When male crickets go silent: How females adapt and respond

Hawaiian field crickets once relied on their mating calls to attract partners. Over recent decades, most males have lost this ability due to a mutation called “flatwing.” The mutation changed the wing shape of males, silencing their songs.

While this adaptation has helped the male crickets avoid a deadly parasitoid fly, the change has also reshaped their social interactions.

Previous research was focused on how the flatwing mutation affected male-male or male-female dynamics. But recently, attention has shifted to the less studied space of female-female interaction.

A new study published in the journal Proceedings of the Royal Society B: Biological Sciences explores what happens between females when song disappears.

Interactions of female crickets

In animal behavior studies, researchers often focus on male competition or female mate choice. In non-social insects like crickets, female-female interactions have long been overlooked.

Yet these interactions can influence mating patterns, reproductive strategies, and even evolutionary outcomes. The new research highlights how females engage in social behavior beyond direct reproduction.

Females in many species assess competitors, monitor social status, or respond to environmental cues. These patterns are complex and not limited to higher animals like primates or ants.

Crickets, although not social in the traditional sense, offer many opportunities for female interaction. Females often gather around calling males. This can lead to chance encounters, competition, or cooperation – depending on the context.

Flatwing affects female crickets too

The flatwing mutation only alters male wings but still influences females carrying it. Female carriers show changes in gene expression and physical condition. This suggests the mutation could influence social behavior indirectly.

The researchers, including study lead author Ana Drago, designed an experiment to explore this idea. They used pure-breeding lines of flatwing and normal-wing females.

Pairs were matched or mismatched by genotype and observed under two conditions: presence or absence of male song.

Female crickets and antennal contact

Among all behaviors recorded, antennal contact was the most frequent. This gentle, investigative interaction involves using antennae to explore another cricket’s body. Females did this more often and for longer when male song was playing.

This pattern held even stronger when both females shared the same genotype. Flatwing pairs, in particular, showed a sharp rise in interaction under song. This suggests that both environmental and genetic factors shape social behavior.

“Intrasexual female social behavior was common, expressed by 86.5% of individuals. Females primarily engaged in antennal contact, which is reasonable to interpret as detection and assessment behavior,” noted the study authors.

Changes in cricket behavior

Calling song is a key environmental signal. It can trigger phonotaxis (movement toward sound) and may raise general alertness. In the experiment, exposure to song led females to become more socially active.

This was not just a passive result of increased movement. Females maintained contact for longer durations, suggesting something more than mate search.

These interactions might help assess the partner’s condition or status. Chemical cues, such as cuticular hydrocarbons (CHCs), could play a role here. CHCs provide information about maturity, health, and mating history in many insect species.

CHC profiles in T. oceanicus are sexually dimorphic. Females may use them to determine the sex and fitness of another individual. If song primes females to expect mates nearby, it makes sense they would increase social investigation.

Biting and mounting are rare

Biting, a form of aggression, occurred in about 13% of female crickets. Song made biting more likely but did not increase its frequency. This suggests females escalate rarely, possibly only after extended interaction.

Unlike males, females did not show pre-bite displays. They targeted legs and abdomens rather than heads.

Sexual behavior among two females was even rarer. Only two mounting attempts occurred, both under song and between same-genotype pairs. One was accepted.

The low frequency may reflect the female’s stronger sex recognition or a lack of behavioral overlap with male courtship.

Genes and song shape interaction

The researchers also investigated indirect genetic effects and genotype-by-environment interactions – situations where one individual’s genetic makeup influences the behavior of another.

In pairs with the flatwing genotype exposed to song, female behavior showed greater variability, indicating this genotype may be more socially sensitive.

This aligns with previous research showing increased plasticity in flatwing males. The song environment interacted with both the focal and partner genotype. Together, these shaped how much and how long females interacted.

Female crickets affect male success

Flatwing males avoid parasitism by staying silent. But their success depends on female choice. If female behavior changes based on genotype and social context, it may affect male survival indirectly.

“The reproductive success of flatwing males is inherently tied to female mate choice, which has been suggested to potentially be a stronger factor than flatwing satellite behavior in reducing parasitism risk,” explained the researchers.

“It is therefore possible that female-female social behaviors indirectly influence parasitism risk, though this requires further study.”

In dense populations, where female encounters are more frequent, these patterns could have a major impact.

The silence that protects males may also reduce the social complexity among females, reshaping communication and competition across generations.

Even silent crickets stay social

Crickets may be quieter today, but their social worlds are not silent. Female-female cricket interactions, once ignored, now offer clues to how evolution plays out in subtle, indirect ways.

By exploring these relationships, researchers uncover how behavior, genetics, and environment blend to shape even the smallest creatures’ lives.

“The results of this study urge that future research pays due attention to any sex that may be understudied in a given system. This is crucial to uncover intrasexual social, sexual and aggressive behaviors that may subsequently affect intersexual dynamics,” concluded the researchers.

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