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Hosts Anthony Hanson, Dave Nicholai, and Bill Hutchison at the University of Minnesota alert growers, ag professionals and educators about emerging pest concerns with Minnesota Field Crops, including corn, soybean, small grains and alfalfa. They offer useful, research-based pest management solutions.
Dr. Anthony Hanson, IPM Educator - Field Crops
Dr. Bill Hutchison, Coordinator of the MN IPM Program
Dave Nicolai, Crops Extension Educator & Coordinator of the Extension Institute for Ag Professionals
Welcome to the University of Minnesota's IPM Podcast for Field Crops. I'm your host, Anthony Hanson. So we've been on break for a little while now this past year, and we've been working more on programs like our Strategic Farming Field Notes program, kind of like another podcast that we have here. In the meantime, we did have a special set of episodes we recorded this year. It was actually the fiftieth anniversary of Integrated Pest Management that we're celebrating.
Anthony Hanson:So this was a collaboration between multiple universities that we got together and did some special segments on kind of the history of IPM and also some of the things we've done especially here in the state of Minnesota. We have two special episodes to help celebrate the fiftieth anniversary of IPM. One is with Doctor. Bob Wright with the University of Nebraska Lincoln. I was interviewing him talking about the history of IPM, kind of how it got its start, and then we switched roles a little bit.
Anthony Hanson:In that case, Doctor. Wright was interviewing me about kind of the history of soybean aphids a little bit. What do we do when a new invasive pest comes in? And how do we tailor our IPM plans to dealing with a brand new pest in the system? How do we start from scratch pretty much?
Anthony Hanson:So let's lead off with Doctor. Bob Wright.
Bob Wright:Happy fiftieth anniversary of IPM from the University of Nebraska.
Anthony Hanson:Happy fiftieth anniversary IPM from the University of Minnesota. Welcome everyone. I'm Anthony Hanson, an Extension Educator in Integrated Pest Management from the University of Minnesota. And today we'll be talking with Doctor. Bob Wright from the University of Nebraska Lincoln.
Anthony Hanson:Now, today we're going talk a little bit more about a little bit of the history side of Integrated Pest Management. And I thought this would be a good opportunity for Bob to talk about kind of one of the seminal papers that came out in about 1959. So welcome here, Bob, if you want to introduce yourself a little bit more.
Bob Wright:Yes, I'm Bob Wright, an entomologist and extension IPM coordinator at University of Nebraska. Work primarily on field crop insect pest management.
Anthony Hanson:All right, thanks Bob. So the paper that we're talking about is kind of getting into this idea of, we talk about IPM or integrated pest management. A lot of questions come up, where does this term integrated come from or what does it mean? And in this case, there's one paper that kind of got the term started a little bit. It's the integration of chemical and biological control of the spotted alfalfa aphid, the integrated control concept.
Anthony Hanson:So this is one that I know you were excited about talking about just in terms of kind of what this meant for the field of IPM, both just for the history, but then also spotted alfalfa AVID too. So you wanna talk a little bit about why this is important to the IPM concept?
Bob Wright:Well, if you've taken a course in IPM, you've probably either heard this paper referred to or the concepts. And a couple of important ideas came out in this paper. The most important was they introduced the concept of the economic entry level and economic threshold, which we still talk about in IPM. And the economic entry level is a simple way to talk about it is if you have an insect damaging a crop, and if you treat it with an insecticide to prevent damage, and you could save $10 an acre, but the treatment costs were $20 an acre, you would lose money. So the idea is that we need to scout and document the level of insects and injury and have information about whether it would pay to treat basically.
Bob Wright:And so the first concept is the economic entry level, there's the break even point, and then also economic threshold. We need to back away a little bit and have a lower level for the economic threshold so that you have time to implement an action and control the insect before it exceeds the economic injury level. And those ideas were first introduced in this paper. Interestingly, Stern et al. Paper never described how to calculate an economic entry level or economic threshold, and it was almost ten years later before that was actually done.
Bob Wright:And then as you mentioned, they promoted the concept of integrated control, which later got changed into integrated pest management. And they were looking to integrate biological and chemical control in response to the introduction of the spotted alfalfa aphid in California.
Anthony Hanson:So Bob, one thing that was happening, I remember reading about this too, is with spotted alfalfa aphid, they were relying primarily on their insecticides. And what was happening with the biological control in that case?
