of them closely, you will notice a black spot on the nest surface. These are red wood ants, Formica polyctena. They often form huge and dense clusters on the nest surface, in which many ant workers (even queens!) are involved throughout the whole spring.
You may be asking intuitively: Why are they doing this on the nest surface? A long time ago, Zahn (1958) suggested that when ants return to their nest after sun basking, they could transfer heat and thus contribute to the increase in nest temperature. It has been confirmed that sun-basking behavior contributes to the spring nest heating (Chanas and Frouz 2025b). Although the effect on the nest temperature is low, there are other factors which can contribute to the spring nest heating within overall nest thermoregulation. And that is what our research questions were: What factors cause the ants to form clusters on the nest surface? How often do clusters occur?
Sunning clusters, the remarkable phenomenon, occurred in all nests we studied. We were surprised that there was no significant relationship between the occurrence of sunning clusters and nest volume and nest shading, even though such nest properties were shown as crucial in ant nest thermoregulation (see references in our article). Our results suggest that there is a high variation of workers performing sun-basking behavior among individual nests, as similarly shown by Kadochová et al. (2017). It also means that each nest has slightly different microclimatic conditions. Each nest inhabits many ant individuals, which can behave according to it and then ensure optimal temperature conditions in the given nest.
Why do we call clusters “sunning?” Because when the sun shines, ants form clusters on the nest surface, and the main heat source is the sun, so they form “sunning clusters.” This is their distinctive and conspicuous behavior, and it has attracted the attention of several scientists interested in ant nest thermoregulation.
The frequency of clusters strongly depends on the nest temperature and the duration of daylight, unlike the air temperature, which has a lower effect. Thus, at lower nest temperature, ant workers tend to form sunning clusters during warm periods of the day, with a higher outside temperature. At higher nest temperature, clusters are formed during the cold period of the day. We found that the breaking point of the nest temperature where clusters peaked was 4.68°C and of the daylight was 12 h and 40 min. After that, sunning clusters declined very slowly, which you can see only by the statistics. The low nest temperature is very interesting; we expected a different breaking point of nest temperature. Why such a low nest temperature? But sun-basking behavior is just one of several mechanisms within nest thermoregulation. The fact that you do not know something is even more interesting because you can still further ask, think, and feed your curiosity by trying and setting up new experiments and expanding knowledge and contributing to the science and then the whole society to moving on.
Sunning clusters did not completely disappear at the nest temperature above 20ºC, where the opposite was shown by Kadochová et al. (2019). There was rather a gradual decline of clusters. Higher nest temperature accelerates reproduction and is crucial for their proper brood development (Rosengren et al. 1987, Porter 1988). At such high nest temperature, they do not need to further form sunning clusters. Although some workers can still perform sun-basking behavior by their individual need.
If you look at the daily dynamic of occurrence of clusters, you can see that the pattern is different in early spring and different in late spring. Thus, the daily dynamic changed significantly in early and late spring (Fig. 2). In early spring, when the nest temperature is low, sunning clusters peaked in late morning and then decreased. In late spring, however, we found that once a nest heated up, the clusters became much less frequent and occurred without a clear diurnal pattern but in obvious association with colder weather.
We had a huge dataset. A large dataset was generated, including nineteen cameras (Fig. 3). By using the cameras, we were able to notice something that the ordinary eye would not notice in the field. When you have “more eyes” looking at something, you are more likely to notice things you had not considered—because the mind tends to only see what it is prepared to see. In this case, we noticed clusters in association with colder weather that occurred sometime even in late spring. Such clusters we called “non-sunning clusters” (Fig. 4). This was a surprising finding, prompting the question: Why do they occur there under a cloudy sky or in cold weather for most of the day in early spring—and sometimes even during brief periods in late spring? These clusters likely have no significant effect on the regulation of nest temperature. But it can bring new insight into the organisation of ant colonies, but it needs further investigation. Currently, we are working on further findings based on another dataset that will expand our knowledge of ant nest thermoregulation.
Since ants are ectothermic animals, the formation of clusters can be quite “mechanical”. Due to their reaction to change the nest temperature and environmental conditions. A simple and plausible algorithm for cluster formation could be based on environmental conditions and social cues: in cold weather and in the presence of other workers on the nest surface, individuals tend to cluster together. When the nest surface is cold, they seek sunlight when available; when it becomes hot, they move into shaded areas to avoid overheating (Kadochová et al. 2019). Similar to how people enjoy basking in the sun during early spring but more avoid it during the peak of summer, red wood ants adjust their behavior based on nest and air temperature. However, unlike humans, they form clusters—an adaptive strategy that reduces their surface-to-volume ratio, helping to minimize heat loss compared to individual ant workers.
