Oregon State University Extension Service

105 – Tyson Wepprich – Insect Apocalypse? (in English)


Andony Melathopoulos: [00:00:00] From the Oregon State University Extension Service, this is PolliNation, a podcast that tells the stories of researchers, land managers, and concerned citizens, making bold strides to improve the health of pollinators. I'm your host, Dr. Andony Melathopoulos, Assistant Professor in Pollinator Health in the Department of Horticulture.

Recently, there's been considerable attention around the decline of insect populations across the world, and I thought this would be a great opportunity to catch up with Tyson Wepprich, who is a Research Associate here at Oregon State University. Just a couple of weeks ago. He released a paper that documents and analyzes changes in butterfly abundance in Ohio over 20 year period.

In this episode, you're going to hear the nitty gritty of how these kinds of studies are conducted. And what are some of the key assumptions that go into plotting these trend lines? In addition, Dr. Wepprich is going to shed some light as to what is potentially driving these declines, because they have a global character to them; the studies in Europe seem to be matching the studies that have been conducted here in the United States. 

This is also a great episode if you're interested in getting involved with monitoring, and Dr. Wepprich has some great suggestions on how to set up these kinds of monitoring programs, some of the challenges, and some of the rewards that you can get as a volunteer, if you are involved in monitoring.

I hope you enjoy the episode.

Tyson. Welcome to PolliNation. 

Tyson Wepprich: [00:01:49] Hi, nice to be here. 

Andony Melathopoulos: [00:01:51] Now, there's been a lot of talk over the past year about large scale insects die offs. Most of the major newspapers have had a story about a looming insect apocalypse. What's prompting these stories? Why are they coming out now? 

Tyson Wepprich: [00:02:03] That's a good question. And, we've had long-term insect monitoring, especially for butterflies in Europe for decades, since the seventies.

And they update their numbers every year, but they don't get the kind of press that started two years ago on insect declines. And I think that can be traced back to a shocking paper that came out two years ago, from Germany, and what they found was a 75% decline in insect biomass of flying insects over about 30 years.

Andony Melathopoulos: [00:02:46] Let me get this straight. So they weighed, they must've sampled and weigh these insects over time, and they said over this period, they saw a decline. What was the period? 75% decline over how long? 

Tyson Wepprich: [00:02:58] Over about 30 years, I think. 

Andony Melathopoulos: [00:03:00] Okay. Alright. Okay. So this prompted a lot of attention, as opposed to these butterfly surveys that were chugging along, there was this big 75% decline in this paper... and keep going from that.

Tyson Wepprich: [00:03:12] And so 75%, it's just a really big number. So, you know, people saw that and then I think started paying more attention to studies that were focused on insect abundance. You know, previously we've used a lot of the great insect monitoring data sets to look at how insects are responding to climate change, because they are a group that shows really quick responses to climate change, like phonology changes, or they'll have more generations per year with warmer temperatures. Butterflies, and other insects.

And so, I think we weren't really using the data sets to focus on abundance except for maybe like rare species that we were thinking about, like, how do we have conservation management for the rare species? And we weren't really thinking about how are the common species doing. 

Andony Melathopoulos: [00:04:10] Okay. So if I get the straight, the attention, refocused on this problem because suddenly people started to look at the numbers, not just how many species do we have in this state? It started to switch to how many did we have in the past and how many do we have in the present? And those studies have really prompted this question of long-term insect decline, abundance. Gotcha. 

Now we've had previous episodes where we've talked about how difficult it is to establish population trends among native pollinator populations.

And I just want to get at how methodologies, how do researchers establish whether population is going up and down? And I would imagine there's gotta be a lot of factors driving insect diversity and abundance across landscapes. And so it also liked to hear you talk a little bit about what are some of the assumptions that are kind of bound up with those methods?

Tyson Wepprich: [00:05:00] Yeah. So measuring insect abundance is really hard. You know, I have a 24,000 transect walks that volunteers in Ohio have made over 20 years at about a hundred sites. An incredible amount of effort; they go out and count butterflies on their transects 30 times a year. 

