Older female crickets are more responsive to male mating calls than their younger counterparts, a recent study led by a Carleton student found.
The research is part of the thesis of Karen Pacheco, a biology master’s student, and was supervised by Carleton biology professor Susan Bertram.
The study placed virgin female crickets of different ages on a spherical treadmill, similar to a trackball on a computer mouse. A cricket mating call was then played from different directions and the trackball measured the crickets’ movement and direction.
The study found that younger crickets moved quickly but inaccurately toward the sound, suggesting either that they are more choosy for mates, or are not developed enough.
Middle aged crickets 10 to 13 days into adulthood—post adult moult—moved furthest and at the highest speeds toward the sound.
Older crickets, 22 to 28 days post adult moult, moved accurately toward the call, but not very quickly.
Pacheco said part of the reason for studying crickets was that Carleton had a stock of the insects—the Jamaican Field Cricket Gryllus Assimilis, according to the study—that were not being used for other experiments.
Because the Gryllus Assimilis doesn’t fly and can be held in place easily, it was also easy to measure its movement toward sound compared to animals like flying insects or fish, she said.
“They don’t carry many diseases or parasites that are dangerous. They reproduce quickly, so we can have a lot of them whenever we need them. They’re relatively easy to maintain. You also don’t have a lot of ethics to deal with because they’re invertebrates,” Pacheco said.
The lifespan of the cricket varies depending on each species. In the wild, they might not live very long. In a lab, they can live up to four months, Pacheco said.
For the mating signal, Pacheco said she edited a recorded cricket call to match the sound of a male cricket that was raised on high-quality food.
The trackball used in the study was previously being used at biology professor Jeff Dawson’s neighbouring lab to study cicadas, Pacheco said.
“We had to do quite a few alterations to get it running. [Dawson] helped a lot to bring it together and make it work,” she said.
She said Dawson also helped with coding the computer programs for the experiment, providing materials, and writing the paper.
As part of the study, Pacheco said she also collected data for the next chapter of research she is writing. This study allowed her to determine the most responsive age for crickets, and now she will study how that group responded to volume.
“I’m going to look at how the loudness of a signal influences their response, whether they prefer loud signals or quiet signals,” she said.
