This invited paper is part of the Symposium-in-Print: Photobiology in Asia.
Neuroanatomical Approaches to the Study of Insect Photoperiodism†
Article first published online: 26 FEB 2007
Photochemistry and Photobiology
Volume 83, Issue 1, pages 76–86, January/February 2007
How to Cite
Shiga, S. and Numata, H. (2007), Neuroanatomical Approaches to the Study of Insect Photoperiodism. Photochemistry and Photobiology, 83: 76–86. doi: 10.1562/2006-03-31-IR-863
- Issue published online: 26 FEB 2007
- Article first published online: 26 FEB 2007
- Received 31 March 2006; accepted 17 August 2006; published online 21 August 2006
The anatomical locations of three components of insect photoperiodism—the photoperiodic photoreceptor, photoperiodic clock and hormonal effector—are summarized and compared between species. Among photoperiodic photoreceptors, either the retinal or extraretinal types or both are operative, and there is no general relationship between phylogeny and photoreceptor type. The photoperiodic clock comprises time measurement and counter systems. Currently, it is generally accepted that circadian oscillators are involved in the photoperiodic clock. Several recent studies have raised the possibility that timeless, a circadian clock gene, plays a role in the photoperiodic clock in flies. The dorsal protocerebrum has been identified as an important region regulating the endocrine system for adult, pupal and embryonic diapause controlled by photoperiod. In the blow fly Protophormia terraenovae, neural connections between circadian clock neurons and indispensable neurons in the pars lateralis for diapause induction in the dorsal protocerebrum have been demonstrated. This neural network may provide the access needed to investigate the neural components of the photoperiodic clock.