Sex-Specific Control and Incomplete Matings: Sperm Removal Behaviour in a Bush Cricket Species

In sexually promiscuous species, sperm removal behaviour (SRB) is a male strategy to increase reproductive success by displacing rival sperm prior to insemination. This behaviour may, however, impose costs on both sexes, generating sexual conflict. We investigated the sex-specific control over SRB in Metaplastes ornatus, a bush cricket species exhibiting this behaviour. We used a double mating design experiment and recorded morphometric measurements from a wild population in Greece. We found that lighter females likely had more successful matings, while body mass did not affect SRB duration in either sex. Repeatability analyses suggested a potential, albeit weak, female influence on SRB duration. We also identified high rates of unsuccessful matings after the initiation of SRB, where behaviour was initiated but terminated before spermatophore transfer. These events were associated with shorter SRB durations and fewer behavioural breaks. A pilot analysis revealed that males with narrower subgenital plates may have greater mating success. Our results suggest that female traits and behaviour could play a critical role in shaping the outcome of SRB, indicating potential female counter-adaptations in this sexually antagonistic system.