University of Minnesota #IPM50

University of Minnesota Extension https://extension.umn.edu/crop-production
University of Nebraska Crop Watch https://cropwatch.unl.edu/

For more information on IPM in the North Central Region visit www.ncipmc.org 

Transcript

Speaker 1 (00:03):
Welcome to a special Pest Central limited series celebrating the 50th anniversary of Integrated Pest Management. This collaborative effort focuses on the history and future of IPM in the North Central region and features university faculty and agency staff interviews from around the region.
This work is supported by the USDA, National Institute of Food and Agriculture and the North Central IPM Center. This podcast is edited and produced by Michigan State University Extension. MSU is an affirmative action, equal opportunity employer. Michigan State University Extension programs and materials are open to all.

Anthony Hanson (00:58):
Happy 50th anniversary IPM, from the University of Minnesota.

Bob Wright (01:04):
Hello, this is Bob Wright. I'm an entomologist with the University of Nebraska in Lincoln and Extension IPM coordinator at UNL. I work in field crop entomology, and this series of podcasts is to commemorate the 50th anniversary of IPM being announced as a federal policy. We've been talking the last, this podcast and the last one, about the role that invasive insects have played in the development of IPM and we're going to focus on the soybean aphid in this podcast. Joining me is Anthony Hanson from 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 (02:00):
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 Shoe over on our horticulture side of things too. And primarily, my training, I'm an entomologist. 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 startup in about 2000 is when it showed up in Minnesota. 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 (02:45):
After the soybean aphid was first detected, how did growers respond when it started showing up and higher numbers in Minnesota?

Anthony Hanson (02:54):
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 would be looking at organophosphates, pyrethroids and so on, 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 injury level where that's going to establish.
Early on in about the early 2000s, it was about 2003, 2004, and five and so on, there were multi-state 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.
This was 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, its Rag Hill et al., 2007. So about seven years for that to officially be published at least, but that information was generated within roughly a few years, at least. So it was a pretty quick response. But before then, it definitely was the 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. 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 (05:00):
And I just mentioned before we move on from insecticides, historically, we 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 the soybean aphid?

Anthony Hanson (05:43):
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 Dr. George Heimpel who was at the University of Minnesota and some projects way back in about, no, early or rather late 2000s and Binodoxys communis was one, parasitic 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 over winter as well here in Minnesota.
But over time, there were other species that were looked at too and eventually, in recent years, we've seen Aphelinus certus populations take off quite a bit. 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. 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. It was already in the US decades prior, but just so happened to actually do pretty well in soybean aphid so that's why we see pretty high numbers in our soybean plants.
This gets 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. 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 (07:48):
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 some of the native natural enemies, as well as introduced natural enemies have built up and helped suppress soybean aphids. The other major effort we have relative to IPM is plant resistance and that also is a long term effort to develop plant resistance and get it commercialized. Can you tell us about what was done with plant resistance research?

Anthony Hanson (08:33):
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. 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 2009, 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. 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, for herbicide resistance. So there are public varieties and 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. You can start to see just how for one fairly recent species here, soybean aphid, even though it's been 20 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.
It's definitely something where when we have all of 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 that 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. It's definitely an interesting case for how IPM works in the modern day.

Bob Wright (11:24):
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 and then as well as funded 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 (12:14):
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? 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 (12:40):
And for Minnesota, where can people find out more information about IPM?

Anthony Hanson (12:44):
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.

Bob Wright (13:03):
Okay, and for University Nebraska, our crop IPM information is at the cropwatch.unl.edu website that has current information on entomology, plant pathology, and weed science.

Anthony Hanson (13:19):
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. In this case, I do tend to have 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 (13:44):
Okay. Thank you.

Anthony Hanson (13:46):
Yep. Thanks Aaron.

Speaker 1 (13:51):
Thanks for joining us to celebrate the 50th anniversary of Integrated Pest Management. Check the show notes for resources mentioned in this podcast and be sure to subscribe so you don't miss any future episodes.