In the name of cricket sex, humans need to stop making noise

The mating behavior of crickets may be significantly affected by those sounds, according to a study published Monday in the journal Behavioral Ecology.

The reproduction of field crickets is important to the worlds of plants, humans and animals. Because field crickets eat lots of plant materials rich in cellulose, their fecal matter is easily decomposed by bacteria and fungi.

"Their activity, then, greatly accelerates the energy and nutrient flows in an ecosystem and provides plants with a much more abundant reservoir of highly available, essential growth factors," according to a Penn State New Kensington blog post.

Field crickets' diets also help to manage weed growth on both natural and human-made ecosystems. Additionally, crickets are essential food sources for some birds and other animals that have crucial roles in providing our food, timber, medicine and recreation.

"Humans are continually changing the characteristics of environments, including through the production of anthropogenic noise," said study coauthor Sophie Mowles, a senior lecturer in animal and environmental biology at Anglia Ruskin University in England, in a news release.

"As mate choice is a powerful driving force for evolution through sexual selection, disruptions may cause a decline in population viability. And because anthropogenic noise is a very recent evolutionary selection pressure, it is difficult to predict how species may adapt."

Why noise pollution may confuse mating crickets

Male crickets have an innate playlist of songs from which to choose to attract potential mates: The calling song attracts the female, then the courtship, or mating, song induces the female to mate. A fighting chirp sends warnings to other male suitors. And what both sexes need for all these things to happen are highly sensitive organs on their forelegs, so that they can receive sound.

To assess the effects of environmental changes, the researchers paired female crickets with silenced male crickets in ambient noise conditions, artificial white noise settings and recorded traffic noise conditions.

The researchers allowed the males to court the females, and when the males tried to sing their mating tunes, the researchers played artificial courtship songs that ranged from low- to high-quality.

When induced to mate by a high-quality courtship song amid ambient noise, female crickets mounted the males sooner and more often. But when those crickets were subjected to white noise and traffic sounds conditions, the quality of the mating song didn't help the frequency and duration of females mating with males, the study said.

"Traffic noise and the crickets' courtship song do not share similar acoustic frequencies, so rather than masking the courtship song, we think the traffic noise serves as a distraction for the female cricket," said lead author Adam Bent, who led the study as part of his doctoral program at Anglia Ruskin University, in a news statement.

Mating songs are labor-intensive; they require male crickets to expend a lot of energy and therefore hold key details about the males' qualities, the study said — so human-made noise may have changed how the females perceived the males when deciding on a mate. This blurring also could affect male crickets' health if they work to produce a more impressive mating song, and therefore those crickets' survival, too.

"At the same time, female crickets may choose to mate with a lower-quality male as they are unable to detect differences in mate quality due to the man-made noise," Bent added, "and this may lead to a reduction or complete loss of offspring viability."