Dr Michelle Dickinson: on Moths ability to hear the thirsty screams of plants

Recent research has uncovered a fascinating phenomenon: when low on water, some plants emit high-pitched clicking noises, inaudible to human ears but detectable by certain insects. These ultrasonic “screams” might be nature’s way of signalling distress—and they don’t go unnoticed. 

New research published in the journal BioRXiv found that female moths use their sensitive hearing to listen to these ultrasonic signals steer clear of thirsty plants when laying eggs. This behaviour ensures their caterpillars hatch on healthier plants, with a better chance of survival. 

The researchers placed fertile female moths in a controlled arena. When given a choice between a hydrated tomato plant and a thirsty one, the moths overwhelmingly chose the silent, hydrated plant. But the researchers didn’t stop there. 

In another experiment, two hydrated plants were placed in the arena, with a speaker next to one of them playing recorded distressed clicks. Again, the moths avoided the “noisy” plant, favouring the silent one. These results suggest that the sounds alone, even without visual or olfactory cues, are enough for moths to make a decision. 

What’s even more fascinating is that these moths had no prior exposure to plants. Raised entirely in a lab, they had no opportunity to learn this behaviour. Their response to the ultrasonic signals appears to be hardwired in their genetics, highlighting the intricate connections between insects and plants in nature. 

This discovery isn’t just a marvel of biology; it could have practical applications in the real-world. One could be pest management. By broadcasting ultrasonic distress signals, farmers might discourage moths from laying eggs on healthy crops, potentially reducing the need for chemical pesticides. 

Many insects have ultrasonic hearing, suggesting that this type of interaction might be widespread. 

This research invites us to rethink what we know about communication in nature. Beneath the threshold of human hearing lies a hidden world where plants and insects exchange critical information—a world we are only beginning to understand. 

LISTEN ABOVE

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:06):
You're listening to the Sunday Session podcast with Francesca Rudgin
from News Talks edb.

Speaker 2 (00:13):
Enjoining me now is doctor Michelle Dickinson with her science
study of the week.

Speaker 3 (00:16):
Good morning, good morning.

Speaker 2 (00:17):
Now, when I heard about the study where moths can
hear the thirsty screams of plants, which is so fascinating
in itself, I thought back to another study that you'd
brought in where you talked about plants emitting this very
high frequency that we would need humans would need to
get a little machine. What was it was the machine
that you could monitor, you know, when to water you're pardly.

Speaker 3 (00:40):
So this is why I did this study because that
previous study where we finally learned that plants can do
this ultrasonic scream. This is that we can't hear upset
that my plants are screaming at me. Well then, because
you know it's like it's summer, so my poor tomato
plants every time, I'm like, I'm so sorry. You know,
they just always seem to thirsty. And then that study
that we talked about two years ago, these these people

(01:03):
have gone. I wonder if anybody else is listening to
these screams and apparently insects.

Speaker 2 (01:08):
AH.

Speaker 3 (01:08):
So beautiful study. It's in the journal bio Archive. It
is free if you would like to read it. The
oper Sauce And basically, they've took these moths and these
are lab reared moths. And this becomes important later on.
So they have never seen a plant before. They've been
brought up in a lab, no exposure to anything other
than a lab box. And they put them in this

(01:29):
arena filled with plants and they were fertile musts, so
they're ready to lay their eggs. And they decided to
watch where they laid their eggs. And what was interesting
is they put them in a box with tomato plants,
and one was a very thirsty to market plant and
one of them was a very healthy water tomato plant.
And they watched all of the musks go to the
healthy tomato plant and lay their eggs ah and ignore

(01:50):
the screaming one. And they said, well, are they ignoring
them because they're looking at it and going, that's a
bit of a disheveled plant. Are they kind right? Are
they sniffing the plant and going that doesn't smell like
a healthy plant, or are they listening to it? So
then they put a bunch of healthy tomato plants into
this box, and then they put a little speaker in
there that screened the same scream of a thirsty to

(02:14):
Marti plant, even though it wasn't thirsty, and all of
the muths only laid on the non screaming healthy tomato plants.
So it can't be visual because the plants look the same.
It can't be smell because the plants smelled the same.
So they must be listening to the screams of the
plant and going nah, not here. So why would a
muth care? Or must lay eggs and those eggs tend

(02:36):
into caterpillars, and the caterpillars need a healthy plant.

Speaker 2 (02:39):
You want to give health plan?

Speaker 3 (02:42):
Yeah, but these must have never seen a plant before,
so they're listening to a queue that they've never been
exposed to, which shows that it must be genetically hardwired
in the moss to listen to whether or not a
plant is thirsty and healthy or not make that decision.
Why does this even matter? Why does Michelle care? Why
is the study of the week? Well, think about it.

(03:02):
What do we care about in agriculture reducing pesticides? What
do pesticides? Do they reduce the amount of insects that
are eating our plants. So maybe the solution, and this
is moving on from our two thousand and three where
we're like, we could put these little speakers into our plants.
That's one of those day. What if we did the opposite.
What if we put a speaker next to all of
our healthy crops that pretended our plants were thirsty, and

(03:24):
then the bugs would go lay eggs elsewhere.

Speaker 1 (03:26):
Ha. I love it.

Speaker 2 (03:29):
I just study the original study you brought and just
stayed with me because I sometimes I walk around my
house and go, I really need to one of my plants,
and they're all just quietly screaming, which is quite ubseute.

Speaker 3 (03:41):
Do you know if we could hear our plants, I
don't think any of us would own plants.

Speaker 2 (03:44):
I don't. Well, that's the way, and unfortunately it's not
probably not ideal to bring the mothster and have them
laying you know, chiky plants, to walk out who's lying,
what we're and all that kind of thing. So I'll
just keep better water, That's what it comes down. Yeah,
and just know that they are screaming at you.

Speaker 3 (03:58):
We just can't hear it. But all of the insects
seem to be able to hear it. They did the
study on musk, but they know that a whole bunch
of other insects have that same frequency that they can hear. So, yeah,
just think of your plants are screaming, and know that
all the things around you are noticing while you're walking persons.

Speaker 2 (04:13):
So if you took me to a large field, would
you be able to cover it with the sound that
was required? Do you think to cover us?

Speaker 3 (04:18):
Who knows?

Speaker 2 (04:19):
I don't see why this research.

Speaker 3 (04:22):
I don't see why not. Yeah, and so why not
put a speaker in our crops and just make our
plants sound like the Thursday and the bugs will go else.
Well it's a theory, but it's a good theory. I
like this study.

Speaker 2 (04:33):
I love it too, Michelle, thank you so much. Have
a lovely Christmas. Thank you with your twins. I'm sure
they're very excited about Christmas. It's a beautiful age too. Yeah,
Santa's finally a person. Oh great, So we're gonna have
a fab one.

Speaker 3 (04:47):
Thank you so much.

Speaker 2 (04:48):
We will see you in the new year.

Speaker 1 (04:50):
Take care for more from the Sunday session with Francesca
Rudkin listen live to news talks it'd be from nine
am Sunday, or follow the podcast on iHeartRadio