Just when you thought it was safe to go back near the water… army ant predation on river turtle nests

By Sean O’Donnell, Ph.D.

All photographs by Jana Reintjes

Based on the short communication “Predation on nests of three species of Amazon River turtles (Podocnemis) by underground-foraging army ants (Labidus coecus)” by Da Costa Reis M., Reintjes J., Chen D. and O’Donnell S. in Insectes Sociaux.

East of the northern Ucayali River in Peru is a geologically subsiding basin crossed by winding rivers and extensive wetlands. Much of this topographically flat region is flooded for several months annually by seasonal heavy rains. In this basin is the privately owned and managed Tapiche Reserve, a protected area of about 6000 ha that spans the Tapiche River. The reserve “land” is mostly under water at least two meters deep during the flood season. When the waters retreat, sandy beaches on the Tapiche River edges are visited by females of three species of Amazon river turtles (genus Podocnemis). Like sea turtles, Amazon river turtles lay their eggs in nests dug into beach soils.

(Top) A female Amazon River Turtle (Podocnemis species) nesting on a Tapiche River beach. (Bottom) A researcher removing eggs from a Giant Amazon River Turtle (P. expansa) nest.

Turtle eggs are subject to heavy human poaching on the Tapiche River, so the Tapiche Reserve staff (co-authors Murilo Reis, Jana Reintjes and Deborah Chen) have run a river turtle rescue and head-start program annually since 2012. They collect eggs from the reserve’s beaches and rear them in a guarded hatchery built on a beach at the reserve lodge. Eggs are placed in artificial nests in the hatchery, dug to dimensions that match the natural turtle nests. 

(Top) Preparing artificial nests for Amazon River Turtles in a hatchery at the Tapiche Reserve Lodge. (Bottom) Completed turtle hatchery.

Turtle egg rescue efforts were especially successful in 2020. Over 9000 eggs were collected from 240 nests of three species of Amazon River Turtles, including the first nests of the critically endangered Giant Amazon River Turtle recorded in the area. Unfortunately, in fall 2020, the hatchery was attacked by subterranean army ants (Labidus coecus). The ants entered the nests by tunneling from below. The ant raid, never visible from the surface, was impressive in its extent and its persistence. Many thousands of polymorphic L. coecus workers were observed when the turtle nests were checked over the course of nine days in October; we believe the raid was continuously active throughout this period. The army ant raid grew in intensity over time and turtle mortality in one section of the hatchery, which contained the youngest turtles, approached 90%.

(Left) A partially excavated turtle nest being raided by Labidus coecus army ants. (Center) A turtle hatchling with most of the tissue removed from its body cavity; note the L. coecus worker clinging to the carapace. (Right) Damaged turtle eggs and a dead hatchling from a raided nest.

Paleotropical driver ants (genus Dorylus) regularly attack and consume vertebrates (Gotwald 1995), but it is often assumed that the blunt, non-crossing mandibles of Neotropical army ant workers preclude piercing of vertebrate skin and predation on vertebrates. Our paper adds to a growing literature suggesting vertebrates are on Latin American army ant menus more often than has been recognized (O’Donnell et al. 2005; Sazima 2017; López-Martínez et al. 2020). Relatively immobile vertebrates (including eggs and nestlings) may be especially vulnerable to Neotropical army ant predation. Larger-bodied L. coecus workers have impressive muscle-filled head capsules and large mandibles. Our observations suggested the ants entered turtle eggs and were also able to access hatchlings’ body cavities via soft tissues such as the eyes and yolk sacks. Army ant venom may also be relevant. Hatchlings that were stung by L. coecus workers appeared to be temporarily paralyzed, and some turtles died after being stung.

            The L. coecus raid on riverside turtle nests raises interesting questions about access to the Tapiche beaches by mobile subterranean ant colonies. A small area around the lodge remains marginally above water (all of the soil is saturated) at the height of the flood season, but there are few other patches of land within several kilometers in all directions. There are two possibilities to explain a Labidus raid reaching the lodge beach: either these usually subterranean ants have some way of persisting in the area through the flood, perhaps by moving into trees or rotten logs above the water level, or the ants traveled several kilometers underground from the nearest dry land to reach the banks of the Tapiche River.   

Amazon River Turtles that survived the L. coecus raid being prepared for release in a nearby oxbow lake.

Army ant behavior present challenges for preventing predation on natural turtle nests and hatcheries. Army ant raids are massive and mobile, but some species such as L. coecus can raid continually for several days against rich food resources. Turtle nests in clusters on a beach or in a hatchery can suffer extensive damage from an army ant raid. Constructing hatcheries to prevent ant worker access from the soil beneath may discourage army ant predation, as long as abiotic conditions appropriate for turtle development can be maintained.

References

Gotwald Jr, W.H. 1995. Army ants: the biology of social predation. Cornell University Press.

López-Martínez GA,  Rondón-Zabala JI, Martínez-Parales E, Moya-Arévalo RH, Rodríguez OA (2020) Depredacion por insectos de nidos y neonates protegidos de Podocnemis vogli (sabanas inundables del Casanare). Acta Biol Colom 25:354-358.

O’Donnell, S., M. Kaspari, J. Lattke. 2005. Extraordinary predation by the Neotropical army ant Cheliomyrmex andicola: Implications for the evolution of the army ant syndrome. Biotropica 37: 706-709.

Sazima I (2017) New World Army Ants Eciton burchellii kill and consume leaf-litter inhabiting lizards in the Atlantic Forest, Southeast Brazil. Trop Nat Hist 17:119-122.

Interview with a Social Insect Scientist: Ajay Kumar Harit

You can read Ajay’s recent research article about x-ray tomography to compare construction properties of the nests of wood-feeding and fungus-growing termite species here.

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

Hi, I am Ajay Kumar Harit and are presently working as a Research Associate -III at the School of Environmental Science, Mahatma Gandhi University, PD Hills, Kottayam, Kerala, India. I have been studying termite biology, behaviour, and its influence on natural ecosystems and society for over 14 years. During this tenure, I was part of several national and international funded projects related to termites. I will continue exploring the special attributes of termites for as long as possible.  

Our interviewee, Ajay Kumar Harit

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

I have started my journey with termites 2007 onwards as my Master of Philosophy (MPhil) dissertation work and it has been going on until now. I obtained my Master degree (MSc) in Zoology with specialisation in entomology, but build-up my interest in termite research after my MPhil degree when I gathered more knowledge about termites and their importance in nature.

