Hidden interactions

Leafcutter ants assiduously farming fungus, bumblebees picking up tiny amounts of electricity given off by flowers – all part of an invisible tapestry of interaction that is unfolding all around us. This episode celebrates the intricacy of our natural world.

Fundamental Research

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Transcript

00:00:00:00 - 00:00:39:24 Abigail Acton This is CORDIScovery. Hello and welcome to this episode of CORDIScovery with me, Abigail Acton. Did you know that when antelopes browse on an acacias leaves, the tree will emit ethylene, which acts as an alarm signal to other acacias nearby? The gas can spread for 45m. Within half an hour, the trees that pick up the signal flush their leaves with very bitter tannins to make them less palatable to the antelopes. 00:00:40:01 - 00:01:00:07 Abigail Acton In high concentrations, the tannins can even be fatal. Most of us are focused on what we can see, touch and feel or hear. We can hear one another. We know that some kind of communication is happening when a dog barks, but we are less aware of the interactions going on all around us that we don't perceive. So let's think again. 00:01:00:09 - 00:01:27:12 Abigail Acton Leafcutter ants diligently farming fungus bumblebees, picking up tiny amounts of electricity given off by flowers. All part of an invisible tapestry of interaction that is unfolding all around us. And perhaps we can work within that interconnecting web. Could the warning gases emitted by cereal crops under attack by pests lead to a more targeted approach to pesticide use, For example? 00:01:27:14 - 00:01:51:06 Abigail Acton Welcome to this episode of CORDIScovery, where we are celebrating the unperceived intricacies of the world with Daniel Robert, professor of Bio Nanoscience at the School of Biological Sciences at the University of Bristol in the UK. Daniel explores how insects respond to weak electrostatic fields, a previously unsuspected form of interaction between plants and their pollinators. Hello, Daniel. 00:01:51:09 - 00:01:52:21 Daniel Robert Hello. Nice to be here. 00:01:52:23 - 00:02:11:20 Abigail Acton Good to have you. Ted Turlings is based at the University of Neuchâtel in Switzerland, where he is professor of chemical ecology. By unraveling how plants defend themselves against insect attacks and how specialized insects have evolved, Turlings’ team hopes to create novel, sustainable methods of pest control. Hello, Ted. 00:02:11:22 - 00:02:12:24 Ted Turlings Hello, great to be here. 00:02:13:05 - 00:02:28:11 Abigail Acton Nice to have you. Associate professor of ecology and evolution at the University of Copenhagen in Denmark. Jonathan Shik is particularly interested in ants, their coexistence with other species and how they survive in diverse environments impacted by climate change. Hi, Jonathan. 00:02:28:13 - 00:02:29:18 Jonathan Shik Hi. Great to be here. 00:02:29:22 - 00:02:49:19 Abigail Acton Nice to see you. Daniel, I'm going to turn to you first. The ElectroBee Project investigated the first example of electro reception in a non-conductive medium that we have seen: The bumblebees ability to detect and learn about the weak electric fields that arise when they approach a flower. So can you tell us a little bit more about what electro reception actually is, Daniel? 00:02:49:24 - 00:03:25:04 Daniel Robert Indeed. Well, electro reception is the capacity of organisms to detect electric fields and all charges. So it had been studied for a good 60 years now in, in sharks and rays and usually aquatic animals in a conductive medium, which is water. So there it's quite well understood how it works. However, it had never been considered in a non-conductive environment such as the air, where as we know most of the species live, including an awful lot of arthropods. 00:03:25:06 - 00:03:31:22 Daniel Robert So we took on that little challenge to say, okay, if it exists in the water, could it, could it exist in the air? 00:03:31:24 - 00:03:40:02 Abigail Acton Fascinating. Absolutely brilliant. And what did you do actually to establish whether this was actually happening? Tell me a little bit more about the experiments you conducted in ElectroBee. 00:03:40:07 - 00:04:06:00 Daniel Robert So we first realized that there was something going on electrically when we looked vaguely at YouTube videos first, and then reproduce that in the lab, looking literally at pollen jumping from flowers to bees, and having a few students in the lab that were of a mixed breed. If you want some people were physicists some were biologists, we all look at it and a physicist said, but look, they don't drop. 00:04:06:00 - 00:04:30:01 Daniel Robert The pollen doesn't drop randomly. It goes straight. According to that nice little curve that you can see that on that video there is an electric field. So from then on we actually thought, okay, it may well be that because all the matter is charged in the universe, it's not only on Earth and between bees and flowers that we had to study the electrostatic charges taking place between bees and flowers. 00:04:30:03 - 00:04:51:04 Daniel Robert So we did the experiments where we gave bees a choice, basically go to a particular type of flower we put in the lab that was very artificial at the beginning, and one was actually with electricity and a bit of sugar, and the other one without electricity and without sugar. And we asked the question, can they learn? Can bees learn the difference between the two? 00:04:51:06 - 00:04:56:05 Daniel Robert And lo and behold, that was one of these moments of surprise that actually they could tell the difference. 