Regardless of the effects on environmental or human health, Americans have similar, and tepid, feelings about invasive species control
There are more than 6,500 invasive species in the United States that have caused immeasurable damage to native ecosystems. Mechanical control, like weeding; chemical control, like applying pesticides; or biological control, like introducing specialized insects, are all strategies scientists use to combat invasive species. However, public perceptions of invasive species management aren’t always clear and can impact the long-term success of projects.
In a new paper in People and Nature, Wade Simmons, a PhD candidate at Cornell University, studied public perceptions of introduced species management. Simmons mainly works on biological control of water chestnut (Trapa natans), an invasive species in New York.
To complete the study, Simmons and his collaborators presented a representative sample of the American public with a set of scenarios around invasive species management. The team structured the stories using four basic building blocks of introduced species management: a target species, a proposed method of control and the level and type of associated risks. In order to avoid bias, they didn’t specifically name the three methods of control—chemical, mechanical or biological—but rather described the mode of action in the scenario. The stories were general and didn’t provide many specifics with the goal of getting to the heart of Americans’ attitudes toward each management intervention.
We spoke with Simmons to learn more about Americans’ attitudes towards invasive species management and how scientists may be able to build public trust.
What made you want to complete this study and how did you design it?
If you tell someone you do biocontrol science, they’ve got all kinds of questions and assumptions. You can see a lot of suspicion and alarm bells going off in people’s minds. But perceptions of modern biocontrol, especially of plants as being unpredictable or risky, do not match the overwhelming positive track record. I had this nagging question—is biocontrol really more controversial with the American public than other forms of control, like mechanical or chemical? If you asked people in a standardized way, how much do these ideas really diverge?
To get away from some of that ambiguity, we standardized our experiment just for control of plants and insects. Insects and plants were a good place to start because there were comparable biological, chemical and physical control methods across species. We also recognized that people’s emotions, attitudes and values seem to stand apart across taxa. We were really careful in choosing descriptive words and avoiding emotional ones. For that reason, we didn’t label species as invasive but used descriptors like “a plant species has arrived in a place where it didn’t previously exist and is causing negative effects on the environment.”
As researchers, we want to use the most evidence-based and effective management strategies, but those aren’t always the most socially acceptable. This study was a first step in mapping out public feelings towards shared, fundamental components of management.
What did you find?
Overall, our findings suggest that many standard practices for managing introduced species are not broadly accepted by the U.S. public. Unsurprisingly, we found greater support for management considered low-risk relative to high-risk scenarios and that mechanical control is generally more acceptable than both chemical and biological control. These two methods often had similar levels of low support.
We didn’t specifically test why mechanical control was more acceptable, but it likely relates to its familiarity: people understand cutting down a tree or pulling weeds. What happens as chemicals break down, or biocontrol insects spread more widely in the environment is less clear to most people.
The problem is we just don’t have very good evidence that mechanical control is an effective way to reduce the impacts of nonnative species, at least at scale. It’s problematic that the method with the most social acceptability is perhaps the least effective, and the method with the best supporting evidence—biocontrol—has the lowest acceptability.
We also found that acceptability for managing plants and insects did not differ, nor did the acceptability for management with risks to human well-being compared to risks to native species. We didn’t define risks in a granular way, so it’s likely that we’d see a separation in attitudes when risks became more specific to respondents’ personal situations. Still, it was heartening to see the concern for native species. This leaves really inviting follow-up directions for future research.
What are your big takeaways from this project?
Our work shows that managing introduced species continues to be controversial, and public support for management should not be assumed for projects. We also find a disconnect between what can work, at least at scale, and what is popular. So what can we do to try to increase public support for management, or at least better communicate and defend the important management work that is being done?
We know from plenty of other work that simply giving people more information is not an effective strategy for changing minds on its own, but we do see a clear need for more evidence here. Many management projects are motivated and justified by the desire to protect native species or ecosystems, yet we often lack the appropriate evidence to judge the impacts of nonnative species or evaluate whether management actions are making a difference toward these goals. Removing so many acres of an aquatic plant may be a success if the goal is opening up space for human recreation, but it doesn’t tell us anything about whether water quality improves or if native species recover. Without better outcome monitoring, accountability for management actions can break down, and these management actions may be more susceptible to controversy if claims of benefits can’t be corroborated.
Controversies surrounding nonnative species will likely never go away, but the intensity of the disagreements may be inflamed if controversial actions are not well supported by evidence. And the need for evidence can change over time. In early stages of invasion, when threats and harms are unclear and chances of eradication are high, taking actions without clear evidence may be well justified. But for species that are well established and have been targeted with management for years, the evidence justifying their management should also grow and deepen, and that is commonly not the case.
The burden of building a culture of greater outcome monitoring should be a shared responsibility, and it is on funders to require it in grants and on scientists and managers to test, develop and implement it together. Showing that action “X” can lead to species “Y” recovering may meaningfully change people’s attitudes, or it may not, but it seems extremely important in terms of accountability for actions being taken with public money, on public lands and for public benefits. While the controversies may never go away, our understanding of risks and outcomes of management should grow over time so we can better determine which species should be managed, and how, with our limited conservation resources.
