In this week’s episode, host Kristin Hayes talks with RFF Senior Fellow Rebecca Epanchin-Niell, who recently coauthored a journal article with RFF scholars Alexandra Thompson and Tyler Treakle about the role of the public in detecting invasive species. Pointing to a recent incident in which a member of the public spotted an Asian giant hornet in Washington State, Epanchin-Niell describes how more than a quarter of detections of invasive species—and possibly more—stem from these citizen scientists. Recognizing the essential role of the public, policymakers can make it easier to alert authorities about the presence of unusual species.
Listen to the Podcast
- Early detection is important: “Early detection is key for helping minimize [invasive species’] long-term impacts … The earlier you detect something, the more likely you are to be able to eradicate it right off the bat, or help slow its spread, or conduct new research to figure out ways to help mitigate impact.” (15:19)
- The role of the public in spotting non-native species: “There’s a whole range of folks who can contribute to detecting a new invasive species. An example that has been in the news a lot … is the Asian giant hornet; people might’ve heard of it as the ‘murder hornet.’ This was discovered by somebody stepping out on their front porch and seeing this giant, crazy-looking hornet, which they actually recognized from a YouTube video they had seen. They ended up calling local authorities, and it ended up leading to a lot of efforts across Washington and Oregon [to try] to keep the species from establishing.” (17:15)
- Governments can encourage public contributions: “I think there are a lot of opportunities to further leverage the contributions of the public—just making it easier to log if a member of the public finds something that’s unusual, or reducing the barriers to picking up the phone and making a phone call.” (26:43)
Top of the Stack
The Full Transcript
Kristin Hayes: Hello, and welcome to Resources Radio, a weekly podcast from Resources for the Future. I'm your host, Kristin Hayes. My guest today is Rebecca Epanchin-Niell, a senior fellow here at RFF. Becky's research focuses on ecosystem management, particularly on understanding how human behavior affects ecological resources and identifying strategies to improve that ecosystem management. Much of her work has focused on invasive species, including strategies to control established invaders, improvement of monitoring strategies, and cooperative management.
Invasive species is the topic of our discussion today. In particular, we're going to be talking about a new paper that Becky coauthored with RFF colleagues Alexandra Thompson and Tyler Treakle on public contributions to early detection of new invasive pests. We'll talk about how citizens have a critical role to play in identifying emerging threats from invasive species and how Becky and her team worked to quantify the public contribution to pest detection. Whoever thought that talking about finding weird bugs in your backyard could be so interesting? Stay with us.
Becky, I am so glad we're at long last hosting you here on Resources Radio. I'm really looking forward to this conversation. Before we talk about invasive species and your new study in particular, can you tell our listeners a little bit more about yourself and how you came to be interested in environmental economics as a field of study?
Rebecca Epanchin-Niell: Sure. It's really great to be here, Kristin. It's nice to finally be on Resources Radio as a guest here. Thank you. It's kind of funny because I actually discovered environmental economics pretty late in life. I actually thought I was going to be an entomologist. I was a nerdy little kindergartner, thought I'd be an entomologist when I grew up. Starting off in Southern California—we lived in suburban Los Angeles—I used to spend my time gathering up insects and grasshoppers and butterflies in the backyard, and bringing them inside to study them. I literally would bring them in.
Kristin Hayes: Alive or dead?
Rebecca Epanchin-Niell: Alive. I'd keep them, I'd feed them, I'd take care of them, and then I'd let them go again. Later that moved on to salamanders and frogs and bowls and turtles. When I was in undergrad, I originally thought I was going to be pre-med. I loved systems, and thinking about systems, and how to fix them, and people are basically just biological systems. But then I actually took a class called Ecosystems of California. I was like, oh my gosh. Not only is this amazing stuff, but also here is somebody who's a famous ecologist, and his job is to study ecosystems. And I was like, well, I could study ecosystems. I can be an ecologist. So I declared earth systems as my major. One of the requirements for it was to take an environmental economics class. I actually was kind of a stubborn ecologist at that point. I thought economics was this source of all of the world's problems, all our environmental challenges. And I didn't want anything to do with it.
