Living on leaves: mites, tomenta, and leaf domatia.

Structures on the surfaces of leaves strongly affect phylloplane mites. Glandular trichomes defend against some plant parasites but can also mire predators. However, leaves with tomenta of nonglandular trichomes are often inhabited by large populations of predatory mites. Tufts of hairs and other minute structures in the vein axils are called leaf domatia. Comparative observations and experimental data demonstrate that leaves with domatia have enhanced levels of predatory mites. By accumulating predatory mites, leaf domatia act as a kind of constitutive defense against herbivores. Mites benefit from leaf domatia by securing a safe place for oviposition and molting. Like several other plant structures, leaf domatia are the manifestation of a long-term and mutually beneficial interaction between plants and arthropods.