Cycle biologique de Drusus rectus (Trichoptera) dans les Pyrénées centrales: Influence de la température et de l'enneigement

Abstract

The duration of the life cycle of Drusus rectus lengthens with the following sequence of biotopes: biotope without snow at low altitude (1 year) - biotope without snow at high altitude - biotope covered with snow at high altitude (2 years). Very low temperatures cause a slight retardation of growth. At a similar température, this retardation is much more marked under the snow than in the biotopes that are without snow, and chiefly affects the first-instar larvae. These are phytophagous and do not develop in the absence of periphyton. The size of both the larvae and the adults is related to the length of the life cycle. © 1975 Masson.