Scientists Just Came Up With the Craziest Way to Protect Your Kale

Check out this sickada beat.

<a href="http://www.shutterstock.com/pic-114082759/stock-photo-freshly-harvested-kale-cabbage-stems-on-a-white-background.html?src=pAbx6OsOqhDVBjEniMtq1A-1-15">Peter Zijlstra</a>/Shutterstock

Fight disinformation: Sign up for the free Mother Jones Daily newsletter and follow the news that matters.


A version of this story was originally published on Gastropod.

Farmers searching for an eco-friendly way to combat pests in their fields might someday have a surprising new weapon: speakers. It may seem crazy, but scientists hope that sound systems bumping just the right noises can prime plants to pump up the levels of their own, innate chemical protection.

That’s just one of the ways that researchers are eavesdropping on the sounds of the farm in order to improve agriculture, as we report on this episode of Gastropod, a podcast about the science and history of food. From James Bond-inspired spy devices that can capture the wing-beats of hungry insects, to microphone-equipped drones patrolling henhouses in search of sick chickens, we discover that sound has the potential to help reduce pesticide use, make our vegetables even more nutritious, and even improve animal welfare.

Mozart for Plants
The idea that plants can hear and respond to music has a long and checkered history. Charles Darwin made his son, Francis, play the bassoon in front of an herb while he watched to see whether its leaves twitched (the plant was unmoved); Barbra Streisand caused a veritable explosion of color when singing to her tulips in the musical On a Clear Day You Can See Forever; and, as recently as the 1970s, UNC Greensboro physicist Dr. Gaylord Hageseth claimed that his experimental “pink” noise could make turnips sprout much faster.

While the claims that playing Mozart in a cornfield will lead to a dramatic increase in yield have proved impossible to replicate, scientists are sure that plants do respond to sounds in their environment, with small changes in gene expression, for example, or slightly different germination rates. But, as Heidi Appel, senior research scientist at the University of Missouri, told Gastropod, “We never understood why plants would have that ability.”

Pest Sounds
Intrigued, Appel teamed up with her colleague Reginald Cocroft, a behavioral ecologist, to focus on a sound that, they thought, might be particularly useful to plants: the vibrations caused by insect feeding. “These are one of the earliest and most quickly transmitted signals plants have that they’re being attacked,” said Appel. And while plants can’t hear insects the same way we do—they don’t have ears, after all—they can sense vibrations, much like club-goers feel the thump of bass or worshippers hear an organ reverberate through a church. “In that case, your body is a substrate,” picking up the sound vibrations, Appel explained. “That’s much more like what plants experience.”

Plants that had undergone audio training responded to the caterpillar attack by producing much higher levels of mustard oil.

To test their theory, Appel and Cocroft used lasers to measure the minute leaf tremors, about 1/10,000th of an inch, that caterpillars make when they munch on Arabidopsis (rockcress), a spindly relative of cabbage and broccoli that is commonly used in plant research. Next, they played those sounds back to one set of plants, and left the control group in peace. Finally, they let the caterpillars loose on both plant populations. Astonishingly, they found that the plants that had undergone audio training actually responded to the attack by producing much higher levels of mustard oil, their innate pesticide—which made them much less appetizing to the hungry caterpillars.

“That was very exciting and we were very happy,” Appel said. “But, at one level, we thought, ‘So what?’ Plants might respond to everything.” So they tested the plants again, this time using recordings of wind and treehoppers, a bug that looks like a thorn and sings with a high-pitched whine but does not like to dine on Arabidopsis. In response to these vibrations, however, the plants produced no increase in mustard oil. With this elegant experiment, Appel and Cocroft had solved a basic question of plant evolutionary biology: Plants evolved the ability to respond to sound vibrations in order to recognize and ward off attackers.

Musical Mustard
In doing so, Appel and Cocroft may have also hit upon a potent environmentally-friendly pesticide. Perhaps a field full of speakers blasting the sounds of crunching caterpillars might help terrified crops prime themselves to ward off a real attack, removing the need to apply chemical pesticides. This summer, Appel and Cocroft are testing commercially useful Arabidopsis relatives in the brassica family, such as kale and Brussels sprouts, to see if they demonstrate the same response.

But, as Appel pointed out to Gastropod, the use of sound might have an even more direct impact on our health. While plants evolved these chemical responses to deter pests, for humans, they often provide both flavor and health benefits. In fact, the sulfurous compounds produced by Arabidopsis and its fellow brassicas form the basis of America’s favorite hot dog condiment, mustard. And those same chemicals are actively being studied by cancer researchers for their potent health benefits. Maybe, by playing predator sounds in the field, farmers could actually grow more healthful plants.

