A new study from Anglia Ruskin University (ARU) has investigated the mating behavior of female field crickets under different acoustic conditions. The researchers found that when crickets are exposed to traffic noise, they are no longer picky about who they choose for a mate.
Understanding how crickets are affected by traffic and other types of noise could help safeguard the future success of the species.
To gain the attention of a potential mate that is nearby, male crickets perform a courtship song by rubbing their wings together. Because the song is energetically costly, it can provide the females with important information about the male’s fitness and other qualities.
To investigate, the researchers paired female crickets with silenced male crickets under three different conditions: ambient noise, artificial white noise, and recordings of traffic noise captured at a ground level.
When the males attempted to perform their songs, an artificial courtship song was played instead that was either high or low quality. In some experiments, no song was played at all.
When exposed to ambient noise, the females mounted the males much sooner and more frequently when a high-quality courtship song was played back.
However, a high-quality courtship song provided no benefit with exposure to white noise and traffic noise. The researchers found that under these conditions, mate selection and mounting frequency were not influenced by the quality – or even by the presence of a song.
The findings suggest that man-made noise interferes with the perception of the females as they make important mating decisions, which could affect the overall fitness of a population.
“In the short-term, we found that males paired with high-quality songs in noisy environments are receiving no benefit over those paired with a low-quality song, or no song at all. As a result, males that produce high-quality songs may attempt to expend more energy into their calls to gain an advantage, potentially affecting that individual’s survival,” said study lead author Dr Adam Bent.
“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, and this may lead to a reduction or complete loss of offspring viability.”
“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.”
“Humans are continually changing the characteristics of environments, including through the production of anthropogenic noise,” said study co-author Dr Sophie Mowles.
“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 evolutionarily selection pressure, it is difficult to predict how species may adapt.”
The study is published in the journal Behavioral Ecology.