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

Termites, because they are one of the oldest social insects and are well-developed, highly systematic, and civilized. They play a significant role in soil and nutrient dynamics in the natural forest ecosystem. The unique quality of termites is the degradation of lignocellulosic waste (only this insect has this capability). Termites are also globally used as medicine by some of the ethnic communities. They are also consumed by human beings and other animals as they contain high-quality protein. 

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

I personally felt, my entire research journey is memorable, each and every moment has its own story to express.  Although for me, most memorable and challenging was the Ex-situ development (Rearing/culturing) of termite colonies under laboratory condition and its application in degradation of lignocellulosic waste, which I achieved during my doctoral work. 

In my career, culturing of termites in the laboratory and observing the first batch of termite eggs in my culture was the best moment of my research (that day I was the happiest person in my department), and has given me immense pleasure as well as the confidence to pursue and complete my research work.  


A typical nuptial chamber (A), termite eggs and adults (B), The adult and the nymphs performing trophallaxis (C), and nymphs, young once, adult, and the pillar-like structure constructed by young once at initial stage of colony development at laboratory condition (D)

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

Truly, I do not do it directly or in a systematic approach, but I do it indirectly when sharing my findings with my teachers, colleagues, friends, students and scientific social network sites such as Research Gate, Academia, Google Scholar etc. In addition, I also discuss the findings of my research with other scientist groups, local people, farmers, and staff of the forest department to get their point of view and suggestions.

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

Working with social insects is laborious work, time-consuming and often field-oriented, which is less appreciated by society and other research groups. However, social insects play a significant role in sustainable development. In the last decade, less importance has been given by funding agencies to conduct research on social insects due to the very limited number of scientists working on social insects, globally.

Also of notice, very few students express their interest to study and research social insects because of limited job opportunities. To overcome this, we should call for multiple research approaches and methods-based projects, meaning collaborative research with an allied subject should be conducted. We need to build-up teams/groups of scientists based on the different social insects they study, national-wise, state-wise, and if possible, area/district-wise. 

Discussion with staff from the forest department and team members: Ajay Kumar Harit

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

This depends on the situation and demand to nature, society, and evolution. Particularly the influence of termites in natural ecosystems is poorly explored when compared to other social insects like bees and wasp as well as other ecosystem engineers such as earthworms. Termites also play a big role in nature, society, and even for human beings. I think it is a debatable question why termites have been given moderate importance compared to other social insects.   Also, we should focus on the exploration of new aspects of social insects especially termites, their biodiversity, and comparative studies among other groups of insects. 

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

Currently, I am reading two books:

1) How Insects Work, An Illustrated Guide to the Wonders of Form and Function―from Antennae to Wings by Marianne Taylor (2020).

2) Extraordinary Insects: Weird Wonderful by Anne Sverdrup-Thygeson (2019)

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

Spending time with family and friends, exploring a new place, meditation, cooking, listening to music, reading, and cricket.

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

I talk to my family and friends, meditate, or spend time cooking and listening to music. Sometimes I also like to go near water bodies (river or sea; based on the condition) and relax. 

Sample collection during a field visit at a semi-evergreen forest by Mr. Naveen Babu (right) and Ajay Kumar Harit (left)

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

Some study material as it will be good to study in this undisturbed area, some cooking stuff to try a new dish and some electronic safety device to communicate in an emergency and protect me.

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

Three people play a significant role in my research career: my Ph.D. supervisor (Dr. S. Gajalakshmi), and my PDF mentors (Dr. Pascal Jouquet and Dr. E.V. Ramasamy), and of couse my family members. These are the four pillars that taught me different aspects of research and improved my research career. 

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

People have wrong opinions about social insects, especially termites, which are totally misleading to society as well as young people. Whereas termites play a significant role in society as well as in the ecosystem. We just need to explore the special attributes of termites such as degradation on lignocellulosic waste, found in huge quantities. The handling of this waste is a big problem around the globe. However, termites can handle it in a very efficient way as they do it in the natural ecosystem. I think this aspect should be explored in future work.

Secondly, termites also play an incredible role in soil and nutrients dynamic, which is also not much appreciated. Termite mound soil has a higher nutrient value in comparison to the surrounding soil, which could be used as manure for agricultural fields to enhance the soil fertility, as proven by African researchers. This needs to receive more attention in the future. 

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

Pondicherry University, Puducherry, The Indo-French Cell for water science (IFCW), Civil Engineering Department, Indian Institute of Science, Bangalore (IISC), India, and the Western Ghats region of Kerala (forest and water bodies). Such a nice experience to explore many beautiful places and learning a lot, which I never expected during my graduate and postgraduate education.

Interview with a Social Insect Scientist: Joe Velenovsky

You can read Joe’s recent research article about protozoan abundance of Coptotermes gestroi and formosanus kings and queens during the transition from biparental to alloparental care here.

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

My name is Joseph Francis Velenovsky IV, but I go by Joe. I am a Ph.D. candidate working in the Chouvenc/Su labs at the University of Florida’s Fort Lauderdale Research and Education Center. My research focuses on the mutualistic protozoa within Coptotermes formosanus and Coptotermes gestroi. For this publication we investigated the abundance of protozoa within kings and queens during incipient colony development. We found that the protozoan abundance of both C. formosanus and C. gestroi kings and queens changes dramatically during this time. A large portion of my Ph.D. work is focused on determining the protozoan community of C. formosanus/C. gestroi hybrids. I specifically am investigating how the community changes during incipient colony development and which protozoa are harbored by older hybrid colonies. This study system has afforded me the opportunity to investigate incredibly interesting questions about termite biology and symbiosis.      

Joe Velenovsky while on a hike at Fern Forest Nature Center in Coconut Creek, Florida.

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

I developed an interest in social insects while pursuing a bachelor’s degree in biology at Towson University. When I began my studies at Towson, I thought I was going to pursue a career in marine mammalogy because that had been my dream since I was a child growing up in Ocean City, Maryland. My aspirations quickly changed while I was working with Cryptocercus during an undergraduate research experience in Mark Bulmer’s lab. I became fascinated with Cryptocercus and the works of Christine Nalepa. After completing my bachelor’s degree, I went on and completed a master’s at Towson on antifungal defenses in Cryptocercus and termites.         