Appel is testing this hypothesis with an African plant that is currently harvested for medicinal use, to determine whether caterpillar feeding increases the plants’ production of beneficial chemicals. If so, she can then test whether playing predator sounds has the same effect. “When we look at a plant as a source of flavor or medicine, what we are looking at is the product of millions of years of evolution of the plant interacting with its own pests—and those are largely insects,” said Appel. Insects that, it turns out, plants can hear.

This is the first of a two-part series exploring the relationship between sound and food. Listen to this episode of Gastropod for much more on the experimental history and emerging science of acoustic agriculture, from the perfect bovine playlist to the lost rhythms of Southern farming. And, if you like what you hear, subscribe to make sure you don’t miss out on hearing the difference between hot and cold tea, learning how the sound of tiny bubbles in soda changes its taste, and discovering the science behind pairing wine with music.

WE'LL BE BLUNT

It is astonishingly hard keeping a newsroom afloat these days, and we need to raise $253,000 in online donations quickly, by October 7.

The short of it: Last year, we had to cut $1 million from our budget so we could have any chance of breaking even by the time our fiscal year ended in June. And despite a huge rally from so many of you leading up to the deadline, we still came up a bit short on the whole. We can’t let that happen again. We have no wiggle room to begin with, and now we have a hole to dig out of.

Readers also told us to just give it to you straight when we need to ask for your support, and seeing how matter-of-factly explaining our inner workings, our challenges and finances, can bring more of you in has been a real silver lining. So our online membership lead, Brian, lays it all out for you in his personal, insider account (that literally puts his skin in the game!) of how urgent things are right now.

The upshot: Being able to rally $253,000 in donations over these next few weeks is vitally important simply because it is the number that keeps us right on track, helping make sure we don't end up with a bigger gap than can be filled again, helping us avoid any significant (and knowable) cash-flow crunches for now. We used to be more nonchalant about coming up short this time of year, thinking we can make it by the time June rolls around. Not anymore.

Because the in-depth journalism on underreported beats and unique perspectives on the daily news you turn to Mother Jones for is only possible because readers fund us. Corporations and powerful people with deep pockets will never sustain the type of journalism we exist to do. The only investors who won’t let independent, investigative journalism down are the people who actually care about its future—you.

And we need readers to show up for us big time—again.

Getting just 10 percent of the people who care enough about our work to be reading this blurb to part with a few bucks would be utterly transformative for us, and that's very much what we need to keep charging hard in this financially uncertain, high-stakes year.

If you can right now, please support the journalism you get from Mother Jones with a donation at whatever amount works for you. And please do it now, before you move on to whatever you're about to do next and think maybe you'll get to it later, because every gift matters and we really need to see a strong response if we're going to raise the $253,000 we need in less than three weeks.

payment methods

WE'LL BE BLUNT

It is astonishingly hard keeping a newsroom afloat these days, and we need to raise $253,000 in online donations quickly, by October 7.

The short of it: Last year, we had to cut $1 million from our budget so we could have any chance of breaking even by the time our fiscal year ended in June. And despite a huge rally from so many of you leading up to the deadline, we still came up a bit short on the whole. We can’t let that happen again. We have no wiggle room to begin with, and now we have a hole to dig out of.

Readers also told us to just give it to you straight when we need to ask for your support, and seeing how matter-of-factly explaining our inner workings, our challenges and finances, can bring more of you in has been a real silver lining. So our online membership lead, Brian, lays it all out for you in his personal, insider account (that literally puts his skin in the game!) of how urgent things are right now.

The upshot: Being able to rally $253,000 in donations over these next few weeks is vitally important simply because it is the number that keeps us right on track, helping make sure we don't end up with a bigger gap than can be filled again, helping us avoid any significant (and knowable) cash-flow crunches for now. We used to be more nonchalant about coming up short this time of year, thinking we can make it by the time June rolls around. Not anymore.

Because the in-depth journalism on underreported beats and unique perspectives on the daily news you turn to Mother Jones for is only possible because readers fund us. Corporations and powerful people with deep pockets will never sustain the type of journalism we exist to do. The only investors who won’t let independent, investigative journalism down are the people who actually care about its future—you.

And we need readers to show up for us big time—again.

Getting just 10 percent of the people who care enough about our work to be reading this blurb to part with a few bucks would be utterly transformative for us, and that's very much what we need to keep charging hard in this financially uncertain, high-stakes year.

If you can right now, please support the journalism you get from Mother Jones with a donation at whatever amount works for you. And please do it now, before you move on to whatever you're about to do next and think maybe you'll get to it later, because every gift matters and we really need to see a strong response if we're going to raise the $253,000 we need in less than three weeks.

payment methods

We Recommend

Latest

Sign up for our free newsletter

Subscribe to the Mother Jones Daily to have our top stories delivered directly to your inbox.

Get our award-winning magazine

Save big on a full year of investigations, ideas, and insights.

Subscribe

Support our journalism

Help Mother Jones' reporters dig deep with a tax-deductible donation.

Donate