To reduce the use of pesticides, Sean Schoville looks back millions of years

This article, by Jacob Wologo, 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.

Sean Schoville sitting in a desk chair wearing a white shirtCold War-era propaganda told of a pest so powerful that the United States would drop it on German crops to diminish food supplies. That pest was the Colorado potato beetle, and although it was never actually used as a weapon, it caused damage to German farms as well as American ones. According to the USDA, it continues to cause millions of dollars of damage to American farmers annually.

To try to curb those damages, Sean Schoville, associate professor in the Department of Entomology at UW–Madison, is studying how the Colorado potato beetle adapts to environmental changes like insecticide use. Schoville has found that ancient adaptations that allowed the beetle to eat poisonous plants have also given it the ability to detoxify pesticides. Because of this, farmers either use more chemicals that are costly and can be a health hazard to surrounding communities, or they lose their crops to the insects. Schoville is developing a fundamental understanding of the Colorado potato beetle’s unique adaptations, which will lead to more intentional pesticide use and more sustainable farming practices. 

Although the Colorado potato beetle is native to North America and poses no immediate threat to humans, it became a major pest once people started farming on the land it lived on. The beetle’s diet shifted from native plants to cultivated ones such as potatoes, eggplants, and tomatoes, which are major staples for the American food supply. 

That dietary shift was not harmless for the first farmers to encounter the beetle. 

“It’s a pest that’s been one of the main things driving the pesticide industry from the beginning,” Schoville said. “Potatoes were a hugely important crop, especially in the 1800s.”

With the Colorado potato beetle threatening such important crops, farmers resorted to using poisons called insecticides to control the beetle’s population. However, each time farmers introduced a new insecticide, the Colorado potato beetle developed resistance.

“Control of the potato beetle was paramount, so they learned to throw all sorts of things at it.,” he said. “It has found a way to avoid dying from these insecticides and to actually be successful. So it has a long history of overcoming these toxins and managing to thrive.”

The potato beetle has a secret to its success hidden in its DNA. Schoville found that, millions of years ago, the Colorado potato beetle evolved to eat poisonous plants, and today that adaptation is being used to resist the poisons farmers try to use to control its population. 

“There are certain pathways that [the beetles] evolved to detoxify plant chemicals, and they’re leveraging those pathways to detoxify insecticides,” Schoville said. “So they’ve figured this out millions of years ago, probably, and now are using those same tools to help them combat insecticides.”

Schoville is studying the beetle’s DNA to develop a fundamental understanding of the adaptations that allow the Colorado potato beetle to resist poisons. With that knowledge, farmers will be able to control populations better by applying targeted insecticide use, ultimately leading to less insecticide use and therefore more sustainable farming practices. 

“Right now, we sort of blanket the whole area with insecticides,” he said. “But what if we could just pinpoint those key hotspots and really control them there and step back from excessive management in other places?”