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

My favorite social insect is not a eusocial insect, but rather the subsocial xylophagous cockroach Cryptocercus. I personally find Cryptocercus adorable because of its nesting habits, morphology, and monogamous mating system. Aside from these reasons and perhaps more importantly, Cryptocercus is my favorite social insect because it is an excellent extant model of what the ancestor of Cryptocercus and termites may have been like.     

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 thus far was when Mark and I successfully identified the antifungal gene termicin within Cryptocercus. This was memorable for me because I was part of finding out that both Cryptocercus and termites have termicins, and therefore that the antifungal defenses of Cryptocercus and termites likely were present in the ancestor of both groups. During my Ph.D., there have been quite a few memorable discoveries that I am excited to share with the scientific community as I complete my doctorate.   

A soldier and an egg mass from a 3-year-old laboratory-reared C. gestroi colony. Photograph by Thomas Chouvenc.

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

I currently do not teach or do outreach, but while at Towson I was both a TA and adjunct faculty member, and I hope to make teaching a large part of my career after my doctorate. While at Towson, I incorporated both Cryptocercus and Reticulitermes into my introductory biology labs during the unit on evolution and natural selection. One of my favorite teaching activities was bringing a family group of Cryptocercus to the lab and allowing students to see these unique cockroaches up close.

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

One area of social insect research that I think is of particular importance is the study of social insects that have become established outside of their native range. Social insects are often successful invaders if given the opportunity by human activities. Within its introduced range, C. gestroi is a serious threat to both structures and native tree species (see Chouvenc and Foley 2018 in Florida Entomologist). There are countless other examples among termites, ants, bees, and wasps of invasive social insects having highly detrimental effects on native species within their introduced range. I believe that the study of invasive social insects is a high priority within social insect research, that researchers should continue to examine the impacts that invaders have on native species, and that investigating differences between the biology of social insects in their native range compared to their introduced range is of the utmost importance.

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

An area of particular contention among social insect researchers is the evolution of eusociality within the different social insect groups. Since we cannot travel back in time and observe the evolutionary process ourselves, it is likely that these debates will continue. The differences between the evolution of eusociality in termites compared to Hymenoptera is an incredibly interesting area that should continue to be a focus of research.   

Pseudotrichonympha, Holomastigotoides, and Cononympha from C. gestroi. Micrograph by Joe Velenovsky.

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

The last book I read besides social insect and biological literature was Is Fred in the Refrigerator? by Shala Nicely. The book is a memoir about the author that details her experiences with OCD. As someone who was diagnosed with OCD at an early age, I found the book entertaining and inspiring. I would recommend the book not only to individuals with anxiety disorders, but also to other people because the book is a good read and does a great job of showing that OCD is nearly always not the disorder that is portrayed in popular culture.     

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

I enjoy going on walks and looking for unique insects and plants with my girlfriend Jean. I also am an avid runner. I like to run both shorter distances such as 400m and 800m sets and longer distances such as a 15K. I can see a half-marathon in my future, but I am not ready quite yet.  

Joe Velenovsky observing a large dragonfly (Aeshnidae) at Fern Forest Nature Center in Coconut Creek, Florida.

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

I attempt to be present in the moment and to primarily focus on a single task at a time. I am not always successful, but I have found that attempting to be mindful enhances my productivity and decreases my level of stress. I also run a lot as I mentioned previously.   

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 multi-position ladder and a machete because these items should assist me in gathering fruits and protecting myself from predators and weather. Assuming that I am leaving my old life behind to live on an uninhabited island, I believe I would bring a solar-powered laptop so that I could document the organisms on the island. My hope would be that one day that laptop would be found.

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

I have been incredibly fortunate to have learned from a lot of great scientists during my academic career, but if I had to pick one researcher who has had the greatest influence on my growth as a researcher, I would pick my advisor Thomas Chouvenc. He is a brilliant researcher who always strives to see the “big picture” and has taught me to attempt to do the same. He also has taught me that time is the most important asset I have and that how I spend my days is actually how I spend my life.      

Pseudotrichonympha leei from C. gestroi. Micrograph by Joe Velenovsky.

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

My advice for undergraduates that are interested in social insect research is to become involved in a social insect lab while in undergrad and to read and comprehend the literature. Performing research in undergrad is really the only way to find out if you enjoy research because you can read about research extensively, but until you are actually in the lab it is impossible to know if you enjoy the research process.    

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

I have been fortunate to have visited Gillian Gile’s lab at Arizona State University in Tempe, Arizona a few times during my doctorate. Gillian and her lab members are a huge part of the research I am leading on the protozoa of C. formosanus/C. gestroi hybrids, and I thoroughly enjoyed visiting her lab and learning from her and her lab members. I also enjoyed the change in climate while visiting Arizona and the different insects and plants compared to Florida.

Interview with a Social Insect Scientist: Inácio Teles e Gomes

You can read Inácio’s recent research article about the natural history, habitat preferences and population dynamics of Pheidole oxyops here.

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

I am Inácio Teles e Gomes, a young Brazilian ecologist who uses ants and their interactions as his favorite model to test many ecological theories and hypotheses. Moreover, the biology and natural history of some ant species also amuse me. I´m a postdoc at Universidade Federal de Viçosa, in Viçosa, a little countryside town in the state with the best food available in Brazil: Minas Gerais.

Fieldwork in the Pantanal wetlands, Mato Grosso do Sul, Brazil

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

The roots of my interest in the natural history of our world come from my early childhood. It is hard to define a reason or a unique stimulus. I´ve always been a science enthusiast. I used to read about astronomy, dinosaurs, I love documentaries about nature, I really loved my atlases about the world and the human body (by the way, give children an atlas!). When I decided to study Biological Sciences, I became drawn to ant ecology due to a number of factors such as luck in finding the right people and opportunities in my way and the amazing world of the ant societies, their importance to the world and the great answers they can give to us.

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

I suppose at this point I have given out a spoiler. I really like all social insects, specially the Hymenoptera, but ants are for sure my favorite ones. Their importance to the planet, to biodiversity and the role they have on the ecosystems they occur are enthralling. In addition, the answers they can provide to our ecological and biological questions make them even more special.

Experimental study on the Azteca ant’s effects on their mutualist Cecropia plants. Atlantic rainforest fragment in Viçosa, Minas Gerais, Brazil.