00:04:56:11 - 00:05:13:13 Abigail Acton Wonderful. And how did that manifest itself? I mean, first of all, how did you measure the amount of electrostatic being given off by the plants? And I think we're talking about the same thing that happens when we stand near cathode ray television. If anyone can remember those. Yeah, if I'm just a blossom revealing my age a little bit here, but the hairs on your arms would stand on end. 00:05:13:13 - 00:05:17:24 Abigail Acton Or a balloon at a kid's birthday party rubbing on your head. We're talking about that type of electric charge, aren't we, Daniel? 00:05:18:03 - 00:05:20:19 Daniel Robert That's exactly that. These are very weak fields. 00:05:20:19 - 00:05:33:00 Abigail Acton Yes, well, exactly. Weak fields and invisible. So tell me more about how you actually measured how much charge was being given off by the flowers. And, and also, you say the bees learned. How did you see that actually happening? How did you test that they were learning? 00:05:33:00 - 00:06:06:15 Daniel Robert So well, one of the challenges was, of course, to make these fields visible or measurable. So they are small, but they're measurable. The problem was that there is no camera or microphone equivalent to measure electric fields. What you can measure, however, is the effect of a field that the field has on an object. So we shortcut the whole argument by saying okay, let's provide differences in electric fields with a bee and have that bee by associative learning, learn whether there is a high probability of them finding the source of sugar. 00:06:06:17 - 00:06:29:24 Daniel Robert When there is an electric field to that particular flower, and we could measure by the behavior of the bee whether they could measure that field or not. And of course, in a control experiment, we canceled everything that we know was in that particular, flight arena. We canceled all the electric fields, and we showed that bees that had learned to find the source of sugar with respect to the presence of a field. 00:06:30:01 - 00:06:44:18 Daniel Robert When the field was not there, they were unable to find a source of sugar, even though they knew they were learning bees. And that's the good thing about bees is that you can teach them stuff, and then and then basically test them, whether they remember, but whether they can still find the source of what they want, the sugar. 00:06:44:22 - 00:06:46:07 Daniel Robert So that's what we did. 00:06:46:09 - 00:06:52:18 Abigail Acton Wonderful. And I understand that you at one point had them flying through hoops. Can you explain a little bit why you were making the bees fly through hoops? 00:06:52:23 - 00:07:17:16 Daniel Robert Indeed. Because we wanted to know quantitatively what sort of charge bees have. It had been reported in in the in the 70s and 80s that bees were charged positively. And that also gave us a bit of a hint that indeed there would be an interaction electrostatic like the balloon you were mentioning before. So one way to measure electricity or electrostatics without a contact is to produce a hoop or a ring made of copper. 00:07:17:20 - 00:07:40:01 Daniel Robert And we could also train bees to fly through hoops. And we had to do that. That was much fun. And as the bee as a charged object flies through the hoop, it induces a little current and measuring that current, fencing unit we like to use, we could actually make sure that we knew that the bee was providing a charge towards the flower. 00:07:40:03 - 00:07:59:21 Daniel Robert But then of course, we also measured that the flower is reacting to that charge, and it's called. This is called technically mirror charging. But what happens there is that if it becomes we'd say five charges towards the flower, that flower will summon minus five charges. So there is going to be a plus minus game going on where the flower is not there. 00:07:59:22 - 00:08:05:04 Daniel Robert Passive sitting quietly. It will actually play that electrostatic game with the bee. Wow. 00:08:05:04 - 00:08:11:01 Abigail Acton So there is really direct interaction going on between the two of them. Excellent Daniel. Why? What's the benefit? 00:08:11:04 - 00:08:39:04 Daniel Robert And that was the key question because we thought okay pollen jumps from a flower to a bee. This was not before obviously Aristotle saw that. I mean, there is a first, you know, early reports on that. But for us, what was important is that when we saw the bees interacting with the flowers, the flower was changing its electric status as a function of the visitation of the bee, which gave us, the idea then that not only there was an interaction, but the bee knew about it. 00:08:39:06 - 00:09:18:23 Daniel Robert And that was a key question. Do bees know about the presence of these fields and following from that to cut the long story short, the idea was if the flower changes its electric status, it may well be that when a bee fly across a meadow that not all flowers are equal electrostatic, and if flowers that have been visited by bees have a different electricity or a different level of electrostatics, that gives information to the bees as we tested in the lab in the first place, that that flower is more ripe with nectar or pollen, and that bees foraging efforts, because time is precious for bees, are not really worth it. 00:09:19:01 - 00:09:29:23 Daniel Robert And that's what we could show, is that when, if, when amongst many flowers, if some have a different status, the bees readily measure that and try to avoid these flowers but go back later. 00:09:30:00 - 00:09:46:03 Abigail Acton That's fantastic. That's fantastic. And of course, also I would imagine I mean, you must have also considered other insects. I'm thinking, for example, what about night pollinators that are working with senses beyond color and vision, maybe sort of moths and stuff there? The evening pollinators, night pollinators, does that enable that process? 