Bob Wright:Well, they were using broad spectrum insecticides in those days, such as organophosphate and organochlorine insect icides, which kill off a lot of natural enemies. And prior to the introduction of the spotted alfalfa, a lot of the work in California was trying to develop biological controls for the existing alfalfa insects, which were primarily caterpillars and other aphids. And they were using conservation of biological control agents, strip harvest to conserve the natural enemies, even using products of bacillus thuringiensis were commercialized at that time. Typically when we have an invasive insect, until we do the basic biological research to develop an IPM program, the only option for an emergency control is an insecticide. And unfortunately the insecticides they were using at that time, the organophosphates and organochlorines, ended up having residues in alfalfa, which was used in dairy production.
Bob Wright:Then we had high levels of insecticide residues in milk, as well as worker safety issues using these highly toxic insecticides. So there was a lot of need to develop a way to reduce insecticide use and still provide for economical production of alfalfa.
Anthony Hanson:And I feel like on the insecticide front, this is one of the topics that we talk about a lot, even in the current day, where if we over rely on our insecticides, if we lose our biological control, that's often an added cost that sometimes causes more issues for us down the line when it comes to farming. And that's something that we see with alfalfa today, whether it's alfalfa weevil, potato leafhopper. This concept kind of comes into play pretty often where those two are very intertwined, it seems like.
Bob Wright:And the other issue that they didn't run into in California, but we run into nowadays is when we rely primarily on insecticides, we may come up with insecticide resistance issues as well.
Anthony Hanson:So Bob, how about the current day for IPM? We talk about this integrated control concept morphed into integrated pest management. How is this interaction working in our current IPM systems for a variety of crops?
Bob Wright:Well, we continue to have new insects that get imported to The US. And when they first are introduced to an area, oftentimes they're introduced without their naturally occurring biological controls and do very well. And until we have time to do the research to develop biological controls and other integrated pest management practices, oftentimes the first thing growers respond to, or the only choice they have is to use insecticides. In some cases we have more selective insecticides than we did in 1950s, but still a lot of times we're using insecticides that suppress biological control and are not a sustainable way to control insects.
Anthony Hanson:And Bob, I think that's a good segue into a future episode we'll be having here looking at soybean aphid as a good example of an invasive species where we had to develop an IPM program for. But in the meantime, are there any other resources you would want people listening to know about for specifically IPM resources from Nebraska?
Bob Wright:Well, probably the best site is our cropwatch.unl.edu website that has information on entomology, weed science and plant pathology issues for crops in Nebraska.
Anthony Hanson:All right, thanks Bob. And this was an interview with Doctor. Bob Wright from the University of Nebraska. So like Doctor. Wright mentioned, IPM really was based in a lot of the economic entomology of the time that we use as a basis for our IPM today.
Anthony Hanson:It's not all based on economics, but really that is the center of things a lot. And that's really what feeds into a lot of things like our next topic with soybean aphid. Know a lot of folks are familiar usually with the soybean aphid economic thresholds, and that's kind of a bit of a poster child for what we'll talk about next.
Bob Wright:Hello, this is Bob Wright. I'm an entomologist with the University of Nebraska Lincoln and the Extension IPM coordinator at UNL. I work in field crop entomology. And this series of podcasts is to commemorate the fiftieth anniversary of IPM being announced as a federal policy. And we've been talking in the last, this podcast and the last one about the role that invasive insects have played in the development of IPM.
Bob Wright:And we're going to focus on the soybean aphid in this podcast. And joining me is Anthony Hanson from the University of Minnesota. And he's going to be talking about some of the activities that led into the development of IPM programs for soybean aphid. So Anthony, you want to introduce yourself?
Anthony Hanson:Thanks, Bob. Yep, like you said, I'm based out of University of Minnesota. I am the IPM Extension co coordinator there in the field crop side of things. We also have Marissa Shu over on our horticulture side of things too. And primarily my training, I'm an entomologist.
Anthony Hanson:I cover all things IPM now in my extension role as a IPM educator, but I especially focus on the insects and I spent a lot of my time working on soybean aphid and seeing that basically start up in about, oh, about 2000s when it showed up in Minnesota. And I was back in high school then, but I still remember actually seeing at least either entomologists or some scouts coming out into fields randomly looking for soybean aphid. So that's kind of where I got my start a little bit on that one there.
Bob Wright:Okay, after the soybean aphid was first detected, how did growers respond when it started showing up in higher numbers in Minnesota?
