title: A circadian system is involved in photoperiodic entrainment of the circannual rhythm of Anthrenus verbasci.
abstract: In the circannual pupation rhythm of the varied carpet beetle, Anthrenus verbasci, entrainment to annual cycles is achieved by phase resetting of the circannual oscillator in response to photoperiodic changes. In order to examine whether a circadian system is involved in expression of the periodic pattern and phase resetting of the circannual rhythm as photoperiodic responses, we exposed larvae to light-dark cycles with a short photophase followed by a variable scotophase (the Nanda-Hamner protocol). When the cycle length (T) was a multiple of 24h, i.e., 24, 48, or 72 h, short-day effects were clearer than when T was far from a multiple of 24h, i.e., 36 or 60 h. Exposure to light-dark cycles of T=36 h had effects similar to exposure to long-day cycles of T=24h. The magnitude of phase shifts depended on the duration and the phase of exposure to the cycles of T=36 or 60 h. It was therefore concluded that a circadian system is involved in photoperiodic time measurement for phase resetting of the circannual oscillator of A. verbasci.
authors.affiliation: Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Tomoyosi
authors.initials: T
authors.lastname: Nisimura
authors.forename: Hideharu
authors.initials: H
authors.lastname: Numata
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000528:radiation effects; D001517:Coleoptera / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects*; D007814:Larva / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects; D008027:Light; D017440:Photoperiod