The life strategies of mites

This study tries to discern life strategies developed by mites. The concept of adaptive strategy is defined, and the methodology followed is justified. Six species, considered as models of mites living in contrasting habitats, are compared: Steganacarus magnus (Nic.) (Oribatida), Adoristes ovatus (Koch) (Oribatida), Nothrus palustris Koch (Oribatida), Dermatophagoides pteronyssinus (Trt) (Acaridada), Tetranychus urticae Koch (Actinedida) and Hypodectes propus (Nitzsch) (Acaridida). For each population-environment system, the degree of selectivity of the habitat is estimated in relation to its constraints and perturbations. The main state variables of the mite populations are described (especially density and spatial structure), as well as ontogenetic and demographic features (phenology of immature development and life history). Finally, dispersal and certain behavioural traits are taken into account, in order to complete the study. Comparisons between these models clearly reveal gradients ranging from the saprophagous Oribatida to the parasitic Acaridida. The significance of these gradients is discussed in connection with the environmental characteristics of the mite populations chosen.