Endogenous circadian rhythm is a crucial tool for survival of the sand-desert tenebrionid beetle Trigonoscelis gigas Reitter

The beetle T. gigas is interesting as a successful survivor among competing species in a hostile, arid, environment (the sand-desert), and as a promising biological model system in laboratory experiments. Behaviour and motor activity rhythms of T. gigas were studied in the field, using autonomous monitors. In order to avoid extreme temperatures, this beetle developed a peculiar behavioural strategy: narrow time windows for activity tin the morning and in the evening). The rest of the time it spends deep in the sand, at constant comfortable temperature and in continuous darkness, in temporal isolation. We demonstrated that there are no available Zeitgebers for the beetle during its rest interval. Hence, a reliable circadian clock is the only way for T. gigas to implement the proper timing of its activity. It means, that the circadian timing system of this beetle is not just a source of relative advantage, but is a crucial prerequisite of survival.