Anthony Hanson:Yeah, and that was a challenge and is a challenge for invasive species as a whole. That first year or two especially when you start to notice you have a new problem insect or any invasive species, you have pretty limited options. Your toolbox is not really established yet. So for insects, a lot of times we're going to go to our broad spectrum insecticides. So in that case for soybean aphid, we'd be looking at organophosphates, pyrethroids, and so on.
Anthony Hanson:And early on, that's the challenge deciding, okay, when do you spray? Is it worthwhile? Are you actually getting a return on investment? And then that's that whole question of the economic threshold or economic entry level where that's going to establish. So early on in about the early 2000s, it was about 2003, 02/2004 'five and so on, there were multistate experiments going on in these fields where University of Minnesota helped lead part of this, but it was about six states in total across the North Central US looking to see what amount of damage is correlating to the amount of yield just based on soybean aphid counts or cumulative aphid days.
Anthony Hanson:So this is quite an undertaking a little bit here to look at that, but it was about 19 location years or field years we call them. And so this paper was published at Ragsdale et al, 2007. So about seven years for that to officially be published at least, but that information was generated, you know, within roughly a few years at least. So it was a pretty quick response. But before then, it definitely was a question of farmers growing up and spraying possibly on a schedule and not much rhyme or reason or connection to how much return on investment there was there.
Anthony Hanson:So that definitely helped on the insecticide side of things. But because we're talking about this through the IPM podcast, when we talk about economic thresholds, insecticides are not the only thing in the toolbox. So Bob, we do have a few others to talk about here as well once we get past the insecticides that do wrap into this network of IPM for soybean aphid.
Bob Wright:And I just mentioned before we move on from insecticides, historically, haven't had a lot of insects that needed regular insecticide use in soybeans. And so growers were not used to spraying insecticides and we didn't have a lot of tools for economic thresholds. So this was a first from that guide point. But one of the problems when we use broad spectrum insecticides is that it suppresses biological controls and that's an important leg of IPM. So what was done to try to encourage and understand what's going on with biological control of the soybean aphid?
Anthony Hanson:Yeah, Bob, and that's another prong of our IPM program we have for soybean aphid currently. So while the research was going on looking at insecticides and economic thresholds, there was also work being done to see what were the natural enemies up to. Were they starting to at least attempt to control soybean aphid to some degree? Or could we import natural enemies from its native range, especially over in China? And I remember working with Doctor.
Anthony Hanson:George Heimpels, who was at the University of Minnesota, and some projects way back in about the late 2000s, And Bionidoxis communis was one parasitoid wasp that was imported over, basically put into quarantine facilities to see if it was going to affect any other non target insects, and at least at the time was approved. However, that did not manage to control soybean aphid. It seems like it didn't overwinter as well here in Minnesota. But over time there are other species that were looked at too, and eventually in recent years we've seen A. Feline ascertainis populations take off quite a bit.
Anthony Hanson:Now this is actually an accidental introduction. It's not known exactly how it made its way to The US, but it seems to be showing up in pretty high numbers for controlling soybean aphid to some degree. And another natural enemy I will mention are lady beetles. They come up a lot in conversation. The Asian lady beetle especially was not introduced here to control soybean aphid.
Anthony Hanson:It was already in The US decades prior, but just so happened to actually do pretty well in soybean aphids. So that's why we see pretty high numbers in our soybean plants. But this gets to your question, Bob, of our natural enemies in the soybean fields. They tend to be susceptible to our broad spectrum insecticides. So if we spray too early, we do run the risk of wiping out our natural enemies or specifically reducing the populations, and then we lose that control that holds the populations down to some degree.
Anthony Hanson:So it can be a bit of a treadmill if we are overusing our insecticides because we knock out one of our other tools to some degree.
Bob Wright:I guess we don't know exactly what is causing this, but the last several years we haven't had as widespread soybean aphid populations in the Midwest. Some people speculate it's because native natural enemies, as well as introduced natural enemies have built up and helped suppress soybean aphids. But the other major effort we have relative to IPM is plant resistance. And that's also as a long term effort to develop plant resistance and get it commercialized. But can you tell us about what was done with plant resistance research?