So I had never taken an economics course. I actually postponed it until spring quarter of my senior year. And then I took this class that just opened up a whole new way of understanding interactions between people and natural systems, and how people make decisions, and why decisions and markets can lead to environmental degradation. Not only that, but I learned that there's this whole set of tools and economic tools, policy tools, for helping address those.
All of a sudden I was like, oh my gosh, how in the world did I push this off until the last quarter of my senior year? I went on to go study butterflies for my master's. So I was kind of doing the entomology work, but all along the way taking economics courses too. I ended up deciding to pursue my PhD in environmental and natural resource economics. I continue to link ecology to economics to try to understand systems, think about how to manage systems, and design policies to help remedy some of the environmental challenges that we face.
Kristin Hayes: Wow. Okay. That's great. I'm a little embarrassed that I didn't know nearly as much of that as I should have, given how long we've worked together, but that was fascinating. So thanks for that introduction. I learned something too.
We're here to talk about some new research that you undertook with two other RFF colleagues, Alex Thompson and Tyler Treacle. The research is about methods of detecting invasive species. I know invasive species is an issue that you've looked at a lot. So I wanted to start with one—or at least one—stage setting question. To kick things off, let me ask about the scale of the problem. Why do countries care about invasive species in both environmental and economic terms, and how big a problem are we talking about? I know those are very broad questions, but any light that you can shed on why invasive species matter would be great.
Rebecca Epanchin-Niell: I'm just going to start off with the question of what we mean when we're talking about invasive species. Some people like that term, some people don't. But essentially what we're thinking about here is non-native species. These are species that are introduced from one region of the world to another region where they end up causing ecological and economic harm, as well as harm to human health. In general this is because species, in their native range, evolve over millennia. This is the context of these species and these species interactions. But when you take them out of that system and put them in a new system, they may lack predators or competitors, or a disease that might have kept their populations in check, for example. You're putting them in a system of species that aren't used to interacting with those species.
In some cases, though not all—in fact it's not necessarily even a large proportion—those species end up being really problematic in those new systems. They end up reproducing and spreading and causing impacts on the landscape. In particular they can cause ecological harm. As I mentioned, they don't necessarily fit in the system. Invasive species are actually cited as being a source of imperilment for about two thirds of the species listed under the US Endangered Species Act. So they can cause a lot of harm to native species.
For example, the emerald ash borer is a species that was introduced likely through wood packaging material coming in with trade, and it has spread across the east coast. It's decimating ashtrays, because it harbors a pathogen that kills the ash. So we're seeing near functional extinction of ash trees. In addition to the loss of ecosystem services associated with those trees, we’re losing practical economic services, such as losing the wood we’d use for making baseball bats. It also requires a lot of expenditure as different communities and homeowners have to remove dead ash trees from their yards to avoid the hazard of them potentially falling on people. They actually fall quite easily once they die.
So we have these invasive species that can disrupt systems in these ways. Cheatgrass is an example of an invasive grass introduced out west that changes the entire fire cycle in a region that previously experienced fire cycles every 40 to 70 years. Now, they burn every few years and are converted from a perennial grassland to an annual grassland. So you lose the benefits of livestock foraging for native species, and you have the added costs of fire suppression and air quality impacts from fires. You have these big ecosystem changes. They also can impact crops. You can have direct impacts on crops. For example, there’s something called citrus greening, which is caused by a pathogen that is spread by non-native insects. It's infecting citrus across Florida and spreading it into Texas. It essentially makes the fruit bitter, and often unsellable, causing massive impacts on the citrus industry.
Right now, a lot of work is focused on trying to keep it out of California, where it also could cause severe impacts. So you have these impacts upon crops, but then there are also potential trade consequences. Countries might say, if you have this particular pest there, we don't want your crops. It's going to impact trade or increase costs. So there's impacts on species, ecosystems, and human health, with mosquitoes, for example, vectoring diseases. All in all, estimates have put the annual impacts of invasive species around $160 billion. That potentially could be a gross underestimate, because that's just accounting for damages and control cost. There are many different factors that aren't necessarily easily quantified in the marketplace. But just to give a sense of the impact, there are also studies that have shown impacts of 12 percent of GDP in some developed countries. So, I mean, these are non-negligible impacts.
