Post-copulatory sexual refractoriness is maintained under the control of the terminal abdominal ganglion in the male cricket Gryllus bimaculatus DeGeer

Abstract

The location of the center that controls the change underlying mating termination and subsequent sexual refractoriness was investigated in the male cricket Gryllus bimaculatus DeGeer. In intact males, hooking movements of the genitalia did not recommence after the spermatophore was extruded during copulation, while other copulatory movements such as body thrusting and cereal vibration recommenced under the female. In males with the connectives cut anywhere between the brain and the terminal abdominal ganglion (TAG) immediately after spermatophore extrusion, hooking movements were no longer elicited by artificial stimulation of the abdominal tergites and cerci, while other copulatory movements were still evoked. The isolated adbomen containing 5 ganglia, or even only the TAG showed a time-fixed (about 50 min) sexually unresponsive state when separated immediately after spermatophore protrusion (new spermatophore formation). TAG-separated males all recommenced courtship and copulation attempts many hours or days after the operation. Spermatophores in pre-copulatory operated males were spontaneously extruded some time after operation. They showed copulatory movements to artificial stimulation of the tergites but no further hooking movements. Intact males paired with uncopulatable females, whose genital chambers were closed with wax, entered the sexually refractory stage 1–3 times within 5 h through abnormal self-spermatophore extrusion, while TAG-separated males did not, and remained permanently sexually receptive to females. Pre-copulatory males exhibiting spermatophore extrusion during cryogenic inactivation of the connectives were all in the sexual refractory stage when they recovered. These results suggest that the switching and timer functions underlying the male reproductive cycle are contained in the TAG.