Anthony Hanson:Yeah, this is actually a subject that's a little more near and dear to my heart because I spent most of my PhD dissertation working on host plant resistance. So if you think about back to 2000 when soybean aphid first showed up in The US, the first paper or one of the main ones that came out was Hill et al in 2004. So it was really a short turnaround time to find initial plant introductions that had some resistance to soybean aphid. However, like you mentioned, this is a long term project working with crop reading. So it takes quite a while to take a line that you have resistance in and try to cross it into existing high yielding varieties.
Anthony Hanson:In many of these cases, these are lines that were found again over in the native range in China and other parts of Asia, and some of these may not necessarily have been suited for our agronomic uses in The US. So there's been some slow uptake of these traits. But I do remember in about 02/2010, there were a couple traits out there that we could use for our fields. They're called rag genes, rag1 especially. But it's been harder and harder to find those on the market lately.
Anthony Hanson:So there is some work going on on the university side of things to get some of these basically pyramided traits in RAG1 plus RAG2 and a few other genes like that, as well as some other traits, say, like for herbicide resistance. So there are public varieties in the pipeline that should be available either to growers as part of their university's seed program or to possibly license those out into industry lines that could eventually work their way in. So we're hoping to see those traits out there later. But the main thing with host plant resistance is that it does reduce the pressure on our insecticide use. So if we can reduce that, not only is it a little friendlier for our natural enemies that tend not to be affected by host plant resistance, but it also does help with our insecticide resistance issues too, which have popped up for soybean aphid.
Anthony Hanson:So you can start to see just how for one fairly recent species here, soybean aphid, even though it's been twenty years now, this is a modern example of how IPM works, where we have this network of multiple control tactics and they do have interactions between each other. So it's definitely something where when we have all these tools working together, we can try to make sure that one of the tools is less likely to fail or have issues in a specific year. And then it's also helping out the growers too, where it's hopefully a little less worry if we have multiple tactics in play. If you only have one, then you're having to really watch and make sure that you're getting that one tactic used correctly. But then there's that high chance of failure too for insecticide resistance we mentioned.
Anthony Hanson:So it's definitely an interesting case for how IPM works in the modern day.
Bob Wright:And I guess it also points out to the need for continued research as we have challenges come up like insecticide resistance or insecticides available on the market change over time as well. Before we end, I wanted to mention one issue is that we made relatively rapid progress and had involvement of multiple states in part because we got very good support from the commodity boards, particularly in the North Central Soybean Research Program, as well as the soybean commodity boards in individual states, then as well as funding from USDA NIFA. Some of the competitive grants take longer to get, but oftentimes the commodity boards can respond quickly to a problem that shows up.
Anthony Hanson:Yeah, for soybean aphid, that continues to be our main pest. We still keep an eye out for in Minnesota. But when we talk about new invasive pests coming in, one of the new ones that's in the works right now is soybean gall midge and how do we deal with that? And that's one that's still very much a work in progress, but a good example of how these IPM teams across states work together when we have issues like this come up.
Bob Wright:And for Minnesota, where can people find out more information about IPM?
Anthony Hanson:In general, ours is split up on the University of Minnesota Extension website, generally by crop, but we will have information on diseases, insects, and weed control, basically split up by crop. So if you look up University of Minnesota Extension, you'll be able to find our information throughout the whole website. On that note, Bob, too, I should mention our Minnesota Crop News blog, and this is one where usually individual educators will post their own articles, usually timely things they're seeing out in the field. And in this case, I do tend to have, you know, IPM updates on there, whether it's soybean aphid, alfalfa weevil, or other insects of interest, especially. So these blog setups are a good way for information to get out there to growers in a more timely manner.
Bob Wright:Okay, thank you.
Anthony Hanson:Well, thanks everyone for listening. So we are going to be putting the IPM podcast on pause for a while, basically because we are working on that strategic farming program and we are doing a lot of our podcasting through their four IPM topics, whether it's insects, diseases or weeds topics, and then getting into agronomy as well too. So in the meantime, I'd like folks to definitely check out those programs. We do have options to listen to some of those as a podcast, you can see those as videos as well for some of these webinars that we do. So be sure to check out the episode description and we'll have more information for you there about the Strategic Farming Program that you can use as a follow-up for what we've used as our traditional IPM updates through the seasons.
Anthony Hanson:Thanks again everyone, and we'll see you both with our online resources that we have with podcasts or other webinars, and our in person sessions that we have for pest updates throughout the season. And feel free to get a hold of me too, Anthony Hansen, I'll have my email in the episode description too if you ever have any pest questions that come up, especially on the insect side of things.