00:09:46:03 - 00:10:16:00 Daniel Robert Indeed. So that was a little research. And in the ElectroBee project we boarded up the scope to see what other pollinators could do about this. Now, of course, I'm not going to say that all insects and all flowers do the same thing. We know that there is a vast diversity, but we could measure that some moths were electrostatic charged as well, whilst some of those, like hawk moths, will fly very fast, who have a very high wind rate, actually do not charge up as much. 00:10:16:02 - 00:10:37:15 Daniel Robert So there's a whole different currency, so to speak. Some will have different tricks to their trade there. And but we think that in general this is something that flowers need to do is to keep the customership of the pollinators. And for that they use good smell, they use good colors, good structures. And we would like to add to that, that they need to have also a very enticing electric field. 00:10:37:15 - 00:10:39:24 Daniel Robert As odd as it may seem at first. 00:10:40:01 - 00:10:52:05 Abigail Acton That's just absolutely wonderful. It is totally a hidden world, isn't it? And massively complex. And are you seeing any other examples, Daniel? For example, predator prey interactions rather than pollinator and pollen. 00:10:52:08 - 00:11:17:18 Daniel Robert Yes, indeed. I mean, we focused on pollination because this is where we saw the phenomenon first and it came to our minds. But now we went a bit broader. And indeed, one of my students, Sam England, managed to record with this hoop system I was talking about before the charge of predatory wasps, like the common vestibular, the common wasp, and also some wasp in Costa Rica, placing these hoops in front of wasps nests. 00:11:17:22 - 00:11:36:11 Daniel Robert You have to be brave to do that. And then we could measure that there was a charge. But then he also measured caterpillars, and we saw that caterpillars are more likely to engage into a defensive behavior and stay in that defensive behavior. When the electric equivalent of the flight of a wasp, if you want, because they have an electric field. 00:11:36:11 - 00:11:56:13 Daniel Robert So we could record that with electrodes. And if we play back in the absence of wasps, this electric signal through the air, which is not conductive to the caterpillars, they will actually stay in that defensive mode and all start flailing, start to jump off of the leaves. So there are all sorts of dramatic or sometimes less dramatic behaviors. 00:11:56:13 - 00:12:21:16 Daniel Robert But caterpillars, we think, now, are aware of the presence of their predators through the electric field that arises between themselves and the predator, whether it's generalizable to old caterpillars and wasps I can't tell you that. But for those that we've observed only at least three examples, including in the tropics, we can see that now there is a new channel between prey and predators that has, has being opened by that. 00:12:21:19 - 00:12:38:16 Abigail Acton It's just wonderful. I think. I love doing these podcasts, and I'm reminded very regularly of a vague feeling of arrogance. You know, we always seem to think that we know everything that's going on, and then we open a page and suddenly there's a whole world of stuff that that we haven't previously considered very closely at all. Thank you so much. 00:12:38:16 - 00:12:43:01 Abigail Acton That was fascinating explanation. Does anyone have any questions for Daniel? Yes, please. Ted. Go ahead. 00:12:43:14 - 00:13:03:00 Ted Turlings So, Daniel, you were explaining to us that this allows this electrical charge from the flowers allows these wasp to determine which flowers carried them the most pollen or nectar, the bumblebees. Doesn't this open the possibility for the flowers to cheat that they would actually manipulate their charge? 00:13:03:05 - 00:13:14:05 Abigail Acton I'm just going to step in because I think that's a wonderful question. And actually, Daniel, I was wondering too. I mean, for example, can wasps mask, I mean, do the creatures in the plants play with this? Because, I mean, it must've been around for millennia. 00:13:14:07 - 00:13:51:09 Daniel Robert I think so. I think this is an excellent question, because we know that as soon as they are signals between different organisms, they can be as different as a plant and a wasp will be or caterpillar. There will be some room for exaggeration of traits, but also for concealing the truth. We think that flowers that will benefit from what is called in the trade flower constancy, where the pollen needs to go back to the flower of the same species, with serial pollinators that actually stick with the same type of flower day by day, that will not be of to lie. 00:13:51:10 - 00:14:12:16 Daniel Robert However, there are other flowers that are more ephemeral, that open need maybe even to be a bit shaken or be self pollinated. And or the pollen has actually a very much higher specific and can afford to be somewhere else, but then be picked up again this possibility. So what Ted is asking is that indeed some flowers may not react the same way. 00:14:12:20 - 00:14:28:05 Daniel Robert We haven't found an example yet, sadly, but the idea would be then that they are. Perhaps the electricity is just used to attract and mimic what good, attractive flowers are. Just like all the flowers would have a good color and a good scent, but they would have a good electrical taste. If you want. 00:14:28:09 - 00:14:48:13 Abigail Acton Fabulous! Thank you so much! That was excellent Daniel, really appreciate that. I'm going to turn to you, Ted. Actually, I'm beginning to feel a bit sorry for caterpillars, and the listener will now find out why. So your project AGRISCENTS set out to develop a novel detection device that can interpret when a plant is giving off odors, indicating that they are under attack. 