Interview with a Social Insect Scientist: Rafael Carvalho da Silva

You can read Rafael’s recent research article about the chemical composition on the cuticle of the German wasp Vespula germanica here.

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

My name is Rafael Carvalho da Silva, but my close friends call me Rafa. I am currently a Ph.D. student at Universidade de São Paulo (USP), Ribeirão Preto – SP / Brazil. I developed my research project at Laboratório e Comportamento e Insetos Sociais (Lab CEIS), which is led by Professor Dr. Fabio Santos Nascimento. I got my Master’s degree in Science (Entomology – 2018) at the same university, and since 2016 have been studying how cuticular hydrocarbons (CHCs) are used by social wasps to mediate different types of interactions. During my Master’s, I focused on studying one species of social wasps to evaluate whether CHCs would reflect information concerning the dominance hierarchy system. Now, in my Ph.D. project, which I started in 2018, I am interested to study the role of brood (mostly eggs) as communicative sources in the societies of wasps and the effect of juvenile hormone in physiological modulation (e.g. chemical signaling and reproduction).

Team of the Laboratório de Comportamento e Ecologia de Insetos Sociais (Lab CEIS)

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

I have always been passionate about animals during elementary and high school. The disciplines such as Science and Biology were always the ones that I was mostly interested in. I remembered spending hours observing foraging trails of leaf-cutting ants, when I spent my holidays at my grandmother’s house. During the first two years of my Bachelor Biology course, I was interested in studying frogs to check how temperature affects tadpole development, and also if foam nests protect eggs from the temperature variation during the day. In my third year, because I attended an Entomology course, I switched to insects. Also, I received a didactic grant to teach about insects in a public high school. So, after these two nice experiences, I was sure that after finishing my bachelor course, I would enroll in an Entomology postgraduation program. Ribeirão Preto city was always my first option, because not only has it one of the best universities in the region, but also an Entomology degree is highly prestigious nationally and internationally. My current advisor offered me a volunteer internship to survey wasp nests distributed on the campus of Ribeirão Preto, and so my journey with the wasps started.

Fieldwork conducted at the beginning of 2020 at Universidade de São Paulo, Ribeirão Preto – SP/Brazil

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

Even though I had already worked with different social insects during the past years, my favorite species is Mischocyttarus cerberus. I, of course, would choose a wasp species, because besides their importance for the environment providing ecological services (e.g. predation of several crop pests and pollination), they also perform many interesting behaviours. The species Mischocyttarus cerberus is a primitively eusocial wasp species that is commonly found in shed locations on campus where I work. They build small nests without an envelope, which allows us to stand in front of their nests and easily observe adult females interacting with each other and the brood – it is almost impossible to not feel excited about the way they interact with each other. The most interesting fact about them is that they organize themselves in a dominance hierarchy system, in which aggressive acts (e.g., biting) are used to induce other females to leave the nest and forage, for instance. Further down below, you can find a picture of a nest of M. cerberus containing females with a yellow face and males with a white face.

Nest transference of the swarming-found wasp Polybia sp. during my volunteer internship at Universidade de São Paulo, Ribeirão Preto – SP / Brazil

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

Conducting a project with my favorite wasp during my Master’s and later having the chance to publish the results of my discoveries “Dominance hierarchy, ovarian activity and cuticular hydrocarbons in the primitively eusocial wasp Mischocyttarus cerberus (Vespidae, Polistinae, Mischocyttarini) (da Silva et al. 2020 Journal of Chemical Ecology)”, was definitely the best moment in my research so far, until now. Even though Mischocyttarus wasps are common in Brazil, the number of studies investigating the role of CHCs in their societies is still low compared to social wasps from other genera Polistes, Ropalidia and Vespula.

Nest of Mischocyttarus cerberus containing females (yellow face) and males (white face).

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

Yes, since my Bachelor I undertake activities for science communication. During the third and fourth year of my Bachelor studies, I received a didactic grant to teach about insects in a public high school. In my fourth year, I volunteered to teach Agronomy students for an Entomology course. Additionally, I had always participated in citizen science events, where I presented the professional career of a Biologist, to convince people why insects are good and not bad. During my Master’s and now as a Ph.D. student, whenever I am invited, I give lectures about wasps or chemical ecology.  In 2019, I returned to my old elementary school to give a talk to show my trajectory as young scientist to children and teenagers. When I have the chance, I enjoy doing something like this a lot, because through these moments we may cause a positive impact for science and specifically insects, and even may inspire someone else’s life. On campus, because I videotape wasp nests outdoors, it is common that people get curious and come to ask me what I am doing. Then I explain that I am studying the behaviour of wasps, and they often ask me with a weird face “Why wasps?”. In these moments I think that it is fundamental to teach people about these animals, and maybe try to change their perception about insects in general as well. Considering the difficulties of science in Brazil, even when I am not formally doing science communication, I am still trying to reach different people personally or online and teach them how science is important for all of our lives.

