Location of the reproductive timer in the male cricket Gryllus bimaculatusDeGeer as revealed by local cooling of the central nervous system

The location of the reproductive timer for the post-copulatory, time-fixed, sexually refractory stage was investigated in the male cricket Gryllus bim aculatus. This stage was defined as the interval between spermatophore prot rusion and recommencement of copulation or a calling song. To inactivate th e central nervous system locally and reversibly, different body regions wer e cooled to 10 degreesC for 20-30 min after spermatophore protrusion. A beh avioural test then measured the duration of the refractory stage after male s recovered from cooling. Males with the head, thorax and anterior abdomen cooled did not show a lengthening of that stage. Tn contrast. males with th e entire abdomen or even the posterior abdominal segments containing only t he 6th and terminal (7th-11th) abdominal ganglia showed a lengthening of th e refractory stage up to, but not exceeding, the cooling duration. When 20- min cooling was interposed twice after spermatophore protrusion, the refrac tory stage was lengthened by about 40 min, indicating that interposed cooli ng did not reset the timer. These results are in agreement with our previou s hypothesis that the reproductive timer for the refractory stage in the ma le cricket is located in the posterior abdominal ganglia, possibly within t he terminal abdominal ganglion.