Diapause

Definition

A hormonally mediated, reversible state of arrested development and suppressed metabolism that enables an organism to survive predictable periods of adverse environmental conditions. Unlike simple quiescence, diapause is initiated before conditions become severe and requires specific environmental cues—typically photoperiod, temperature, or moisture—to both enter and terminate. In insects, diapause can occur in any life stage (egg, larva, pupa, or adult) and involves profound physiological reprogramming, including altered energy storage, stress resistance, and cell-cycle arrest.

Etymology

Greek diapausis 'a pause, interval', from diapauein 'to pause, bring to an end'.

Example

The flesh fly Lucilia sericata enters larval diapause in autumn: mature third-instar larvae burrow into soil rather than pupating, overwintering in a metabolically depressed state until spring warmth and lengthening days trigger pupariation.

Related Terms

• Quiescence
• Aestivation
• hibernation
• pupariation
• Photoperiodism
• endocrine regulation
• cryoprotectant

Usage Notes

Diapause is distinguished from quiescence (direct, immediate response to harsh conditions) by its predictive timing and obligatory physiological preparation. The term applies broadly across arthropods and other invertebrates; in vertebrate contexts, 'hibernation' or 'torpor' are preferred. Specialists specify the stage (embryonic, larval, pupal, or adult diapause) as the mechanisms and ecological implications differ substantially.