00:14:48:15 - 00:14:53:15 Abigail Acton Ted, what drew you to the role of volatile chemicals in biotic interactions? Please? 00:14:53:17 - 00:15:13:24 Ted Turlings Yeah, this, this goes back a long time when I started my PhD, which I did at the University of Florida. And, I was given the task to find out how parasitic wasps, which are similar to the wasp that Daniel was describing, they the prey on caterpillars, how they find these caterpillars and then they lay their eggs in there. 00:15:14:01 - 00:15:45:20 Ted Turlings And, after some behavioral assays, I discovered that they actually use plant odors to find caterpillars that are feeding on a plant. And when studying that in the more detail. We discovered that the plants are responding to caterpillar attack by producing a very specific odor that then attracts these wasps. And this odor, the fascinating part about it is that it's not just a mechanical damage that these caterpillars do, but there's something in the oral secretions and spit. 00:15:45:21 - 00:15:59:05 Ted Turlings If you want of the caterpillars that is recognized by the plants, and then they start synthesizing new and volatile compounds that they then emit. And this plant of volatiles is attracting these wasps. 00:15:59:09 - 00:16:12:21 Abigail Acton That's just stunning. Really, really. Can you tell us a little bit more about this? Because I believe that you conducted experiments where the plants weren't necessarily being damaged by the caterpillar, but the wasp is still coming. Tell me a little bit more about the experiments you conducted. 00:16:13:02 - 00:16:42:12 Ted Turlings Yeah. Then we actually to find out that these oral secretions were important in this context. We mechanically damaged plants ourselves and found that if you don't add caterpillar spit to the damaged areas, the volt emissions were much, much lower. And several of these compounds that they normally emitted in response to caterpillar attack were not emitted. So that's how we were able to prove the importance of this oral secretion. 00:16:42:12 - 00:17:03:00 Ted Turlings And then we developed a bioassay where we even could incubate plants. And we worked with maize plants that we cut at the stem and just put them in a solution with or without caterpillar spit. And then we saw a tremendous difference in the volatiles emitted by the plants, even if the leaves were not damaged after several hours. Yeah. 00:17:03:02 - 00:17:13:23 Abigail Acton How intriguing is that. Absolutely. And so and this is absolutely fascinating, but do you have some sense of an application that could then grow out of this knowledge that we have. 00:17:14:03 - 00:17:39:16 Ted Turlings Yeah, that's exactly this AGRISCENTS project. Looking into that. So the idea there was that if the Wasps were able to recognize plants on the caterpillar attack, would we also be able to detect that? And if their odor is specific enough, then you could maybe even detect what insect is feeding on the plant on the basis of the odor emitted by the plant. 00:17:39:18 - 00:17:54:02 Ted Turlings And there are subtle differences in what different caterpillar species, but also other insects and even pathogens like bacteria and fungi that detect plants induce the plants to start producing specific odors. 00:17:54:07 - 00:18:09:02 Abigail Acton And these odors that the plants produce are they systematically in order to protect themselves, like, for example, with regards to the predatory wasps? Or are they simply emitted as distress signals without an end goal, as it were, by the plant? Do they each have a target? 00:18:09:06 - 00:18:32:01 Ted Turlings Yeah. What the original function was is a little bit hard to determine but we also, as you mentioned, that the, at the beginning of this podcast is that there is also this option of plants interacting with each other to treat these odors. And that's one of the possible functions. I hate to use the word communication because it might be just eavesdropping. 00:18:32:01 - 00:18:40:20 Ted Turlings Let's put it that way. A neighboring plant can pick up that odor, realize that there's a caterpillar or another, 00:18:40:22 - 00:18:42:00 Abigail Acton A challenge of some sort of. 00:18:42:00 - 00:19:11:04 Ted Turlings Challenge. Yeah. And then they start, preparing themselves for that possible attack. And they can do that also by increasing actually, their responses in the, in terms of producing defense compounds or also producing these odors to detect the natural enemies of, of the herbivores. And, yet we have done quite some research on that, and we have found out that pathogens and insects induce considerably different odors, and that we actually can pick up on that. 00:19:11:04 - 00:19:34:18 Ted Turlings And we now have tested several sensors that can detect these odors in real time. And the eventual goal will then be to have that install those sensors on a rover, for instance, that goes through a field of maize plants and smell individual plants and then give immediate real time feedback to farmers where there is a problem. 00:19:34:18 - 00:19:45:11 Ted Turlings And, you could even imagine that the same rover with, than apply something to kill that pest and logical thing with the pesticides that we're also looking at other options. 00:19:45:17 - 00:19:46:16 Abigail Acton Such as what Ted? 00:19:46:22 - 00:20:05:11 Ted Turlings One of the possibilities of really looking into nematodes, tiny little worms that kill insects, within 1 or 2 days, they are parasites of the insects. And we have developed now a formulation of that we can inject into the will of a maize plants, the center of a mouse, plants with nematodes. And it actually works. 