IS: Who are you and what do you do?

RG: My name is Raghavendra Gadagkar and I am currently a Professor in the Centre for Ecological Sciences at the Indian Institute of Science, Bangalore, India.

I do several things:

I research questions concerning the evolution of cooperation and conflict in animal societies, using the Indian paper wasp Ropalidia marginata for my empirical research.

I teach evolutionary biology, behavioural ecology, sociobiology and organismal biology to doctoral, masters and undergraduate students.

As President of the Indian National Science Academy (until recently) and with other similar affiliations, I contribute toward the promotion of science and good science policy in India and elsewhere.

IS: How did you end up researching social insects?

RG:  I was fond of catching and watching insects, frogs and other moving creatures as a child. In college I encountered several colonies of Ropalida marginata on the windows of the zoology department. I could not help watching them out of curiosity and have not since looked back. R. marginata also converted me from a catcher (they sting) to a watcher (their behaviour is fascinating). At first I watched them merely as a layman. Then I began to study them scientifically, but only as a week-end hobby. After my PhD in molecular biology, I converted my hobby into my full-time profession.

IS: What is your favourite social insect and why?

RG:  The tropical primitively eusocial wasp, Ropalidia marginata. I have been studying it for over 40 years and it continues to present me with new intellectual challenges and continues to give me great delight. I have not felt the need to look beyond, with the exception of occasionally studying the congeneric Ropalidia cyathiformis, but only to understand R. marginata better.

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

The discovery of behavioural caste differentiation into Sitters, Fighters and Foragers through the use of multivariate statistical analysis of quantitative behavioural data, in the early 1980’s remains, to this day the most exciting and memorable moment. Several factors have contributed to the special status of this early work. It was my first scientific discovery outside of molecular biology, it was made entirely by following my instincts rather than by following the literature and it has remained the starting point for almost everything I have done since.

IS: If teaching is part of your work, what courses do you teach? Has your work on social insects helped to shape your teaching?

RG: I teach courses in evolutionary biology, behavioural ecology, sociobiology and organismal biology to doctoral, masters and undergraduate students. During the last five years my undergraduate students regularly perform field and laboratory experiments with ants, bees and wasps.

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

RG: The most recent book I have read is “Half-Earth: Our Planet’s Fight for Life” by EO Wilson. I would strongly recommend it to any and all persons. It is a remarkably well-written and passionate plea to treat the planet responsibly. Besides, it is brimming with the most recent scientific discoveries, described in Wilson’s inimitable style and laced with Wilson’s priceless wisdom.

IS: Did any one book have a major influence in shaping your career? What was the book and how did it affect you?

RG: Two books that I read as a first-year undergraduate changed my life: King Solomon’s Ring by Konrad Lorenz and The Double Helix by James Watson. Both books described great science but their real magic came from the fact that they described the process of doing science.

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

RG: When I was doing molecular biology, watching wasps was my hobby. When watching wasps became my profession, I needed a new serious hobby, besides reading book and watching movies. My new hobby is to break the boundaries of scholarship and bring together the natural sciences, social sciences, humanities and arts, both in research and in teaching.

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

RG: Just keep going – there is no other way! My science itself is a hobby so that things never really get that tough.

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

RG:  The answer to this depends on where the island is located and how long I would have to be there. Besides, today, this question has become a bit trivial – most people on the planet would say: “my smartphone is enough”. That would be my first choice with or without internet, as long as I can power it with batteries. I am not that much of a field biologist and my passion is more in watching than in catching. I suspect that I could spend endless time watching all kinds of animals, especially insects for which I need almost nothing.

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

RG:  My science teacher in sixth grade inspired me to become a scientist, my biology teacher in 8^th grade inspired me to become a biologist, WD Hamilton and EO Wilson have been my role models.

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

RG: The same advice that I would give to any young researcher hoping to do any kind of science – avoid fashions and try to do something original and creative and minimize your dependence on what is hard to get (funding, equipment or whatever is hard to get). In the context of social insect research today this translates into studying behaviour in the field.

