Does microhabitat structure affect foliar mite assemblages?

Abstract

1. Habitat structure is an important factor influencing population dynamics and trophic organisation of terrestrial invertebrates. The phylloplane zone on vascular plant leaves is topographically complex, containing a multitude of microhabitats such as leaf hairs, lesions, and structural refugia such as domatia, which may modify interactions between resident invertebrate communities, colonisers, and subsequent trophic relationships. Leaf domatia are small indentations on the underside of leaves and are often inhabited by potentially beneficial mites and other arthropods.2. This study investigated the relationship between domatia availability and foliar mite assemblages in contrasting habitats (native forest, plantation forest, and pasture) using a standard test plant (the endemic New Zealand shrub Coprosma lucida, J.R. & G. Forst.).3. Diverse woody native vegetation types supported higher numbers of mite species than either plantation forest or pastoral grasses. The highest number of mite species occurred in the native forest (63%), plantation forest (38%), and pastoral grasses (25%). In the native vegetation type, experimental C. lucida leaves with domatia supported higher mite densities, greater colonisation success, and more diverse mite assemblages than those without domatia. Mite assemblages within the pastoral site were significantly different from the other two vegetation types. Only one fungivorous mite species, Orthotydeus californicus, occurred compared to five mite species in native and plantation forests.4. This study indicated that foliar mite assemblages in native vegetation on experimental C. lucida shrubs are influenced by domatia availability, resident foliar mites, and local mite assemblages.