Vincent Vaughn-Uding has a brown marmorated stink bug in a cup, and he’s trying to convince it to leave.
“This one’s deciding to be difficult,” he says, gently coaxing it out onto the branch of a holly bush sitting in a vase in the Oregon State University undergraduate’s lab. “In general, bugs are annoying. They’re very finicky.”
Vaughn-Uding needs the stink bug to stay relaxed so it won’t fly away — and so it’s not too freaked out to strike up a conversation with the other stink bug already hanging out in the holly.
“We put a male and a female on a plant and … we hope for the best that they start talking to each other,” he says.
The bugs don’t talk the same way we do, but they do communicate — with vibrations.
The plan is to record the insect communication so farmers can use the sound against insect pests.
Since there was agriculture, there were agricultural pests — and farmers trying to control them. For insects, growers mostly rely on pesticides, which we know can have real consequences for wildlife, people and our environment.
But if Vaughn-Uding’s new insect-mimicking robot is successful, it would provide farmers a targeted way to control pests without the use of toxic chemicals.
“Our big thing,” he says, “is reducing how much pesticides need to get used.”
The device they’ll use to achieve these goals is called the Pied Piper.
“There’s a really well-known story of a village that has a pest problem,” says Chet Udell, director of the Openly Published Environmental Sensing Lab (OPEnS) at OSU, which is developing the device.
As the story goes, a stranger shows up offering to help. The Pied Piper plays his pipe, and all the rats in town are lured away.
“We thought that was a really appropriate thing for what we were trying to accomplish with the bugs,” Udell says.
“— Excerpt from "The Pied Piper of Hamelin" by Robert Browning
And ere three shrill notes the pipe uttered,
You heard as if an army muttered;
And the muttering grew to a grumbling;
And the grumbling grew to a mighty rumbling;
And out of the houses the rats came tumbling.”
The Pied Piper works by taking advantage of how some insects communicate. Many do this by using chemical signals called pheromones, but others rely heavily on vibrational communication.
“They experience vibration more the way we experience sound,” says Rex Cocroft, who studies insect communication at the University of Missouri. “It’s a very big part of their sensory and social world.”
Cocroft says the vast majority of animal sounds on Earth are the sonic and vibrational songs of insects and spiders.
Humans have evolved to pick up airborne pressure waves, which our brain interprets as sound.
“But once it becomes vibrations traveling through a solid surface, then we have to touch it with our hands to pick it up, or some part of our body. And our senses aren’t really designed to capture a lot of information [that way],” Cocroft says.
But insects use vibrations to communicate many things — where to find food, when predators are around, territory — but the most common use of vibrational communication is to help them find mates.
“It’s all about saving energy. The females must use as little energy as they can so that they can produce as many eggs and many offspring as they can,” says OSU entomologist Vaughn Walton, who leads the Pied Piper project.
Saving energy means being as efficient as possible in finding a mate. Some insects do this by playing an elaborate game of telephone. They vibrate their abdomens and the sound travels through whatever they happen to be standing on.
“The mates will find that signal, they will zone in on them and they will be able to mate,” he says.
The Pied Piper device does something very similar — it will play an insect’s call to lure other insects in.
“We’re sort of training this little robot musician, right? To sit out in a vineyard and listen for these bugs and do something very typical in music, which is call and response, the Marco Polo,” says Udell.
Walton is testing the device on an insect called a treehopper at an experimental vineyard plot at Stag Hollow Winery in Yamhill, Oregon.
“With red blotch, we’re seeing reduction in photosynthesis in the plant itself,” Walton says. “What that translates towards wine making is that you have less of these volatiles that we as humans love in wines … And the perception is that the quality of those wines are not as good.”
Protecting Oregon vineyards
The Pied Piper is not pretty. It’s essentially a computer in a small dry box, with a stiff wire and a microphone coming out the side. The electronics are protected by a larger, open plastic housing.
But looks can be deceiving.
“With Pied Piper, we’re trying to find an environmentally friendly way without using any toxic pesticides,” Walton says.
Walton and Stag Hollow owner Mark Huff approach a row of grapevines at the edge of a field.
“This one right here,” says Huff, pointing to a grapevine with a small cluster of young BB-sized grapes.
“Why this one?” Walton asks.
“It’s doing well, therefore might attract the insects,” Huff responds, laughing.