00:20:05:15 - 00:20:23:08 Abigail Acton Do they? Do they work? That's good, because I must admit I have, and the world of the nematode, I was plagued by slugs in my garden this summer, something chronic I applied nematodes two or three times and slugs really seem to not mind at all. So I hope that your nematodes are more effective than the ones I was using. 00:20:23:08 - 00:20:40:08 Ted Turlings Actually, we have worked with the slug nematodes as well and they kill much, much slower. And that could actually take weeks to months before they kill their slugs. So in the case of caterpillars, they get attacked, get killed within two days. Okay. With just 1 or 2 nematodes, you kill them right away. 00:20:40:11 - 00:20:51:09 Abigail Acton Wow. Okay, so there we go. Fellow gardeners, keep applying the slug nematodes. It won't work all at once. Thank you very much. Super. Do we have any questions for Ted? That was excellently explained. Thank you. Yes, please. Daniel. 00:20:51:15 - 00:21:14:17 Daniel Robert It's fascinating. It's really great because it really unveils what Ted is doing there. This hidden aspects of if it's communication leaves dropping. I think at the end it doesn't matter at all. There are so many, so many different complexities. I was wondering, Ted, whether because we know there are lots of caterpillars that become toxic as they choose to eat plants to actually deter predators. 00:21:14:19 - 00:21:39:06 Daniel Robert Is there a relationship between the toxicity, you know, the non palatability of these caterpillars and the way they can secrete these various substances that become their demise as well? Is there a double game there that actually some caterpillars have managed to avoid and still be deterrent but also deterrent to to to all what is negative to them through a same process of toxic fission. 00:21:39:12 - 00:22:06:23 Ted Turlings Yes. Specialized insects that are able to actually sequester the defense compounds of plants. And these specialists have found ways to detoxify these compounds themselves there. And we just recently published a paper on a beetle in that case where the larvae feed on the roots and the adults feed on the leaves, and those adults are able to sequester the defense compounds from different plants, different toxins. 00:22:07:00 - 00:22:24:03 Ted Turlings And that was not known yet that they can actually sequester multiple different defense compounds, and they transfer those compounds to their eggs that are then protected against the predators. And that's, it's another fascinating world that is a bit different from the communication aspect of it. 00:22:24:05 - 00:22:27:07 Abigail Acton Well, it's relevant when we think of it as interactions rather than communication. 00:22:27:08 - 00:22:28:11 Ted Turlings Yeah, exactly. 00:22:28:11 - 00:22:46:08 Abigail Acton It's interconnection and interaction, actually. Frankly, a bit mind blowing. I think it's wonderful. Absolutely brilliant. Thank you very much for that question. And for that answer. I'm going to turn to Jonathan. Jonathan, the ELEVATE Project looked at the interaction between leafcutter ants and the fungus they farm. All right. So we're still talking here about this kind of notion of symbiosis really. 00:22:46:10 - 00:22:51:21 Abigail Acton Leafcutter ants act as farmers. I mean, this is not something that immediately comes to mind. Jonathan, tell us more, please. 00:22:52:01 - 00:23:19:02 Jonathan Shik So, yes, if you've ever had the chance to, visit a rainforest in the New World from, you know, Panama to Argentina, you'll often see these massive highways with thousands and thousands of ants just foraging. And it's kind of one of the most iconic scenes from a rainforest. And what they're actually doing is climbing to the tops of the trees and cutting all sorts of leaf fragments from hundreds of different species, and then taking them back to the nest where they disappear underground. 00:23:19:08 - 00:23:45:22 Jonathan Shik And it's what happens underground that's really interesting to me. And it turns out, like you said, these ants are real farmers. They vertically transmit a crop just like human farmers from generation to generation. They protect it from all sorts of pests and pathogens. They create an optimal growth environment underground, and it is their food source. It converts plant material that they can't eat and to an optimized nutritional reward that the ants depend on for their livelihood. 00:23:46:02 - 00:23:54:20 Abigail Acton Okay, I did wonder. So thank you very much for answering that. So when you say creating a food source, the ants don't eat the fungus itself, I presume, do they? Or do they eat what the fungus produces? 00:23:54:20 - 00:24:03:05 Jonathan Shik So they eat the fungus? The fungus produces these very specialized like domesticated fruits, like an apple on an apple tree. 00:24:03:07 - 00:24:10:15 Abigail Acton Okay. But obviously then it doesn't damage the fungus at core, because otherwise they'd be eating their own kind of necessary crop. 00:24:10:17 - 00:24:26:22 Jonathan Shik No, it's. You're right. It's a very unusual thing for a fungus to do to provide food for another organism. But it turns out, because this is an obligate some these different species depend on each other. They can't live without each other. But it makes sense evolutionarily that the fungus just gives some nutrients to the ant farmers. 00:24:27:00 - 00:24:37:20 Abigail Acton Right? Without even getting damaged itself. Really, literally, like apples on trees in fact. Okay. Fascinating. And so what were you particularly interested in within the ELEVATE project? What did you consider closely there? 