Circadian Rhythms of Locomotor Activity Mediated by Cryptochrome 2 and Period 1 Genes in the Termites Reticulitermes chinensis and Odontotermes formosanus.

Simple Summary: Almost all insects demonstrate a wide variety of behavioral, physiological, biochemical and molecular circadian rhythms during their natural selection process. Some examples of the circadian rhythm in insects include the sleep–wake cycle, foraging time, migration and hormone fluctuation. Although the circadian rhythms of activities have been studied in several termite species, the molecular mechanisms of circadian rhythms in termites are unclear. In this study, we observed that, even in complete darkness, the termites Reticulitermes chinensis and Odontotermes formosanus showed clear circadian rhythms of locomotor activity. Knockdown of the clock genes cryptochrome 2 (Cry2) and period 1 (Per1) impaired the circadian rhythms of locomotor activity in constant darkness in the two termite species. We verified that locomotor activity in subterranean termites is controlled by the circadian clock. Thus, this study contributes to a better understanding of circadian clock mechanisms in subterranean insects. Locomotor activity rhythms are crucial for foraging, mating and predator avoidance in insects. Although the circadian rhythms of activity have been studied in several termite species, the molecular mechanisms of circadian rhythms in termites are still unclear. In this study, we found that two termite species, R. chinensis and O. formosanus, exhibited clear circadian rhythms of locomotor activity in constant darkness along with rhythmically expressed core clock genes, Cry2 and Per1. The knockdown of Cry2 or Per1 expression in the two termite species disrupted the circadian rhythms of locomotor activity and markedly reduced locomotor activity in constant darkness, which demonstrates that Cry2 and Per1 can mediate the circadian rhythms of locomotor activity in termites in constant darkness. We suggest that locomotor activity in subterranean termites is controlled by the circadian clock. [ABSTRACT FROM AUTHOR]