Andony Melathopoulos: [00:05:24] Really? 

Tyson Wepprich: [00:05:25] Right. And so that amount of effort just can't be duplicated everywhere. So we do the best we can with the data we have. And so, I'm very aware of the limitations and the best systematic monitoring insect data. And so, you know, I respect people who try to do what they can with museum specimens because museum specimens allow us to go back further in time. With monitoring data, we only have the most recent two decades for Ohio, or four decades for the UK and European monitoring programs. 

Andony Melathopoulos: [00:06:08] I'm gonna just stop you for a second. So, there's really two kind of basic methodologies. The one is where people go back to the, like you said, those... what sparked this all off, kind of going back to the same locations over time and looking at changes.

And then the second one is, which seems to kind of get you back in time further to see longer term trends as you, somebody went out collecting for whatever reason, and they deposited an insect in a museum. And you kind of compare the present to the past, even though it doesn't have that standardization that the more recent surveys would have.

Tyson Wepprich: [00:06:44] Right. And so the standardization is really important for abundance. And so it's really difficult to estimate what abundance 50 years ago was for a certain species just based on who decided to collect that species and put it in a museum. It's really tough to know how that compares to the whole insect community that was present at that time, and what the goals were for the collector. 

I've seen some studies out of Europe that compare a species richness, or just how many species were present, like in the Netherlands and in Germany. And they've used museum specimens to go back in time about 150 years. And so they can look at the museum records and say, Oh, well, these species were collected in our country, they're no longer here. And so that's not abundance, but it's still a record of what we've lost over time. 

Andony Melathopoulos: [00:07:46] Right. Okay. So it gives you a sense of what's been lost, but it can't say, well, there was thousands of these things, and now they're kind of, they're hard to find now. Yeah, he would register them both as being president in the County.

That doesn't change. Okay. Gotcha. Okay. So, so some of the assumptions are... so it sounds like these museum studies have an assumption of abundance being sort of equal, in a detection, but what about these more contemporary surveys of going out and monitoring on a transect. Do they have some assumptions that, you know, one needs to be aware of?

Tyson Wepprich: [00:08:24] Absolutely. So it's interesting because a lot of the statistics and the methods we have for abundance are based on vertebrate wildlife studies. And so they have the benefit of, you know, putting a collar around a cougar and knowing its exact age and where it is and how long it lives. And so the methods for vertebrates can account for many assumptions that insect monitoring can't do.

So, you know, during a butterfly flight period, you have butterflies flying into your transect, flying out of the transect, and an emerging from chrysalises and dying really quickly because they're insects. And you don't know who the individuals are, unless you are capturing them and marking them, which we don't ask volunteers to do.

And so we have a lot of assumptions for insect abundance that other scientists may not have to deal with, or other scientists may be able to account for. 

Andony Melathopoulos: [00:09:35] I imagine the other thing that's kind of common to all these studies is, you know, in an ideal world, you'd grid up the state, and wherever the algorithm told you to go sample you sampled, but that must not be... when you, especially to get that volume of data, you have to rely on volunteers and often volunteers have restrictions of what they can do and work and where they can go. 

Tyson Wepprich: [00:10:00] Right. And so that's another interesting point that a recent paper by Arielle Fornier came out that looked at whether selecting sites non randomly can sort of bake-in abundance declines.

So like, if you're starting a new monitoring site and you go to a place that has high numbers of a certain butterfly species that you're interested in, chances are, it's probably not going to be as high the next year, just because you saw it in a year where its abundance was really high and that made it easier to see and choose that site.

And so they did a, just a simulation model to try to see if non-random site selection meant that you were going to have negative population trends. And so they found that it was a significant factor, or it could be. And so that kind of made me re-examine some of the butterfly monitoring assumptions. And one thing that... I think the butterfly monitoring is robust to this because we're not just selecting the best site based on one species, but we're looking at multiple species together.