00:24:37:20 - 00:24:57:03 Jonathan Shik So I've always been fascinated by how ant colonies work. Each individual ant is pretty dumb. You know, I spent many hours watching them in the rainforest, on trash bags and on the leaf litter, just watching them forage. And if you make a footprint in the in the leaf litter, some ants of some species will just wander aimlessly for hours, you know, in circles. 00:24:57:05 - 00:25:26:11 Jonathan Shik But somehow these farming ants are able to manage these incredibly complex, sophisticated farming systems. And so I was wondering how they could do that. And I specifically focused on new nutrition and communication with the ants, with the fungus, because human farmers know exactly what blends of nutrients are best for their crops. My question at the heart of my grant was, how did the ants know which blended nutrients make their fungus crop grow the best, and how can they actually detect that? 00:25:26:11 - 00:25:32:17 Jonathan Shik And can they make complex nutritional decisions, right, to optimize productivity of their, their food crop? 00:25:32:19 - 00:25:39:06 Abigail Acton And I notice also that you were interested in sort of different climatic impacts as well. So that situations would vary depending on the context. 00:25:39:09 - 00:26:02:17 Jonathan Shik Yeah, I think that's true. These ants range like all the way from Southern New Jersey, different species, not necessarily leaf cutting ants, but it's actually quite diverse lineage of ants that are all farmers, that are all related to each other all the way to Argentina. So they range from, rainforest to desert to, grassland. So they have to be able to grow their crop in really diverse habitats. 00:26:02:19 - 00:26:16:08 Jonathan Shik And they've also, unlike humans who have been farming for about 10,000 years, these ants have been sustainable farmers for about 60 million years. So how they managed to thrive across all this? Climate change was also a key interest of mine. 00:26:16:11 - 00:26:27:13 Abigail Acton Yeah, sure. And so how did you go about studying the leafcutter ants? I know, for example, you went to Panama. Can you tell us about some of the experiments you conducted in the Panamanian rainforest? Must have been quite a challenging environment. 00:26:27:15 - 00:26:50:11 Jonathan Shik Yeah, so we worked near the Panama Canal, the Smithsonian Tropical Research Institute. And it's quite a beautiful forest. There's these huge container ships navigating the Panama Canal. But we're just with our head in the leaf litter, looking for ants. But one of the things we did, like I mentioned, we actually stole bits of leaf material from foraging leafcutter ants as they walk by, and we let the ants go on their way. 00:26:50:13 - 00:27:09:07 Jonathan Shik And then we collected all this plant material, and we analyzed it for all sorts of nutrients and, and all sorts of secondary metabolites, like toxins that the plants might produce. And in this way, the ants could tell us what nutritional blends they're actually foraging for, how they're kind of what I call navigating a nutritional landscape of hundreds of plant species. 00:27:09:09 - 00:27:20:10 Jonathan Shik And whether the nutrients that they're foraging for in the field match the nutrients that we can actually measure in the lab, that maximize the performance of the fungal cultivar in a Petri dish. 00:27:20:10 - 00:27:28:15 Abigail Acton And did you then try growing the fungus in the labs with the nutrients that the ants had been collecting, and also without, I guess you had to control? So what did you get? What was the result? 00:27:28:19 - 00:27:57:14 Jonathan Shik So it's complicated because nutrition is always complicated. But we could show that things like protein can quickly become toxic to the fungus. When you grow it in a Petri dish. And yet somehow the plant material that they're foraging in the field has more protein than you would predict would be optimal. We were able to show that there's all sorts of secondary nutritional interactions to actually make the protein palatable to the fungus and allow it to, to thrive, despite getting a bit too much protein in the field. 00:27:57:16 - 00:28:10:03 Jonathan Shik Not only that, but the ants can really detect how much protein that they're depositing on the fungus, which is quite interesting. Absolutely. We don't exactly know how they do that yet, but they can. And that's part of the research we're currently working on. 00:28:10:03 - 00:28:25:11 Abigail Acton And they modulate, I guess, how much they say they supply to stay within parameters that are secure for the fungus. Fabulous. Well, this is what the ants get out of it. You can see all the effort that goes into it and why they get the ant equivalent of apples from the apple tree, as it were. What does the fungus get out of all of this? 00:28:25:17 - 00:28:49:05 Jonathan Shik Well, it gets protection and it gets to be vertically transmitted. So when a queen new queen flies away from her colony at birth to start a new colony, she takes a little bit of fungus in her mouth. Then she mates with several males. The males die. They're just flying spur missiles. She falls to the ground, loses her wings, digs a hole, and then spits out that little bit of fungus from her colony at birth and starts to take care of it. 00:28:49:09 - 00:29:03:24 Jonathan Shik Then she lays eggs from her mating and starts to produce workers and the colony grows into a new colony so the fungus doesn't have to produce mushrooms, doesn't have to invest in reproduction. It gets free food by the ants and it gets dispersed to the next generation. 