For Huff, dealing with pest problems is constant work.
“Every grower of grapes in Oregon, from the moment that the grapes unfurl from their buds, you are thinking about it all the time,” he says. “And if you’re in the organic business, like we are here, you have a very limited amount of tools in the tool chest [to control pests].”
Walton attaches the device’s microphone and wire speaker to the grapevine, where it will listen for treehoppers.
“[When it detects a pattern it recognizes,] the computer will send a mating signal through this wire back onto the stem. And so if the insect senses the signal sent from the computer, it will eventually, in theory, walk back on this wire,” he explains.
Then the Pied Piper snaps a photo of the bug, allowing the farmer to confirm the presence of the pest.
Luring treehoppers out into the open is a bigger deal than it may seem. They’re experts at staying hidden and difficult to detect.
But testing of the Pied Piper has shown that treehoppers can’t resist the charms of a sweet-talking mechanical mate. The researchers have been able to capture photos of treehoppers lured in by the call.
“Having a sensitive measure to know when that species is there is very useful in and of itself. One of the goals of pest management is to apply controls only when and as you need them,” say Cocroft, who isn’t involved with the project.
But while detection is important, Walton and his team have even grander aspirations for the Pied Piper.
Birth control, but for bugs
The hope for the Pied Piper robot is to use the device’s communication with treehoppers and other insects to keep them from making babies. It’s a technique called “mating disruption.”
“Mating disruption is kind of like birth control,” Walton says. “You have an adult female that… should lay eggs within three or four days of its early life cycle. If you can delay that, you can cut the [reproductive] capacity of this insect sometimes in half, sometimes by 90 percent.”
The idea is to confuse and distract — anything to keep the bugs from finding each other and mating.
Mechanical vibrations could be used to compete with living males.
“You would need to know how the males sound, and … replicate that sound, that vibrational pattern. That will compete with the live males for the females’ attention. Or it could confuse the female,” says Dowen Jocson, a pesticide safety educator in Washington State University’s Department of Entomology.
Another strategy could be to drown out all of the communication.
“I equate this to being in a bar or a club with very, very loud music. You can’t have a conversation, you can’t get people’s names, you can’t get people’s numbers,” she says.
“I do see it as being a solution to a lot of the pesticide resistance treadmill that we’re in,” she says. “If we use this vibrational mating disruption and lower the population just by a bit, I think that’ll help a lot.”
Learning new languages
It’s been OSU undergrad Vincent Vaughn-Uding’s job to train the Pied Piper to recognize treehopper calls. Now with the stink bugs, he’s expanding its repertoire.
“We’re working on getting the devices to work for brown marmorated stink bugs, which are another pretty major agricultural pest,” he says.
The stink bugs are recent invaders in the Pacific Northwest and they’re starting to cause damage to hazelnut crops.
But to speak to stink bugs, Pied Piper has to know the language, and that starts with recording their communication — with a vibration-sensing laser called a vibrometer.
“It can measure just vibrations in a thing you pointed at … with very high accuracy,” he explains, focusing the instrument on the holly branch.
“We can get recordings that the [Pied Piper] can play back later in order to lure the insects towards it. And it’s also how we can figure out how we need to tune our detection algorithm — like what dominant frequencies and harmonics we need to look at,” Vaughn-Uding says.
With the two stink bugs on the branch and the vibrometer focused in, the recording — and waiting — begins.
“They usually take a little while to get acclimated before they start doing stuff,” he says.
He turns towards his laptop and hits record. The waveform of the recording scrolls out on the screen — a visual representation of the vibrations being converted to sounds humans can hear. Suddenly a defined blip appears.
“I think we already got a chirp,” he says quietly.
He plays back the recording, and a wall of static plays over his laptop speakers. But under it all, a weird descending ‘whaaomp’ — the glorious song of the brown marmorated stink bug.
With this recording, the researchers will be able to program the Pied Piper to interact with stink bugs in the wild. And since the Pied Piper would only be speaking the specific language of the stink bug, Walton says no beneficial insects or other organisms will suffer.
“I think the key thing here is that it only affects the target insect, and it will not affect anything else,” he says. “It’s cleaner for everyone that lives here. It’s clean for the environment, better for our salmon and our rivers.”
And going forward, the more insect songs the Pied Piper learns to play, the more pests it could mesmerize and lead astray.