And so, you know, some will be abundant in that first year and some not, and that will cancel out to some degree. Although I do worry about butterfly monitoring sites that don't manage for butterflies probably have a lot of forest overgrowing the open fields that might lead to butterfly declines, or just fewer butterflies counted at those sites.

Andony Melathopoulos: [00:11:44] Okay. Well, thanks for laying that terrain out. And I guess, you know, thinking about a place like Oregon, where we don't have a lot of historic records and very varied landscape, what would be, what do you sort of envision as being like the best way to proceed forward with generating long term data sets?

What's the, you know, from your experience looking at this field, what is the, what should a state aspire to? 

Tyson Wepprich: [00:12:12] That's a good question. And I think. Butterflies are popular because they're so easy compared to bees. And I know you're working on the Bee Atlas for Oregon, and I think, with butterflies, it's not as important to have a taxonomists identify every single one to species.

And Paul Hammond may disagree with me, but I think in Ohio, the volunteers identify the species. They don't collect them. And I think that's good enough for butterflies, but it wouldn't be for other groups of insects. So for Oregon, that's a good question. I like how some of the recent bee monitoring and Oregon is trying to send people out to different parts of the state and say like, this is a priority area that we don't know anything about, let's get a volunteer out there. 

And so I think that's really important. I've looked at a lot of the, iNaturalist observations made by volunteers on their phone app, just to see like where people are counting butterflies and, you know, it's mostly where people live near cities. And so I think getting people to sample outside of cities would be a good first step for butterflies in Oregon.

Andony Melathopoulos: [00:13:31] Okay, well, let's take a quick break. I want to get back to your recent work that just was published about two weeks ago now, looking at butterfly declines in Ohio.

Okay. We're back. So you had a paper release just about two weeks ago on long-term decline of, butterflies in Ohio, or at least population trends. First of all, I saw there was some press on this. Can you tell us a little bit about the experience of the media coming and asking?

Cause I know the media is very interested in this topic. What was the experience like getting interviewed by broadcasters on your paper?

Tyson Wepprich: [00:14:19] Yeah. So, the paper came out in early July. And you know, the week before I worked with the press office at Oregon State University to write a press release that was made available to reporters before the article came out.

And so a couple had seen it and interviewed me over the phone to help them write their article to come out the same day as the journal article was made available online. And what's kind of funny is that there wasn't really a press embargo because I had posted a preprint on bio archive that was available for anyone to read weeks before.

But having the press release out there, I think, made reporters more interested in it. So I think that was important to work with the press office. And then, there was a wide range of, news reporters who talked to me and all the interests was concentrated in like the first three days.

And then I haven't really heard much after that. And so I think you have to be ready to see an email and make a phone call right away to talk to someone for 20 minutes to answer their questions so that they can turn around and write it on a deadline. And so there was also a wide range of, you know, quality of articles that came out, you know, some led with, the title "Butterfly Death," which I, you know, I didn't write that.

I'm sure the writer didn't write that. Some were click baity, some were really well done and, many of them just used the press release, quotations directly instead of interviewing me, so having the press release was like, I was doing interviews with everyone. 

Andony Melathopoulos: [00:16:13] It does sort of raise the issue of science journalism, I guess, in terms of, you know, I imagine there's not a lot of staff, covering science issues and being able to assess work as a journalist in the way you would do a political story; it must be hampered somewhat. 

Tyson Wepprich: [00:16:29] I think so. And so I was mostly talking to interns who were the ones going through press releases and finding new stories. And I was a little disappointed that I didn't get much press from Ohio where the study was performed by the volunteers. The Eugene daily newspaper covered it, but I didn't get an Ohio newspaper yet.

Andony Melathopoulos: [00:16:52] Okay. So here in Eugene, Oregon, not in Ohio where the study was. So tell us a little bit about this study. So you've already tipped your hand a little bit there; it involved a lot of volunteers, tell us where this data came from? And tell us a little bit about the structure of the study.

