The behavioral & chemical interactions of parasitoids, insect herbivores, and plants with Joe Lewis

Hi, friends, this is Jon, and this is the Regenerative Agriculture podcast where we talk about the agronomic science and the cultural management practices that regenerate plant health, soil health and public health, and of course, very importantly, regenerate farm profitability in the pathway to achieving all these other outcomes. I'm really excited to be having a conversation for this episode with Joe Lewis, who has been on the forefront of a lot of foundational research on how insects communicate with their environment, with their plants, and with identifying target insects. So I'm really excited to have Joe here. He has also published a new book recently titled A New Farm Language. And this is a topic that's really important to me personally because I think we constrain ourselves a lot by the choice of words that we use. Words are powerful and if we constantly refer to things as pests or weeds or pathogens, then to some degree we're creating the reality that we expect. And we would be wise, I believe, to choose better words and to develop a new lexicon and a new language. So, Joe, the title of your book really spoke to me a lot. I really appreciated it and thank you for being here today. Can you tell us a little bit about your background and your story and what brought you to doing some of this foundational research?

Sure, John, and it's, let me say it's a delight to be with you today. I'm looking forward to the conversation. I've seen some of your work and your broadcast and I'm excited to be a part of today and it's an exciting thing and we share so much of the same view and, and hopefully we can have a good conversation and communicate some of those to the audience. So I look forward to it and my background. You know, of course, I'm just completed a, an exciting career as a scientist in the field of entomology and agriculture specifically. But, you know, after 40 plus years of academic research and being in that field, I want to point out my earlier years were far from scholarly. I grew up in a very remote rural area of South Mississippi as a sharecropper son. My father was illiterate, couldn't read, write a single word. The earlier years of my life, no electricity, no running water, none of the modern conveniences. And then I had the opportunity later to go to, through and have a good education and to be a part of the modern technology and in the world from a very different view for, for 40 plus years. So I've seen the world from both sides now. And let's talk a little Bit if I could, about those earlier years. You know, I refer to it and I speak of it as being like Charles Dickens is the worst of times and best of times. It was the worst of times. And that type of life, it can be very rugged. And particularly as from a perspective of today when we're used to our air conditioning and all the modern conveniences of running water and those kind of things. But it was the best of time in that we were a part of nature. We didn't just see nature, we were of nature. When you do not have any electric lights and those type of things, number one, you have to live as a part of nature and hear the sounds of nature, see and feel nature. You have to do things by the light because you don't have the convenience of electric lights and other kinds of things. You don't have the commotions of all the commerce. And you hear and see and experience nature in a very, a very, very different way. And you can read and you understand the language of nature. And I think that is huge. You also see the true marvels and understand and appreciate the fact that nature is a web. You don't see it in the reductionist view that we do at the current time. As Rachel Carson said, in nature, nothing exists alone. And you see and experience that. And you, you see it's truly a system, nature. And our world is a made up of systems within systems. But in our modern world, we centralize and specialize things and you see it in parts. And we lose so much in, in the power. And we've become very interventionist oriented. So I watched that occur over my life in the earlier stages as that took place.

This process of fragmentation and this, this mechanistic view of trying to identify and understand the parts, I think is based on the premise, the mistaken belief that if you understand the parts, then you can also understand the whole. And I think we're beginning to recognize that that is not the case. You cannot understand the whole just because you recognize the parts. And this is really a challenge in our agricultural research because if anything is a description of managing an ecosystem, it should be agriculture. And yet our science, our agricultural science has all been fragmented to where we have people studying very specific things rather than the whole ecosystem.

Absolutely. And let me compare that a little bit about kind of what I saw earlier and go back and say a couple of things of that. Because of the way I grew up and saw those things, it helped me to see things different and observe things as I got into my research. So hold that I want to come to that, not forget it. But see, as you grow up in true subsistence farming way, we lived and farmed, we were sharecroppers, we didn't own the land. So we lived on, maybe had access to maybe 50 acres or something like that where we had to make our living and actually grow our food. We had five acres cotton as a cash crop. That was the only, I guess, money that we had. Everything else we grew our food in, in that kind of living, you see the interaction of the parts. You have chickens, you have cows and, and you have your mew and you have the cotton and corn to feed the cattle and the chickens, who all were free range chickens. So you knew your connection to the land. You, you had the cows, you milked them, you had to turn the butter all, all those things all the way back to the land. You understood those connections and the interactions of the part. You also saw things like if you had martin houses and so forth, to see them to chase the hawks and to protect the chickens. You, you saw all the, you know, the interactions and, and for a child with a robust curiosity, which I have, you're exploring and you see the adventures, the beauty and also the power within the natural world and, and how interactive and integrated it was. It, you didn't see it in its part. So seeing the world in that way, I think it helped me in the research not to break things in its part so completely. We understood for even as we studied. I got into a very strong interest very early in my career of biological control and natural enemies of herbivores, primarily the parasitic wasp that became the primary subject of my study. And I could see when you took those little parasitic wasps out of nature and start producing and left once you, once you unplug them from that natural system, you didn't have the same organism. Wow. It was very, very different. So that gets it the point that you were making. And so I think it helped to understand the world is an integrated system and to get the best of research and to understand natural systems, you have to study it in its whole. And so that's the way we did our research.

So tell us a little bit about the research. I mentioned briefly that you were a pioneer in an early group of researchers looking at developing biological controls and kind of practical entomology from an agricultural perspective.

Yeah.

Tell us about what brought you there and what got started.

