Love, hunger, and fear unite all organisms on this planet, every organism; a bacterium, a cat, a whale and us. That is really what we most care about.
Shannon Olsson, is a chemical ecologist and group leader of the Naturalist-Inspired Chemical Ecology (NICE) Lab, at National Centre for Biological Sciences (NCBS) in Bangalore. In this blog-conversation, we bring forth her research work, on how an organism can identify and differentiate object or source in its ecosystem. Are you now wondering why it is crucial?
Let’s take few examples to start with. A bacterium uses chemical sensors to distinguish between toxic chemicals or sugar solutions. A plant as well has to identify which nutrients to absorb from soil; it can locate toxins, it knows when an insect is chewing on its leaves and has defense mechanisms to protect themselves. Olsson further adds, “While they do not just identify objects, they identify these things as love, hunger, and fear”.
As the environment gets more complicated, and an organism evolves in complexity, it becomes essential to identify and respond to these external cues. It is necessary for the organisms’ survival to accurately identify an object or source as food, danger or mate. Further, organisms need to distinguish food from poison, evade threat and/or where to mate; for healthy progeny.
While they do not just identify objects, they identify these things as love, hunger, and fear
The NICE lab’s research philosophy has evolved over the years. Their questions now target not just mere object identification, but the instinct behind that identification. They want to understand how ‘love’ – the ability to pass on genetic material, ‘hunger’ – the need to source food and ‘fear’ – avoiding danger in the ecosystem food chain, works.
The lab, for the most part, works on insects. Their small size does not mean their intake of sensory input from surroundings, processing of information and accurate object identification are any less critical to their survival. Unlike larger organisms, insects usually have to fend for themselves right after the eggs hatch. So how do insects take decisions?
(Shannon Olsson, and the members of NICE lab)
Olsson chose three distinct projects: a hoverfly or ‘flower-fly’, a white coffee stem borer and an apple-fly to uncover some of the mystery and intrigue that surrounds our understanding of the insect thought process. She stumbled onto hoverflies quite serendipitously. Her close friend, neuroscientist Karin Nordström in Uppsala, Sweden, had noticed that hoverflies are attracted to only certain types of flowers while ignoring the rest. Later at NCBS, she had a student show her the same species of hoverfly but found pollinating Primula, the beautiful wild purple flowers that grow around 4800 meters above sea level in Sikkim. She was struck by how despite the vastly different climatic factors, hoverflies in both Uppsala and Sikkim seem to be behaving the same way. What are the criteria these flies are using to select the flowers they visit?
The experiment called for thorough fieldwork. Olsson, Nordström, and their teams systematically collected data on the different sensory cues that the flies may be used to differentiate amongst these flowers such as color, smell, humidity pattern, temperature, carbon dioxide level and others. This data collected in Bangalore, Sikkim, and Uppsala were then modeled using statistical analysis methods by Josefin Dahlbom, a postdoctoral fellow in Nordström’s group. The analysis yielded some of the “ideal” cues or statistical signatures of “model” flowers or in other words, flowers that would individually be attractive to the hoverfly at the three different locations.
(Artificial ‘model’ flowers – image courtesy Aditi Mishra)
Olsson and a postdoctoral fellow from her team V.S. Pragadheesh then used paper cut-outs to make artificial equivalents of these simulated model flowers matching the color, smell, shape, and size of these mimics with the predicted parameters for use in field tests across the three locations. An initial test run in Bangalore was successful. Encouraged by that Olsson did her first field test in Sikkim in May 2016. Experimenting, Olsson admits frankly “was a terrifying thing” because even though, she had designed the flowers, there was no control on the hoverflies. They were all crouching around the paper flowers waiting for the flies to come. Much to her joy, the hoverflies did come. “I was just screaming, we were so happy. Because it was a big gamble. We did not know if they would come”, remembers Olsson as the first hoverfly landed on the Sikkim mimic. Subsequent field tests in Sweden and Bangalore showed similar results. However, what surprised Olsson was that the artificial model that attracted wild hoverflies in Sikkim, drew the flies in Sweden and Bangalore as well; despite the fact that no real flower actually looks or smells like the model in either Sweden or Bangalore.
Much to her joy, the hoverflies did come…. I was just screaming, we were so happy. Because it was a big gamble. We did not know if they would come
The obvious question that arose was what were the cues or combination of cues that attracted the flies in the first place – color, shape, size or smell. As Olsson and her group explored the signals further to understand which signal and in what proportion was the deciding factor for the hoverflies, they were faced with concepts like the absence of color or shape — ideas that called for artists and designers. Graduate student Aditi Mishra from the group is currently in the process of deconstructing this model one cue at a time, to gain further insight on what the minimal flower model could be.
