In a fascinating display of evolutionary adaptation, male crickets in Hawaii have developed a unique purring call to evade the parasitic Ormia ochracea flies that lay eggs on their bodies. However, the flies are pushing back by becoming increasingly sensitive to the new frequencies.
Crickets and Flies Engage in a Quiet Evolutionary Battle
Hawaii‘s male crickets have been trying to evade their buzzing boogeymen for years. The parasitic flies, known as ‘Ormia ochracea‘ , lay their eggs on the crickets, which hatch into larvae that eventually feed on their hosts. However, the crickets have found a way to counterattack.
Crickets belong to the order Orthoptera, which also includes grasshoppers and locusts.
There are over 900 species of crickets worldwide, with the most common being the house cricket and the field cricket.
These insects have a distinctive chirping sound produced by rubbing their wings together.
Crickets undergo incomplete metamorphosis, meaning they go through three stages: egg, nymph, and adult.
They feed on plants, fungi, and other small organisms.
Crickets Adapt to Evade Flies
In response to the introduction of the parasitic flies in 1989, some male Pacific field crickets (Teleogryllus oceanicus) rapidly evolved a new wing shape that produces a purring or rattling call. This unusual sound may have allowed males to ‘sing’ to females without alerting the flies.
Flies Push Back
Researchers wondered if the flies would adapt to the crickets’ new song. To find out, they compared Ormia ochracea flies from Hawaii and Florida. The team measured how the flies’ hearing neurons responded to specific sound frequencies and how the flies reacted to different cricket songs.
Flies are insects belonging to the order Diptera, with over 125,000 known species.
They have a single pair of wings and a distinctive body structure.
Flies undergo complete metamorphosis, consisting of four life stages: egg, larva, pupa, and adult.
Houseflies can carry diseases such as typhoid and cholera, while fruit flies are often pests in agriculture.
Flies play a crucial role in ecosystems as pollinators and decomposers.
Flies Develop Increased Sensitivity
The study revealed that Hawaiian ‘flies’ are more sensitive to frequencies at around 5 and 10 kilohertz, which dominate normal and purring cricket songs. They were also more likely to move in response to cricket purrs. In fact, nearly 20 percent of the ‘flies’ caught using traps with recordings of cricket songs were responding to purring or rattling sounds.
Evolutionary Arms Race
The findings suggest that an evolutionary arms race is underway between crickets and flies. The crickets have adapted their song to evade detection, but the flies are pushing back by developing increased sensitivity to the new frequencies. This coadaptation may eventually lead to a game of cat and mouse between the two species.
The evolutionary arms race is a phenomenon where two or more species engage in an ongoing struggle for survival and reproduction.
This concept, first introduced by biologist Paul Ehrlich and mathematician Peter Roughgarden in 1987, describes the cyclical process of adaptation and counter-adaptation between predators and prey or competitors.
The arms race leads to increased fitness and specialization among species, but also raises questions about the sustainability of such a dynamic.
Understanding the Next Steps
More data on the ‘flies’ hearing could provide valuable insights into how the crickets might respond next. Researchers believe that understanding this evolutionary battle can help predict how an innovation race between crickets and flies is likely to play out.
- sciencenews.org | Crickets and flies face off in a quiet evolutionary battle