Well, the, as I was saying, I got developed interest real early just from looking at insects and agriculture and particularly production of cotton and, and corn and row crops in the South I developed a strong interest in the natural enemies. And particularly the model that we can discuss a bit here that we use were the parasitic wasp. And what we recognized, if we were going to use biological control and to move away from so much emphasis on pesticides and interventions and captured the natural power built within. These were very important thing. And the key to their reliability and successful employment was how does a female parasitic wasp find those herbivores. And so that became the key point of our study very early, because you think about it here you have a little parasitic wasp that can develop only in a certain types of caterpillars that's playing hide and seek with them in a huge field of cotton and all the vegetative growth. How do they find those little caterpillars and deposit an egg within them? So that, that was the heart of the subject. And as we begin to uncover some things, it really got exciting because one of the things that we found was the plant has attributes we had no idea that existed. We found in the first discovery, the first report of the fact that plants, when they're being fed on by a caterpillar or any other herbivore, they have an attribute that we did not know, and that was they have the ability to begin to produce and emit body odors like an SOS signal, sending out a cry for help to their natural enemy and recruit them to their aid. And the wasp is able to locate the host based on that signal from the plant. Had we suggested that a few years earlier, we would have been left out of the profession. But it is an inducible response. So we really got into working out how does this occur? What's the mechanism by which a plant can talk and send signals to their bodyguards. We will call them the parasitic wasp. And what we found is that when the caterpillar or any herbivore we later found is that all plants have this ability. As we went on, but when we first discovered we were working primarily with corn and cotton. When you, when they wound the plant, they start munching on the fruit or leaf or whatever wounded. The plant detects this feeding and begins to crank up a set of chemical factors and produce a group of, you know, 6, 7 to 10 compounds, A, A blend of body odors and emit those odors. And these are quite volatile materials that the, and the wasp, now you don't see it, but the wasps can see it. It's kind of like a smoke signal that the plant is emitting to recruit them. And this is now what we found using wind tunnels and other, other study methods is if you just wound the plant with say a razor blade or somehow cut it or wound it, this doesn't happen. What happens is that there's an elicitor we found in the spit of the caterpillar. And if you take the spit of the caterpillar and put on, you wound it artificially and put the spit of the caterpillar, you get the same thing that happens naturally. So there's an elicitor. And we are working with Jim Tomlinson, who was my chemist friend that did all this work with me, this elicitor triggers the plant and to do that, so you have to have the spit of the caterpillar. And he and his group identified that chemical, which was a fatty acid. Anyway, this is the way that has occurred. Now, each herbivore, they do it for any feeding, but they produce a different blend, slightly different for each herbivore. So if you have an army worm and a bow worm, aphids, any other insect feeding on it, they're producing these body odors for each one of these. Now, because of that, it would be of little value if, if the natural enemy, if the parasitic wasps couldn't recognize the difference between these, if you see what I'm saying, then. So the blend is a little different and they recognize the blend for each what on their host, they were able to distinguish it.

So, wow.

So basically I want, I want to hear your comment, but just to say it is because they're sending a little different. It's like you're going into the store and you're getting different items and you have a barcode and the barcode is a little different. For each, they are sending a different signal and the parasitic can, they're talking to the wasp and they're telling them something's feeding on it and what it is. So there. It's actually truly like a language, if you see what I'm saying.

Wow. So plants produce a unique signal for every pest, every insect, herbivore. Just look at that. I just used the word pest again. For every insect, herbivore that feeds on them, a unique one for each one. What, what is the distance that this signal reaches? What's the sensitivity of these parasitic wasps? And how, how accurately can they perceive which plants are infected or which fields are infected?

We know it's like parts per billion. It amounts to the fact that if you're sitting in this room and you had a few molecules just emit, they can pick it up. It's incredibly sensitive. And they can navigate and follow These odors in a little turbulent environment. We actually did those kind of studies and found that they're able to navigate those very good. So it really is a incredible sensitive system that is certainly in the range of the same thing as a bloodhound. We did those types of studies. Now there's another side of this John. Since there's a different blend and because they're emitting these all these odors and they're in response to any herbivore feeding on it. And they also the plant, let's say you have a. The bow worm for example that's feeding on cotton. These are the cornea worm or an army worm. And what our study was really with wasp of the bow worm primarily we did some with army worms too. But these are polyphagous insects as we call them. They feed on a variety of different plants and all these plants are signaling the signal. The, the. It's the same basic mechanism in the plant, but it's different on different plants. So what I'm saying is they've got to follow a different signal in cotton or corn or some early season annual that their host is feeding on. So they can't afford to hardwire this signal. They just don't have the in aid ability in a specific plant signal sent to them. So they how do they respond to a different blend or signal variation from one plant to the next or one age of plant to the next, they can't hardwire that. So we find the accomplish they have to learn. Yeah, that's exactly it. They learn and they are incredibly good at learning and we really work that success system out. So let's talk a little bit about that learning mechanism. What they do is it's the same as occurs in vertebrates. In 1988 we actually reported in Nature the first demonstration with these wasps of true associative learning. With these insects, what happens when they encounter the site and there's the caterpillar host and they have feces where they have fed or they touch the caterpillar they've set. There is a chemical in the feces actually comes from the parotropic membrane. That's the. And are only insect itself. The caterpillar. This we find that we didn't identify that. But it's a glycoprotein, a real heavy compound chemical that is host specific. This is hardware. This is what you call in associative learning, the unconditional cue. It's hardwired. And when they touch this with the antenna. They have their antenna, they Have a taste receptors and also taste receptors on these, on the ovipositor. And they make this contact. They link whatever volatile odors are with that. So it's an associative link. When they taste while they smell, they learn this odor, which is the condition cue, and they learn this odor means host. It's like saying this is what the host is feeding on. This is what they smell like in this patch of host. And they start following that specific signal so they can learn and update every time they encounter a different patch of host and know what they're feeding on, how it smells. So they then learn that plant signal for that situation. You see what I'm saying? It's, it's an incredibly quick in that the learning process, if you release a habit was it naturally occurs in a patch of host. For about the first two or three hosts they encounter, it's a little slower. But then they learn what's occurring in this patch and the efficiency gets real strong through learning. So the wasp learns and the catapult plant sends its signal. And they are working together as allies, competing and managing this sneaky caterpillar that's caught between the two, kind of between the devil and the deep blue sea.