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

The answer to this question comes from the first question I had in the beginning of college and that became the central idea of my first scientific study. In the city I lived at that time, I used to see many ant’s nests with feathers around their entrances and asked myself why.  We were finally able to publish the paper a few years later, “Why do Pheidole oxyops ants place feathers around their nests?” (Gomes et al 2019) and it had a great repercussion in the social media, many blogs and sites worldwide published articles about the study and even Scientific American came to interview me. Normally we have the feeling that only few people are reading our work but at this time I was sure that its reach was greater.

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

Unfortunately, in the last years I am more distant from science outreach than I would like. I was a teacher for a few years before engaging my doctorate studies. During this time and undergrad, I engaged in many science outreach projects and environmental education, from children to elderly people, and from very poor communities to upper class schools. One of those projects was a school’s demand to apply the project-based learning with a 5 years-old students’ class that had had many experiences with leaf-cutting ants in their vegetable garden and with fire ants’ attacks on some students. This one-year experience working close with those children and their teacher was particularly awesome and also became an article, “The role of the project-based learning in the construction of scientific knowledge: working environmental education concepts using ants as models” (“O papel do Ensino por Projetos na construção de conhecimento científico: trabalhando conceitos de Educação Ambiental utilizando formigas como objeto de estudo”) (Faria et al 2012), but sadly it is available only in Portuguese.

            In informal contexts, I have always expressed a scientific explanation and point of view regarding various matters, particularly to friends and others who are interested in listening. I try to make some of my profiles in social media a place for science communication for all, and not only within my scientific circle. However, I admit I should be doing more. These dark times of science denial require from us (but not us only!) to kick up our heels and do better science communication.

Seed removal experiment in a dry forest in Jataí, Goiás, Brazil.

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

            Social insects are crucial for the functioning of ecosystems as we know them. The biomass of ants and termites represents a great part of the animal biomass in terrestrial systems and some of the processes they are involved in are not even still acknowledged. Bees are the key drivers of pollination. However, we are just beginning to understand all the patterns and mechanisms that maintain such services. Unfortunately, we also know very little about the basic biology and natural history of most of those species, especially those from the tropics. I really count on such studies to be more valued and encouraged.

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

            I think that the origins and maintenance of sociality are still a good issue for debate, but I´m not updated about this theme. Ant-research wise, the existence and/or importance of different trade-offs in many ant ecological traits, at different scales, from the individual to community, is a good example of controversy.

The author’s lab team in the Campos Rupestre (rocky-grasslands) of Serra do Cipó, Minas Gerais, Brazil.

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

Beyond the scientific literature, the last books I read were a three book series of epic fantasy novels called Mistborn, by Brandon Sanderson. I think that if you like fantasy, you would like this series, the author creates a novel concept of magic and is very interesting, although it is quite youth literature.

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

I really like the outdoors, trekking or just hanging out and having fun with friends, at the beach or visiting a waterfall. But my favorite hobby for sure is to play volleyball. I once had to choose between trying to be a professional player or going ahead with studies. The academia won me over but I look forward to every moment spent on a court playing.

The author’s ‘hobby team’.

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

I am an optimistic person! I cannot remember a moment that things were tougher than now, especially in Brazil, and especially for scientists and teachers. But I believe we can turn the tables. The opposite of believing is death.

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

When you ask so, I promptly imagine a tropical island. In that case, I would bring good sunglasses, a good book and a comfortable pillow.

Mount Roraima, Venezuela.

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

I have met many remarkable scientists and professors in my career and many of them influenced me positively, while others negatively. But Professor Ricardo Campos introduced me to the world of ants when he was doing his PhD and I was only a freshman. We have been part of the same professional groups ever since and I am really grateful for this partnership.

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

My advice goes not only to insect researchers but to everyone and anyone who wants a career in academia: do not go with the flow and think hard if this is what you really want. It’s a hard climb to the top and not everyone makes it – it does not only depend on hard work. If that researcher plans to find work in Brazil, I would suggest, think twice, three, four times if that is what you want. Being a researcher in Brazil nowadays is hard! But if that is what you have chosen to do, then I recommend lots of reading, try to learn as much as you can from everyone, and don’t be shy to display your abilities and weaknesses. And never let the academic arrogance possess you!

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

That´s a hard one! I have been to so many wonderful places because of science! But one that frequently pops into my mind is the archipelago of Anavilhanas, the second largest river archipelago of the world, in the upper Rio Negro, in the heart of the Amazon Forest. The brightest night sky is there!

The beautiful sunset of the Archipelago of Anavilhanas, Amazonas River, Brazil.

Going, going, gone – The remarkable Cerrado biome in Southern Brazil

Or – Salve as sobreviventes: a notável diversidade de formigas no fragmento de Cerrado que representa a única área de proteção do bioma na Região Sul do Brasil (Veja o texto em portugues abaixo)

By Aline M. Oliveira

Based on the research article “Save the survivors: the remarkable ant diversity of the last protected fragment of savanna in Southern Brazil” by Aline Oliveira and Rodrigo Feitosa in Insectes Sociaux.

In a scientific article recently published, researchers from the Universidade Federal do Parana (UFPR), Curitiba, Brazil, highlight the importance of a small fragment of Cerrado (Brazilian Savanna formation) in the state of Parana, based on the study of the ant fauna occurring in this area. Emphasizing the need for measures to guarantee the preservation of this fragment, which is the only protected area of the Cerrado biome in the Southern Region, and criticizing the neglect of the state and federal governments on environmental preservation in Brazil.

Cerrado State Park and its surroundings.

The ant sampling was conducted in 2015, at the Cerrado State Park (CSP), located in the Northwest of Parana state. That region represents the southern limit of Cerrado in Brazil and is one of the most fragmented portions of the biome. Only one of those fragments is a conservation area, protected by law, the CSP.

Vegetation structure of Cerrado State Park. A researcher is taking notes.

Ants were sampled using pitfall traps in the soil and trees. Ground pitfalls are plastic cups buried in the ground with the opening at the same level as the soil surface so that ants fall into the container when they are walking on the ground. In this method, water is added to the container, with some detergent to break the surface tension. We also used arboreal pitfalls to collect ants in the vegetation, which are plastic cups attached with adhesive tape to tree branches, with water and human urine solution, an excellent attractive for arboreal ants. The ants were processed and identified at the Laboratório de Sistemática e Biologia de Formigas of Universidade Federal do Paraná and deposited at the Padre Jesus Santiago Moure Entomological Collection (DZUP).