In conclusion, red wood ants tend to form clusters on the nest surface in early spring when nest temperatures are low or when workers are exposed to cold conditions. This behavior likely persists into late spring during chilly mornings, evenings, or periods of cold weather. In essence, the formation of sunning clusters is closely tied to nest temperature, air temperature, and daylight availability. Red wood ants appear to integrate cues from both inside the nest (internal temperature) and the external environment (sunlight or cold) to decide whether or not to form sunning clusters on the nest surface.
References
Chanas P., Frouz J. 2025b. Sunning clusters of ants contribute significantly, but weakly to spring heating in the nests of the red wood ants, Formica polyctena. Eur. J. Environ. Sci. 15: 28–33. https://doi.org/10.14712/23361964.2025.4
Kadochová Š., Frouz J., Roces F. 2017. Sun basking in red wood ants Formica polyctena (Hymenoptera, Formicidae): Individual behaviour and temperature-dependent respiration rates. PLoS ONE 12(1): e0170570. https://doi.org/10.1371/journal.pone.0170570
Kadochová Š., Frouz J., Tószögyová A. 2019. Factors influencing sun basking in red wood ants (Formica polyctena): a field experiment on clustering and phototaxis. J. Insect Behav. 32: 164–179. https://doi.org/10.1007/s10905-019-09713-0
Rosengren R., Fortelius W., Lindström K., Luther A. 1987. Phenology and causation of nest heating and thermoregulation in red wood ants of the Formica rufa group studied in coniferous forest habitats in southern Finland. Ann. Zool. Fennici 24: 147–155.
Porter S.D. 1988. Impact of temperature on colony growth and developmental rates of the ant, Solenopsis invicta. Journal of Insect Physiology 34: 1127–1133. https://doi.org10.1016/0022-1910(88)90215-6
Zahn M. 1958. Temperatursinn, Wärmehaushalt und Bauweise der Roten Waldameisen (Formica rufa L.). Zoologische Beiträge 3: 127–194.
Luisa is a researcher at Johannes Gutenberg University Mainz. She specializes in studying the life-history traits of ants, their senescence, and the genetic and non-genetic mechanisms influencing queen fitness. Read her latest article in Insectes Sociauxhere.
Queens, and kings in termites, are highly fertile and long lived insects. But certainly there is variation to which extent they are fertile. We were intrigued to understand what causes variation in fitness traits?
We wondered if very fertile queens were also more successful by producing very fertile daughters. Is this caused by a genetic factor or perhaps the maternal status, such as maternal age? Old mothers might produce less fit queens and workers, and this can have a detrimental effect for the future of the whole colony. The negative effect of parental age, known as Lansing effect, has been documented across a wide range of taxa but not yet investigated in social insects.
We used Cardiocondyla obscurior ants as model given their high variability in fertility and longevity. We investigated how fertility varies by selecting mothers that produced a low and high number of eggs after 15 weeks. We profited from a study in which we monitored a batch of queens in controlled conditions for their entire life (Jaimes-Nino et al., 2022), and monitored their daugthers too, to test if they presented a similar fertility and longevity.
Our model species is polygynous, meaning that a large number of queens cohabit within a single colony. However, it is known that those queens that live longer, produce also more eggs (Kramer et al., 2015) and more queen daugthers (Jaimes-Nino et al., 2022). Previous studies have shown that queens remain heathly for a long portion of their lives because their mortality rate and gene expression pattern remain stable until old age (Harrison et al., 2021; Jaimes-Nino et al., 2022). Therefore, it is important to test whether old queens produce daugthers that are equally fit compared to those of younger queens, given that they produce the majority of them within the colony!
Our results showed that mothers and daugthers do not “look” alike — they do not have a similar fertility or longevity. This could indicate that their genetic background does not account for the observed variation. This can be expected from C. obscurior, as it exhibits extreme inbreeding.
Furthermore, contrary to the Lansing effect reported in other taxa, we found that daugthers produced by old mothers were just as fit as those produced by young mothers. This aligns with the hypothesis that, since the majority of sexuals are produced later in life, there must be mechanisms in place to maintain the health of these queens as they age! We believe that selection against aging remains strong in older queens. The specific mechanisms by which C. obscurior queens are able to produce equally fit daugthers at such advanced ages awaits further investigation.
Strikingly, the maternal lines differed in productivity suggesting background variation influenced by the maternal environment or male quality. In this species, ergatoid males (worker-like males) figth against rivals to monopolize queen access. Our study offers new avenues of research, to disentangle the effect of mother, father and developmental environment, on the final reproductive success of queens.
