Timing of the Action of Photoperiod and Temperature On Events Leading to Diapause and Development in Pupae of Heliothis Punctigera (Lepidoptera: Noctuidae)

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Abstract
Diapause in H. punctigera occurs in the pupa at some stage between pupation and the pupal-adult apolysis. Its occurrence is induced by 12 L: 12 D photoperiod, which is specifically effective during the last half of larval life, and by low temperature (19°C). Irrespective of the conditions during larval life, the insects do not diapause if subjected to high temperature (28°C) after feeding ceases and before the pupal ecdysis. The insects are most sensitive to high temperature during the short perioid between the larval-pupal apolysis and pupal ecdysis. At both 28° and 19°C the brain and thoracic glands secrete almost simultaneously to trigger the larval-pupal apolysis, which occurs almost immediately after the release of the hormones. High temperature during the prepupal period results in an increased rate of development from pupal ecdysis to emergence of the adult.