The team during field work, installing the traps.

Comparing the ant fauna found in CSP with another 30 localities of Cerrado across its entire distribution in Brazil, the CSP is the third most diverse, with more than 130 species, including several savanna specialists, species rarely sampled, and species still unknown to science. These discoveries are important as the ants perform important ecological functions in almost every terrestrial ecosystem, such as predation, soil aeration, and seed dispersal. These results highlight the impressive biodiversity and potential of CSP to reveal scientific novelties.

Ground pitfall trap, with rain protection.

Still, recent studies have shown that, in the face of future climate change, the southernmost fragments of Cerrado would be a likely refuge area for many groups of animals. So, preserving the last protected fragment of Cerrado in southern Brazil is a strategic action that can aid the conservation of many species in the future.

Arboreal pitfall trap, with caught ants inside.

Despite the huge biological importance of this area, it is currently surrounded by deforested areas and by monocultures. The use of pesticides in these areas is certainly harmful to the species of animals and plants in the CSP. The plantations of Pinus, which is an exotic tree, is especially concerning because it can invade the park areas provoking losses to the natural biodiversity.

Padre Jesus Santiago Moure Entomological Collection (DZUP), Universidade Federal do Paraná, Curitiba, Brazil

Therefore, we propose the urgent creation of new conservation units that incorporate other fragments of Cerrado in the state of Parana, including ecological corridors between these fragments, allowing the contact between populations of organisms that are currently isolated. This will be only possible with the immediate action of government agencies. However, the government of Paraná opposes these measures by approving policies allowing the exploitation of protected areas by private companies. This is especially concerning considering the politics of the Federal Brazilian government, which openly promotes deforestation and illegal exploitation of natural areas in Brazil, especially by the drastic reduction of environmental inspectors and funds for scientific research. 

The team of researchers during field work. From left to right, Heraldo Vasconcelos (UFU), Rodrigo Feitosa (UFPR), Aline Oliveira (UFPR), Jonas Maravalhas (UFU)

Em um artigo científico publicado recentemente, cientistas da Universidade Federal do Paraná (UFPR), destacam a importância de um pequeno fragmento de Cerrado no estado, através do estudo das espécies de formigas que ocorrem nessa área. Enfatizando a necessidade de medidas para garantir a preservação desse fragmento, que é a única área de preservação desse bioma na Região Sul, e ressaltando o descaso dos governos, estadual e federal, com a preservação ambiental.

A coleta das formigas para o estudo foi realizada em 2015, no Parque Estadual do Cerrado (PEC), por pesquisadores das Universidades Federais do Paraná e de Uberlândia (Minas Gerais). O PEC está localizado no noroeste do estado do Paraná, essa região é o limite sul do Cerrado no Brasil, sendo uma das regiões onde o bioma se encontra mais fragmentado. Apenas um desses fragmentos, o PEC, é uma unidade de conservação protegida por lei.

Para coletar as formigas, foram utilizadas armadilhas no solo e nas árvores, chamadas pitfall. Os pitfalls de solo consistem em um copo plástico enterrado no chão de maneira que a abertura do copo fique no mesmo plano que o solo, e assim, as formigas que estejam caminhando próximo a armadilha, caiam nela. Nessas armadilhas são utilizados água e detergente, que tem a função de quebrar a tensão superficial da água, para que a formiga que caia no copo não consiga sair. Nas armadilhas nas árvores, os copos são fixados nos galhos utilizando fita adesiva, porém o conteúdo do copo difere da armadilha do solo, sendo utilizado água com urina humana, que é um forte atrativo para essas formigas.

As formigas coletadas foram levadas para o Laboratório de Sistemática e Biologia de Formigas, sediado na UFPR, onde os exemplares foram estudados e depois depositados na coleção científica da universidade.

Os pesquisadores compararam o PEC com outras 30 localidades de Cerrado distribuídas em todo o Brasil e descobriram que essa região é a terceira área com maior diversidade de formigas, mais de 130 espécies, além de espécies raras, espécies especialistas de Cerrado, e outras espécies ainda desconhecidas pela ciência. A grande diversidade de formigas é um indício de que o parque abriga uma grande diversidade de outras espécies, uma vez que as formigas têm interações ecológicas com inúmeras espécies de plantas, de insetos, e de outros animais, como pássaros, anfíbios, repteis e mamíferos. Elas também realizam funções no meio ambiente como aeração do solo, ciclagem de nutrientes, e dispersão de sementes. Isso destaca a importância de preservar o parque, e consequentemente, toda a fauna existente nele.

Apesar da importância desse parque, ele está bastante ameaçado, basta olhar o seu entorno, que veremos uma gigantesca área desmatada, que dá lugar a plantações de monoculturas, como Pinus, soja, milho e outras. Essas plantações se utilizam de agrotóxicos que podem chegar ao parque e afetar as espécies que vivem lá. Além disso, espécies como Pinus, que é exótico, podem invadir a área do parque, podendo causar o extermínio das plantas nativas. Portanto, ações devem ser tomadas para ampliar a proteção de Cerrado no estado do Paraná, através da criação de novos parques, e a criação de corredores entre eles, incluindo áreas de vegetação nativa que estejam em propriedades privadas. Essas medidas, no entanto, exigem incentivo financeiro e legal por parte das agências governamentais. Porém, na contramão disso, o governo federal incentiva publicamente o desmatamento e exploração ilegal de áreas naturais no Brasil, especialmente pela drástica redução na fiscalização ambiental e fundos para pesquisa científica. Alinhado a isso, o governo estadual aprovou recentemente uma lei que permite o uso exploratório de unidades de conservação por empresas privadas, que se for feito sem colocar a preservação da biodiversidade em primeiro lugar, pode representar mais uma ameaça para essa área que já está em risco extremo.  

Interview with a Social Insect Scientist: Sruthi Unnikrishnan

You can read Sruthi’s recent research article about the dominance behaviour of primitively eusocial wasps here.

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

My name is Sruthi Unnikrishnan. I am pursuing my post-doctoral research in Dr. Axel Brockmann’s lab in National Centre for Biological Sciences, TIFR, Bangalore. I am currently studying the behavioural maturation in Asian honeybees.

