Volatile anesthesia suggests functional separation of clocks underlying circadian rhythms and photoperiodic responses...

Photoperiodism, the ability to respond to changes in day length, enables many temperate organisms to adapt their life cycles to seasonal variations. Although much research has focused on the molecular mechanisms of the circadian clock in photoperiodism, the relationship between the clocks that govern daily behavioral rhythms and the photoperiodic response remains unclear. Here, we used the volatile anesthetic agent isoflurane to investigate this relationship in the parasitic jewel wasp, Nasonia vitripennis. Six hours of isoflurane administration (IA) during the first (Zeitgeber time [ZT] 0) and second halves (ZTs 6 and 8) of the photophase followed by constant conditions, induced a phase delay and a phase advance in the activity onset, respectively, while IA at these ZTs followed by dark and light cycles cancelled the IA-induced phase shifts. Interestingly, daily IA during the second half of the photophase (ZT 8) in the light-dark cycles increased the incidence of diapause. These results indicate that IA affects both locomotor activity rhythms and photoperiodic responses, but in an inconsistent manner. The present results are consistent with the possibility that the clock regulating behavioral rhythms is at least partially independent of the system controlling photoperiodic response in this species.