PULLMAN, Wash. — Dowen Jocson is using vibrations to disrupt pear psylla pests as they attempt to mate.
The insects, which damage pear trees by sucking their sap and destroying their leaves, communicate via “songs” that attract mates so they can reproduce.
Jocson uses an accelerometer to record the mating calls of the insect pests and playback devices to send vibrations down the stems of the plants.
She plays the male pear psylla songs as a deterrent, overwhelming female senses and forcing males to compete with one another. She also plays back a range of white noise frequencies, canceling out some mating songs.
Jocson also plans to use sticky traps in pear orchards, using the female vibrational song to lure males.
For another experiment, she’s replicating an orchard trellis using galvanized wire attached to the stem of the plants, sending vibrations through the wire.
She said her vibrational playback experiments so far have yielded “promising” results. If Jocson is successful, her findings in pears could be used on other pests that attack other crops.
“It opens up a whole new area of study for all of these crop pests,” she said.
Jocson grew up on Saipan in the Northern Mariana Islands, surrounded by jungles.
She wasn’t always interested in insects. She planned to study evolutionary biology, but realized she could help reduce the use of pesticides and develop new pest management tools for organic and conventional agriculture.
“I’ve shifted completely — I love bugs,” she said.
She got her master’s degree studying the effects temperature has on the vibrational signals of treehoppers, which are not a pest.
Temperature fluctuations affect an insect song’s pitch, she said. “As temperature increases, the pitch increases, because their body warms up and they can move faster, so they can produce more vibration.”
While working on that project, she realized most insects use vibrational communication to attract mates and wondered if it could be used as a way to control pests.
As a graduate student from 2015 to 2017, Jocson worked in the laboratory of St. Louis University biology professor Kasey Fowler-Finn.
Fowler-Finn credits Jocson with using “a communication system of which very few people are aware — substrate-borne vibrations” to find a more sustainable approach to pest management.
Jocson creatively combines basic and applied sciences for better outcomes for food supplies, she said.
“She gets really into her research, from creating ring tones from the songs of the insects she studies to dressing as her organism for Halloween,” Fowler-Finn said. “She also used to keep spiders in matchboxes when she was a kid and bring them out to fight them. When I heard about this, I knew she was going to be good at insect research!”
Jocson recently received a USDA National Institute of Food and Agriculture grant for $180,000 for three years, adding more field studies to her work.
After she finishes her Ph.D., Jocson aspires to work for university extension, so she can help organic and conventional farmers.
“In a lot of the research fields, you’re always in the lab, you’re a scientist in your own world, but you never get to see how your research affects other people and where it actually reaches,” she said. “I really want to work with farmers and growers closely to see what they need and see if we can develop and create and help them.”