Tyson Wepprich: [00:17:05] Yeah, so a number of people in Ohio were really concerned about butterfly losses, starting in the eighties, because there were, a few species that were native to tall grass prairies that were extripated or made locally extinct in Ohio as those habitats were converted to farmland. 

So after some of these species disappeared from Ohio, the Ohio lepidopterist, and the Ohio Department of Natural Resources, and the Cleveland Museum of Natural History, and the Dawes Arboretum, and many volunteers came together to create a monitoring program in the hope that they would learn about declines of butterflies before they became lost to the state.

And that that started in 1995. Around Cleveland and then it slowly expanded to more volunteers. Now there are about 80 active sites in any given year around the state where volunteers will count butterflies along a transect that they return to every week from April to October. And they count every butterfly that they see within a certain distance of their transect.

Andony Melathopoulos: [00:18:23] You know, it's remarkable to me in a couple senses. The first one is, you know, I often think, Oh, there's a lot of attention to bees, but in maybe 20 years there won't be. It's nice to see a program that starts with a crisis that sustains itself. That's really remarkable. 

Tyson Wepprich: [00:18:37] Yeah. I'm amazed that they built it into such a large program.

Illinois has a monitoring program that started a few years before Ohio. But Ohio was kind of the second one and they built it into probably the largest one in terms of the amount of data they collect. And many other states have started monitoring programs now, too. And I imagine it's really hard to start one because like, one year of data, or two years of data, isn't going to tell you much.

And so it's tough to sustain a program during those first years where you're collecting data with no end point. And it doesn't become really useful to scientists until it's has many years of data. 

Andony Melathopoulos: [00:19:26] Okay. I totally understand that. I think that's a real... it's a hard sell to a funding agency. For example, "you got to do this for 30 years. Can you support, some base infrastructure so we can pull this off?"

Tyson Wepprich: [00:19:38] And I don't recommend that every monitoring program wait 20 years before publishing or sharing their data. What I'm excited about as a next step that someone may do is looking at the states with different monitoring programs in North America, in the United States and ask if we're seeing similar trends in different states. Even with states that may only have five years of data, I think combined with their neighboring states that have the same species, you could learn a lot about how butterflies are doing more widely. 

Andony Melathopoulos: [00:20:13] Okay. Well, describe to us what the volunteers actually do. What's the data point? What are they doing? 

Tyson Wepprich: [00:20:19] They walk their transect and they keep track of every species of butterfly they see and the number of that species. And so every week they have a total count for each species that they saw that week. 

Andony Melathopoulos: [00:20:36] So what are they walking? It's just kind of like a grassy area and they just kind of pace?

Tyson Wepprich: [00:20:43] They just walk slowly so that they can count butterflies. They don't want to count the same one twice. So they don't. They try to keep it moving.  And the sites vary. Some of them are people's backyards that they've planted with butterfly food plants. Other ones are parks , either Metro parks or state parks.

A lot of them are environmental education centers that are using it as a teaching tool. And, so there's a wide range of sites. There are a wide range of volunteers who range from academics to amateur experts, to environmental educators, to people brand new to butterflies who just want to learn.

And monitoring is actually a great way to learn butterflies. Because when you start in the spring, you start with like one or two species flying and you identify them and you learn them. And you maybe add a couple more species every week. And so it's like a manageable way to learn all the species in an area.

Andony Melathopoulos: [00:21:47] Okay. Oh, that's fantastic. And okay, so all this data... start, they do their walk, they write on a piece of paper, they send it in... anyways, at the end of all this process for years of accumulation of data, you show up. 

Tyson Wepprich: [00:21:58] Yeah. And I was just really lucky because I was doing a grad school at North Carolina State University, and I was working with my advisor on conservation of a rare endangered butterfly that's only found on one military base in North Carolina. 

And I thought I would be a field biologist, but most of my experiments didn't go as planned. And, I got more and more into statistics instead, and I was just lucky to know someone who knew someone who knew the people in Ohio who were willing to share this accumulated data with me. 

