Developments in the use of predatory mites for biological pest control

Predatory mites (Acari: Phytoseiidae, but now also Laelapidae) have gained momentum as agents for successful biocontrol of plant pests. The time has gone where they were mainly considered for the control of spider mites. Various new predatory mite species have been identified for the control of other groups of pests, either plant-feeding insects or mites other than spider mites, feeding on either aboveground or belowground plant parts and feeding either concealed in plant structures or exposed on a leaf. However, do we really understand why these predatory mites are so effective? In this article we review the underlying mechanisms and generate new questions, based on case studies of our own research on biocontrol of thrips, whiteflies, bulb mites and eriophyid mites with the use of predatory mites. Finally, we 'wrap up' by providing a brief ecological and phylogenetic perspective on predatory mites and their use in biocontrol.