OSU student surprised professor with unique pest control innovation
By BERIT THORSON | Capital Press
Holly Golightly waters the carnivorous plants in Oregon State University’s greenhouse at the Oak Creek Center for Urban Horticulture. Berit Thorson/Capital Press
CORVALLIS, Ore. — An Oregon State University student is experimenting with a unique type of plant. It controls insect pests by eating them.
Holly Golightly, 23, was a senior soil science major at OSU taking a class last year with professor James Cassidy about organic farming and gardening when he mentioned the greenhouses were struggling with fungus gnats.
While still larvae, fungus gnats can damage plants and put them at risk for disease.
A different idea
Normally, fungus gnats can be avoided by strict watering practices or combated by pesticides or beneficial insects. But Golightly had a different idea.
She had heard a podcast that covered carnivorous plants and their various uses, including pest control. She wondered if they could be used against the fungus gnats found on their plants.
Cassidy’s first thought when Golightly suggested using carnivorous plants for pest control was that there was no way it would work. Internally, he dismissed the idea. He hadn’t heard of it being done, and he didn’t want the extra work that comes with failed student projects.
The professor of soil science at OSU has been the faculty adviser for the student-run, organic farm on campus since its conceptual start 23 years ago. His knowledge and experience told him the idea wouldn’t work.
“But, I mean, the mission is to teach and say ‘No’ to nothing,” Cassidy said. He wants students to try and fail or succeed on their own terms as much as possible. So, Cassidy used money from their sales of herbs and vegetables to support Golightly in testing her idea.
She bought a variety of carnivorous plants, including two species of sundews, a butterwort, venus fly traps and two species of pitcher plants. She wasn’t sure which would best control the fungus gnats, insects that thrive in damp areas such as greenhouses.
“This was the first time I really had the chance to start a project like that myself,” Golightly said. “I’m super grateful that James helped get the project started and was willing to go along with it. It’s been really fun.”
Using carnivorous plants as pest control may be difficult to popularize, said Melissa Scherr, a researcher with OSU Extension, in an email.
“It’s a hard sell in nurseries that are trying to keep soils only as wet as needed to avoid water borne pests like fungus gnats,” she wrote.
Historically, Cassidy and his students controlled the fungus gnat population with organic-approved pesticides and careful watering techniques. But watering a greenhouse can be difficult, and the plants in it have often been overwatered by students.
Carnivorous plants
Along with stricter watering practices this year, Cassidy and Golightly believe the carnivorous plants have helped control the pest population.
Golightly has been caring for the plants for about a year, but there has been no formal study of the intervention. She said it would be too difficult at this time to produce meaningful data since they only have one greenhouse and limited funds.
But they haven’t had to use any pesticides, and the plants caught fungus gnats throughout the season.
The forked sundews, Drosera binata, have been especially full of gnats.
Drosera binata sundews seem the most promising for fungus gnat control, according to Holly Golightly. Berit Thorson/Capital Press
Adult gnats aren’t drawn to nectar, which is how pitcher plants attract prey. Sundews, on the other hand, don’t need nectar-oriented prey because they have thin, sticky leaves that prey fly into and get caught in. This makes them good candidates for ensnaring fungus gnats.
The forked sundews also seem to do well in the greenhouse conditions compared to other carnivorous plants, Golightly said. They grow quickly and seem to be more heat tolerant than the cape sundews she bought.
They also have more surface area than some other plants due to their branching leaves, Golightly said.
“I’ve learned a ton about carnivorous plants,” she said. “I’ve learned, aside from that, that if something interests you, it probably interests other people, too, because I’ve made a lot of connections with people since I started getting into this. Turns out a lot of people like carnivorous plants.”
Recently, Golightly took cuttings from the mature plants for propagation.
The propagated plants should provide further protection for Cassidy and Golightly next growing season, and allow them to tell if their approach works or if it was a lucky set of coincidences.
“During this spring propagation season, I never saw any fungus gnats,” Cassidy said of the vegetables he grew. “It seems to be working, but I just don’t quite believe it yet, so I want more (carnivorous plants).”