AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 3 259-R264, Copyright © 1980 by American Physiological Society
Circadian control of oviposition activity in Ostrinia nubilalis
S. D. Skopik and M. Takeda
Oviposition activity in the European corn borer, Ostrinia nubilalis, is
under circadian control. Light cycles entrain the rhythm, and the system
free-runs in constant darkness (DD) with a circadian period (tau). The
lability of tau is evident in the DD free runs following entrainment to
various light cycles. Oviposition activity is strongly suppressed in
constant light but a circadian rhythm is initiated upon transfer to DD. The
phase-response curve (PRC) for 1-h light pulses is type 1, not type 0 as
predicted by Beck's dual system theory. The PRC can be used to predict
entrained steady states in non-24-h light cycles (T's). Predicted phase
relationships between the light component of the cycle and the rhythm in
T19 and T26 are in close agreement with the observed peaks of oviposition.
Symmetric skeleton photoperiods (two 1-h light pulses per cycle) also
entrain the rhythm to the shorter of the two alternatives that are possible
in these regimes.