At a time when our environment and climatic conditions are changing rapidly, these studies become all the more meaningful because they give us clues on how a native plant or animal can adapt to habitat loss.
Adaptation could also be necessary for the arabica coffee plant in Coorg, Karnataka to prevent an insect from destroying acres of coffee plantations. The insect is the coffee white stem borer, a beetle that is one of the most severe pests of the coffee plant. The borer lays its eggs on the stem of the plant, then the larvae bore through the stem, killing off the plant’s circulation, but because the larvae remain inside the stem, it is difficult to kill them with pesticides. Uprooting the trees is not an option because coffee plants are not short-living, unlike rice. They are practically trees. So uprooting a high-yielding infested plant is costly for the farmer. By the time the season ends the larvae would have already metamorphosed into an adult borer and flown to infest another plant.
(White coffee stem borer beetle – image courtesy Sriraksha Bhagavan)
Approached by a Coorgi coffee-grower for help, Olsson and her graduate students Sriraksha Bhagavan and Santosh Rajus worked with the Coffee Board of India to set up a field lab in Coorg to carry out an on-field experiment to study the beetle behavior. The lab was a tent of transparent netting wrapped around a coffee plant. Sriraksha and Santosh released 795 borers onto the plant and monitored it through 10 am-4 pm every day. Their observations showed that the insects do not necessarily need to mate on the plant. Post-mating the females fly to the coffee plant to lay their eggs. However, the stems are not their landing strip of choice, nor are the coffee berries. The leaves are. It maneuvers itself onto the stem only from the leaf. A series of simple elimination experiments further confirmed their theory. It was indeed the coffee plant leaf and even more specifically its smell that helped a borer pinpoint the location of the plant, a fact that this made sense because insects have the keenest noses, 10 million times more powerful than a human beings. To further add to their evidence, Santosh isolated the volatiles from the leaf and passed them over a single beetle antenna to check if there was a change in electrical activity in the beetle antenna neurons. The experiment was definitive meaning that the borer could indeed detect the coffee leaf smell, ergo its identification of the arabica plant leaf.
The lab was a tent of transparent netting wrapped around a coffee plant. Sriraksha and Santosh released 795 borers onto the plant and monitored it through 10 am-4 pm every day
(White coffee stem borer beetle – image courtesy Santosh Rajus)
There was more meat to the problem. It has already been observed that the borer prefers arabica plants to the robusta variety but the reason why is not known. To understand the mechanism by which the borers avoid robusta, Olsson and her group performed the same experiment as above except that this time, the borers had to choose between two coffee plants – arabica and robusta, under a vast tent. Contrary to what the farmers reported though, the controlled experiment showed that not only do the borers get attracted by the robusta; they even preferred the robusta over the arabica to lay their eggs. Once the eggs hatched, the group allowed the larvae to feed on the robusta plant — first on its bark and then gradually the wood. As the beetles bore into the wood, they found that the plant senses the infestation and actively releases compound(s) that kill the insects.
Suggests that precautions against casual use or overuse are necessary to avoid creating toxin-resistant beetle varieties as has been the case for many pesticide-resistant mutations in other insects
Sriraksha followed up this experiment with detailed toxicology and chemical analysis of the compound to understand the composition of the toxin(s) more precisely. More importantly,the experiments confirmed that robusta would be a highly efficient trap crop. Once the beetle’s mobility pattern has been studied further, the group plans to help the farmers strategize with crop laying in their plantations. Following a statistically optimized geometric model while laying the trap crop in an arabica plantation would lead to higher survival rates for the arabica plants. However, Sriraksha and Santosh have observed that not all robusta plants are equally resistant to beetle attack which suggests that precautions against casual use or overuse are necessary to avoid creating toxin-resistant beetle varieties as has been the case for many pesticide-resistant mutations in other insects.
Olsson’s work has ventured beyond merely what insects think and into how their ‘thoughts’ or rather, object identification, affect their decision-making process in real life. An apple-fly, originally native to the United States and currently a captive in her lab at NCBS is Olsson and her graduate student Pavan Kaushik‘s test subject. Their experiment attempts to reveal how the fly analyses two different cues like vision and smell to zero in on the location of an apple. Which is important because as Olsson says “the apple is its whole world. They mate on the apple.”
