Temperature‐dependent changes in circadian patterns of cricket premating behaviour

Abstract

ABSTRACT. Male‐calling and female‐walking in Teleogryllus commodus (Walker) is mainly performed during the night (in LD 12:12 at constant temperature). Cold nights of 1–7°C switched both activities from night to daytime. After cold exposure it took several transient cycles until the original phase angle difference to lights‐out was re‐established. The involvement of a circadian clock in these processes was revealed by observing the free‐running rhythm in constant light after a cold night. The rhythm was delayed, evidently due to the resetting of the biological clock by the cold exposure. This temporal alteration of premating behaviour in males and females is discussed in relation to intraspecific consequences, its adaptive value in natural conditions, and with respect to the potential parallel effects in parasites and predators.

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

“…Adult T.commodus change the timing of their calling song pattern after a cold night, and they become diurnal singers because of a phase shift of the underlying circadian mechanism (Loher & Wiedenmann, 1981). Similar phase shifting occurred in the present study when last and penultimate nymphs were exposed to a cold night prior to LD/LL ( Fig.…”

“…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 (5-8°C) 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.…”

“…The results show that the underlying circadian mechanism controlling the calling song rhythm of T.cornmodus is not only present in the last larval instar, but also reacts in the same manner as the adult circadian mechanism does in response to cold nights (Loher & Wiedenmann, 1981). The free-running rhythm continues undisturbed through the moults, so that the various physiological changes involved in moulting appear not to interfere with the circadian pacemaker.…”

“…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 (5-8°C) 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 Hot-Blooded Insects

“…In general, insects wait to become active when environmental temperatures are appropriate. Although calling frequencies would drop sharply during cold nights, in the laboratory the crickets do not drop calling frequencies when nighttime temperatures in the dark are reduced to II-7°C; instead, they switch both female walking and male singing activities to the daytime, when it is normally warmer (Loher and Wiedenmann, 1981) . the season.…”