Kristin Hayes: Right, non-trivial numbers.
Rebecca Epanchin-Niell: Non-trivial numbers.
Kristin Hayes: It sounds like one of the main interfaces here is between countries, right? When we talk about trade and whether products can come in from one place, or go out from another and sort of, I'm sure every country faces different invasions, if you will, depending on their own histories. What trade has looked like in the past, what their climates can or cannot allow it to flourish, what their predator populations look like. It sounds like every country probably faces this to some degree. But would you say that some countries are more invested in addressing invasive species than others? Either at the outflow end, or dealing with the problem once it's happening internally? And if so, why those differences?
Rebecca Epanchin-Niell: You kind of hit the nail on the head with a hammer. In terms of just thinking about these species, you have these different histories and different contexts in which invasions are occurring. So some countries might be more susceptible because of the resources that they have at risk, or their climate suitability. Also we have different histories in terms of how long different countries have been engaged in trade and travel, and the primary means by which species are moved around is through trade, travel, and historically, human migration.
And so you have these different histories at play. Countries that have had trade and imports for a particularly long time often have some of the most impactful domestically established invasions because they've been here for a while. They've had a chance to spread and they're causing impacts. But those countries also are some of the ones that might be best prepared to set up policies to fight this and have the capacity, the resources, to be able to develop policies to prevent the introduction of new invasions.
Whether it's through doing risk assessments of potential commodities that might be being brought in, or doing inspections at the border of commodities coming in. Importantly, invasive species are introduced both intentionally and unintentionally. They aren't introduced intentionally to become invasive, but they're brought in as pets, brought in as plants and whatnot, and then can escape into the wild.
A lot of developing countries have had less experience with invasive species in the past, but they also might be more at risk because of their dependence upon natural resources, and now are facing increasing trade and increasing travel. In fact, the World Trade Organization Agreement on the Application of Sanitary and Phytosanitary Measures is this big agreement between nations about how to manage invasive species, particularly plant pests in trade. There is an agreement that signatories should help facilitate biosecurity technical assistance to developing countries. This is both to help protect those countries, but is also, in some ways, self-serving, in that the more that an invasive species spreads, the more sources there are for future subsequent spread. Just like we've seen with COVID unfortunately. There's a lot of differences across countries in terms of both their capacity and political willingness to put in different stringencies for protections.
Kristin Hayes: Even as you're talking, this makes me wonder if there's going to be some blip in the data for 2020 given how much less global movement there was in 2020 compared to other years. I'm not sure that really applies to trade to the same degree, but certainly people movement and things like that. I'd be curious if that shows up 20 years in the future. But for now, just understanding that most of the flow does happen in the context of trade, I think is a really good, a really good stage setting. So, thank you.
Rebecca Epanchin-Niell: Can I actually just make one comment on that? Because we have these different pathways, I talked about trade and travel. Historically most of the trade is big cargo ships coming in. But increasingly, we have so much other trade that's going on. We have individual parcels being shipped when you go to your favorite online vendor, and you can order so many different things that then may be shipped directly from another country. All the commodities that are coming in through major ports are being subject to inspection, and subject to different policies. But things that are sold by direct consumer purchasing actually are a potential growing risk, which is much harder to manage. And that’s being accelerated.
Kristin Hayes: Oh boy. Always something new to keep on top of, I guess. But, okay. So let's get into this new research. You and your team looked at detection methods. So that is how people identify invasive species populations in the first place. I do want to clarify one thing. So this is particularly focused on early detection, before spread has widely occurred. And is it focused on the United States as well? Or were you looking at multiple countries?
Rebecca Epanchin-Niell: Yes, yes. All of our data collection and analysis was focused on the United States, but we then did some comparisons with data from New Zealand.