Andony Melathopoulos: [00:22:39] Fantastic. Cause I imagine at that point in the program, an assessment of what it meant over time was really overdue. 

Tyson Wepprich: [00:22:48] Oh yeah. And I didn't even, for grad school, I didn't even look at abundance. Because, I was studying changes in phonology, and changes and the number of generations. Some species were attempting each year. Kind of thinking about butterflies and climate change, and I had all the data to look at abundance, but I didn't because I was like, Oh, well, that's just bean counting. That's not important.

And so it took the recent press coverage of global abundance declines before my coauthors and I went back and looked at abundance. 

Andony Melathopoulos: [00:23:25] Wow. Okay. So tell us, what did you find? So after you went through and reanalyze that data what was the overall change, and tell us a little bit about the structure of that change.

Tyson Wepprich: [00:23:34] Okay. So overall, when you look at all the species of butterflies together at the same time, it's not good news. So, they are declining at about 2% per year and over 20 years, that total decline is a third. So volunteers in 1996 could expect to see a third more butterflies... 

Andony Melathopoulos: [00:24:03] Than they would in the present.

Tyson Wepprich: [00:24:05] Yeah. And then they are in the present. 

Andony Melathopoulos: [00:24:08] Well, that's, that's really dramatic. 

Tyson Wepprich: [00:24:09] Yeah. We compared that to the other long-term butterfly monitoring programs in Europe to see if it was a faster rate or a slower rate. And we were really surprised that the programs in Europe that have been going on longer have also had about a 2% per year decline in their total abundance of butterflies across all species.

Andony Melathopoulos: [00:24:36] That's peculiar. 

Tyson Wepprich: [00:24:38] Yeah, I think it's, there's similar places. So the UK and Ohio, and the Netherlands, and Catalonia. The places where people are monitoring and all these programs are volunteer selected, so they are close to populated areas that have a lot of human land use pressure, or changes to the butterfly habitat.

So I don't think it's that surprising, but I think it could be totally different in non-temperate regions like the tropics or places with less human modification of the habitat. 

Andony Melathopoulos: [00:25:16] Before we get into why similar areas around the world may have similar declines, tell us a little bit about the structure of the decline. Were all the species going down at the same time? Where some improving or some going faster? What did you see?

Tyson Wepprich: [00:25:29] Yeah. So there's a wide range of how the individual species are doing and that's common in all monitoring programs. You have some that are doing well, and some that are doing worse. And so, when you look at the species in Ohio, we looked at 80 different ones. Half of them are stable, or they might have a trend in one way or another, but it's not strong enough for us to declare increasing or decreasing. 

Andony Melathopoulos: [00:26:01] Okay. So half the species, it's hard to tell if they're going up and down because it's just so much fluctuation.

Tyson Wepprich: [00:26:06] Right. Insect populations change so much year to year and from site to site, sometimes it's hard for a statistical model to say whether it's trending in a certain way.

Andony Melathopoulos: [00:26:18] All right. What about the other half? 

Tyson Wepprich: [00:26:19] And so of the other ones that showed either an increase or a decrease three times as many were decreasing compared to increasing. And so, we also looked at what traits these different species had, to try to learn what environmental causes might be that would make some species do well, and others do worse.

And we looked at whether they were generalists or specialists on the food plants that they eat. Or, how many generations they did per year, or whether they were Northern species or Southern species, depending on where most of them are found. And we looked at some other things too, but the strongest factors explaining why some species declined, were factors having to do with responding to temperature.

So this suggests that for some species, climate change is playing a role in how their populations are doing. So like species that only do one generation per year and species that live more in Northern, cooler places generally did worse than species that could do many generations per year or lived in warmer Southern regions.

Andony Melathopoulos: [00:27:51] I can see why in earlier in the interview, you said it'd be really important to do other states. Cause it could be a matter, I suppose, of them leaving Ohio and going to Canada. 

Tyson Wepprich: [00:28:00] Yeah, I think that's a big question. Because yeah, we don't know how much insects are reshuffling where they are, versus declining in one place and not being compensated somewhere else.

