Before scientists turned the volatile chemicals into sounds and played them for human listeners, they exposed ants to them and measured their responses. Photo by Jean-Luc Boevé
Sept. 23 (UPI) -- When translated into sound, the chemical defenses deployed by insects make for some pretty good haunted house music, capable of creeping out ants and humans alike.
There's only so much small insects can do to defend themselves physically. To ward off predators, many insects must resort to chemical warfare, using various secretions to make themselves smell foul and taste bitter.
Typically, scientists study chemical defenses by staging predator-prey interactions called bioassays.
But in a new study, published Thursday in the journal Patterns, researchers translated the chemical compounds secreted by sawfly larvae into sounds and measured the responses of human listeners.
Researchers quantified the reactions of listeners by measuring how far volunteers backed away from the speakers through which scientists played the eerie snippets of sound.
Many of the 50 study participants described the secretions-turned-soundbites as unpleasant -- some even said the sounds were frightening.
The Belgium scientists responsible for the novel experiment liken the sounds to clips from the background music for a horror film.
Interestingly, scientists found the chemicals that best repelled ants produced the sounds the most repulsed human listeners.
Entomologist Jean-Luc Boevé, researcher with the Royal Belgian Institute of Natural Sciences in Brussels, first began turning volatile chemicals into sounds in 2009.
"You have small molecules like acetic acid contained in vinegar or pungent formic acid emitted by some ants, they're very volatile and diffuse into the air rapidly," Boevé, co-author of the new study, said in a press release.
"So, I thought it would be possible to translate a high or low volatility into high or low tones, as well as other chemical traits into other sound traits," Boevé said.
To translate a chemical or some other object into sound, researchers use a process called "sonification."
Boevé and his research partner, informatics engineer Rudi Giot, translated the chemical properties of different compounds -- a compound's molecular weight or functional classification, for example -- into sonic parameters, including pitch, duration and timber.
When fed into a synthesizer, the chemical-turned-sonic data produced snippets of music.
"Typically, a sonification process is used to detect particular phenomena in large datasets," said study co-author Giot, researcher at the Higher Industrial Institute of Brussels. "Examples of such phenomena are earthquakes in seismologic data, or network hacking in internet data streaming."
Because scientists were able to confirm a correlation between the way ants and humans reacted to chemicals secreted by sawfly larvae, researchers estimate sonification could be used more broadly to study the efficacy of chemical defenses.