Leaf hair tufts function as Domatia for mites in Quercues agrifolia (Fagaceae)

An identifying feature of Quercus agrifolia Ne ́e (Fagaceae) is the presence of hair tufts on lower leaf surfaces. In other plant species, hair tufts act as domatia for arthropods such as mites, which in turn feed on leaf fungi or small herbivores and possibly benefit plant health. However, this mutualistic relationship remains untested in Q. agrifolia. In this study two primary questions were addressed within a natural stand of Q. agrifolia in San Luis Obispo, CA: 1) Do hair tufts act as domatia for mites? and 2) Does the removal of hair tufts impact mite abundance, herbivory or fungal pathogens on leaves? In an observational study of 377 leaves from 20 trees, we found a significant association between the presence of hair tufts and the presence of mites. When we experimentally removed hair tufts, we found a significant reduction in mites, yet there was no impact on leaf herbivory or necrosis. We conclude leaf hair tufts on Q. agrifolia serve as domatia for mites, but we found no evide...