J Co mp Physiol A (1991) 1 68 : 159- 164 Journal of Com t " Senso,>" para Ive Physiology A © Springer-Verlag 1991 Neurohormonal control of the mating interval in the male cricket, Gr y JJus bimaculatus DeGeer Takashi Nagao h , Teiichi Tanimura 2 ** and Tateo Shimozawa 3 *** l Centre for Experimental Planls and Animals , Hokkaido University, Sapporo , 060 Japan 2 Division of Behavior a nd Neurobiology , National Institut e for Basic Biology, Oka zaki, 444 Jap an 3 Zoo logical Institute, Faculty of Science, Hokkaido University, Sapporo , 060 J apa n Accepted October 24, 1990 Summary. Between two mating acts of the ma le cricket (Glyflus bimaculatus) , spermatophore protrusion (SP) a nd courtship stridulation (CS), there is a fixed time interval. This interval lasts about 1 h. During the period from SP to CS, the male cricket does not stridulate nor make any type of mating sound (post-spermatophore protrusion silence: PSPS) and tolerates external sensory stimuli. We examined the effects of injections of hemolymph and ganglia extracts on the interval. Extracts o bt ained from crickets which had just started CS (CS crickets) and those which had finished SP (SP crickets) we re effective. The extracts were fractionated by ul- trafiltration. Fractions with a molecular weight of less than 1 kdalton affected the length of the PSPS. The fractions from both the hemolymph and the mesothorac- ic ganglion of CS crickets shortened the PSPS. On the other hand, the fractions from the hemolymph and the brain of SP crickets lengthened the PSPS. We estimated, by gel filtration, the molecular weight of the effective fractions from the mesothoracic ganglion and the brain to be 100-200 daltons. We also examined the effects of biogenic amines on the PSPS, Octopamine shortened the PSPS, whereas serotonin lengthened it. The results in- dicate that at least two neurohormones from the brain and the mesothoracic ganglion reciprocally control the elicitation of CS and provide an appropriate interval in the mating sequence of the male cricket. Octopamine and se rotonin are possible candidates for these neurohor- mones. Key words : Neurohormone - Mating interval - Cricket - Octopamine - Serotonin Abbrevia tions: CP copu la ti on; CS co urtship stridulation ; SP sper- matophore pr otrus ion ; P S P S post-spermatophore pr otr usion silence * To whom offprint requests should be sent Present addresses: ** Biological Labo rator y, K yusyu University 0 I, Ropponmatsu, 8 10 Japan . *** Section of Sensory Inform at ion Processing, Research Institute of Applied Electricity, Hokk aido University, Sapporo , 060 J apa n Intro duction The reproductive behavior of insects usually consists of several repertoires. In many cases, mating behavior involves an orderly sequence of activities performed through the courtship to copulation (Huber 1955 ; Alexander 1962a, b; Manning 1966 ; Loher and Rence 1978) . Th e sequence of activities, however, is not as rigid as motor programs would be. Part of the sequence may be skipped or repeated depending upon the external conditions (Nagao and Shimozawa 1987). Both the ner- vous and endocrine systems coordinate to synchronize the internal physiological state with the external con- ditions and consequently lead to overt reproductive be- havior. Hormonal factors play an import a nt role in the transition between mating and nonmating motivation. Sexual m at uration , male receptivity, the production of a sex attractant , the refractoriness of a mated female, and her oviposition have been considered (see reviews Barth and Lester 1973 ; Truman and Riddiford 1974; Raabe 1986). In the sequence of their mating behavior, male crick- ets Gryl/us bimaculatus stridulate a characteristic court - ship song and attempt copu lation (CP). A few minutes after the consummation of CP , the male protrudes a sper matophore in the ventra l phallic lobe (sper- matophore protru sion : SP). The spermatophore will be transferred during the next CP o About I h later, the male again sta rts a courtship song stridulation (CS) and subse- quently performs the mating sequence. This pattern of periodical mating is observed if a receptive female is present (Fig. I). In a previous paper (Nagao and Shimozawa 1987), we showed that the ma le cricket po ssesses an interval timer which determines a fixed time interval between SP and CS. The period of post -spermatophore protrusion silence (PSPS) is rema rkab ly stable, even in the face of di sturb ances such as the removal of a spermatophore. The interval timer works independent ly of behavioral acts during the PSPS. Its mechanism appears to involve both neuronal and hormonal factors because (1) the