So when we think about the capacity to learn, there's the capacity to learn these various odors, which is really remarkable. But plants also change in structure and shape as they grow and mature as well. And I would imagine that the locations where caterpillars are found on plants also change as plants mature. We know that some larval insects focus on feeding on blossoms or on corn silk, for example, or something like that.

So.

Is there also learning that goes on in regards to the location of where these caterpillars might be found or these larvae might be found?

The deeper the well, the sweeter the honey. The further we get into this, the richer it gets. Yes. Not only did they learn these wasps, we talk about smart insects and that's read. I use the title, you know the subtitle, Talking Plants. Smart Insects. These little wasps, yes, they, they learn color as well. So if you have a caterpillar feeding on plant at one time and it's feeding on a bud that's shaped a certain way and most of them are on these tender buds that in that situation or another, as the plant grows further along and produces, like cotton, a white bloom, they not only learn the odor, if they are feeding primarily on white blooms, they learn to go for those colors as well as the odor and. Or the shape. They can.

We.

We found they can learn shape. They can. Now there's a hierarchy of those that if you had the right shape and the wrong odor that would. It's. They actually use the odor as the primary. But it's an overlay so that they learn the combination of those. But it is really learn all that information and make use of it. So they are very good at this. Now the, the they are also let me point out, are nectar feeders. The adult parasitic wasps. They are free, free living. They don't even know they to produce the young, they've got to lay the egg and the, the larvals and other stages grow on the caterpillar. The adult wasp is free feeders and they feed on nectar. So plants like cotton produce what's called extra floral nectar. And that's the. It's under the leaf they have a little nectar source. When the plants produce this nectar that gives them a stronger alliance with the wasp. If they can provide that food for the adult wasp as well as the source for reproduction of the young, they're able to support those natural enemies strong. But the wasps actually learn to locate odor sources in the same way. They taste sugar, water. If we, we could do this in the lab, taste sugar while they smell an odor. They learned that odor means food. You could at the same time train them. One odor for food and another odor for host. And if they're hungry, they'll go to the one that's associated with the food. If they're well fed, they'll go to the one. So what they can do is learn. Let me maybe getting a little head. Let me back up. What. It's an incredible system to have these different appetitive needs. They have a need for food, they have a need for hosts, these appetitive needs. They're able to integrate that on in a brain no bigger than a pinhead and learn these different wow. And retrieve it and respond based on current need. If they're hungry, they go to the odors that they've learned associated with food. If they're well fed, they go to the one with the host. So a plant. Actually the other thing we saw John, is that if a, if the plant is being attacked and has caterpillars feeding on them, they increase the flow of extra flora nectar. So they are competing. What it amounts to is these different plants out here are competing for different bodyguards. And if you have a plant that's producing the food as well as the host, they, the U.S. see that the wasp kind of develops an affinity for that plant. And so they actually are able to support the bodyguards better.

This, this leads me to a question I was going to ask just a moment ago. You've already partially answered it. And that was from a. From a practical perspective, what is the capacity of these parasitic insects, and particularly parasitic wasps, which we're talking about, what is their capacity to provide effective control over an entire field? Particularly today we have these really large fields, hundreds of acres in size. And I would almost have had the assumption prior to what you described a moment ago that there would be a pronounced edge effect where these parasitic wasps might come in from weed strips and so forth along the edges and have an edge effect. But it sounds from what you're describing that they may be able to cover an entire field.

Yeah, they can. Now that's, that's on the assumption that, see what the plan has these attributes, if you, if you predict, you know, that one time they bred a line of cotton that was nectarless with the assumption that if you don't have the nectar because things like the moth, the pests, certain pests feed on the nectar too. And so with the idea that if you didn't have the nectar, you would have less things like bow worms and army worms. But what we didn't think about at that time was, well, the natural enemy has this too. So, you know, you need that. And so yes, if, if the plant is not producing the food directly, then they've got to travel away and go get food. And once they get hungry, because they've got these searching, parasitic wasps have got to find their food once in a while and stop and feed and then go back because when they get hungry, they, for their energy, they've got to move. So understanding these attributes and what resources the wasp needs is very important. But yes, if you understand that and assure and make a point to see that the plant provides all those needs, it can operate just within the field and they're much more efficient. That's the value of having this kind of information. It not only allows you to develop plant with maximum attributes to support the natural enemy, it also allows you to provide the right agronomic practices so those attributes are maximized. For example, we found with the signaling ability, if you get too much nitrogen, you can disrupt this or certain varieties of cotton production don't produce it as well. And we were losing some of this in our domesticated varieties because we didn't know this attribute exists.

That's really intriguing because excessive applications of nitrogen are a common characteristic of commercial cotton.

It is true. Now, just to go a bit further and Talk about how not only does the plant produce and the parasitic wasp learn in association with food as well as the host.

It's.

It's important to understand that they, they mark their. Where they kind of carry a map within their searching area is they search a patch and they encounter a site for a caterpillar host and they crawl around on the leaves or sting that caterpillar. They leave a mark so that they don't come back and waste time on that again. So as they're operating, they kind of map where have they been. And they have trails to tell them hey you, you're going back over the same territory. And you know what is interesting is they recognize the difference between their mark and other wasps of the same species mark.

And.

Not only that, they recognize whether this it's their mark or another female's mark and whether it's a sister mark versus not a sister. We actually did studies in situations where we would compare the response to their mark, their own mark, that of other sister females and another unrelated member of the same species, conspecific, but not a sister. And they actually prefer if they have, if they have a choice and have to operate only in the duplicated space, they will go and operate in that space versus their own. They avoid. They recognize the difference between odors is the point. Wow. And also there's the question, what about this very first when they, when the wasp emerge and they are completely naive. They haven't encountered. How did they, how did they know what host plant to research? And they have preferences for some plants over others. This that's built in. But also when they're coming out of the cocoon, they get certain information. They carry a knowledge, it's called mother learning. When it emerged within a cocoon and the host that they developed in expense a cocoon, they weave a little bit of the frass and odor of the plant that they had developed on and they emerge from that with that preference for that plant that. But it's not hardwired. It's learned information they get from their cocoon.

