Action de la photopériode sur le cycle biologique et la diapause d'Anabolia Nervosa curtis (Trichoptera - Limnephilidae)

Abstract

Larvae were reared under different photoperiods of 24 hours which were kept constant throughout development. These experiments showed that:- under a middle photophase (10-12 hours) all larvae entered diapause and remained in this state indefinitely;- under a long (≥ 16 hours) or a short (< 8 hours) photophase, larvae metamorphosed either directly or after a limited diapause.The resumption of development of animals conditioned to undergo an unlimited diapause was brought about by a long photophase (≥ 15 hours) who must go on for about 12 days and be prolonged up to two months before all larvae metamorphosed.A photoperiod with a short photophase (< 8 hours) could also break diapause but its effectiveness was much less. This breaking was brought about more readily in males than in females.The experimental results that agree with findings in the field give an explanation for the rare occurences of adults in summer. © 1980 Masson.