Scientists from St. Olaf College and the University of Denver have discovered that a parasitic fly in Hawaii has developed super-sensitive hearing to track crickets.
The study, published in Current Biology, shows how these flies have adapted to detect the mating songs of Pacific field crickets, a crucial step for their survival.
The flies, Ormia ochracea, were likely introduced to Hawaii by Polynesian settlers and European cargo ships.
They depend on crickets for their larvae, which burrow into the crickets and develop inside them.
The flies must find crickets to survive, and their improved hearing helps them locate their hosts more effectively.
A battle between flies and crickets
Biologists have long studied the relationship between crickets and these parasitic flies.
In previous research, Professor Robin Tinghitella from the University of Denver found that some male crickets evolved new, quieter songs through wing mutations to avoid attracting the flies.
However, the new study shows that the flies have now evolved better hearing to track down even these changed songs.
“This is a classic example of adaptation and counter-adaptation,” said Tinghitella. “The crickets change their songs to avoid being found, and the flies improve their hearing to keep up. It’s an ongoing battle, and we are excited to see what happens next.”
To understand these changes, the research team collected Ormia ochracea flies from Hawaii and Florida to compare their hearing abilities. They conducted two types of experiments: behavioral tests and neural tests.
These experiments measured how well the flies could detect different cricket songs, including typical songs, purring songs, and rattling songs.
The results showed that Hawaiian flies had evolved a more sensitive hearing system than their Florida counterparts. They could easily detect the most common, louder cricket songs. Surprisingly, they could also pick up on the softer purring and rattling songs, showing just how advanced their hearing has become.
“Understanding how these flies evolve their hearing gives us insight into how animals adapt to their environments,” said Professor Norman Lee from St. Olaf College. “It helps us learn more about how animals find food, avoid predators, and interact with each other.”
The study also has potential applications beyond biology. Scientists believe that studying these flies’ unique hearing abilities could inspire new technologies, such as better hearing aids or sound detection systems.
Future research will explore whether female crickets have also adapted their hearing to better detect the new songs of male crickets. This could provide more clues about how species continuously adapt to outmaneuver each other in nature’s evolutionary arms race.
“This kind of research also gives students valuable hands-on experience,” said Lee. “It’s exciting to see undergraduates at St. Olaf contribute to discoveries that help us understand the natural world.”