So would that be some of the information, the learned information that is lost when you raise insects in the laboratory?

You're right on, John. We actually did that demonstration and it explains some of the release of lab reared parasitic insects in. In attempts to use them like biopesticides, mass produce them. And really we were seeing situation where they just didn't respond good. And that's the explanation is that if you rear these wasps on artificial hosts feeding on artificial diet, they're not Able to have respond until now. You can train those wasps and get them, but you have to provide that training and that rearing for them. Because if you. Those wasp. We actually did comparison wasps feeding from, emerging from host feeding on artificial diet versus natural plants. And the natural plant was much stronger from the first because they, you know this, you, you see this and it looks like it's built in, but it's not. It's learned information.

So the take home from what you're describing in essence is that rather than thinking about these predatory insects as biocontrols and purchasing them from a lab and releasing them, we really need to create ecosystems on our farms that propagate them naturally and that they're naturally present.

We came to the conclusion, we refer to it as input substitution. You still using inputs and using natural enemies or other kinds of things as bio pesticides kind of thing. Your most powerful method of first choice is to use a built in natural system. They're much more effective because of a number of these types of attributes that we didn't understand. As I was saying, as this interaction is going on there's. It's. It's built to operate together. It. Because of the feedback loops and so things that we're describing. You've got the. The power of the whole is greater than the sum of its part. And you take any part of it and you try to use that as putting it together by mastery and release. And it's not the same as those natural system because all these things that we don't fully understand and come together, it's, it's much more powerful than mass rearing and releasing. You know. Now if you. There's certain ways you can improve on these. For example, in Europe they use certain parasitic insects in greenhouses. And the way they get this to operate rather than mass rearing these in laboratories, they actually for an example they deal with parasitic insects of white flies and other kind of things in the, in the greenhouse. And they take donor plants and they grow the white flies in the little cages. That's over. And they have a system where the wasp as it grows from its host on these donor plants and they placed in that they emerge and naturally in that greenhouse and go to the produce plants and they operate because they're building it in and using these donor plants, if you see what I'm talking about. Because that way they get, they emerge in that system naturally and get key information that they needed to operate. So you, you have to find a way nature, it gives us the way if we will Copy nature and draw on that. But without all this information, and it's so complex, the interaction, it's much more powerful to use the built in system and rather than trying to put it together with these artificial applications.

So far you've mentioned two different potential management strategies from a plant management perspective that really stand out to me. One is you mentioned the impact of excess of nitrogen fertilization which is so common. Secondly, you've mentioned the, the value of these extra floral nectaries. And it occurs to me that the, the sugar production of these extra floral nectaries and the volume of nectar being produced is almost certainly going to be correlated to the photosynthetic potential of photosynthetic activity of these plants. This is one of the pieces that we've observed that it's possible to greatly increase photosynthesis in plants when they have good nutrition and again also when they don't have excess of nitrogen. So for those of you listening, this is in our work at advancing eco agriculture, we actually have a lot of success and a strong track record of greatly reducing nitrogen applications on cotton and other crops by as much as 60 to 70% and increasing photosynthesis. So if you would like to have more information about that and learn how to do that or want to work with a consultant on your farm, please connect with our team at AEA and we can help guide you through that process. So Joe, thinking about all of this, the question emerges of what is the potential of this knowledge? What's the potential if we apply it successfully? To what degree can we reduce insecticide applications? To what degree can we develop an ecosystem where we're not dependent on pest control products?

We can, we can essentially back them out. I'm satisfied to that John, that if you have a good healthy ecosystem, and that's where we need to focus, the fact that these built in systems is the first, is the first team inputs and, and interventions must be a second team. So we, we provided and wrote a paper and produced, I think it was 1998 and published it in the Proceedings of National Academy of Science. After finding a number of these discoveries that we are talking about and we came to the point of view that we've got to move back to a total systems approach to pest management and agriculture production. Because the natural system is a powerful system and nature tells you the way to do this. And we can see for an example, we use cotton as our model in that study and showed that if you understand that system and use it, you can essentially remove the input of pesticides and a lot of your things like herbicides. And we showed that there are two key pieces that are important. One is that you needed to perennialize the system row crop systems that are highly disruptive because you have clean tillage and so forth. You create this monoculture and you kind of have to redo the growth curve all over every year because you're starting with a clean till feel. And you the idea in this monoculture production system of getting rid of with tillage and other things, everything but the crop itself, all these other plants. Planting ditch row to ditch row is not a. Not a good system. And so perennialize the system as well as understanding these quality attributes of what truly is a healthy plant. And you do it right and keep copying and operating with nature, you can essentially back them out. But the information about high input system, for example, that nitrogen and phosphorus. I think that you, you're probably aware a lot of the studies that we we're finding that the phosphorus and the nitrogen recommendations that were provided for years was too high. There's a lot of good information about that recently.

Yeah, they're just continuing to go up.

Yeah. And there's all kind of environmental impact of that nitrogen, for example, and runoff and effective on waters and streams and rivers. But for example, in cotton, particularly when we were able to eradicate the boll weevil, we moved in in Georgia, for example, from 20 applications 17 to 20 treatments per year of pesticides, insecticides to three or four within the first three or four years. And we were in on the way to backing them completely out. But it's important to understand the power within the system. And I like to compare it because people can visualize and see it easy to health maintenance. If you know, in managing your health rather than using painkillers and antibiotics and those things, your first emphasis should be on good nutrition, rest, exercise and those types of things. And then it's okay to use an input once in a while, a painkiller, but use it as the second team and very sparingly. And understand this as a part of the rule of nature. Anytime you're using some intervention, whether it be a painkiller, an antibiotic into the natural system, it's disruptive because it can't operate as a part of that built in system. So you need to use it sparingly and not as the first team. And the same thing with any high input system interventionists, pesticides, fertilizers and these things use inputs interventions as the second team. Your first team is those built in mechanism of pest control and fertilizers and that type of thing. But first team is the built in system.

