Strategies to save insects: In lieu of pesticides, Christelle Guédot’s “integrated pest-pollinator management”

This article, by Alexander Leat, is part of a series highlighting members of the Office of Sustainability’s Experts Database. In a collaboration with instructor Madeline Fisher’s course, LSC 561: Writing Science for the Public, students interviewed campus sustainability experts and produced short feature stories. 

Christelle Guédot headshotMost of us seldom think about the countless insects that surround us, and if we do, it is because they are a nuisance: a fly to swat, or a cockroach to stomp. But for growers of fruit crops, insects cannot be ignored. Pests can cause substantial damage to their livelihood and rob the rest of us of the fresh fruit we enjoy. 

To combat this, many growers turn to pesticides to protect their crops. Yet those pesticides can be harmful by killing off the pollinating insects that fruit crops rely on. An estimate from 2019 concludes that one in six species of bee has disappeared from their native regions. Without pollinators, many fruit crops cannot reproduce effectively, something just as harmful to crop yields as the pests could have been.

It is this conflict that Christelle Guédot and her lab are working to solve. Guédot, an associate professor and extension specialist at the University of Wisconsin–Madison, studies sustainable ways to manage pests while protecting pollinators. Guédot and her team focus on two broad strategies that look for pesticide alternatives: behavioral management, which applies chemicals to control pest behavior, and cultural strategies, which changes how fruit growers grow their crops. 

“To be kind of broad,” Guédot said, “cultural strategies are anything you can do to prevent pests from becoming pests in the first place.”

Most modern pest management relies on the use of pesticides, which when sprayed over crops kill just about any insect that comes in contact with them. However, not all of those insects are pests. Many are beneficial pollinators crops need to reproduce. In fact, Guédot said, “less than 1 percent of insects are actually pests.” The problem, she explained, is that when you have large areas with a single type of plant, such as fruits, you are concentrating a resource that pest insects want, attracting more of them. How, then, do you manage those harmful pests while preserving beneficial pollinators?

Guédot calls her strategy “integrated pest-pollinator management,” and it is built on the idea that of existing pest management strategies, only chemical management—using pesticides—truly harms pollinators. So she is working to refine how we use pesticides and find alternatives when possible. 

The first strategy her team Guédot’s team developed is behavioral management. This technique relies on the use of naturally occurring chemicals that insect species use to communicate to attract pest insects to specific areas while having no effect on other species. Using these chemical lures, her lab has begun using an “attract-and-kill” strategy: they attract pests to prepared areas of farmland and spray them with pesticides there. Not only does this strategy spare pollinators, she explained, but it can reduce the sprayed area of a farm by as much as 96 percent.

Beyond refining our use of pesticides, Guédot’s work also focuses on cultural strategies, or changing how growers grow their crops to prevent pests from becoming a problem at all. A number of different techniques fall under this category, from the planting of trap crops to attract and intercept pests to laying down mulches around certain crops. In one case, Guédot’s lab found that laying down plastic mulches beneath raspberry plants reduced fruit fly infestation by 50 to 70 percent. In fact, the farm where that study was performed has reported that it is going to continue using it on its own, as the mulches not only reduced infestation but also increased crop yield.

Guédot is far from the only researcher doing this sort of work. She has colleagues in countries around the world, with each looking to improve the ways we grow food without harming the environment or the insects that help us grow it. Guédot’s work, and the work of people like her, is based on appreciation for some of nature’s most unfairly maligned species. 

“We love insects,” Guédot said. “They are super important for any ecosystem, for the planet, and there’s so much that that they provide for the planet—not for humans, [but] for the planet in general.”