“We did find a significant reduction in calling but only when the nematamorph was almost ready to emerge,” she said. The researchers infected some crickets with worms and left some without and found that infected crickets called less frequently between 22 and 30 days after the parasites entered their bodies. “You have to have a really fit individual to be a good caller.” In nature some male crickets hang around the chirpier insects waiting for the chance to mate with an approaching female. “Calling is really energetically expensive,” Wise de Valdez said, noting that the researchers first had to identify the crickets that made the most noise in populations. The cricket chirp, produced as male insects rub their wings together, also uses up a lot of energy resources that parasites feed on. Crickets make noise to attract mates, but the action can also attract the unwanted attention of predators that eat the insects - an act that hardly favors horsehair worms. Observing that the worms were able to implant this suicidal impulse into the crickets, Wise de Valdez wondered whether they could alter behavior like calling in their hosts. Once the host is inside, the worms exit their bodies, leaving the insects to drown. They grow inside their hosts until they get large enough to fill most of the body cavity of the insect.īut the horsehair worms need water to lay their eggs, so they have developed a special ability in which they convince their insect hosts to commit suicide by jumping into a water body.

Horsehair worms are parasites that enter the bodies of crickets and other insects at a younger stage in their lives. But her team’s research shows that some house crickets ( Acheta domesticus) infected with horsehair worms ( Paragordius varius) call less frequently in later stages of the parasites’ development.

“Whether it’s an evolutionary adaptation, we can’t say,” said Megan Wise de Valdez, an assistant biology professor and coordinator at Texas A&M University-San Antonio and senior author of a new study published in the Journal of Parasitology. Parasites may be able to affect the way that crickets use mating calls to suit their best interests, according to a new study.

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