I want to make sure I'm understanding clearly. One of the pieces you described, you mentioned that you went from 17 to 20 insecticide applications. You reduced it down to three or four with the potential of going to zero, if I understood correctly.

Yeah.

What, what were the mechanisms or behaviors or actions that prevented going to zero on a large scale? Was it just the inclusion of nitrogen and other factors?

Well, not more than that. I think it was the fact that we just, we had to be careful. We were very cautious to not remove it until you knew you were safe. We were getting there to remove it, but it was still not knowing enough. See, sometimes we're working with growers and situations and you're careful not to recommend or say, hey, don't treat, don't do this conventional application yet until you know it's not going to get the person into problems. So some of it was the lack of experience in how much you could. Because a lot of times see you, you may have a pest outbreak that was reaching what has been established as the economic threshold. And you, if you waited another day or two, you may not need that application. But until you know, you're very careful not to recommend some more of it that was occurring. We maybe could have gotten by without it and we're on the way to do that.

You know, it strikes me just what you just said, that we have these defined economic thresholds and perhaps we should wait a day or two. All of a sudden it occurs to me that in the IPM approach we identify economic thresholds of quote unquote pests, but we're not monitoring and not measuring in most cases the development of the parasitic insects. And perhaps if we included those as a variable, we might come up with new thresholds for what actually defined economic impact.

Oh, you're absolutely right, John. Let me give you an example of a thing that occurred during these late 80s and 90s when a lot of this work that we were doing was taking place with cotton. Some of the things that were occurring, we had outbreaks of beet arming worms that had not previously been pests of cotton. And there was a little parasitic. Well, and basically it was a result of backing out some of these pesticides that had been used earlier. Had some cases where we were seeing beet army worms incontinent that had not occurred. Well, a little parasitic wasp called Cotisia Margin Adventures. It's a little braconid parasitic was. And yeah, army worms were occurring in little Clusters, they would have egg masses and it'd be a little cluster of small caterpillars feeding on the plant. This was one of the things that happened when this wasp attacked this cluster of caterpillars and they completed the development, have these little white cocoons on the leaves and the farmers could see those. And it was their first experience of seeing nature at work and natural systems. And they would have these army worms that looked like they were going to be a big outbreak. And all of a sudden you see these little white cocoons all over the field. It became a very powerful demonstration of natural control at work and it became very helpful.

And.

What they began to see as a result, when those cocoons were appearing, if you didn't left it alone in a few days, it was gone. The problem was no longer existent because of it being easy to see. It became a very strong encouragement to that nature operate. And yeah, with a little more experience and, and understanding these natural systems. And so it's there often the built in system is there. It's just a need to pursue it more. But you have to operate with it as a whole because once you do intervene, you disrupt the system, you have the primary pest and then it triggers a secondary pest. And this type thing, that's, that's what we have to do. We have to, we have to work with it as a whole system.

When you speak of primary pests and secondary pests, it actually reminds me of something that I have read about and I've observed is that we now have pests in cotton and other crops, or I should say insects that are reaching much larger populations and are much bigger problems than they were historically. I wondered if you have any perspective on that. Why is that? What are the changes in the system that are bringing that about?

Restate that question again.

Well, we now have insects like stink bugs that are causing major problems on cotton that aren't even described as being an issue 20 years ago.

So what has changed? What's different? Very good point. And particularly for an instinct bug. Yes. What's happened in the post boll weevil area in the southeast, in Georgia included as one of where I'm operating, we've had stink bugs that's become a pest that was never a pest before. And part of it is the fact that as you were able to back these high inputs out, you get a different situation. But they're also use of transgenic cotton has been used as a way of controlling things like bollworms. We actually have found and have some studies showing that when you have that transgenic cotton and you are not getting the bowworm activity even at a moderate level in the feel that you had in the, in the response of the plant to the bowworm producing these signals to recruit the natural enemy that we had talked about earlier. Actually we have studies to show that that presence of the bowworm at a moderate level that the plant manages and suppresses with the use of its natural ally, those chemical changes actually prevented the stink bug because those chemical changes, they had a crossover of suppressing the, the stink bug. Wow. You see what I'm saying? It's actually.

Wow. So essentially the presence of my understanding, my interpretation of what you just said is that the presence of bullworm pressure changed the production of plant secondary metabolites to have a suppressive effect on the stink bug population. That's incredible.

And see, that's an incredible system interactions. It is a system and that's the key central point I want to stress it really strongly is, is you got to work with it as a system and to understand and appreciate the fact that these built in mechanisms are there and they're because of all these things that we've shown that the plan has the ability to signal, it has built in ways to support its allies and to operate in conjunction with them. This powerful system gives you avenues that are far more powerful than any pesticide if you will understand them and copy that system. You know, it's kind of like what just described. It's like a vaccination that has more than one benefit, that it's broad. It actually you can't have any good guys till you have a few bad guys. You need early season, a few herbivores to charge the system to jump start it early in the season. It's like a vaccination and it's broader than just that one system that you may understand.

So this is, this is perfect, this is a perfect indictment of the word pest. These insects are not pests when they are present early season and that they're actually having a positive impact on the plant and the overall ecosystem.

And, and I emphasize the fact that when you say pest, when you, when you get what you see and interpret as a pest rather than, rather than saying what did I use to kill that pest? It's vital that we, our first question is why is that pest a pest and what's out of balance and how can I correct that and bring that back into balance rather than what I use to intervene and kill that pest? It's huge difference in approaching it that way.

So a Few moments ago you mentioned in passing the impact of transgenic crops. But what you're describing in essence is that if you have a BT cotton crop, which is the vast majority of cotton planted today, then you prevent this vaccination from ever occurring in the first place. You prevent these beneficial worms from being present, which then leads to serious later infections of stink bug and perhaps other insects as well. Am I understanding that correctly?

