Populationsbiologische Untersuchungen zur Art Entomobrya nivalis (Collembola)

Abstract

Contribution to the population-biology of Entomobrya nivalis (Collembola). - To caracterize the size of a collembole the length of the fourth antennal segment ( = A4) is introduced. The relation A4: body-length can be expressed as y = 0.273 x 0·967, y being the A4-length and x the body-length. The size structure of a field population of E. nivalis in different microhabitats was determined from September 1980 until November 1981. There is one annual generation produced, hatching in July in the litter layer, growing until autumn and hibernating as subadults; only a few animals hibernate as adults. From our results and the data of other authors we conclude, that two different types of migration can be observed in a population of E. nivalis: 1. Adult females inhabiting the tree strata throughout the year descend to the ground for oviposition. After 1 to 2 moults juveniles of the new gener? ation climb up into the tree zone. We suppose that humidity is responsible for this behaviour. 2. At the beginning of winter the main part of the population leaves its summer habitat and retires for hibernation under the bark of the spruce trees of the research plot.