Motivated by Ronald John Prokopy‘s cardboard experiment in the 60s where he hung objects of different shapes and colors covered with glue from a tree to test if apple flies are attracted to them or not, Kaushik and Olsson have designed a virtual reality game for the fly. Kaushik tethers these flies to a needle with superglue and places them in front of a visual panorama that he creates through software coding. The visual cues for the fly are virtual apple trees, complete with well-defined leaves and fruit-laden branches. The needle holding the fly is surrounded by concentric tubes with valves all around. The tubes themselves are connected to a suction pump and an odor box. The setup controls how much of the odor cue the fly can sense at a time and also the wind factor that it would otherwise face in the real world, thus providing an additional direction cue.
Designed a virtual reality game for the fly
(Apple-fly virtual reality setup – image courtesy Pavan Kaushik)
Kaushik measures the fly’s wingbeats with particular emphasis on the wingbeat amplitude difference. The latter gives direction to the fly’s virtual flight much like a swimmer pushing harder with his right hand on the water in order to turn left while swimming, or vice versa. As the software senses this difference it feeds the information back to the panorama so that it moves accordingly giving the fly a full-blown “virtual reality”. Kaushik can control what odor cue and how much of it he wants to give the fly at any point in time. So the “apple trees smell like apples.” Together, the setup is akin to the fly using a steering wheel or “joystick” says Kaushik, to move towards its object of preference.
The NICE lab virtual reality (VR) setup is a resounding success. The apple fly is observed to fly towards the apple tree, responding to both the visual and the odor cues. “Honestly to get these flies to be able to behave in a completely artificial world by being held by the neck and do things that I sat at Cornell University and watched them do in nature is such a leap of faith that I wasn’t sure it was possible,” Olsson remarks. To her, the success of the experiment is even more meaningful in that the virtual reality setup did not need to be the ‘perfect’ mimic of an apple tree for the fly to behave as it does in nature. Kaushik and Olsson’s virtual reality game is in a way, a mini testbed for evolution. Their positive result with the VR setup implies that apple-flies respond to a basal limit too; millions of years of evolution have taught them to respond not only to the ‘perfect’ cues in nature but also to elemental ones.
Honestly to get these flies to be able to behave in a completely artificial world by being held by the neck and do things that I sat at Cornell University and watched them do in nature is such a leap of faith that I wasn’t sure it was possible
Understanding the behavioral pattern of an insect at the end of the day can be equivalent to decoding a black box. Shannon Olsson and her NICE lab do it by ‘thinking like a fly’ – four rather cryptic words that were the only piece of advice Thomas Eisner, famous entomologist and naturalist at Cornell University had given Shannon during her Ph.D. years. However, more than that, her naturalist-inspired ecological studies also involve unique ecosystems. Which means not only do we come away from the study knowing more about the insects themselves but also the premise behind some of their decision-making process that is fundamental to their survival.
Shannon’s goal through each of her projects is to help people realize how closely related we all are in nature in this very game of survival and that — “Maybe by coming up with these ways of empathizing with the natural world it can help us as a human race to be able to save it.” The talented bunch at the NCBS NICE lab is doing just that, one insect at a time.
Shannon Olsson and her NICE lab do it by ‘thinking like a fly’ – four rather cryptic words that were the only piece of advice Thomas Eisner
Author
She is an erstwhile scientist with a deep passion for science communication, science policy and outreach – a person of many hats. Science, to her, is a way of thinking. Trained in theoretical soft condensed matter physics, through the years she has branched out in various other directions, away from pure academia. She always tries to put on a scientist’s hat in order to bring in her own spin to the work she does. Currently, her professional interests lie in science communication, policy and project specific strategic communication. Having worked in unusual roles in multiple research institutes and also in an embassy science department, she has learned that strength in targeted communication requires command over both science and language, subject and matter. She tries to develop a skill set that includes both, and she is open to new experiences, new areas of growth that give her an opportunity to keep on learning.
Editor
Artist
Ipsa provided the cover image. She is a post-doctoral fellow at Instem, Bangalore. She tries to communicate science through visual arts as a medium. Collecting graphic books, tree trash, and reading brain pickings is few of her favourites. Follow and purchase her artwork at Ipsawonders (Facebook, Twitter, and Instagram). She will be happy to hear praises and non-praises at ipsajain.31@gmail.com.
The NICE Lab
The field photographs are provided by Aditi Mishra, V .S. Pragadheesh, Sriraksha G. B., Santosh Rajus and Pavan Kaushik. Follow them at Facebook and Twitter.
Blog design: Rituparna Chakrabarti
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