References
Harrison, M.C., Jaimes Niño, L.M., Rodrigues, M.A., Ryll, J., Flatt, T., Oettler, J., et al. 2021. Gene Coexpression Network reveals highly conserved, well-regulated anti-ageing mechanisms in old ant queens. Genome Biology and Evolution13: 1–13. https://doi.org/10.1093/gbe/evab093
Jaimes-Nino, L.M., Heinze, J. & Oettler, J. 2022. Late-life fitness gains and reproductive death in Cardiocondyla obscurior ants. eLife11: 1–17. https://doi.org/10.7554/eLife.74695
Kramer, B.H., Schrempf, A., Scheuerlein, A. & Heinze, J. 2015. Ant colonies do not trade-off reproduction against maintenance. PLoS ONE10: 1–13. https://doi.org/10.1371/journal.pone.0137969
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 Sociauxhere.
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 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.
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.
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 DiasPart 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
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.
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.
Oscar Vaes is a biologist interested in data analysis and scientific communication. He has just completed his PhD in Belgium. His latest work on “inactive” ants in colonies can be found here.
IS: Who are you, and what do you do?
I’m a Belgian biologist and recently finished my PhD about activity levels in the red ant Myrmica rubra, at the Université Libre de Bruxelles. At present, I’m trying to put my knowledge of data analysis to good use, an aspect of research that I really enjoy and in which I’m trying to improve.
IS: How did you develop an interest in your research?
Simply by working on them. Basically, I’m curious to understand how things around me work, hence my interest in biology. This, combined with my attraction to animals, meant that I was predisposed to take an interest in social insects. However, it was really when I was looking for a research topic for my master thesis that I developed an interest in ants.
IS: What is your favorite social insect, and why?
So far, I’ve only worked on one biological model, Myrmica rubra, and although it doesn’t treat me in the best way during my experimental manipulations or field harvests, I still have to choose it. Being only at the beginning of my research career, I feel I’ve only glimpsed the tip of the iceberg, so I’m sure this favorite animal will evolve over time. Yet, I think it will always be a species of ant. I believe that they occupy a special place in the collective unconscious and fascinate people. I never tire of seeing the reaction people have when we tell them we’re studying the behavior of ant colonies. It is always a fun icebreaker.
Queen, worker and larva of Myrmica rubra. A) Young worker carrying a larva. B) Queen without wings. C) Young worker (top) with light cuticular pigmentation and queen (bottom) standing over a larva. D) Larva (2nd instar).
IS: What is the best moment/discovery in your research so far? What made it so memorable?
My best moments are usually when I get to share with researchers from other laboratories, at conferences. These moments are always very enriching, and have the instant effect of taking us out of the tunnel vision we might have when working for months on our subject in an office.
In terms of discoveries, I based much of my PhD subject on the hypothesis that there was probably a large proportion of inactive individuals in colonies of the ant I worked with. Having confirmation that around 30% of our species’ colonies form a distinct group of nurses, foragers, and domestics, and that we could cross-reference their characteristics with those of other species, was one of those really exciting moments when the prospects for future experiments develop and become clearer.
IS: Do you teach or do outreach/science communication? How do you incorporate your research into these areas?
Passing on knowledge is something I really enjoy doing. I’ve always been attracted to teaching, without actually doing it professionally. As a result, I try to value the moments when I can explain my research and simplify it. I find that being able to explain complex phenomena in a simple way is a great asset, but it also reflects the fact that we ourselves have understood things in depth. So practicing simplifying/explaining research is also a way of assessing one’s own level of knowledge.
IS: What do you think are some of the important current questions in social insect research, and what is essential for future research?
There’s no particular research topic that stands out for me, and this is no doubt linked to the fact that I don’t yet have a global vision of the study of social insects. However, the development of computer tools has made it much easier to acquire certain types of data by automating their collection and processing in much greater quantities than was possible in the past. I think we need to keep a critical eye on the effect these tools have on the observer, his or her ability to interpret results or even spot phenomena. I have several examples in mind of times when I’ve spent weeks turning over data presented in spreadsheets in search of answers to questions we were asking ourselves, only to have the answer right under my nose all along on the videos of my colonies. Although computer tools are a great help most of the time, they tend to distort our vision of results. There’s nothing like the eye of the experimenter to give you a first-hand view of the phenomena you’re about to dissect!
IS: Outside of science, what are your favorite activities, hobbies, or sports?
