Effects of female forelimb autotomy on mating success in the band-legged ground cricket, Dianemobius fascipes nigrofasciatus

Autotomy enables orthopteran species to escape from predators but imposes costs on escape speed and mating success. In the band-legged ground cricket Dianemobius fascipes nigrofasciatus , we attempted to measure the autotomy time of the forelimbs, middle limbs, and hind limbs to understand whether limb position affects autotomy speed, a critical factor of escape success from predators. All limb types, including the second forelimb, were autotomized almost instantaneously under direct observation. We also examined how female forelimb autotomy affects mating success, egg number, and hatching rate among three groups: intact females, females with a single forelimb autotomized, and females with both forelimbs autotomized. Each female was paired with an intact male, and we assessed mating success based on whether any of the laid eggs hatched. We also measured the total number of eggs laid and the hatching rate among treatment groups. Females with intact forelimbs showed the highest mating success, whereas females with both forelimbs autotomized showed the lowest. Egg number did not differ significantly among treatments, although the estimated mean was highest in the single forelimb autotomy group and lowest in the double forelimb autotomy group. Hatching rate, reanalyzed using only females that produced at least one hatched egg, was significantly lower in the double forelimb autotomy group than in the other groups. These findings highlight the importance of forelimbs in cricket reproduction, probably through their roles in maintaining mating posture and, possibly, in auditory perception.