PSI-MUTATION AFFECTS PHASE-ANGLE DIFFERENCE, FREE-RUNNING PERIOD AND PHASE-SHIFTS IN AEDES KROMBEINI (STEGOMYIA)

A new mutation, designated as psi-mutant, affecting the timing of the circadian oviposition rhythm was discovered the in natural population of Aedes krombeini. This mutation advanced the phase of the ovipositio n median in an entraining light-dark cycle of 12:12 h by ca. 7.0 h and shortened the free running period tau in constant darkness (DD) by ca . 4.0 h. Early oviposition in psi-mutants was also observed when while free-running in DD they were subjected to 24-h temperature cycles (29 degrees C for 12 h and 18 degrees C for 12 h). When the phase respons e curves (PRCs) for light pulses against DD as background were measure d, the PRC for the psi-mutant had large delaying phase shifts, whereas , that of the wild strain had small delaying phase shifts.