Most people probably hear buzzing and chirping when they imagine what a bug sounds like, but there are thousands of insects that humans can’t hear.
Rex Cocroft has made a career out of capturing the live performances of one species – treehoppers – to better understand how they communicate. The University of Missouri professor of biology, who studied music before science, attaches tiny microphones to a silk plant stem on his desk to demonstrate.
“So this plant is humming with tree hopper sounds,” he said. “Most of those are actually males singing to each other.”
With the microphones connecting to a small speaker, a melody of low drones and crackling becomes audible. It’s coming from the vibrations of thorn-like bugs that live on the plant’s stem.
FOR THE PAST 30 years, Cocroft has been a pioneer in the study of insect vibrational communication and the larger field of biotremology – which focuses on the overall production, reception, and behavioral effects of animal vibrations. His work has helped scientists better understand how these insects communicate. And with more than 3,000 species of treehoppers across six continents, there might be a lot being said.
“Most of the sounds out there have never been heard by humans, and you can literally go into a backyard in Missouri and hear a sound that no one has ever heard before,” he said. “And it might be something rather strange and interesting that no one has ever heard before.”
Now more researchers are studying insect vibrations to find new and practical applications. Researchers at Oregon State University, for instance, are using robots to mimic insect sounds to protect vineyards from pests. Washington State University researchers have looked into protecting pear trees from a pest species called pear psylla by disrupting their mating vibrations and reproduction rates.
While Cocroft is not solely responsible for the growth of his research field, many of those scientists have credited Cocroft for his contributions and personal impact.
AT ST. LOUIS University, Kasey Fowler-Finn and her colleagues are trying to understand how climate change could impact insect populations.
“We look at how it affects the rates of mating, how it affects how they sound, and whether they can still detect each other, even though temperature makes animals sound different,” said Fowler-Finn.
They do this by using the chirping rates of crickets as a sort of thermometer, since muscle vibrations are faster at hotter temperatures.
BIOTREMOLOGY has grown over the years, but it’s still a relatively small research community. “We all kind of know each other,” said Fowler-Finn.
Fowler-Finn’s post-doctoral research advisor was Cocroft. She also considers him a mentor; one who’s helped develop inexpensive equipment and software to make the field more accessible for researchers in countries where resources and funding are limited.
She said Cocroft has even helped her students build equipment to record and process their own research.
“Truly some of my projects would not have been possible without his assistance and feedback,” she said “He just has a real mind for figuring out the exact way to design experiments to get at the questions he is asking.”
