High incidence of leg autotomy in urban crickets

Predation is an important selection pressure affecting animals. Predation has both consumptive and non-lethal effects. Because it is often difficult to estimate the extent to which non-lethal effects occur, we focused on autotomy as an indicator of non-lethal effects occurring in urban habitats. Autotomy is expected to indicate that individuals have escaped from predators. The incidence of leg autotomy in the cricket Dianemobius nigrofasciatus was compared between urban and rural habitats. The incidence of autotomy was higher in urban than in rural habitats. Failure to moult and conspecific aggressive interactions were not the main factors contributing to the incidence of autotomy in these crickets. The ease of autotomy and risk-taking tendencies did not differ among habitats. These results indicate that the incidence of autotomy reflects predation failure, and the non-lethal effects of predation are more likely to occur in urban habitats.