Yes, you are. And let me stress this even further. Practically all cotton production in US now is Bt cotton. And in Georgia the boll weever was eliminated by 1990 and from BT wasn't delivered and put in place until three to four years later. During that interim, we had already reduced the number of pesticides from about 17 to 20, as I was saying, down to three or four that had already occurred before BT Continental. We are still at three or four or five. Primarily because of the stink bug.

And the so BP cotton hasn't reduced insecticide applications at all.

No, not if you look at those numbers. It was already there. Now think about it. All the studies that we've done, if you look in the literature, there are two parasitic wasps that we use for our model system called Microplitis crucipedes, cardiocules and Agriceps. Those two wasps that are probably two of the most studied parasitic natural enemies in the world through the 80s and the 90s. And with our model system and a lot of other people have studied those parasitic wasps only attack bower. The two species, the budworm and the bow worm, Heliothis zia and Helio coverpezia and Heliothis fluorescence. The budworm and the bollworm are the corn earworm. Now with cotton BT cotton exclusive. We're talking about huge acreages all over the cotton belt. You have no bollworms because you have put this in. And the approach to prevent resistance is like shooting for 100% keel. Well, huge acreage. There are no bone worms out there. You can't have any good guys unless you have a few bad guys. So if you're having no bollworms, suddenly they're all removed from this huge acreage. Where do these where. What's happened to these two parasitic wasps?

I'm sure the populations have crashed.

In fact the microphones crusty pieces. It's a real question. It's hard to find it existence. So what is the. What is the ricochet effect of suddenly removing. Yeah, okay, they're not a pest. But we are having to stack genes to keep this BT cotton and keep Those bow worms out of there. It's, it's a. What impact it's having is an unknown. But it is, we know it has to be having an incredible effect on the natural enemy system because this is not only a pest, it's also a resource for natural enemies. You have to look at the whole system and that's a great concern to me. And nobody is studying what is the, what is the other ricochets that's occurring in this system in addition to these parasitic wasps. If it's true which the data that in a couple of those papers says that it's, it's all, it's. It's contributing to the outbreak of the stink bug. And what, what else? What, what's this protein that this plant is transgenic plant to produce this toxin that is producing that has to come from somewhere.

Yeah.

And we don't know what all is is going on. But there are two guides that I always point out that you need to use. And if you want, if we are going to move to a built in natural system that we're talking about, if that's going to be our first team, then the transgenic is not. And there are two attributes or two components that I like to say is one is it target specific and it's on an as need basis. Let me explain that those two pieces are important elements in when you're dealing with managing a system. The if you use parasitic wasps or natural enemies for example as your control system to manage pests, if you're fostering them there, they have those attributes. They have what's called density dependent system. That is if the pest gets down to a low level they don't continue to occur. You know the old cycle of the predator and the prey and the fox and the hare. It's then if the pest gets low, the predator backs off and if it gets high it applies again. So it's on as need basis. Your pesticide or in this case BT cotton doesn't operate that way. It's every plant is producing that toxin all day, the entire plant, everywhere. Whether you need it or not. No matter how low the pest gets, you still producing it 100% every plant. So there's no density dependence there. The other thing, it's not target specific. It doesn't, you know, your parasitic wasp, they only attack that pest on those plants that need it. Not all over the field. And the BT cotton or like a pesticide, if you spray your field, it's not target specific, it's being expressed everywhere. Now that's why in this, the system that we talked about, the plant calling the natural enemy, it's inducible, not constituent, this little signal to recruit the natural enemy that's produced in response to the damage. It's only induced when you have a pest feeding. If you spray a pesticide, it's expressed whether it's pest there or not. It's not target specific. And on and as need basis you see the difference. It's. It's being expressed everywhere. That's why these things are so disruptive, because they're expressed without regard to density dependence and they're not target specific.

And I think as time goes by, if we look back at our history of developing various technologies for use in agriculture ecosystems, whether those might be fertilizers or pesticides or transgenic crops, it seems practically always 20 or 30 years in the future, at some point in the future, we begin observing and discovering all of these secondary and tertiary impacts, unintended consequences that we don't know about. And I'm actually reminded of an experience, you know, many cases, as with the case of Bt cotton, it's so widely adopted that we no longer observe comparisons. Where are the comparative fields or the comparison fields where there is no Bt cotton? And how would that look different? In many cases we don't know because we don't have those comparisons. But we did actually. We have been working with a grower who does have a comparison of Bt versus non Bt cotton planted in the same field and grown together. And we observed one startling difference. The following season, the weed populations in the two sections of the field were completely different. The section of the field that had Bt cotton had much more aggressive weed species that were much more difficult to control.

Why?

I have no idea. Did it change the microbial populations as a result of different plant metabolites? That's just interesting that we, and I guess in reality I also can't say that it might have been just the BT because there were different varieties as well. There might have been other things going on that I don't know about, that it was really interesting to observe this very pronounced and startling difference as a result of different types of plants, different varieties of plants being planted into the same soil and managed in practically identically the same way.

Well, you're making a very powerful point. We know I have, I work with a grower to talk about in full chapter, Alton Walker. In fact, I was at Mississippi State with him and he now is a consultant and a grower in East Georgia. And he by his own, just as a kind of A almost a hobby. He's producing several hundred acres of cotton every year and he is using moving at a system of COVID crops and input. And he is trying a very strong ecological approach using these principles that we're talking about. And he cover crops is a very important part of his work. And he's. He's convinced in his system that you do not need to be tea cotton produce and also that you don't need the level of herbicides. And because of his production system for the last several years he has the highest quality dry land cotton in that area. As he won the award for the best quality his staple inked and all other attributes of the crop is not only is he producing and without the use of the high input system he's getting better quality. And why is the quality? He feels certain it's because of the quality of the soil and he doesn't need as much irrigation dry land cotton is and he's also now producing corn which often you know you. They basically thought you could not grow corn in that area without irrigation. Well he's able to do it. When he uses this cover crop system and improving the organic quality and the residue increase in the soil he's able to. His moisture holding capacity is much important, much greater.