Andony Melathopoulos: [00:28:15] All right. I can imagine as well , that there must be lot of land use change. I imagine Ohio, you know, in 1995, probably still very industrial and, more so than it is in the present, is different from it is today. I think about corn and soybean, the agricultural changes. Is there any indication that these land use changes are having an effect?

Tyson Wepprich: [00:28:40] It's really tough to know because we didn't look at each individual site to see how it was changing.  On a statewide basis, land use change, or the population in Ohio kind of peaked in the seventies, or it's plateaued in the seventies and it's been growing more slowly since then. And so the areas that our sites are in don't have a lot of wholesale land use change, compared to other states. But we do think that habitat quality is probably declining, and the reason we say that is because even some species that you'd expect to do really well in human modified habitat, like cabbage whites, have their abundance declining in Ohio.

Andony Melathopoulos: [00:29:34] That's remarkable. 

Tyson Wepprich: [00:29:35] And so. I think seeing that just made us think that there is a habitat quality issue, more so than just a habitat loss issue. 

Andony Melathopoulos: [00:29:46] Cause that would be a butterfly you would see from, right across the continent. So it would be, less, climate related factors, maybe have less of an influence cause it seems to be resilient to that.

Tyson Wepprich: [00:30:00] But it's really tough to...  I've looked at environmental data that we could try to correlate with the declines, and what's difficult is that so many things are changing at the same time that it would be really difficult to say that it's one thing over the other.

So for example, temperatures have warmed in Ohio, at a rate that is about a third of a degree Celsius every decade. And that affects the insects. It makes the growing season longer for them. So if they could take advantage of it, it might be good. If they're a Northern species, that's bad.

And at the same time, pesticide use and farm management has changed over the last two decades. But many of the pesticides that people are worried about for pollinators have increased at the same time as the temperature change.

Andony Melathopoulos: [00:31:00] So you can't say which is... 

Tyson Wepprich: [00:31:01] Yeah, it's really hard factor.

Andony Melathopoulos: [00:31:03] It is. If you had a gradient where, Oh, there's this and that happened there and that happened, then you'd be able to perhaps pull these things apart. But when they go up at the same time, it's hard to describe. Okay. 

Tyson Wepprich: [00:31:16] It's tough to say that it's one factor and not the other. I think that'd be a great study for someone to do with this Ohio data in the future, is to try and assess on a site by site basis, which environmental factor might be affecting certain species more than others at that place. 

Andony Melathopoulos: [00:31:38] Fascinating work. I'm really excited to have caught up with you. I know lots of our listeners are... I'm hoping that the interview has sort of two effects, one sort of, putting into context what these studies mean for the general public, but also really trying to motivate people to do this kind of survey. It sounds like these volunteers have worked exceptionally hard over prolonged periods of time to bring this data to light. And, I think it's really motivational and inspiring. 

Tyson Wepprich: [00:32:03] Yeah. I think there are butterfly monitoring programs in many different regions ,now that listeners could participate in. And you know, this has motivated me to try to become a better natural historian. I'm not great at identifying butterfly species, but I'm using iNaturalist and binoculars and trying to learn more. And even something like iNaturalist observations, when verified by other people so that you have the identification, correct, that information gets submitted to a giant database online that future scientists will probably use to try to assess insect declines going forward. 

Andony Melathopoulos: [00:32:49] Oh, and I'd be remiss. I wore my North American Butterfly Association t-shirt today just for this interview. 

Tyson Wepprich: [00:32:55] Oh, good. 

Andony Melathopoulos: [00:32:57] There is a chapter in the Eugene area and they, I think they've done a couple of July through July they've done butterfly counts. I think, if anybody's interested, we did have a podcast about a year ago with NABA, but we'll link the NABA website up, the local chapter here. If you want to get involved with that kind of work. 

Tyson Wepprich: [00:33:15] Yeah, that'd be great. 