I’d say bicycles are one of my main interests. Basically, it’s always been my means of transport in Brussels, but as I was working with it, I became interested in the mechanical side of things. This basically means I have several unfinished project bikes laying in a corner of my garage. Recently, I’ve been enjoying discovering the Belgian countryside by bike, and I have to say that it’s a fantastic tool for that. I also enjoy discovering new sports and eSports disciplines. I love the feeling of beginning to understand the reasoning behind the actions of professional athletes or players, of developing a form of expertise in a new discipline. Since it’s also more fun to share interests with others, I often get sucked into people’s passions.
IS: What is the last book you read? Would you recommend it? Why or why not?
It’s not related to my research topic, but the last book I read was written by Victoria Defraigne, and is an explanatory book on transidentity. Knowing it was written by a student at my university was the trigger to finally learn about a subject I knew was full of stereotypes and misinformation in my mind. I think that for the moment, this book only exists in French, but I urge people to get informed about a subject still full of misunderstandings.
IS: How do you keep going when things get tough?
To be honest, I think I’m lucky in that I never really have a hard time. I’m very privileged in life, with family and friends all around me, which makes it easy for me to put things into perspective when they don’t go as planned. So far, the difficult periods have all been relatively limited in time, with a clearer horizon in sight each time. So, I find it easier to accept the situation and tell myself that it’s only temporary, as all the previous tough times have been.
IS: If you were to go live on an uninhabited island and could only bring three things, what would you bring? Why?
I always have my pocket magnifier in my backpack, and I use it more often than you’d think. I’d have a hard time parting with it, so I’m going to choose this as my first item. I hope, of course, that by “uninhabited” we’re talking about humans and not local wildlife. In two, I’d say coffee beans, so as to quickly have a plantation to support myself. I wouldn’t accomplish much on a desert island without my morning coffees. As I have no idea about the third, I think I’d let friends choose for me, so I’d have a surprise on arrival, good or bad.
IS: Who do you think has had the most considerable influence on your science career?
I think my PhD promoter, Claire Detrain, takes first place hands down. Then I’d say it’s the rest of the team in her lab. When it came time for me to find a subject for my master thesis in the various laboratories at my university, I gave as much importance to the atmosphere and ambience within the team, as to the research subject. Today, I’m very happy to have followed my intuition, and as a bonus, I’ve taken an interest in our six-legged friends.
IS: What advice would you give to someone hoping to be a social insect researcher in the future?
Not to work on Myrmica rubra! On a more serious note, I don’t think there are any tips specific to the study of social insects. The only mistake I see being made frequently is that of systematically trying to draw parallels between our behavior and that of social insects, but it’s mainly made by a non-scientific audience. I imagine that anyone interested in social insects quickly realizes that a large part of their charm lies in the fact that their group is structured in such a way as to modify the implications that collective responses have on individuals and the group. Over the last few years, I’ve supervised a number of students who have all shown themselves to be very curious and eager for results when working on ants, without having any prior interest in these insects. So, I think we’re lucky to be working with animals that naturally arouse people’s interest and curiosity, which can only be a good thing.
Myrmica rubra workers with the colored tags we use during experiments.
IS: Has learning from a mistake ever led you to success?
Of course it did. One example I really like is when we first started doing individual marking of ants, and we were looking for the best way to do it. We struggled quite a bit with methods we used to perform in our lab, and finally decided to reach out to another researcher who seemed to have great results with a different technique, but whom we had never spoken to. Not only was he willing to give us a detailed explanation of his techniques, but we were able to implement many tips that completely changed our way of tagging. We have been training young researchers to tag ants with great success and will probably be using these tips for many years to come.
In a broader sense, I think that making mistakes reinforces our ability to question ourselves, something that is key when doing science. I find that conducting research helps us accept mistakes and learn from them. Moreover, I believe this translates into being more open-minded in life, deconstructing deep-rooted misconceptions, and being more apt to listen to others.
IS: What is your favorite place science has taken you?
I have a very ‘first degree’ answer to this question. I mentioned earlier my fondness for conferences, and I was lucky enough to attend IUSSI San Diego in 2022. So, I’d say it was one of the highlights of my thesis, where I was able to meet many people whose research inspired me, but also to discover the research subjects of laboratories from all over the world. I really enjoyed communicating my results to an international audience of social insect experts, whose feedback inevitably led to enriching and constructive discussions.
Ben Hoffmann is a researcher based in Australia, focusing on invasive species management. His recent work on invasive red fire ants can be found here.
IS: Who are you, and what do you do?
BH: I am a mid-career researcher based in Darwin, northern Australia, and these days I am predominantly focused on sciences that improve invasive species management, especially achieving ant eradications. That can be as broad as demonstrating the utility of advanced drones, to studying the basic biology of species to determine key aspects that need to form the basis of work protocols.