00:29:04:01 - 00:29:19:19 Abigail Acton Brilliant. Absolutely wonderful. And you mentioned something about the ants protecting it. I think you were touching on the possibility when we previously told Jonathan of the fungus perhaps producing, a compound that could make the ants more aggressive in their protection of it. 00:29:19:21 - 00:29:42:18 Jonathan Shik Yes. So there was work done by another research group that we've kind of started to try to investigate a bit that shows that the fungus metabolizes certain lipids, certain fatty acids, that, that are slightly different than what's in the plant material. And it sequesters those, accumulates them in their fungus tissue. When the ants kind of sense that they can become a little more aggressive and protect the fungus garden. 00:29:42:20 - 00:30:04:04 Jonathan Shik We're so we're currently looking into kind of, as Ted kind of was interested in volatile signals. We're more interested in kind of the kind of long chain carbon or these larger molecules. It kind of coat the fungus garden because we think we need more kind of really targeted signaling from the fungus, ie too much protein in this spot change to carbohydrate. 00:30:04:04 - 00:30:16:19 Jonathan Shik It's or there's really bad plant chemicals here. Take it away or there's a pathogen here. Remove it from the fungus garden. So I think volatiles would be more too broad of a signal. 00:30:16:21 - 00:30:20:07 Abigail Acton Right. Something more more specific and like a tap on the shoulder. 00:30:20:09 - 00:30:21:20 Jonathan Shik Exactly. Yeah. 00:30:21:22 - 00:30:30:15 Abigail Acton I think that's wonderful. Absolutely brilliant. I'm loving this. This is excellent. Thank you very much. Jonathan. Does anyone have any questions for Jonathan? Yes, please. Daniel. 00:30:30:20 - 00:30:51:22 Daniel Robert Jonathan, this is wonderful, wonderful stuff. And I was wondering because I've seen these in the field as well. And I find them fascinating as well. Well I'm not working on them directly. This is amazing. Fungal spores are everywhere and I can see these ants going to a tree and the forage on that tree. And they must be bringing some fungal spores with the leaves. 00:30:51:24 - 00:31:08:10 Daniel Robert Is there any evidence that they select the leaves or they clean the leaves before to prevent some sort of an import of all sorts of pathogens? Fungal pathogenic fungi are not very nice to each other. How do they protect the upper tree, in that case? 00:31:08:12 - 00:31:29:01 Jonathan Shik Yeah, that's a really good question. So there's many different solutions that the ants have and it varies across species. But it has been shown that a lot of plant leaves have things called endo phytic fungi or fungi that kind of live inside the leaves kind of quietly their whole lives. And some of those fungi can produce compounds that the fungus doesn't like inside the nest. 00:31:29:03 - 00:31:55:09 Jonathan Shik And it has been shown by other groups that the ants can select against leaves that have specific bad fungi living inside the leaves. But the ants produce all sorts of chemicals to protect against different, pathogens like fungal and bacterial pathogens. And so the fungus garden sorts of chemicals that so have bacteria that live on their bodies, that produce antifungal and antibacterial compounds that can also protect against this really bad fungus called escovopsis. 00:31:55:09 - 00:32:05:24 Jonathan Shik That's really bad for the fungus garden. And so it's a very kind of, complex web as, as we might say, symbiosis of different organisms, protecting and defending. 00:32:06:03 - 00:32:09:06 Abigail Acton And trying to get around those protections and defenses as well. Yeah. 00:32:09:08 - 00:32:26:10 Jonathan Shik And it's quite interesting if you dig a hole underground, like, you know, half a meter, you'll find a chamber and the soil environment is so dirty. But the fungus garnish is clean, separated from the fungus and a plant root or something. And the ants are constantly interacting with it and cleaning it. 00:32:26:12 - 00:32:35:09 Abigail Acton Very assiduous farming. Thank you. Thank you, all of you that couldn't have been more interesting. It was really, really wonderful to talk with you. Thank you for spending some time with us. 00:32:35:13 - 00:32:36:11 Jonathan Shik Thank you very much. 00:32:36:11 - 00:32:38:17 Daniel Robert Thank you. Thank you everyone. Bye bye. 00:32:38:17 - 00:32:39:00 Ted Turlings Bye. 00:32:39:01 - 00:33:02:04 Abigail Acton Goodbye. If you've enjoyed today's fascinating insight into a hidden world that perhaps none of us have previously thought much about, follow us on Spotify and Apple Podcasts, and check out the podcast homepage on the cordis.europa.eu website for other episodes that are equally interesting. Subscribe to make sure the hottest research and EU funded science isn't passing you by. 00:33:02:06 - 00:33:22:12 Abigail Acton And if you end up chatting to somebody about podcasts you're enjoying, why not name drop CORDIScovery. We've talked about MRI scans of baboons and how they inform our understanding of the development of language, and how it could be possible to collect samples from tiny asteroids millions of kilometers away. In our previous episodes, there's bound to be something that will tweak your curiosity. 00:33:22:18 - 00:33:44:21 Abigail Acton Visit the Cordis website, which has articles and interviews that explore the results research being conducted in a very broad range of domains and subjects, from structural color to structural dynamics. There's something there for you, so come and check out the research that's revealing what makes our world tick. We're always happy to hear from you. Drop us a line [e-mail]. 00:33:44:22 - 00:33:46:06 Abigail Acton Until next time.

