Diapause, a period of arrest of growth and development enables insects to overcome and survive the unfavourable environmental conditions and represents a syndrome of physiological and biochemical characteristics. The nature of diapause in mulberry silkworm, Bombyx mori is basically determined by manifestation of genetic characters and endocrinological mechanisms under the influence of environmental stimuli, such as temperature and photoperiod. Nucleotides and carbohydrate metabolism, production and utilization of sorbitol and glycerol are also equally responsible for induction, initiation, determination, maintenance and termination of diapause. Metabolic conversion of trehalose to glycogen at the induction, glycogen to sorbitol at the initiation and sorbitol to glycogen at the termination of diapause is correlated and in each metabolic shift a key enzyme becomes active in response to hormonal and environmental stimulation.
An attempt has been made in this review article to briefly discuss the nature of egg diapause in relation to genetical and hormonal studies besides nucleotides and carbohydrate metabolism associated with induction, initiation, determination, maintenance and termination of diapause during embryonic development and its significance in mulberry silkworm, Bombyx mori.
