Pests & Predators, Ep 34: Name the pest and stay focused on thresholds for highest ROI

Pests & Predators, Ep 34: Name the pest and stay focused on thresholds for highest ROI by RealAgriculture Agronomy Team Unpredictability continues to define insect pressure in Prairie lentil crops, and new research is helping growers better understand when — and if — action is needed. In this episode of Pests & Predators, host Shaun Haney is joined by University of Saskatchewan researchers Sean Prager and Teresa Aguiar-Cordero to unpack how pest dynamics, economic thresholds, and beneficial insects all intersect in real-world decision making. “The thing is that pest pressure in lentils is highly unpredictable,” says Aguiar-Cordero. “Different insect pests respond very different in the weather and the environment.” While grasshoppers dominated in 2020, she notes recent seasons have seen rising concerns with aphids and lygus bugs, serving as a reminder that scouting priorities can shift quickly. Each pest brings its own type of damage. Lygus bugs inject enzymes that disrupt plant tissue, causing flower abortion or seed damage, while aphids weaken plants over time and can transmit disease. Grasshoppers, with their chewing mouthparts, cause visible defoliation. These differences matter when setting thresholds and determining when control is warranted. But as Prager explains, economic thresholds are ultimately about profitability. “What you want to ultimately do is minimize the amount of input, right, and maximize the amount of output,” he says. “It lets you have a number that you can pinpoint to say, this is when I'm going to start losing money at a greater rate than the cost of what it's going to cost me to fix this problem.” The challenge becomes more complex when multiple pests — and beneficial insects — are present at once. Aguiar-Cordero is working toward a “dynamic threshold” approach that considers total crop stress rather than evaluating pests in isolation. “Instead of asking, ‘Do I have enough aphids or lygus or grasshoppers to take action?’ I would like to start thinking or asking, 'what is the total stress on the crop right now?’” she explains. New tools are helping move that vision forward. From drone imagery to DNA analysis of predator diets, researchers are gaining clearer insight into how insects interact in the canopy. “Using these technologies, I think that can help the management of pest to get to be more integrated, sustainable, practical and realistic,” says Aguiar-Cordero. As Prairie growers face ever-changing pest pressure, that integrated approach may prove essential for making timely, informed decisions in lentil production. The Pests and Predators Podcast is brought to you by Field Heroes, powered by the Western Grains Research Foundation. Visit fieldheroes.ca to learn how beneficial insects can benefit your farm. As BASF celebrates 30 years of InVigor canola, BASF Agricultural Solutions has announced $27 million towards updating and expanding its Saskatoon Canola Breeding Centre of Innovation. Construction is set to begin this spring and will continue through the end of 2027, adding breeding capacity and advanced automation for the InVigor hybrid canola breeding program. Farmers... Foreign. To you by Field Heroes, powered by the Western Grains Research Foundation. Whether you're a farmer, researcher, or educator, visit FieldHeroes CA to learn how beneficial insects can work for you. Welcome to another episode of the Pest and Predator podcast here on RealAgriculture.com powered by WGRF. You know, when do pests really impact yield? Today we're going to hear From Associate Professor Dr. Shaun Prager and PhD student Teresa Aguar Cordero from the University of Saskatchewan. I'm your host, Shaun Haney of Real Agriculture, and we're going to share some new Pulse crop research that explores when pests like Lygus bugs actually cause economic damage. We're going to learn how pest thresholds, natural enemies, and improved scouting methods support better timed integrated pest management decisions. And where does technology fit in, allowing us to not only understand the interaction of pests and beneficials, but also tackle the problem as well. So let's bring in Dr. Prager and Teresa Aguaro Cordero, both from the University of Saskatchewan, to join us. Okay, let's get going here with the Pest and Predator podcast, I guess. Teresa, let's start off with you. What is the main pest management challenge that lentil growers are dealing with right now on the western Canadian prairies? Well, I think that depends in the thing is that pest pressure in lentils is highly unpredictable because different insect pests respond very different in the weather and the environment. So, for example, in 2020, grasshoppers were one of the most important pests in lentils. But in recent years, like, the numbers have been so low, actually, I was struggling last summer to find enough grasshoppers for experiments. And in the case of aphids, like, now they are like, their population is very high. And during, like 23, 24, 25, Lygus bugs also starting drawing, like, more attention in lentil crops. So I think that grasshoppers lies, aphids, but it depends in the year, the weather, et cetera. Yeah. And, and Shaun, that kind of speaks to the. The point that we got to just be on