Kristin Hayes: Excellent. Oh, New Zealand. I hope nothing invades that wonderful place so it stays just as it is. Okay. So what are the main channels by which populations of invasive species are identified at these early stages? How do people find them?
Rebecca Epanchin-Niell: The reason why we were really interested in understanding how different species were detected is because early detection is key for helping minimize their long-term impacts. Just for any listeners who haven't really thought about it, the earlier you detect something, the more likely you are either to be able to eradicate it right off the bat, or help slow its spread, or conduct new research to figure out ways to help mitigate impact. So early detection is really key.
Of course we prefer to prevent their introductions, so detecting them early is really important. There's actually a lot of programs in place. There are different agency programs to help detect invasive species, but we wanted to know what all their different sources are. There are a lot of agency-based programs. Whether it's commodities, surveys, or sniffer dogs at postal distribution centers, or conducting surveys at high risk sites and around ports. Those are all means for agency-based detections. The US Forest Service deploys traps in their forests, when you're around campgrounds for example, to try to detect new pests.
So you have active formal programs for invasive species detection. We also have researchers and extension specialists who conduct pest surveys as part of their work. The other piece that we're interested in is trying to understand the role of the public and industry. So these, what we call in the study, independent sources, are sources who may detect an invasive species, but that's not specifically their job. That's not necessarily what they're specifically going out to do, but they are still contributing to the early detection of invasive species.
That can include members of the public, like a homeowner, or a nursery operator, or a farmer. There's a whole range of folks who can contribute to detecting a new invasive species. An example that has been in the news a lot, in terms of thinking about public detections, is the Asian giant hornet. I think people might've heard of it as the murder hornet. This was discovered by somebody stepping out on their front porch and seeing this giant crazy looking hornet, which they actually recognized from a YouTube video they had seen. But they ended up calling local authorities, and it ended up leading to a lot of efforts across Washington and Oregon, as the survey program is trying to keep the species from establishing.
Kristin Hayes: Fascinating. I'm pretty sure that if I had stepped out on my front porch and seen something new and murdery looking, I'm not sure I would have taken the time to do that. So kudos to that person for knowing enough and for taking the right steps. First of all, I know that conducting this research required the three of you—you and Alex and Taylor—to really think about datasets in some pretty novel ways to really help shed light on how this early detection is happening. So can you say a little bit about where you pulled the data from, and how you ended up kind of combining it in these new ways?
Rebecca Epanchin-Niell: One of the reasons why this question hadn't been answered previously was not because people weren't interested, but it was that there hasn't been data that was specifically collected for this purpose. There's a lot of investments that have been made in terms of putting together databases for keeping track of past detections in traps as part of these more active survey programs. There's data about things that are detected, or outcomes of inspections of agricultural imports at the border. But when trying to think about this through a much broader scope, where things can be detected across any of the 50 states, and you have different levels of insight, data just hasn't been compiled in this way before. In addition, there are so many non-native species established in the United States. What we’re particularly interested in is trying to understand the detection sources for those that might pose harm, those that could be pests, those that could impact crops or forests.
Anytime a new past is either detected in the United States, or there's a significant concern about it being detected in the United States, the Animal Plant and Health Inspection Service (APHIS) ends up bringing together a new pest advisory group to provide expertise and develop a report about the species. This provides information about where it might be able to survive and the hosts that might affect it. They use that to answer key questions, such as: If it's been detected, where was it first detected? What is the understanding of its current distribution? How might it be controlled? It's essentially gathering all the information you might need for making a quick, initial assessment about what the next step should be. I realized that those could potentially have information about sources of detection. It turns out that in many of those reports there was a sentence or two about the way in which the species had first been detected.
So we actually ended up combing—in particular Tyler and Alex, and also another research assistant who had worked on this project early on, Jessica Blakely—had ended up spending a lot of time in these reports and these databases trying to assemble the sources of detection. One of the hard parts is the report might say, “we heard about this from Washington state.” But the question is, was it the department of agriculture that discovered it, or were they responding to the report from somebody who saw it in their backyard?
