Years of research, regulatory hurdles and a team of dedicated experts are the force behind an army of caterpillars currently chomping away on phragmites, an invasive grass species in Ontario.
In 2019, the Canadian Food Inspection Agency approved two moth species able to help control the spread of phragmites, a reed threatening the biodiversity of wetlands throughout the province and other parts of the country. By 2021, a team of scientists released the caterpillars in targeted areas throughout southern Ontario, and they are seeing great results with reducing the spread of phragmites, the insects’ sole source of food.
What seems like a simple, sustainable solution is the result of decades of hard work to make biocontrol a more viable, low-risk option, says Sandy Smith, an entomologist and the director of the Smith Forest Health Lab, which oversees the project. “We always say there’s risk to everything you do, and there’s risk to doing nothing,” she says. “This is another tool for restoration.”
While herbicides are sometimes an option for controlling invasive plants, Smith said phragmites being present in and around water pose a challenge, as chemical runoff could cause problems. Though the caterpillars won’t eliminate the plant entirely—the species, which is not native to Canada, has too much of a foothold—her team is happy with results thus far, especially when it comes to showing the potential of biocontrol done right.
As Smith explains, ecosystems are a delicate balance, and introducing one species to control another can have disastrous effects if not implemented properly. She points to cane toads in Australia as a famous example; initially brought in to manage agricultural pests, they proved ineffective and are now invasive. Cases like that caused a poor perception of biocontrol, but after decades in the field, Smith is seeing public opinion shift, owing in part to climate change and interest in sustainable solutions.
“People will say, ‘Oh, biocontrol isn’t that risky? You’re bringing something over that wasn’t here.’ And I say, sometimes we’ve already made a mess, and this is so well-researched that it doesn’t feel like a big risk compared to what we’ve already done,” says Smith, adding that the goal is to reestablish balance. “Even if we never brought a biocontrol agent, there’s nothing we could do to get rid of phragmites. Now, we brought in another insect, and we’re not going to get rid of that either. We’ve had to change the community because neither one of them belongs here—from my end as an entomologist, we’re creating diversity.”
It can be a lengthy, difficult process to get biocontrol tools approved in Canada, since it usually requires significant money for overseas research so that the risk can be better understood before anything lands on our soil. Also, many players are involved; the phragmites project has brought together Ducks Unlimited Canada (wetlands are popular for duck hunting), Agriculture and Agri-Food Canada, the University of Toronto (where Smith’s lab is housed), and the Centre for Agriculture and Bioscience International in Switzerland, one of Smith’s partner labs where the phragmites testing first took place.
While so many actors on board can be a challenge, Smith says it’s also an important part of overcoming another hurdle: getting people to care. “Success is silent; failure is really loud and in your face,” she says, adding that most people only take notice of invasive species when it affects their everyday life or recreation time.
Amidst the success, Smith says she hopes this story serves as a reminder about the need for everyone to play a part in controlling invasive species. Phragmites’ seeds can spread through boating equipment or even clothing, if people are recreating in an area where they’re present; cleaning materials carefully can help stop the spread. “There is no silver bullet,” says Smith. “But we do have something that’s very hopeful.”
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