Andony Melathopoulos: [00:33:16] All right, let's take a break. We have three questions we ask all our guests. I'm going to entrap you now to find your answers.

Okay. We're back. So, we shamefully don't have a lot of butterfly guests on the show so this is a great opportunity. But also I don't think we've had many people who've looked at longterm population trends. So your answers to these questions will be very, will be great. So the first question we have, is there a book that you would recommend; is there a book that you want listeners to know about?

Tyson Wepprich: [00:33:57] I really like two, and so one is The Butterflies of Cascadia by Bob Pyle. 

Andony Melathopoulos: [00:34:03] I've got it up there. It's a great book. 

Tyson Wepprich: [00:34:05] Yeah, that's what I've been using to try to learn my Oregon butterflies since I just moved out here a couple years ago. 

Andony Melathopoulos: [00:34:11] It's, it's amazing that it has pictures of all the life stages.

Tyson Wepprich: [00:34:15] Yeah, it is. 

Andony Melathopoulos: [00:34:16] I don't know how that was done. 

Tyson Wepprich: [00:34:19] So the other book is, the Caterpillars of Eastern North America by David Wagner. And that's entirely based on caterpillar life stages, and I'm just amazed that they found pictures for all of these different species. And it's fascinating.

Andony Melathopoulos: [00:34:37] Because they don't look the same when they're in a one in star stage to the next?

Tyson Wepprich: [00:34:40] Yeah. 

Andony Melathopoulos: [00:34:41] Really? They change. 

Tyson Wepprich: [00:34:42] They can. Like a lot of butterfly early instar caterpillars look like bird droppings, and then they changed to something else. Like for swallowtail they'll change to look like a snake mimic and later instars. 

Andony Melathopoulos: [00:34:57] That is amazing. 

Tyson Wepprich: [00:35:00] David Wagner I think, is working on a book of caterpillars for Western North America. And so I'm really excited for that book to come out. 

Andony Melathopoulos: [00:35:09] Those are two excellent book recommendations. I'm going to check... well, I've got one of them, but I'm going to check it out the Eastern Caterpillar book and wait patiently for the Western one.

Okay. So then the next question we have is, do you have a go to tool for the kind of work that you do? 

Tyson Wepprich: [00:35:23] well, the honest answer is, R, the computer program. 

Andony Melathopoulos: [00:35:26] So the letter R?

Tyson Wepprich: [00:35:28] Capital R. It's a free, open source, computer program that many scientists use to analyze data, and plot data and, do all the science that we do.

But the most fun tool that I use is a butterfly net because I don't use it as often anymore, but there's nothing more fun than chasing down a butterfly with a butterfly net. 

Andony Melathopoulos: [00:35:52] How do you catch a butterfly? 

Tyson Wepprich: [00:35:54] It depends on the species. And so there are very different hunting strategies, depending on the species. So many like tiger swallow tails, they'll just sit on a flower nectaring, not paying any attention, and they're really easy to capture off the flower. But other ones are just more wily and you have to sneak up on them, crouching down low. Other ones, you just have to run as fast as you can, swing and hope that you catch them. 

Andony Melathopoulos: [00:36:23] I've seen those people in the fields. 

Well, I guess, just to pick up on both of those. So, R, we've had it recommended before. A lot of ecologists  really love R.  Is there some functionality of R that you really... I guess the one thing I always appreciate is it being open source. For people who want to begin to learn it, there's a lot of resources available online and some great books like, this book here, Statistics: an Introduction to Using R, where it gives you a little bit of the program. You don't have to be a hardcore programmer to learn R. You can learn the language fairly quickly.

Tyson Wepprich: [00:36:59] Right. And I think open source means that lots of scientists contribute to it with packages that do a particular analysis. So you might have a problem in R, and you do some searches online, and then you find that someone else has had that problem and solved it already. And so, it's just like there are angels out there to solving your problems for you and writing software that does it. And, it's an amazing community to learn from. 