our toes. Right. Because based on the conditions and those kind of variables, we, we've been dealing with all of them, none of them, different levels of them. Like, we just, we got to be really ready for anything. Exactly, exactly. So even in the time that I've been thinking about pests that eat lentils, what I would have been concerned about, what growers would have told me that they were bothered by, would have changed over the course of years, between years and among years. Right. So, yeah, so what's a problem? One year isn't a problem in another, usually driven by. Which is the one that we're trying to fix. Yeah. So, Teresa, let's. I guess let's hone in on those. Those pests that you mentioned. We got lygus bugs, we got aphids, we got grasshoppers. They. They differ. How do they differ? In the way that they damage the lentils. And. And why does that matter when we're trying to set some of those economic thresholds? They damage land yields in very different ways. So, for example, ligus and aphids both have piercing suck in most parts, but the effect in the plant is very different because in the case of ligus, they piercing and sucking the plant and they inject the saliva and their saliva have enzymes that macerate the plant tissue. So the impact depends first in the crop stage. So in flowering stage, ligus can cause flower abortion, and during the potting stage, ligus can damage very young seeds or even leave these kind of chalk pods or ligus bites on the developed seeds. In the case of aphids, even if they also feed by piercing and sucking the damage, it's different, more like indirect. And they cause plant vigour over time. And the important part here is that they can transmit diseases. With grasshoppers, they are completely different because they have chewing mood parts. So you can saw the damage, like very visible, like in defolation. So these are just differences in feeding behaviour. But we are like. They are also very different in how the weather affects them, as we just mentioned. So are. For me, it's like kind of a puzzle that we need to complete to understand, like a realistic scenario and then like. Yeah. Make decisions of how we can manage them. Yeah, Shaun. Yeah, no, I think. I think Teresa is exactly right. Each of them is a problem. Each of them a problem is in some times and over last decade, people have been working, we've been working to try to, you know, build the tools for some of those things, but each one is its own problem historically. And. And some of them weren't problems even a few years ago. So. So, Shaun, when we look at economic thresholds, like what. We can calculate that based on a bunch of research that, you know, people like yourselves have been doing. But what, like for the farmer on the ground, what does that actually mean in real life? I guess there's two ways to think of that. What does it mean if you think about it relative to your farmer? Right. Your goal is to maximise your profit, really. Right. We think about yield but really what you want to do is you want to maximise my profit, right? You want to make the most money that you can out of your crop. And obviously the most money comes from having the most crop you can sell for the most money, right. For the highest price per bushel or acre or whatever it is. Having said that, there's inputs, right. And so you also have some amount of money that you need to spend to do that. We always think about it as fertiliser, but it's, it's the insecticides and the pesticides of this berry as well. Right. What you want to ultimately do is minimise the amount of input, right, and maximise the amount of output. And the economic thresholds, when it comes down to it, are just a way of giving a more sensible number, right? Something that you can kind of get your head around that should, if you follow it, minimise the number of times you have to apply an insecticide such that you're only really using it when you're actually going to sustain a decrease in yield that's going to cost you money, right? So basically it lets you have a number that you can pinpoint to say this is when I'm going to start losing money at a greater rate than the cost of what it's going to cost me to fix this problem. So, so, Teresa, so adding on top, like let's. In that context, what happens when, when lus, aphids and grasshoppers and kind of a worst case scenario, they all show up together. What, what, what happens there? Sorry, Shaun, what was that? Well, it's like Dorothy, right? It's grass, grasshoppers, aphids and WAG is. Oh my. Yeah, yeah, sorry, go ahead, Teresa. Yeah, they are all together and at the same time we also have other insects that could be pollinators, that could be predators, parasitoids. So for me, like, like, like in, in the PhD, I'm trying to get a kind of a dynamic threshold, like to understand how the presence of other insects can help in the yield. Like, for example, if a lentil crop is at flowering stage, then you need pollinators. So applying pesticide at the wrong time can affect the yield more than the damage caused by the pest itself. Maybe. So it's important to understand how factors like not only environmental factors, temperature, humidity, but also how the natural enemies and the seasonality can influence thresholds. So how could thinking about multiple