Some factors influencing male-male aggression in the field cricket Gryllus integer (time of day, age, weight and sexual maturity)

Abstract

Male field crickets ( Gryllus integer; Orthoptera: Gryllidae) stridulate aggressively and fight vigorously in competition for females. We studied the degrees to which male-male aggression is influenced by time of night or day, sexual maturity, age and weight. Trials were observed between males matched for age and/or weight that had not previously been exposed to each other. Data were gathered on attack latency, aggressive stridulation, time spent in aggressive interactions and the winner of a trial. Aggression was equally likely to occur at any time of the day or night. Sexually mature males were more aggressive than adult males which had not yet produced a spermatophore. Age past sexual maturity did not greatly influence aggression, and heavy males were more aggressive than lighter ones. In repeated trials between the same males, one male in each pair won significantly more contests.