Aggressive behavior in the antennectomized male cricket Gryllus bimaculatus

Abstract

Summary Male crickets (Gryllus bimaculatus) exhibit intensively defensive aggressive behavior toward attacking other males most often culminating in fighting. After the fight, the loser no longer exhibits aggressiveness in a second, separate encounter with another male; rather the defeated male exhibits avoidance behavior. Here we investigate the role of sensory input from the antennae in male defensive aggressive behavior. When we removed antennae from males (antennectomized) we found that antennectomized males show little aggressiveness toward each other whereas they continued to exhibit typical fighting behavior to an intact male. In addition, in a second encounter, antennectomized losers showed significantly higher aggressiveness towards another male than intact losers do. We further found that antennectomized crickets do not utilize visual or palpal sensory input to elicit aggressive behavior. In contrast, intact males showed aspects of aggressive behavior to male cuticular substances before and after winning a fight, and if they lost a fight showed avoidance behavior. It thus appears that antennal sensory information is critical in the mediation of aggressive and avoidance behaviors. However, sensory inputs from the antennae are not necessary to elicit defensive aggressive behavior but are necessary to discriminate conspecific males and initiate attacking them.