Abstract
The Japanese pine sawyer, which emerges once a year and diapauses in its last instar in Japan, was reared under various thermal and photoperiodic conditions on an artificial diet in order to ascertain the effect of photoperiod on the chilling term. When reared at 25℃ LD10:14 for four months before two months chilling at 20℃ LD0:24, 20℃ LD10:14 and 20℃ LD16:8, all the beetles pupated at 25℃ LD16:8 after chilling. When kept at 25℃ LD16: 8 for four or seven months before the two months chilling at either 15℃ LD0:24, 15℃ LD10:14 and 15℃ LD16:8, there were no differences in the proportions of pupation between photoperiods. In comparison between the progenies from the different pairs, the lowest rate of pupation in chilling was shown at 15℃ LD10:14, but the other treatments showed lower rates at 15℃ LD0:24 or 15℃ LD16:8 also. From these results, photoperiod in the chilling term was thought not to affect the diapause termination of this beetle.