A recent photo of Ben taken in Hawaii.
IS: How did you develop an interest in your research?
BH: I was always interested in nature, but in 1990 I did one week of school work experience with Alan Andersen at CSIRO, and ants then became my life passion. I basically never stopped coming to the laboratory with ants that I collected, and then I ended up doing both my undergraduate and postgraduate studies at CSIRO, and ultimately created a job for myself as well. The ants in northern Australia were so incredibly unknown back then, and it was so easy to just go out and find new species, even from my own backyard.
IS: What is your favorite social insect, and why?
BH: Certainly ants over other social insects, but I don’t think I have a favourite ant. I can spend all day just looking at the huge diversity of ants under a microscope, let alone appreciating their incredibly varied biologies and ecologies.
IS: What is the best moment/discovery in your research so far? What made it so memorable?
BH: Oh, there are so many. The joy of having a paper accepted for publication never ceases. But possibly a “best” moment has occurred multiple times when I have successfully achieved an eradication when others have said that it isn’t possible. I do enjoy proving that things are possible.
IS: Do you teach or do outreach/science communication? How do you incorporate your research into these areas?
BH: A little bit. There is always a school group that wants a presentation about ants or being a scientist, or a community group that is interested in knowing what science is being conducted anywhere. Probably my biggest interaction is communicating with the public when invasive species eradication work is conducted on private lands.
IS: What do you think are some of the important current questions in social insect research, and what is essential for future research?
BH: I suspect that I am not following the literature or science focus of most social insect research, only what I learn is important for my work. More often than not these days, it is just basic biology that I am chasing in the literature, and for most species there is practically nothing. I am actually looking forward to retirement so that I can stop chasing grants focused on somebody else’s priorities, and just conduct studies of basic biology. The work would not be interesting to most, but it can be very useful when it is needed.
IS: Outside of science, what are your favorite activities, hobbies, or sports?
BH: As a kid I loved bird watching, and in the past few years I have regained this passion, probably because of the incredible eBird database. My spare time and trips anywhere in the world now involve a lot of bird watching.
Ben and Magen Pettit (his technician) birdwatching in Brazil after the 2018 IUSSI conference.
IS: What is the last book you read? Would you recommend it? Why or why not?
BH: Around the world in 80 birds. It is simply a book about a selection of the world’s bird species and interesting details about them. There is a great opportunity here for somebody to do exactly the same for ants. Nice and easy to read, no plot to remember as I find ten minutes here and there to read a few more pages, and good for increasing knowledge.
IS: How do you keep going when things get tough?
BH: These days I exercise a lot, typically an hour fast walking in the morning, sometimes jogging, and often an hour of swimming in the afternoon. Exercise does a lot to release tension and give thinking time. As much as possible I enjoy the outdoors, and when the weather is good I go camping a lot (even if times aren’t tough). I also discuss any issues with people who might like to listen or even give advice. Among all of that I keep myself charged and enthusiastic as much as possible to find solutions to the many (and seemingly increasing) problems that I face.
IS: Who do you think has had the most considerable influence on your science career?
BH: Easily Alan Andersen. He is an incredible ecologist, regardless of whether the topics is ants or not, he is an incredibly likable person, he is a great science leader, a prolific publisher, etc etc etc. Even in his retirement he is publishing more papers than me which shows me I still have room for improvement.
Photo taken back in 1999, of Ben (middle), Alan Andersen (right), and Jerome Orgeas (left) visiting from France.
IS: What advice would you give to someone hoping to be a social insect researcher in the future?
BH: Go for it! There is plenty of scope and need for such research, regardless of whether the insects are the research focus or just the model taxon being used to test something else.
IS: Has learning from a mistake ever led you to success?
BH: Plenty of times. In fact, it could be argued that most of my career has been based on learning from mistakes. Most of my focus has been how to eradicate species from a landscape, but without causing harm to the landscape, and it is easier said than done. Certainly more failures than successes, but the failures just get you to change what is done until success is achieved. You can read about plenty of my failures in my publications, and I have always found it important to publish my failures so that other people can potentially avoid doing exactly the same and achieve the exact same failed outcome.
IS: What is your favorite place science has taken you?
BH: I love working in NE Arnhem Land, which is stunningly beautiful Aboriginal lands in northern Australia, but then again Lord Howe Island and Norfolk Island are also jewels of the world that I have always loved traveling to. Likewise, I have had the pleasure of travelling to over 40 countries and enjoy a vast array of beautiful places. Don’t think I could settle on a “favourite”.
Camping on a beach in Arnhem Land, Australia with Mogens and Dorthe Nielsen from Denmark in 2005.
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