| Abstrakt: |
Abstract: Diapause intensity in females of the bug Pyrrhocoris apterus (Linnaeus, 1758) is standardly measured as the oviposition delay after transfer to activating long day conditions (18L:6L) and constant temperature of 25°C. We measured pre-oviposition period in bugs originally reared at short day, constant temperature of 20, 25, and 30°C. Before the transfer to activating conditions (long day, 25°C), we exposed the bugs at 5°C for 24 hours. The subsequent pre-oviposition period did not differ from the values measured without the chilling exposure. Thus, the changes of temperature do not function as a stimulus that might accelerate the diapause termination, and the measured values (16, 23, 20 days, respectively) represent the true diapause intensity. We conclude that low rearing temperature decrease diapause intensity in comparison with moderate temperature, but rearing at high temperature produces a moderate intensity. |