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

I had always been interested in animals. But it was after reading Prof. Raghavendra Gadagkar’s book called  “Survival Strategies“ that I became fascinated with social biology and more specifically social insects.

Sruthi at her study site. Photo credit: Thresiamma Varghese

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

I would have to say the model system I worked with for my PhD, Ropalidia cyathiformis. Its a beautifuI, shy wasp, sensitive to human interference and I think a very underrated species, having fallen in the shadow of a more popular sister species, Ropalidia marginata. I believe that R. cyathiformis is a species with a lot of potential to ask many fascinating and wonderful questions. The difficulty to study this species has resulted in its poor understanding which is unfortunate.

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

Actually it was during the analysis of my results for the current paper in Insectes Sociaux. During my analysis it showed that the queen seems to be directing the majority of her aggression towards the PQ (Potential Queen), her immediate successor. This was very exciting to me, because this indicated a certain understanding and perhaps a certain intelligence in them. That they are able to recognise the next successor and target that individual. It was even more exciting because the PQ in turn was targeting the workers. This showed a clear difference in strategy between the queen and PQ and I found that very exciting, because here is a queen that isn’t blindly dominating all the individuals in the colony, but rather had “outsourced“ this job to the next successor. This was a great strategy and not something that we have commonly seen in other primitively eusocial insects. I know it‘s silly, but I felt a little pride for my wasps.

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

I don‘t teach regularly, but I have taught courses in the past as part of being a TA and will be teaching a course on animal behaviour in this semester as well. I usually incorporate my research to better explain how to design and conduct experiments, especially designing behavioural observation schedules without any biases. By providing examples its easier for people to envision the methodology better. I myself find it easier to understand when I have an example. I was also involved in making people aware of the rock bees (Apis dorsata) in apartment complexes. Since the rock bees generally build nests near balconies of apartments, people tend to kill off the colonies due to fear. By making people realise the importance of these bees and making them aware of their behaviour, it reduces such instances of colonies getting culled.

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

I’m not sure about important, because I think every work at the end of the day has its own importance. Personally, for me something that I find interesting is the work on personality and behavioural syndromes in animals. I think social insects are a great model system to study how individual variation might arise and how they might in turn affect group decisions. I feel more focus would be nice on this aspect in social insects.

Nest of Ropalidia cyathiformis.

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

I think in my field, one of the on-going debates is about the categorisation of social insects into different levels of sociality, where does one draw the line for eusociality and sociality and so on. 

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

I read the Mistborn series by Brandon Sanderson. It’s a sci-fi fantasy book series. I really love this genre and in particular I love world building, where there are clear rules about how the world works, which is really beautifully set in these books. Particularly the details of the world-building in this is just amazing!  

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

I love reading and music (both singing and listening). I also enjoy doodling, which is a relatively newfound hobby and I find it a huge stress buster. I also really enjoy doing improv.

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

My parents are my major source of support, the ability to talk to them and just vent out my frustrations and problem or just have a good cry has helped me in a long way. They have been very patient, understanding and extremely good listeners, I think that support has been one of the major reasons I survived through tough times.

Sruthi with her parents at her thesis defense.

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

My kindle for sure, filled with as much books as possible, I can’t imagine going anywhere without it. Also, my laptop and my headphones.

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

It’s hard to pinpoint one person, but my parents have been a great support. They supported me when I decided to choose a slightly different path than was the norm amongst my peers. Another person, I would have to say is my PhD advisor, Prof. Gadagkar. He has very strong ethics and methods of doing science and that has influenced how I myself conduct my research. How to ask good questions, how to design fool proof experiments and how to carry out the experiments without biases are some of the things I learnt from him. My current advisor, Dr. Axel Brockmann has also been a great supportive figure in my life. Brainstorming with him has been amazing and he has helped me appreciate and better understand the molecular and genetic underpinnings of behaviour.

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

To be patient, very patient. Research involving animals and studying them in their natural habitat would most often not go according to what you plan. Several times your model system might not cooperate, or the weather might not or maybe predators of the animal that you are studying might interfere and so on and so forth. There are so many unforeseen circumstances that might come about. Hence, if you ask me, the most important thing a researcher in this field would need is patience and not be dejected and lose hope, but rather strive ahead.

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

I would have to say Rio de Janeiro in Brazil. There was an IUSSI conference in Sao Paulo in Brazil and after the conference I took a trip to Rio and I absolutely loved it! I loved the place, its energy and people! The place was so vibrant and colourful.

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

I would want to investigate the different Ropalidia species that are found in India. There are several Ropalidia species, most of which have gone under the radar. With the strong base laid out by Prof. Gadagkar’s lab with the studies on Ropalidia marginata it could prove as a good comparison point for the other species. It will be especially interesting as there are various levels of sociality present within the Ropalidia genus and just as we found that R. cyathiformis and R. marginata make good examples of comparative systems to study the evolution of social insects, these species would also help in this direction. They make the perfect system to do comparative studies and understand the evolution of eusociality as these species are all of the same genus and have different levels of sociality. The potential for this study would be limitless.

Interview with a Social Insect Scientist: Sara Miller

You can read Sara’s recent research article about the ecogeographical patterns of body size variation in Polistes paper wasps here.

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

SM: My name is Sara Miller. I’m currently a postdoc at Cornell University in the Sheehan lab. My research focuses on why biological diversity evolves and in particular how interactions among animals can drive the evolution of diversity. I now work with Polistes paper wasps, but I did my PhD at the University of British Columbia working on threespine stickleback (a small species of fish).

Sara Miller catching threespine stickleback at North Lake in British Columbia

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

SM: I have always been interested in animals and I think that the question of why are there so many species of animal is one that drives many scientists. I love learning new tools and techniques which makes studying the evolution of diversity a great choice for me. This question can be investigated from many different angles and that has allowed me to work with everything from genomes to live organisms to specimens in museum collections. When I started my postdoc, I decided to switch from fish to social wasps because of how amazing social wasps are as a study system. The small genome size of social wasps and the fact that males are haploids make this a fantastic system for looking at the genetics of diversity. Social wasps are abundant and easy to find so while collecting wasps still requires a net, I no longer need a boat to do research. Social insects are also great because there are decades of amazing work on social behavior for these species but there are still many unanswered questions about diversification in social insects.