Andony Melathopoulos: [00:37:31] You speak about packages; these are things that you load up into R, so that you can do something specific. Is there a package that you worked with a lot that, for aspiring graduate students out there who are working on these kinds of trends that you found exceptionally useful?

Tyson Wepprich: [00:37:44] I would say, GG plot two, which is G G stands for grammar of graphics. And it is really important to always plot your data and look at it and explore it in a graph. So you make sure your statistics aren't lying to you. And so I probably use that more than any other package to understand butterfly trends and any dataset.

Andony Melathopoulos: [00:38:11] Okay. Fantastic. Last question we have, is there a pollinator species in particular, when you see it, you're really excited?

Tyson Wepprich: [00:38:19] It's going to be in Ohio butterfly. I don't have a favorite in Oregon yet, but, In Ohio it's definitely the Great Spangled Fritillary. 

Andony Melathopoulos: [00:38:28] What a name. 

Tyson Wepprich: [00:38:29] I know. I love it because of the name. It's a beautiful big orange butterfly. It's really common; it's not that special, but great name, great butterfly. 

Andony Melathopoulos: [00:38:41] Does it have a specific host plant or tell us... 

Tyson Wepprich: [00:38:43] It eats violets as a caterpillar. 

Andony Melathopoulos: [00:38:46] Oh, that's adorable.

Tyson Wepprich: [00:38:50] I think one thing that is interesting: the females live a really long time compared to the males. So the males will fly really quickly , one generation per year and the females after mating with the males will live months. And so you'll see them into September, but it will only be females in September.

Andony Melathopoulos: [00:39:13] Do they winter as adults? 

Tyson Wepprich: [00:39:15] Oh, that's a good question. They don't. But I'm not sure which stage they overwinter in. Probably larvae? 

Andony Melathopoulos: [00:39:21] I'm not sure.

That was a totally on the spot question, but...

Tyson Wepprich: [00:39:25] Not adults. 

Andony Melathopoulos: [00:39:26] Okay. Well, thank you so much for taking time. I know you got to go out into the field right away, so we appreciate you taking time to talk about  butterfly population trends and your new paper.

Tyson Wepprich: [00:39:36] Yeah. I really appreciate you having me on today.

Andony Melathopoulos: [00:39:47] Thanks so much for listening. Show notes with information discussed in each episode can be found at pollinationpodcast.oregonstate.edu. We'd also love to hear from you, and there are several ways to connect. For one, you can visit our website to post an episode specific comment, suggest a future guest or topic, or ask a question that could be featured in a future episode.

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See you next week.


There has been a lot of attention lately to whether there is a long-term towards declining insect abundance across the world. This week we catch up with Dr. Tyson Wepprich who recently reported on butterfly abundance declines in Ohio over the past 20 years.

Dr. Wepprich is an entomologist who researches insect populations, phenology, and adaptations to climate. At OSU, he works with Fritzi Grevstad and Len Coop on the management of invasive weeds with biocontrol insects. Previously, he was at NC State University, where he worked on habitat restoration for an endangered butterfly, but realized he was a better statistician than field biologist. He switched projects in graduate school to analyze data from long-term monitoring of butterflies in Ohio. He still work on butterflies and how they can tell us about the health of insect communities and about insect adaptations to environmental changes. What he has learned from butterflies informs both his current job and his knowledge about how pollinators may fare in the future. Butterflies, other pollinators, and biocontrol beetles all have life cycles that depend on the climate. He is especially interested if increases in the number of generations insects attempt with longer growing seasons will be beneficial for their populations or not.

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Links Mentioned:

Tyson’s Book Recommendation: The Butterflies of Cascadia (Robert Pyle, 2002); Caterpillars of Eastern North America: A Guide to Identification and Natural History (David Wagner, 2005)

Tyson’s Go to Tool: R and ggplot2

Favorite Pollinator: Great Spangled Fritillary (Speyeria cybele)

Source URL: https://extension.oregonstate.edu/podcast/pollination-podcast/105-tyson-wepprich-insect-apocalypse