Sometimes the nests of Mischocyttarus cerberus are hanging in higher places that requires to use a big ladder to reach them.

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

Well, I would not say the most important, because at the end I believe that all different questions and topics (from describing species to understanding specific processes of insect physiology) have their level of importance and relevance, but maybe the most current questions are covering subjects like the genetic and genomic basis behind social behaviour. In addition to that, considering that we have been facing difficult times because of the pandemic situation, the questions covering subjects like social immunity, such as “How do individuals in a colony of social insects deal with infectious diseases?” are also appealing. Through them we may learn some things that could be applied to our society. I believe the work related to this social immunity topic will be essential in the near future.

Lecture given about “Chemical Ecology” for undergrad students during the XVIII Summer Course in Entomology – Universidade de São Paulo (USP), Ribeirão Preto – SP / Brazil.

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

In my opinion some questions that still generate a lot of discussion among researchers studying social insects are “How do queen pheromones work in colonies of social insects? Are they manipulative signals or are they honest signals?”, “Which traits does juvenile hormone modulate in queens and workers belonging to different levels of sociality? Does it regulate different traits depending on caste (queens = reproductive traits; workers = behavioural traits)? Or alternatively, does it modulate several traits regardless of castes?”. These are questions I have particular interest in and are related to my research topic. As I said, although these are questions that researchers started to ask decades ago, they still generate debate among scientists working on behaviour of social insects.

A Mischocyttarus cerberus female touching the nest with its antennae.

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

The last book I read is called “The third pillow by Nelson Luiz de Carvalho”, which is a fictitious Brazilian novel based on real facts. If you are someone who reads a novel book expecting a happy ending, I would not recommend this one. But for someone who does not mind about the ending, then I would highly recommend it. This is the type of book that you take on Sunday afternoon, have a seat, grab a cup of coffee, and read at once. It is easy reading and has a lot of drama.

A Polistes versicolor foundress looking at the camera.

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

Outside of science, I enjoy taking pictures, going for a walk with friends, spend time just relaxing at home, and watch a good thriller movie, which I am a big fan of. Before the pandemic, I used to gather with my friends whenever possible to hang out, have some beers or eat ice-cream.

Guards of Tetragonisca angustula around the nest tube entrance.

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

When things get tough, I usually do things that I know that are relaxing for me, such as talk to one of my closest friends, go for a walk alone while listening to my favorite songs or just watch a good movie or TV series.

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

Considering that even if I were alone on the island, I would try to do something meaningful to spend my time, I would take with me a notebook, a package with pens and pencils and a camera with infinite memory and solar charger. Having these things would allow me to register and describe the animals (especially insects) on the island.

Workers of Trigona sp. collecting honeydew of treehoppers.

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

Honestly, it is impossible to name a single person, rather I would say that a couple of people were or still are a positive influence on me. While I was still a Bachelor student, three professors were fundamental to me, for different reasons, but mainly because they either got me in contact with insects or because they would give me good advice (Professor Dr. Marcelo dos Santos Fernandes, Professor Dr. Hertz Figueiredo dos Santos and Professor Dr. Kenji Claudio Augusto Senô). I also would like to highlight that my current advisor Professor Dr. Fabio Santos do Nascimento also had a considerable positive influence on my career, because he was the one that introduced me to the world of social wasps and is still advising me on my Ph.D up to this moment. I also give a lot of credit to my co-supervisor Dr. Cintia Akemi Oi, she has, for sure, a great positive impact on my scientific career, starting in 2018, when I had the chance to start collaborating with her while I was still a Master student. She has been always supportive, and we often have moments in which we brainstorm and plan our future projects.

Late instar larvae of Vespa crabro used in one of the projects developed while I was in Leuven in 2019, Belgium.

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

As advice, I would give the following: try to be involved with activities of the lab that you are interested in as soon as possible. Don’t wait and start early! Starting early will even allow you to switch to a different place if the work developed in your first lab does not please you. In addition to that, find a balance between “staying in a place because of the work” and “staying in a place where you feel good”, it will be important to work in a place where you have the chance to learn a lot and develop several skills, but it is equally important to look for a place where you will feel welcome. Lastly, it is important to stay up to date about the work that is being done in your area of study.

Team of Laboratory of Socioecology and Social Evolution (KU Leuven).

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

I would have to say Leuven in Belgium. In 2019, I had the chance of spending three months in the Laboratory of Socioecology and Social Evolution, headed by Professor Dr. Tom Wenseelers (KU Leuven) due to the bilateral project we currently have (USP and KU Leuven). While I was there, I could visit some cities there and got the chance of meeting new people and making good friends. I got involved in different projects and worked with different European wasp species. I do not remember if I ever ate so much chocolate and fries, and drank so many different beers as I did there.

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