Termination of adult diapause by chilling in the small cedar longicorne beetle, Callidiellum rufipenne (Motschulsky) (Coleoptera, Cerambycidae).
Factors affecting diapause termination in adults of the small cedar longicorn beetle, Callidiellum rufipenne, in Japanese cedar (Cryptomeria japonica) logs were investigated. Logs with adults inside were kept outdoors for about one month in September 1995, and chilled at 5°C for 30, 45, 60 or 90 days before incubation at 25°C under LD 14:10 or DD (constant darkness). Adult emergence from the logs occurred more synchronously and earlier in the groups chilled for 60 and 90 days (LC, long-chilled groups) than in those chilled for 30 and 45 days (SC, short-chilled groups) irrespective of the photoperiod. The emergence rate was 100% in the LC groups and 65.9-98.3% in the SC groups. In addition, the number of females which oviposited eggs, mean number of eggs oviposited by each female, and mean hatchability of eggs were higher in the LC than in the SC group. These results suggest that the ovarian development of this species consists of two successive process: the diapause process maintained and terminated by 5°C chilling for 60-90 days, and development promoted by a high temperature (25°C).