La diapause larvaire de Tetrix undulata (Sowerby, 1806) (Orthoptera, Tetrigoidea)

Abstract

The diapause of Tetrix undulata larvae is under the control of both temperature and photoperiod. Short days (1200–1200 and 0800–1600 hours) and intermediate temperatures (25–20 °C) trigger a high diapause response. Under conditions of long days (1600–0800 hours) and higher temperatures (30 °C) all larvae develop without diapause. There are intermediate situations between these two extremes. Females undergo a deeper diapause than males. Under laboratory conditions, one larva can undergo two successive diapauses, the first being light and ending spontaneously, the second being deeper. During sensitive stages, larvae react to variations of the photophase. Reducing the phbtophase induces diapause at different stages according to the time when the treatment is applied. These observations explain the results obtained in the field.[Translated by the journal]