pests together maybe change the way we make management decisions in the field then? Teresa? So one of the experiments that I'm running, it's with drone images. So, for example, I survey my micro plots recording all the insects, like the good bugs and the bad bugs, twice a week and at the same thing, talking images by the drone. My idea is to correlate, for example, the canopy, like all the different indices that we can get from the drone images with the insect population over the time. So this will help us to understand how different pests stress the crop and how that translates into yield loss. So instead of asking, do I have enough aphids or ligus or grasshoppers to take action, I would like to start thinking or asking, what is the total stress on the crop right now? So maybe like, spray is not necessary. Yeah. So thinking you called the dynamic threshold. Right. Is that, is that how you put that? Yeah, yeah. So not looking at the pests in isolation, but looking at them in totality in terms of what is the actual stress or pressure on. On the crop, given those total population levels at that time. Am I summarising that correctly? Yes, yes. Maybe to make the pest management much more integrate like and realistic. Yeah. And where did. Like the. Like, there's natural, like natural enemies are often kind of overlooked in this integrated pest management programme is, you know, as you just alluded to. So I guess, why do you think predators should be treated as a core part of this IPM at this time? So go ahead, Shaun. Sorry. I think it's not fair to say they're overlooked. That's not entirely true. They're just. But it's much more difficult to quantify their effect. Okay. Yeah. And so. And so historically you assume they existed, but you didn't directly factor them in. Right. So you assumed, say, the number of insects you had in your field was somehow being altered by them, but in a kind of a mysterious way, it was kind of a black box. Right? Yeah. And the result of that is you can't fine tune things. And the numbers themselves are dynamic. Right. So the numbers of the good bugs you had aren't consistent over the course of the season any more so than the pests are. And so what Teresa is really trying to get around, get her head around, is ways to account for that. Right. And that allows you to fine tune that number more to take out that kind of unknown factor. So, Shaun, I'm curious, so when we consider those beneficials in the canopy there, okay. Making sure we're considering them, how confident are we that they are going to aggressively do what we think they should be doing in terms of like, you know, being that. That beneficial, that has. That, you Know, taking care of the, the, the, the insects that they're preying on. Do, do we have that confidence? No, that's, that's, that's really why in many ways it is difficult to quantify that. That, that is the trick. And so that is in a lot of ways the major task for Teresa is that sometimes we do, sometimes we do, but in many cases we don't. And the only way to do that is to do historically would be experiments or just a guess or exclusion. So in the past we may know because we would have, say, put a cage around a series of plants and then said okay, well there's no natural enemies in there. And then how many pests are there? And we can sort of compare them and say like, well, the ones with the cages didn't actually do as well as the one without the cage. Something along those lines. But it's far less common that we knew what was actually being excluded from the cages or the extent to which they're doing that. That is. Right. How many things that we don't like are they eating or laying eggs in or killing? And that that's what made that a black box. It's why often. And it's difficult and time consuming. That's why people often just kind of ignored it. Yeah, like we want them to be wolves, not like sloths, like you know, we. Right. It, I, I guess is there like, I, is there things that we can do? I, I guess these are just things wrapping or kind of bouncing around in my simple brain is, are there, do we know if there's things that we can do to entice them to be like more interested or more aggressive? Like, I guess we're still trying to figure that part kind of stuff out too, I guess. Yep. And it's. And it varies by the insect. Right. So. Yeah. Okay, well, very interesting. So Teresa, what do you think is currently missing when it comes to insect monitoring and decision making around IPM when we look at this whole package? Well, I wouldn't say that it's something completely missing because a lot of great work is already being done in insect monitoring. The challenge that I see, it's more about integration of the information and also in the time because as a PhD student I would like to sample many locations across a prairies. But that's simply not realistic given the geography and in the fact that experiments are very time intensive too. So another challenge is timing. And in many cases we only fully understand how insect affect yield at the end of the season. So after all that data have Been analysed. Yeah. And in the case of integration monitoring data, it's like, often hard to get in real time. And tools don't always connect pest pressure with natural enemies, with economic threshold, crop stress, et