So it took a lot of detective work to sort out what the initial source actually was and what was the first detection that brought attention to it, and then that information eventually flowed through different pathways to lead to this new pest advisory group. So we gathered the data from there and through a little bit of sleuthing. Then we also gathered a lot of information about the distribution of the pests, and what the reports said about potential impacts: things like the type of the pest and the setting in which it was first discovered. We were trying to bring all these data together to try to understand, not only what are the relative contributions of these different sources, but are there differences in the types of species that are being detected by these different sources?
Kristin Hayes: Okay, let's talk about the findings then. So what did you and the team discover? Through all your sleuthing, what did you learn about the importance of the various detection channels? Does their relative importance differ by region of the country or even by country? I know you did this comparison between the United States and New Zealand. So tell me a little bit about what you found.
Rebecca Epanchin-Niell: For starters, what we found is that each of these different pathways—including agency detections, researcher extensions, and independent sources, including industry and the general public—all ended up contributing substantially to detections of new invasive species. We found that between probably about a third to a little over a half were first detected through agency surveys of one type or another. About 8 to 17 percent were attributed to research or extension specialists. But more than a quarter—and anywhere from 27 to 60 percent of first detections—were from these independent sources. In particular, the largest proportion was detected by the general public. So members of the community, or homeowners, they are playing a substantial role.
The public, these members of the community, detected the full suite of different pest types. So they weren't only detecting insects or diseases. They were detecting a similar suite of species as the agency surveys. They also were detecting high-impact pests. So I had no idea whether they'd be more likely to detect low impact pests, versus just something that happened to be interesting. But we found that members of the public discovered at least 31 percent of the pests that were thought to be likely to cause high economic or environmental costs to society. So they’re serving a really important role there.
I thought that the public might also not detect things as early, because they're not specifically looking for things, but the results suggested that the public was also comparable with agency-led surveys in terms of detecting narrowly distributed pests. So in other words, that early detection piece. But I have to caveat that these are species, which are being detected by agencies. They have tools, so they might actually have a better idea about the pest’s distribution, whereas something detected by the public may not have much detail to it. So that's an area for future investigation.
When we did our comparison between our data set and the data from New Zealand, we saw that a higher proportion of new pests are detected by independent sources in New Zealand than in the United States. In a sense, that's not too surprising. They actually have a law in place that requires that members of the public report new pests they detect. As an island nation they're very concerned about invasive species. People grow up and learn about them in school from a very young age. There's a lot of investments in terms of protecting the economy and the natural systems within New Zealand.
Kristin Hayes: That's actually a perfect lead into the last substantive question that I wanted to ask you. Given the importance of this independent source detection as a method of detection, I'm very proud to be a member of the public right now. But it sounds like there are some ways the government of New Zealand has really encouraged and even mandated people to engage in this independent source detection. But what can we do here in the United States? Are there other ways in which the government can support more of these citizen science efforts? Are there training options? What would allow this to really become an even more robust early detection system here in the United States?
Rebecca Epanchin-Niell: I think there are a lot of opportunities to further leverage the contributions of the public—just making it easier to log if a member of the public finds something that's unusual, or reducing the barriers to picking up the phone and making a phone call. A lot of states have hotlines that can be called. You do a little internet search and look for that. Anybody can reach out to their local extension office, and usually somebody there can help put you in contact with whoever could come out and see what it is that you're looking at. I think there's a lot of differences between programs here. We're focused on initial detections of an invasive species. And I think that you could do a lot more targeted outreach in cases where there's specific pests that you might be concerned about.
For example, in New Zealand, they're very worried about brown marmorated stink bugs. So there's a lot of awareness programs developed around that. When there are specific pests it kind of helps with targeting this messaging, similar to when the public plays a role in managing a species that's already established and spreading. The public plays a really important role in those contexts as well. So I would say part of it is making those reporting channels very clear.