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

SM: My favorite social insects are, of course, paper wasps! I love the diversity in this group, particularly the color variation both within and among species. Of the 200 or so species of Polistes, my favorite is probably P. fuscatus. Female P. fuscatus have unique facial markings, and other females use these differences to recognize and remember other individuals, making this species (arguably) the “smartest” insect on the planet. My recent research suggests that this new cognitive ability has likely evolved extremely recently, making this species even more remarkable.

A female Polistes fuscatus on her nest. Note her distinctive facial markings!

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

SM: A large component of my PhD was a pretty high-risk project looking for parallel genetic differences between populations of stickleback fish that occurred with and without a predator species. Going in, I had no idea if I would find even a single genetic difference, and I worried that I had spent a lot of time and money on a project that wouldn’t have interesting or interpretable results. When I analyzed the data, to my surprise, I found differences in more than 600 genes – way more than I would have predicted. One of the best things about science is learning something new and being surprised by that answer.

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

SM: I’ve done social insect outreach as part of Insectapalooza, an annual event in which thousands of local residents come to Cornell to learn about the exciting world of insects. Along with the other members of the lab, I explained to visitors why wasps are so cool.  We set up a “meet a wasp” booth where visitors had the chance to touch a male wasp (males lack stingers) and this was a huge hit, especially with little kids. It was really rewarding to see people changing the way they thought about these often-misaligned species.  

Sara Miller talking about facial recognition at Insectapalooza

Otherwise, a lot of my outreach activities are focused on data digitization and increasing data accessibility. Digitizing and archiving data is important because it increases the diversity of users of that data, and provides baseline information for tracking how species respond to global change. In the context of natural history collections, digitizing specimens allows researchers, science educators, and people from all over the world to interact with the specimens in the collection. I’ve been working with the Cornell University Insect Collection (CUIC) and other natural history collections to photograph, barcode, and transcribe label information associated with specimens. Digitizing natural history collections is a gargantuan task and collections need all of the help they can get so I urge other social insect researchers to consider volunteering at their local natural history collection.

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

SM: The world is becoming increasingly difficult for all insects as these species face simultaneous challenges from changes in climate, land use, pesticides, and invasive species. I think that basic research on the ecology of social insects – how they interact with other social and non-social insect species, the impact of social insects on the ecological community, and what factors limit or promote the expansion of species ranges – will be important for understanding how environmental change will affect social insect species and will provide important information on how to mitigate these effects in the future.

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

SM: There are a lot of unanswered questions and interesting ongoing research about which genes or other genetic mechanisms are necessary for caste development, how conserved are these mechanisms across independent origins of sociality, and how did these mechanisms evolve.

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

SM: If I’m not reading for work, I mainly read fiction. The last books I read were, “Dark Matter” by Blake Crouch and “The Circle” by Dave Eggers. “Dark Matter” is a novel about alternative realities and the consequences of the choices we make, and “The Circle” reads like your crazy relative wrote a 400-page conspiracy theory about social media but also happened to be a pretty good writer. I’d recommend them both if you like fast-paced Sci-Fi.

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

SM: I’m an avid reader, and like to go hiking, or do yoga. I enjoy nature photography and working with social insects has been a great motivation to try to improve my macrophotography skills.

A female Polistes metricus wasp collected in 1896 from the region that would later become the state of Oklahoma.

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

SM: When field work gets tough, I always think of this anecdote by Jonathan Losos from his book, “Lizards in an Evolutionary Tree”. Early in his PhD, he spent days unable to do any research because a key on his computer needed to start his equipment stopped working in the rain. Finally, the sun came out, his key dried out, the experiment worked, and he eventually ended up a professor at Harvard University. Just because you encounter setbacks, doesn’t mean that you won’t eventually succeed. Keep going, be willing to be flexible, and try to learn from the experience so you can make completely different mistakes next time!

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

SM: I would bring equipment for staying connected to friends, family, and collaborators.

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

SM: I’ve been fortunate to have a lot of great mentors throughout my career but my PhD advisor, Dolph Schluter, has probably had the greatest influence. He is a meticulous thinker and taught me to consider both the “big picture” of how my research fits into the larger context of science, and to think about all possible explanations for my data.

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

SM: Doing science is much more frustrating and rewarding than learning about science in class. My advice for undergrads interested in a career in science is to get involved in research to see if it is right for you. Contact labs that do research that sounds interesting or look for Research Experience for Undergraduates (REU) programs.

The Polistes collection at the American Museum of Natural History, New York

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

SM: I had the opportunity to visit the insect collections at the Smithsonian Natural History Museum in Washington D.C and the American Museum of Natural History in New York. Combined, these collections have more than 20,000 Polistes specimens from an incredible number of species. It was really interesting both to see species from all over the world and to get a window into the past through these specimens. Some of the oldest Polistes specimens were collected in the 19th Century and it is remarkable to consider how much the world and science have changed since those specimens were collected.

Interview with a social insect scientist: Yoshihiro Y Yamada

You can read Yoshihiro’s recent research article about the influence of photoperiods on caste fate of paper wasps here.

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

My name is Yoshihiro Y Yamada. I am a professor emeritus at Mie University, Japan: I retired at the end of March 2020. I have been studying the behavioral ecology of parasitoids and host-parasitoid population dynamics over 40 years, and I started to study the social biology of paper wasps around 2005. I will continue to study the social biology of paper wasps as long as I am healthy.

Yoshihiro Y Yamada in Zen meditation

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

The late Dr. Matsuura, former professor of Insect Ecology Lab at Mie University, was an expert in the biology of Polistinae (paper wasps) and Vespinae (hornets). I had often talked with him and his students, and I became interested in paper wasps and had several questions about the biology of paper wasps. I am now exploring answers to these questions with my coworker Dr. Yoshimura.

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

Paper wasps. I have observed them for so many years that I feel as if I could understand how they feel, what they want, and what they are thinking about.

Nest of Polistes jokahamae. Photo: Hideto Yoshimura

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

Regarding the field of the social biology of paper wasps, our best discovery is that photoperiod is an important factor for determination of caste fate in the paper wasp Polistes jokahamae (Yoshimura and Yamada 2018, 2021). Bohm (1972) suggested that that photoperiod could influence determination of caste fate in P. metricus, but no researchers have studied the effects of photoperiod in paper wasps since Bohm. Many researchers appear to disagree with the importance of photoperiod. Our preliminary experiments suggest that photoperiod influences determination of caste fate in several other temperate paper wasps. We are sure that most temperate paper wasps use photoperiod as a cue for determination of caste fate.

