The photoperiodic calendar is a seasonal time measurement system which allows insects to cope with annual cycles of environmental conditions. Seasonal timing of entry into diapause is the most often studied photoperiodic response of insects. Research on insect photoperiodism has an approximately 80-year-old tradition. Despite that long history, the physiological mechanisms underlying functionality of the photoperiodic calendar remain poorly understood. Thus far, a consensus has not been reached on the role of another time measurement system, the biological circadian clock, in the photoperiodic calendar. Are the two systems physically separated and functionally independent, or do they cooperate, or is it a single system with dual output? The relationship between calendar and clock functions are the focus of this review, with particular emphasis on the potential roles of circadian clock genes, and the circadian clock system as a whole, in the transduction pathway for photoperiodic token stimulus to the overt expression of facultative diapause.

Institute of Entomology Academy of Sciences of the Czech Republic Department of Ecophysiology Branišovská 31 370 05 České Budějovice Czech Republic

References provided by Crossref.org

Impact of photoperiod and functional clock on male diapause in cryptochrome and pdf mutants in the linden bug Pyrrhocoris apterus

Latitudinal Variation in Circadian Rhythmicity in Nasonia vitripennis

Early transcriptional events linked to induction of diapause revealed by RNAseq in larvae of drosophilid fly, Chymomyza costata

Autonomous regulation of the insect gut by circadian genes acting downstream of juvenile hormone signaling