查看文章

Terrestrial isopods (woodlice) are all included in the sub-order Oniscidea (order Isopoda) of the taxon Crustacea. They are the most successful invaders of terrestrial habítats amongcrustaceans. They are more closely related to crabs, lobsters and water fleas than to other terrestrial arthropods such as insects, spiders or centipedes (Sutton 1972). The ecological role of isopods is decomposition. By their size they belong to the macrodecomposer category together with millipedes. They represent an important level in the detritus food chain. As saprophagous animals they feed mainly on decaying plant material.

Dicotyledonous plant litter and fungi represent a high-quality food for them (Rushton and Hassall 1987). Their role is the fragmentation of dead plant material, thus making it available for mesofaunal decomposing elements, such as springtails and mites. Woodlice'forward'fragmented food in smaller compartments but not really in a digested form. Their assimilation efficiency is rather low, eg 29-64% for Armadillidium vulgare (Reíchle 1967; Saito 1969), 16.2% for Oniscus asellus (Hartenstein 1964), 16.6% for Protracheoniscus politus (Gere 1956), 60% for Cylisticus convexus (Reíchle 1967), 50% for Ligidium hypnorum (Stachursky 1974) and 46.78% for Trachelipus nodulosus (Hornung 1981), all at a temperature of 20 oc. The assimilation efficiency depends basicallyon the animals' body size and on the food quality. That may be the explanation for the diverse results of the different authors. The decomposition of 14C-Iabelled plant material (Lemna gibba) was significantly increased by the presence of Porcellio scaber but the 14C-Iabelled faeces …