I wanted to ask you about the use of COVID crops as them from your perspective. You mentioned a little bit ago the importance of developing perennialized systems rather than annualized systems. And you also mentioned not disturbing soil and not disrupting and having clean fields etc. And I also think about cotton and some of these plants have extra floral nectaries. But there are also many different crops that don't have extra floral nectaries. What is the value of using cover crops to provide a nectar source for wasps during the production season?

That can be if you have a crop that doesn't have that nectar source. You know that extra floor nectar and things on cotton every plants got it and it's a huge because we were quite impressed with the fact that as you begin to get damage we showed that the. The plant actually increases the extra floral nectar flow. And we also have studied these little wasps and showed that once they feed on the plant in that extra flora nectar they develop an a preference for that plant. It's kind of it there we got to realize different plants are competing for these bodyguards and this is a powerful attribute to support. So it's. It's. It's beyond just some physiological benefit.

It's.

And it probably got multiple rose but in the absence of those systems you need that Those alternative sources right there, they can't afford. This wasp can't afford to operate here. And when I need to go feed, travel out to the edge of the field and then come back. It's very important.

And this reminds me of. I apologize I'm forgetting the researcher's name research done in California on organic control of aphids on salad green crops, spinach and lettuce and so forth. And they discovered that if they plant in mixed in with the crop sweet Alyssa as a nectar source at a rate of 100 plants per acre. If my memory serves me correctly, 100 plants per acre was enough to provide a nectar source for the beneficials to where they would provide complete control of the aphids. You think about that 100 plants per acre. That is going to have zero impact on yield, but it's very effective for insect control.

Yeah, well see there's several things that I think that's very important is not. It's important to have what they call a push and the pull you need to provide the. The resources in with the diversity in general principle a more diverse system is better. It's also important that you see in the earlier stages of minimum minimum teal. The idea was just to put more residue in the soil. But we were overlooking the importance of this perennialized system that this. You're relaying natural enemies. Think about it. If you got a clean teal field, it's nothing occur in the ecological growth curve curves and it occurs in a sigmoid manner. You can't get any good guys till you get some bad guys. You've got to begin to get populations. And so natural enemies comes rather late after you get the pest population present and you this real steep growth period that occurs is when you get a lot of oscillations and sometimes you pissed out breaks before you get to equilibrium. And so you having to do that every year. Whereas if you keep a perennialized system, you stay at the top of that curve and you maintain a balance year round and you don't have to go through that lag effect every year. Not only that, it is important that we know now that the tillage disrupts that layering effect that's important in the quality of the soil rather than the disc and the heron put that down and create that turmoil that also loses some of your carbon and so forth in the residue. So this, this perennialized system is a very important element. And so we've been able to move to the idea not only use the COVID crops to put residue back in but to build the diversity and the stability in the system. And there are many attributes to it.

I really like the one phrase you used of relaying natural enemies from season to season. That's very powerful because we're now having increasingly in the regenerative agriculture space, we're having conversations about relay cropping or relay cover cropping. And I like this term of relaying natural enemies from one season to the next. I wanted to go back and also mention, I spoke about the value of sweet alyson for aphid control or as a nectar source. And if any of you listeners want to dig deeper on that, I actually wrote about this research in a blog post on my blog@john kempf.com if you want to go find that and dig deeper. Joe, the, the one question that comes to mind, you mentioned that these relationships between these parasitic wasps and these larval and herbivorous insects have been extensively studied in cotton in particular. What is the potential for this type of interaction to exist in other crops? What is the opportunity for effective insect population management in natural ecosystems or well managed ecosystems for other crops?

Well, I think the principle goes across the board. There's. And you're talking about what, what, which particular you talking about? Any particular interactions Specific?

There's not, there's not any specific ones that come to mind. But yeah, I mean, we have major challenges today with army worms, for example, in different parts of the country. But there's, I mean, obviously there's a multitude of insects that are called pests and we know that they only show up when we have compromised ecosystems or compromised plant health to some degree. Or I should maybe rephrase that. Not that they show up, but they only become severely problematic in compromised ecosystems.

Yeah, well, the, this system that we used as a model is strictly a model. We see it across the board. For example, we shared the wolf prize with John Pickett. He's done the same kind of studies that we've done in our colleagues in the Netherlands operating with the spider mite and, well, different mite systems. In all of these cases, the plant supporting its natural enemy in response to the herbivore is the same system. Two colleagues that we work with in cooperation with in the Netherlands demonstrated this induced signaling and recruiting the natural enemy with predatory mites versus herbivore mites. It ran close to the same time that we first demonstrated it with caterpillars. And it's basically the same way. It's a damage. When a damage occurs, the plant detects this under attacks and begins to recruit these natural enemies. And that Collaboration between the herbivore and the natural enemy operated in the same way. And by the way, we also demonstrated that this, these signals that the. The plant releases that attracts the natural enemy occur primarily during the day. When the natural enemy is active at night you shift to a little different blend that often is a deterrent for herbivore that like moths that overposit at night. So these systems are. They operate in a. They're very broad mechanisms that apparently have a very long standing presence in the evolutionary history of the plants. It's not just a recent occurrence that succumb in evolutionary time. So I think these same systems operate in a very similar way. So I think we can apply these principles that we're talking about. Use of quality of soil, the plant attributes to produce support for their natural enemies to deter pests, all of these things. But it is a web of interaction and it all has to do with quality of soil, a greater diversity use of supporting your natural enemies. Not planning high monoculture, but mixture of plants in the right combination and basically building into the system. High interventionist system rather include chemical pesticides and fertilizers or the plow are interventions that we need to be very careful about and those are second team and it should occur sparingly and with recognizing that these can cause harm and be careful with them.

Joe, this has been such a delightful conversation and you have such a wealth of experience. The question that comes to my mind is what have we missed? What, what. What's the question that I haven't asked? What's the topic you would like to talk about that we haven't touched on? Because I'm sure there's so many different aspects of your experience that we haven't had the space to touch on yet.

