Leaf Surface-Structure and the Distribution of Phytoseius Mites (Acarina, Phytoseiidae) in South-Eastern Australian Forests

Abstract

Habitat structure, at a scale at which we do not normally perceive it, can be an important determinant of species diversity and distribution in arboreal mites. Phytoseiid mites (1552 individuals) collected from the leaves of 75 species of woody plants from 55 forest sites between Noosa Head, Queensland and the Hartz Mountains, Tasmania were found to represent 28 species in four genera: Phytoseius, Typhlodromus, Amblyseius and Iphiseius. About half (38) of the plant species from which phytoseiid mites were collected had leaves with well-developed coverings of hairs on their abaxial surfaces, especially along the veins. Species in the genus Phytoseius were the most abundant mites (46.4% of total), and they were almost entirely restricted to leaves with well-developed tomenta (714 of 720 Phytoseius mites collected from 34 of 38 plant species with hairy leaves). In a test of these observations at three sites in Victoria, phytoseiid mites in general were more abundant on leaves with well-developed tomenta, but only Phytoseius mites were restricted to hairy leaves.