Circadian timing of cricket calling song: a clock persisting from nymphs to adults

Abstract

ABSTRACT. Male Australian field crickets (Teleogryllus commodus, Walker) reared in LD 12:12 h were transferred to LL at different developmental stages and the timing of their circadian calling song rhythm was analysed in regard to the previous zeitgeber. The phase settings for the onset and end of activity were similar in crickets experiencing the LD/LL transition: (i) 3–52 days after the final moult, (ii) within 24 h before the final moult, or (iii) 1–10 days before the final moult. For all groups the results reveal entrainment of the circadian mechanism at the last LD, thus excluding age‐related differences. The rhythms of crickets, transferred from LD to LL as larval instars and also exposed to a reduced temperature (5–8oC) during their last night, were delayed by about 11 h, an effect similar to that in adult crickets after a comparable cold exposure (Loher & Wiedenmann, 1981).The results are interpreted showing that the circadian control of (the adult's) calling song already functions in the previous (non‐singing) larval stages. Since the rhythmicity continued through moults and sexual maturation, it is concluded that the control centres regulating those physiological processes (e.g. pars intercerebralis, corpora allata) are not essential to the basic circadian mechanism.