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

I sometime teach the biology of bees and wasps, including current hot topics and our recent works to high school students and adults interested in the development of science.

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

Regarding social wasps, mechanisms for caste-fate determination and for establishment and maintenance of queen royalty are important themes for current studies. Comparative studies of several species are essential for future research.  In addition, it is important to keep in mind that several factors are involved in the mechanisms.

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

Regarding social wasps, do adults emerge with a caste-related bias? In other words, to what degree does preimaginal caste determination occur? Answering this question is critical for understanding the origin of eusociality and transition from primitive to advanced eusociality.

Hideto Yoshimura, smiling, with a large nest in his hand

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

Pheromones and Animal Behavior: Chemical Signals and Signatures, by Tristram D. Wyatt (2014). I strongly recommend students interested in pheromone communication in animals including insects and vertebrates. The book is quite readable, particularly for people without special knowledge of chemistry. Researchers also might get some hints from the book.

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

Gardening. I am trying to make a garden attractive to animals. When my wife and I have breakfast or tea while watching insects, birds and cats visiting our garden, we have a peaceful and wonderful time.

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

I go to an onsen (hot spring) area for relaxation. In addition, I practice Zen meditation.

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

My wife Tomoko, survival kit including fishing equipment, and sake. I cannot imagine the world without them.

Hideto Yoshiura collecting a nest

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

Dr. Tomo Royama and his book, Analytical Population Dynamics: I managed to understand the essence of population dynamics through him and the book.  I hear that his new book will be published soon.  I am looking forward to reading it.

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

I hope that young researchers will have their own questions and explore them, not just follow current hot topics.

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

Campus and experimental farm and forest of Mie University and mountain and hill areas in Mie prefecture: many insects, including wasps and bees, are found in the areas.

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

I would like to go to subtropical and tropical areas and explore the biology of paper wasps.

How best to sample termites – or the importance of loo rolls

By Paul Eggleton

Based on research for the review paper, in press: “A.B. Davies, C.L. Parr and P. Eggleton. A global review of termite sampling methods. Insectes Sociaux.”

The three co-authors (from left to right: Kate Parr, Andrew Davies and Paul Eggleton) giving out a certificate to a student at a termite identification course in South Africa.

Social insects have always been difficult to sample. Do we count the colonies or the individuals; the organism or the superorganism? The bumble bees buzzing in your garden, are they really separate beings or just flying bits of an individual that is, in fact, much bigger?  But at least bees and wasps fly, so can be sampled using nets or traps that catch insects on the wing, and ants are usually running around on the ground, so can be sampled using traps that they fall into. When it comes to termites, only the reproductive caste flies, and all the wingless individuals, the soldiers and the workers are underground in the soil or hidden in dead wood.  This wouldn’t matter if termites were rare and unimportant things, but, in fact, they make up a huge amount of global animal biomass and are known to be extremely important for ecological processes. This poses a real problem for termite quantitative sampling, which is vital if we are to understand the role of termites in ecosystems. We discuss this in our recent paper, where we review termite sampling methods.

Termites are found predominantly in the tropics, in areas that traditionally have been hard to access. They are at their most abundant in tropical rain forests and savannas, places that are hot and often extremely humid.

Soldiers of Macrotermes bellicosus on the surface of dead wood, Kenya

The most obvious way to sample termites is to extract them from their mounds or nests. Termite mounds are easy to find, and although some of them may have a hard outer wall, are easy to get into. However, this will not give an accurate estimate of the species present as only a small fraction of termites have conspicuous mounds. Most colonies live underground, with no visible external structures. In fact, here are really only two ways to sample termites effectively – sampling them directly by picking them out of where they live or attracting them with baits.

A toilet roll out in the field for monitoring porposes (Sabah, Malaysia)

In dry areas, such as dry savannas and deserts, toilet roll baits are the most effective way of assessing termite diversity and activity. They are essentially cellulose, which is like a chocolate snack for a termite. In fact, termites generally gobble up the outer tissue rapidly and leave the inner roll behind. The termites can be taken directly out of the roll and the state of the roll can be assessed for termite activity. This works because in drier areas there is generally only wood feeders and there are few termites that can be extracted from the dry, hard soil. The main problem is that they are attractive to larger animals, particularly people, and they can, fairly often, be removed or disturbed by pigs or dogs. Toilet rolls are a major part of my group’s field work tools, and shopkeepers are often surprised when you buy their whole stock of loo roll in one go. They must wonder why on earth we need so much!

Toilet rolls waiting to be deployed (Sabah, Malaysia).

In wetter areas the problem there is the opposite – there are too many termites that live in the soil and are not attracted to cellulose baits. Soil-feeding termites become increasingly important as the environment becomes wetter and more stable. They feed directly on the soil and are important elements of the nitrogen cycle. Most of these termites are found living underground, with no obvious nest structures and so digging up the soil is the only way to find them. This is also related to the habitat complexity, as soil feeding termites are predominantly found in tropical rainforest, which show great horizontal and vertical variation, across the ground and up the trees. This means there are more places to search in tropical rain forests than in drier savannas – the soil, in mounds and nests, in and on trees, in dead wood, in the soil, and in the buttress roots of trees.

The authors’ student Fidele, sampling termites using the ‘transect method’ in a Gabonese rainforest.

We recommend some standardised methods in the paper, and essentially propose a standard method, and modifications of it that were developed in the late 90s, by my colleague, David Jones and me.  This involves intensive searching of a 100 m x 2 m “transect”, and takes, a rather gruelling, 20 person hours to complete.  In areas, such as wet savanna, where there are fewer trees, and many fewer places to search, we have reduced this to a fraction of this time, while still retaining the same general principles.

There are some habitats where sampling is harder. Grasslands tend to have surface foraging grass-feeding species that do not come to toilet roll baits and have unpredictable foraging patterns, usually at night. Sampling termites using a head torch is probably a step too far for even the most dedicated termitologist.

Ants can learn lots, fast

by Tomer Czaczkes

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

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

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

The joys of comparative psychology:

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

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

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

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

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

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

Back to the ants   

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

References

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