Original paper
Insect Diapause, an Example of Environment-controlled Homeostasis
De Wilde, Jan
Entomologia Generalis Volume 7 Number 3 (1981), p. 193 - 194
10 references
published: Jul 30, 1981
DOI: 10.1127/entom.gen/7/1981/193
ArtNo. ESP146000703000, Price: 29.00 €
Abstract
Diapause is an arrest of development or reproduction, synchronised with unfavourable parts of the season and protecting the insect against extremes of climatic conditions and lack of food. In the physiological sense it is a syndrome, comprising elements of morphogenesis, metabolism, ecological resistance and sometimes behaviour. The fascinating aspect of facultative diapause (the most prevailing) is the extrinsic control of development, reproduction, metabolism and behaviour which it implies. In studying the causal chain leading from the environment to the subcellular processes, it was soon realized that the neuroendocrine system was an essential substation [Scharrer & Scharrer 1963], and diapause research has in no mean way contributed to the knowledge of this essential coordinating, integrating and regulating apparatus. It was soon realized that diapause induction involves an element of programming and often delayed response, and this has led to the study of storage of environmental information, an extreme example of which is egg diapause in the commercial silkworm. In search of the hormonal control of diapause, the conception of diapause hormones repeatedly emerged, but their evidence remained restricted to Bombyx mori Linnaeus 1758, studied in the pioneer works of Kogure [1933], Fukuda [1952] and Hasegawa [1952]. There are, however, other types of diapause: remarkable enough, in most cases endocrine deficiency but in others increased hormone titers appeared to be prevailing. In the course of this study, the idea of masterglands arose and the cerebral neurosecretory system, the prothoracic glands and the corpora allata have been shown to act as such in diapause in different developmental stages. Thus, in larval diapause an increased juvenile hormone (JH) titre has repeatedly been observed, but in adult diapause invariably a reduced JH titre is causing the state of reproductive and metabolic arrest. In pupal diapause the inactivity of the prothoracic glands and the resulting ecdysone deficiency is essential.