TDK conference 2010

Woodlice (Crustacea: Oniscidea) have adaptated to terrestrial life by different morphological and physiological changes. Their geographical distribution is highly dependent on the rate of adaptation. Woodlice have a very important decomposing role in the ecosystems. They serve as a model taxon for studying envorimental effects (microhabitat) and tolerance relations (niche). Wet litter/soil conditions and high relative humidity are the key factors for their survival.

We have studied three sister-species occuring in Hungary and belonging to the Armadillidium genus. Out of them Armadillidium nasatum (Budde-Lund, 1885) is an introduced one (originates from South - and West - Europe) and survives in Hungary mainly in hot houses of botanical gardens. It is expected to establish in the wild due to global warming processes. Armadillidium versicolor (Stein, 1859) is quite common in Middle-Europe but rather habitat dependent: it appears mainly at river sides. The third species Armadillidium vulgare (Latreille, 1804), is the most widespread and a cosmopolitan one. It is present in a wide variety of habitats, sometimes it is even taken as an invasive species. The three species have different geographical distribution pattern and different tolerance limits against environmental condition. We aimed to study the background factors supporting their ecological tolerance.

We have investigated the morphology of pseudotrachea and cuticula as ’key factors’ against desiccation. We supposed that the differences in the structure of these organs can give an explanation to their adaptation to the altering habitat characteristics. A. vulgare seems to be the most resistent against environmental changes while A. nasatum is the most sensitive one. Light- and transmission electron microscopic studies show clear differences among the three species: they differ in the structure of respiratory organs: thickness of pseudotrachea’s cuticula, ratio of haemolymph space and respiratory space. As we expected the most complex trachea system and the thickest cuticula belongs to A. vulgare.