Well, I don't. I think we've covered the. It's just a matter of where you put the greatest emphasis. But I think the key is is there a common denominator principle that we are talking about here that want to leave and it's a God. And I think to me it's, it's this. That is the thing that we were saying do not realize that what has occurred in, in agriculture is that over the years that we have, as we develop this industrial agriculture era of high intervention systems, we have moved to big monoculture systems and we, we have. In this intervention paradigm we tend to look for what to kill the pest with rather than why is this pest a pest. It's very important that we change that basic paradigm. Always in nature gives you the solution. If we were look at that primarily as our first way of doing what. Why is this pest occurring in any intervention? Occasionally, yes, if there's, I wouldn't tell folks, never use a pesticide. But if you do use that or any intervention, be very careful with it because it doesn't fit in as a part of your feedback loop. Now I guess I would like to make one other point. It's bigger than just agriculture. What we have done is spending a great period of my time on the local city council and other things. All of this thing that's occurred in the change of our agriculture to a very highly centralized, specialized world. I do want to emphasize it's. You can't separate it from our social, human community elements. Not only have we lost the, our sense of connection to nature and the way of managing these agriculture management systems and the piss with a more ecologically landscape approach, we have lost the flavor of our local communities. In these rural areas. If you drive throughout South Georgia, for example, all these areas that were like I grew up with your crossroad grocery store and the little communities that had the butcher, baker, candlestick maker. The world is made up of systems within systems and the natural process is. It's like a stratified system rather than a highly vertical system. And when you go with the realize that the average meal that you put on your table now the chain of custody is like 1500 miles before it gets to your table. These high centralized food systems, it's a high risk force for food security. So I'm kind of drifting over there where I think it's the other question. All this is interacted together and we have a major food security problem and an issue that's of concern because this the same way that the high production, high input agriculture has affected the way we manage pests and cropping systems has also disrupted and has caused a loss in community at the local community level in these rural areas. You know, you, you're. The highways of the country are littered with these little areas that, where you had a, a community crossroads that's not there anymore, you know.

And I would suggest from my perspective that foundational to this loss of rural community is a loss of economic viability and reward in agriculture and in farming where margins have become really narrow. And this loss of economic opportunity has also led to a loss of community in the countryside. And that's, I would suggest that's really one of the foundational, the economic drivers is you achieve what you incentivize and you do not achieve what you disincentivize which is what we have done collectively as a society over the last 70 years. I think this is one of the foundational principles. I really strongly agree with what you just described. But if we want to have a conversation about a regenerative agriculture, we need to remember the regenerative culture part of that as well. We also need to regenerate our rural communities. And to do that we need to regenerate farm profitability. That's really at the foundation and that's why I believe and what we have observed in our work at AEA is that truly regenerative farmers, when the soil and plant ecosystem is functioning well and it's being managed well, they quickly become the high yielding producers, which means. And they also have reduced inputs, which means that they become the low cost producers, which means that they become the high profitability producers as well. And that's really I think at the foundation of what is going to be required to regenerate our rural communities.

Well, yeah, see it gets you off the treadmill. You absolutely, I think a basic law once you start this, these high centralized monoculture interventionist approaches and you lose this built in power through loss of diversity, loss of the natural system. So you, you, you always get on a treadmill of input and that gets to the economics of it. But it also, this creates a centralized specialized system. It moves toward the reductionist system that may be more economic on the short term but it begins to have a diminishing benefit. You always get on a treadmill where it takes more to get the same result. Let me take just a minute to mention if you followed ever Deming's principles. Yeah, well, it's the same principle that I'd like to just take just a moment to apply to the agriculture management system that we're talking about. The Demings principles that were heap Edward Demings put into in the production system. Like for example, if you're producing an automobile, you have an assembly line and this system that where everybody does their little part in the way you manage control or sheer quality is to have an inspector at the end of the line to reject anything that doesn't look right and doesn't fit the system. And you create a game without end that is the assembly line worker operating in competition with the. And they get increasingly creative about getting it past the inspector. That's the. It appears always that to control a pest or any undesired variable is to produce a force like a pesticide to treat an undesired variable or a, you know, anything or an inspector to create quality in there. It's a game without end. And rather than to create a system and, and basically when you have an undesired variable, which basically the way he applied that into the industrial model of producing a product is say you just create this total walk quality work circles where if you have an undesired variable you just engineer it out. The same thing occurs into agriculture production is if you have a pissed out break, just redesign your system so the pest never becomes a piss. It's the same basic principle that we've got to operate in anyway. These are some basic laws that we're talking about and loss of community. And what I've seen is some recent reports when this proposed solution for these things with from management at the federal level and so forth is to build more roads, more fiber optic networks and into these communities and do more of the same. And I just thought that's not going to do it. We got to go back to your point that you're making to regenerative agriculture. And all of that has got to start with us reconnecting to natural systems and understanding operating is a part of our natural world.

Absolutely. Joe, thank you so much. And friends, I hope you enjoyed this conversation as much as I did. There's. I've learned that some people are not aware that we produce show notes that goes with every one of these episodes. If you're listening on a typical podcast platform, you won't have access to those show notes, but if you go to the podcast website@regenerativeagriculturepodcast.com then you'll be able to see all of the show notes. And we also put links in there to relevant links. We'll have links to some of Joe's work that you'll be able to see and read some of his papers and some of the references and things that we discuss in the podcast. I also welcome you to subscribe to the podcast newsletter. You'll be notified every time we release a new episode. And very importantly, if you're a professional grower who believes in testing instead of guessing and you have an interest in adopting this type of approach and methodology to your farm, please connect with our team as well@advancingecoag.com and we look forward to working with you. Joe, this conversation has been an absolute delight. Thank you for being here with us, for sharing your wisdom and I look forward to more conversations in the future.

Thank you, John. I enjoyed it very much. It's a huge subject, isn't it?

Without end.