TEMPORAL VARIATION IN THE PHOTOPERIODIC INDUCTION AND TERMINATION OF ADULT DIAPAUSE IN THE BEAN BUG, RIPTORTUS-CLAVATUS

An examination was made of the variation in the timing of the onset of oviposition when diapause adults were transferred to long-day conditions, and in the timing of the cessation of oviposition when ovipositing adults were transferred to short-day conditions in Riptortus clavatus, by transfer of adults from short-day to long-day conditions or vice versa. There was a significant positive correlation between the duration of the preoviposition period after the first diapause and that after the second diapause, although there was no significant correlation between the duration of the preoviposition period in non-diapause adults and that after the first diapause in the same adults. From these results, the variation in the timing of the onset of postdiapause oviposition appears to be attributable to the requirement for a specific number of cycles by the photoperiodic counter. As time passes after the start of oviposition, the proportion of insects that require a longer period under snort-day conditions for entry into diapause increases.