The activity of saccharolytic enzymes in Collembola is associated with species affinity for caves

The activity of enzymes associated with digestion can reflect food availability and feeding preferences of invertebrates in a particular habitat. Caves are mostly nutrient-poor habitats lacking primary production. In the present study the enzymatic activity of cellulases, trehalases and chitinases was measured in eight collembolan species differently associated with the cave environment: the troglobionts (obligate cave species) Pseudacherontides spelaeus and Protaphorura janosik; the eutroglophiles Ceratophysella denticulata, Folsomia candida and Heteromurus nitidus; the subtroglophiles Hypogastrura aequepilosa and Orthonychiurus rectopapillatus; and the trogloxene (not associated with caves) Megaphorura arctica. Qualitative enzymatic patterns and quantitative differences in species activity were considered in terms of the taxonomic, feeding and ecological classifications of Collembola. Activity of the tested enzymes was confirmed in all species. Cellulolytic and chitinolytic activity seemed to play a crucial role for the discrimination of guilds within all categories. An increasing trend of chitinolytic activity was observed in Collembola associated with the subterranean environment and deeper soil layers, while cellulolytic activity decreased towards more adapted cave forms. Variability in enzymatic activity in cave-dwelling species indicated food specialization across sub- and eutroglophiles and troglobionts, respectively. The results of this study point out that enzymatic activity varies between groups of the cave fauna with different degrees of association to subterranean habitats (cave guilds).