title: Diapause induction and clock mechanism in the cabbage butterfly Pieris melete Ménétriés.
abstract: Photoperiodic control of diapause induction was systematically investigated in the cabbage butterfly, Pieris melete, which enters summer and winter diapause as a pupa. Summer and winter diapause are induced principally by short and long scotophases, respectively; the intermediate scotophases (11-12 h) permit pupae to develop without diapause. Photoperiodic responses under 24-h light-dark cycles at 16.9, 18, 20 and 22 degrees C showed that the hibernation response was temperature compensated, whereas aestivation response was strongly temperature-dependent. The incidence of diapause for both aestivation and hibernation showed a decline at the ultra-short and ultra-long scotophases. Experiments using non-24-h light-dark cycles showed that the length of the scotophase played an essential role in the determination of diapause. The highest photosensitivity differed under hibernation and aestivation conditions. With a 3 x LD 12:12 interruption, a maximal inhibition of aestivation occurred in the L3/2 stage, and of hibernation it occurred in the L4/0 stage. A long-night of LD 10:14 induced hibernation diapause but inhibited aestivation diapause and, conversely, a short-night of LD 14:10 inhibited hibernation diapause but induced aestivation diapause. With a 1-h light pulse at LD 11:13, a maximal inhibition of hibernation occurred 3 h before lights-on (late scotophase), whereas, with a 1-h light pulse at LD 12.5:11.5, a maximal induction of aestivation occurred 2-3 h after the onset of darkness (early scotophase). Nanda-Hamner and Bünsow experiments failed to reveal the involvement of a circadian system, suggesting that the photoperiodic time measurement for diapause induction in this butterfly resembles an hourglass-like timer or a damped circadian oscillator.
authors.affiliation: Institute of Entomology, Jiangxi Agricultural University, Key Laboratory of Crop Physiology, Ecology and Cultivation of Double Cropping Rice, Ministry of Agriculture, Nanchang 330045, PR China.
authors.forename: Hai-Jun
authors.initials: HJ
authors.lastname: Xiao
authors.forename: Xian-Fu
authors.initials: XF
authors.lastname: Wu
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Xing-Fen
authors.initials: XF
authors.lastname: Zhu
authors.forename: Fang-Sen
authors.initials: FS
authors.lastname: Xue
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000528:radiation effects; D001937:Brassica; D002080:Butterflies / Q000254:growth & development* / Q000502:physiology / Q000528:radiation effects; D005260:Female; D008027:Light; D008297:Male; D008675:Metamorphosis, Biological; D017440:Photoperiod