Increasingly, there's a lot of phone apps that can be used. iNaturalist is not an invasive species app specifically, but it's one where you can upload pictures of different species that you find and people online will help you identify them. I've seen examples there, where if somebody takes a picture of something and it turns out that it's a non-native species, people will actually send a message telling them who to reach out to about that. So I actually think there's also a huge role for agencies to better leverage sources like iNaturalist and other online apps, and incorporate those as part of their surveillance system. They can reference them both as another source besides the traps and the actual physical surveys they do on the ground.
Kristin Hayes: I think another thing that I'm reminded of is I know enough about your family activities to know that you spend a lot of time with your kids and your husband outside. So it seems like part of this too is just, in order to know when something is abnormal, you kind of have to know what normal looks like. So just a reminder for all of us to engage with the outdoors so that we can be better citizen scientists in figuring out what's supposed to be there, and what's not.
Rebecca Epanchin-Niell: Yeah, that's actually why I think that sometimes the public is so good and why a lot of the detections by the public took place in, for example, residential areas. If you go out in your yard, you're working in your garden, you see it every day. If you have that sort of interaction, even with your yard, you notice differences and it's a little bit different than if you're out in a forest and you see a tree that's diseased. You might not notice that, but you notice differences in the places that you're really familiar with, and those are particularly important to pay attention to.
Kristin Hayes: Oh, Becky, this has been so interesting. I really appreciate your coming on to talk to our listeners about this very interesting work. Unfortunately we have reached the end of our time to sort of talk about the research. I want to close with our regular feature, Top of the Stack. So let me ask you, what's on the top of your stack? Whether it might be a book, an article, something to listen to, that you would recommend to our wonderful listeners.
Rebecca Epanchin-Niell: Can I cheat and give two quick ones?
Kristin Hayes: Of course, absolutely. Yes.
Rebecca Epanchin-Niell: I've got to give podcasts. Along with Resources Radio, this is one of those podcasts that can provide a different light and perspective on understanding decisions and patterns that we see in the environment, and perhaps even how to change it. And that's Hidden Brain. I can't recall if any of the other guests have brought that up, but it focuses on unconscious patterns that influence human behavior, and the ways that those can influence outcomes in society. Like how we might deviate from what's necessarily in our best interest, or the best interest of society. They bring on behavioral economists, psychologists, and sociologists. I've had a lot of fun with that.
But I also have been doing a lot of reading with my kids over the pandemic, in particular, and it's probably more being with my kids. So when I look at my top of the stack, it's the big pile of books that we have to read. And we've been having a lot of fun with that. But right now we're on a big Austin Aslan kick. He's a young adult writer out of Flagstaff. He writes a lot of science fiction, adventure, and young adult. And one of the things that I really like is, in all the adventures, he pays a lot of attention to the natural world. So it's not the center of some of his books, but you'll just notice details about species or their interactions.
We're reading one of the TURBOnauts books, and it's about having to decontaminate the boats before they go in the water, because you don't want to introduce invasive species. But a book he has coauthored, which is at the top of the stack right now for my daughter is The Endangereds, which is a book he co-wrote with Philippe Cousteau. It's about these superhero endangered species trying to save a species from climate change and habitat degradation. It was the book that pushed my son from being a reluctant reader to an avid reader. Right now, my daughter who is six, is about to sit down and start reading that one with me.
Kristin Hayes: Fun for the whole family. That's great. We don't get too many family Top of the Stack recommendations, so that's awesome. That's a great way to end. So Becky, thanks again. It's been a pleasure and I'm sure I'll talk to you again soon.
Rebecca Epanchin-Niell: Yes. Thank you so much for having me on, this has been really fun.
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Resources Radio is a podcast from Resources for the Future. RFF is an independent, nonprofit research institution in Washington, DC. Our mission is to improve environmental, energy, and natural resource decisions through impartial economic research and policy engagement. The views expressed on this podcast are solely those of the podcast guests and may differ from those of RFF experts, its officers, or its directors. RFF does not take positions on specific legislative proposals. Resources Radio is produced by Elizabeth Wason, with music by Daniel Raimi. Join us next week for another episode.