From Poetry to Pests: An Agcenter Entomologist’s Unlikely Path to Protecting Louisiana Forests

By Olivia McClure

LSU AgCenter

BATON ROUGE, La. — Growing up in scenic upstate New York, Todd Johnson thought he wanted to write for a living, finding inspiration in nature.

“I spent a lot of time outside as a kid, did a lot of mountain biking, did a lot of reading, which got me really interested in writing,” said Johnson, who grew up in Saratoga Springs, a tourist town near the Adirondack Mountains. “I went to college to be a writer. I was really interested in short fiction and poetry.”

One of Johnson’s pastimes was reading interviews with famous writers. After he came across a conversation with the legendary poet Robert Frost — “If you grew up in the Northeast, you read a lot of Robert Frost,” Johnson said — he began to rethink his career aspirations.

“He was like, ‘Don’t go to school and be an English major. Major in a discipline and learn something to write about,’” Johnson recalled.

As a student at Moravian College (now Moravian University) in Pennsylvania, Johnson took Frost’s advice, settling on a biology degree. Today, he is an assistant professor of forest entomology with the LSU AgCenter, where he studies the fascinating world of insects and how they interact with the environment.

One of Johnson’s specialties is wood-boring insects such as the flatheaded hackberry borer, a native, occasional pest of hackberry trees in the southeastern United States, and the emerald ash borer, a related but invasive species that poses a more serious threat to forests and the timber industry. He is working to better understand how these types of insects decide which trees to attack and to identify natural enemies.

Johnson has zeroed in on a couple of keys. First: It’s important to understand that a nonnative, invasive species like the emerald ash borer — which has been damaging ash trees in Louisiana for at least a decade — doesn’t share any history with local trees. It’s a different story for trees in the insect’s native range.

“They’ve evolved defenses against it,” Johnson said. “When this insect gets introduced elsewhere, many of the trees are kind of like a buffet. They’re unable to detect or respond as strongly or at all to that organism because it’s new to them.”

A second area Johnson is focusing on involves insects’ response to the odors and other volatile cues that trees emit. These cues often change when forests experience problems.

“When the tree begins to smell different, things that are looking for that perfect stressed tree are all really strongly attracted to those odors,” Johnson said. “And so they fly in and then they attack the tree.”

This could help explain how invasive species take advantage of already-stressed environments, he said. These insects often are adept at noticing shifts in trees’ condition. And their arrival can spur additional changes to the ecosystem.

“When the invasives move in, they harm the biodiversity, and that changes how the forest functions,” Johnson said. “That alters habitat for insects that are important, that decompose things, that pollinate things, that provide pest suppression in other ways. And you can see these dramatic shifts in an ecosystem as a result of the loss of one or two species. Some of these changes are irreversible. Loss of function cannot always be restored once species go locally extinct or the environment has changed too dramatically.”

It’s that sort of looking at the big picture that Johnson said is crucial to protecting Louisiana’s forests from invasive insects.

“We’re always trying to think towards how is the structure and function of the forest going to change under different circumstances?” he said. “And how do we do that in ways that are consistent with our management goals — whether it’s conservation, whether it’s production?”

Since coming to the AgCenter in 2022, Johnson has enjoyed learning about Louisiana forest and insect issues.

“I’m happy and grateful to be here,” he said. “Forestry is such an important component of the state.”

In addition to his undergraduate degree, Johnson holds a master’s degree from the University of Wisconsin-Madison and a doctorate from the University of Illinois at Urbana-Champaign. He worked as a postdoctoral researcher at the University of New Hampshire.

“I have moved a lot as part of my college and graduate experiences,” he said. “I think in terms of my research, it’s really exposed me to a broad range of forest types and different insects — and sometimes the same insects, like emerald ash borer, which I studied in Wisconsin, New Hampshire and now here. I’m seeing how the same insect might behave differently in these different areas.” 

As a professor, he even gets the chance to be a writer — perhaps not of short fiction and poetry, but of research papers, grant proposals and lesson plans for the classes he teaches.

“We do a lot of writing in our jobs,” Johnson said. “So, in a way, I feel like I did achieve that goal.”