cetera, into one clear picture. So, yeah, that. I think that it's the challenge, time and integration of information. Yeah. And this is really important work. And, And Shaun, I was just thinking about the factors. Right. So if we're, if we're measuring the impact of some sort of pest in a dairy operation, we're, you know, we're. We're in the parlour. It's inside, it's contained. Or a pig barn or a poultry operation. When we're talking about crops, we are outside. So we have, you know, we have different thickness of canopy, we have sunlight, we have cloudy, we have wind, we have no wind, we have cool versus hot and we have. We have. Those are just a few of the variables. I'm sure there are way more. Trying to understand how those beneficials and pests interact in all those different situations and combinations of permutations that. That is what makes this so difficult. Like, how do you actually measure this? Oh, that's a good question. In some ways, you measure it the same way as you've always done it, which is by simple experiments. In other ways, we have new tools that allow us to do that. So. So one of the things that makes what Teresa is doing a little different over the last, say, five, 10 years, the tools that we can do, to use to do some of these kinds of things to answer some of these questions. Well, they either exist now and they didn't, or they've come across. Right. And on other ways, you do things the same way as you always have, which is a bad answer. So for decades, people have done some of this. Right. You would have taken the thing that you didn't like and the thing that eats the thing you don't like and you would have said, I don't know, put it. Put it together in a. In a. In a glass jar or something and like, watch them eat each other. Right? Yeah. And then you said, okay, you know, one lady beetle eats 15 aphids. And so. All right, in X amount of time. And so now we have an estimate. Right. Don't miss on Tyler Wis. Doing the play by play of all that happening too. So. That is exactly right. Tyler loves that stuff. That is exactly what Tyler does. Yes. So if you had Tyler here, you'd have him doing the. Right. And, and, and, and that's what Tyler And I would have both grown up, sort of grown up. I'm not that worried. Oh, but you know, like even, you know, even a decade ago, when we would have started learning, doing, that's what we would have done. And it's what the people who taught me sort of would have done. Right. And that's kind of how you go about it. But this is where technology is sometimes kind of neat. And so Teresa, while she still does some of that, has a whole array of fancier and more expensive methods available to her that allow her to do this in a very different way that including right from the field. And so she's, you know, I mean, maybe she should explain what she's doing, but she can employ things, molecular biology tricks that weren't available until recently or too expensive and remote sensing methods to, to answer some of these questions in ways that we just couldn't otherwise. Theresa, tell Teresa, tell us more about some of these technologies that we're hearing about here from Shaun. Sure. So, yeah, actually technology is like one of the things that excite me a lot in. Yeah. As a tool for pest management. So for example, in my PhD, I am flying a drone to take pictures and then correlate with the canopy stress and then with the yield and with the presence or absence of the different insect pests and beneficials to, well, natural enemies. And Also in the PhD, I'm trying to know exactly what the predators are eating. So for that I'm running DNA extraction from the gut content of ladybugs, damsel bugs, spiders, to understand what are they really eating and apart. Like, alongside my PhD, I also start developing a tool that brings like this threshold and integrate monitoring and ecological context together. So, yeah, in my PhD and outside of my PhD technology, I think that it's like something that is very excited for me because I'm in when like in the past, pesticides were the new innovative tools and today we have apps, drones, AI. So just like insects and agro systems evolve pest management, it's also like constantly evolving. So yeah, using these technologies, I think that can help the management of pests to get to be more integrated, sustainable, practical and realistic. Well, and using all those tools, like using all the tools available to us to try to tackle an issue that we, we know is not going away. We know farmers are challenged with this and as Shaun mentioned earlier, it comes down to profitability. And there's a, there are pests in our canopy that are trying to rob us of yield. They're just every day they're working at trying to chip away at our profitability. And we, we can't just rely on one way of doing it. We do need to open ourselves up and really look at the full toolbox available to us. So really important research and I really do appreciate both of you joining us here today for the Pest and Predator podcast. Thank you very much. Thank you very much. I hope you enjoyed this episode of the Pest and Predator podcast. It's brought to you by Field Heroes, powered by the Western Grains Research Foundation. Visit FieldHeroes CA to learn how beneficial insects can benefit your farm. SA.