Highlighting the article written by T. Takeuchi, R. Takahashi, T. Kyoshi, M. Nakamura, Y. Minoshima, J.-I. Takahashi in Insectes Sociaux

Written by Insectes Sociaux Editor-in-Chief, Michael Breed

In this issue of Insectes Sociaux, Takeuchi and colleagues reveal the genetic origins of an invasive population of Vespa velutina (the yellow-legged hornet) in the western islands of Japan. This invasive wasp is a predator on the honey bee species Apis cerana in its native range and can prey on Apis mellifera outside of its normal range (Monceau et al 2013). Native to the southern part of Asia and to Indonesia, it has also been introduced into Korea and Europe. They use mitochondrial DNA sequences to generate a cladogram for populations of this wasp and are also able to draw conclusions about genetic variation in the invasive population in Japan. Genetic variation may support the phenotypic flexibility exhibited by some invasives and consequently it is an important feature to characterize in invasive populations.

The role of social insects, such as this hornet, as biologically invasive species is well known, principally because of the prominence of invasive ants through the last 100 years in ecological studies and their creation of important issues in public health and agriculture. The numerous exemplars of high-impact invasive ants include the red imported fire ant, Solenopsis invicta, the pharaoh ant, Monomorium pharaonis and the Argentine ant, Linepithema humile. The Formosan termite, Coptotermes formosanus, is a major pest in many habitats.   The western honeybee, Apis mellifera, is invasive throughout the Americas, first as an introduction by European colonialists on the east coast of North America in the 1600s, and then by the introduction of a more aggressive form in the 1950s in Brazil.

In some cases invasive social insects, such as the fire ant and the Argentine ant, are perceived to have essentially overrun an entire ecosystem. These species cause massive shifts in the terrestrial invertebrate fauna, impact the reproductive success of ground nesting birds, and have ripple effects on other trophic levels. However, many social insect invasions occur quietly and go largely unnoticed because the ecological impacts of the invasion are subtle and there are no apparent public health or agricultural implications of the invasion. Whether the impacts are large or small, understanding the processes of biological invasions is a key question in evolution, ecology and behavior.

What makes some social insects such effective invasive species? Ecological flexibility, high reproductive rates, and ability to disperse within the landscape all must be important factors. But many populations of invasive species, social insect or otherwise, survive very narrow genetic bottlenecks. Introductions of species to new areas often involve the transport (typically by humans) of a very small number of individuals or colonies. This may translate into invasive populations with low genetic diversity.

Takeuchi et al (2017) sequenced three mitochondrial genes, COI, Cytb, and 16S rRNA, from samples of V. velutina collected across its natural range, plus invasive populations in Japan and Korea. Their results show that this species is likely monophyletic, but that there are two relatively distinct geographical clades, one in Indonesia and Malaysia, the other more broadly distributed in continental Asia. The invasive Korean population nests within the populations from China, and the invasive Japanese population probably derives from the geographically nearby Korean population.

Significantly, Takeuchi et al (2017) found no genetic variation in these genes in the Japanese population. While their finding is unusually low, even for an invasive that has gone through a genetic bottleneck, it is by no means out of the ordinary to observe invasive social insect populations that derive from a few individuals or a few colonies. In the case of V. velutina, Takeuchi et al. (2017) argue that fertilized queens could easily be carried along in goods transported by humans and that, in a practical approach to regulation of invasions, vigilance for fertilized queens might be useful. It would be very interesting to compare the social flexibility and ecological adaptability of the Japanese population of V. velutina with Chinese populations to see if these features have been affected by the bottleneck.

These findings raise the very interesting question of how invasive social insects are able to retain ecological and social flexibility, keys to being successful invasive species, through periods of small population size. Mechanisms for carrying characteristics that are key to invasiveness through a bottleneck could include having multiple queens in colonies mating more than once, plasticity in phenotypic expression, or rapid evolution of genetic diversity via mutation. Each of these strategies could be effective, and future work building on approaches like those of Takeuchi et al (2017) should help to explain the properties that make some social insects such effective invasive species.

 

References

Monceau K, Arca M, Leprêtre L, Mougel F, Bonnard O, Silvain J-F, et al. (2013) Native Prey and Invasive Predator Patterns of Foraging Activity: The Case of the Yellow-Legged Hornet Predation at European Honeybee Hives. PLoS ONE 8(6): e66492. https://doi.org/10.1371/journal.pone.0066492

Takeuchi T, Takahashi R, Kyoshi T, Nakamura M, Minoshima Y, Takahashi J-I. (2017) The origin and genetic diversity of the yellow-legged hornet, Vespa velutina introduced in Japan. Insect Soc DOI: 10.1007/s00040-017-0545-z