Surprising connections driving the natural world surrounding us

Did you know that when antelopes browse on an acacia’s leaves, the tree will emit ethylene which acts as an alarm signal to other acacias nearby? The gas can spread 45 metres. Within half an hour, the trees that pick up the signal flush their leaves with very bitter tannins, to make them less palatable to the antelopes. In high concentrations, the tannins can even be fatal.

Most of us are focused on what is tangible to us. We hear one another, we know that some kind of communication is happening when a dog barks, but we are less aware of the interactions going on all around us that we don’t perceive. Let’s think again.

And perhaps we can work within that interconnecting web: Could the warning gases emitted by cereal crops under attack by pests lead to a more targeted approach to pesticide use, for example?

Welcome to this episode of CORDIScovery, where we are celebrating the marvellous world of hidden interactions, with:

Daniel Robert, professor of Bionanoscience at the School of Biological Sciences at the University of Bristol in the United Kingdom. The ElectroBee project explores how insects respond to weak electrostatic fields, a previously unsuspected form of interaction between plants and their pollinators.

Ted Turlings, coordinator of the AGRISCENTS project, is based at the University of Neuchâtel in Switzerland, where he is professor of Chemical Ecology. By unravelling how plants defend themselves against insect attacks, and how specialised insects have evolved, Turlings’ team hopes to create novel, sustainable methods of pest control.

Associate professor of Ecology and Evolution at the University of Copenhagen in Denmark, Jonathan Shik is particularly interested in ants: their co-existence with other species and how they survive in diverse environments impacted by climate change. His focus was on farming leafcutter ants and the relationship with the fungus they cultivate, which he explored in the ELEVATE project.

Happy to hear from you!

If you have any feedback, we’re always happy to hear from you! Send us any comments, questions or suggestions to: [e-mail].

Keywords

Leafcutter ants, farming fungus, pesticide, Bionanoscience, ElectroBee, electrostatic fields, AGRISCENTS, Chemical Ecology, insect attacks, ELEVATE, climate change