IPM potentials of microbial pathogens and diseases of mites

An overview is given of diseases in mites, caused by infectious microorganisms. Many pathogens play an important role in the regulation of natural populations of mite populations and are for this reason subject of research on the feasibility to develop such pathogens to biological control agents. Several examples are given of successful application of pathogens for the control of mite pests, but also failures are discussed. Most studies concern fungal pathogens of tetranychids and eriophyids; some of these fungi are possible candidates for biological control agent of species of noxious mites. An interesting group of pathogens form the intracellular symbionts: bacteria that may cause unusual effects in their hosts, such as parthenogenesis, feminization, male killing and incompatibilities. This group of bacteria is present in many invertebrates species and are presently widely studied as new molecular techniques have become available that make detection of such symbionts possible. Attention is also given to quality control of beneficial mites that are being used in integrated control programs. Beneficial mites, as e.g. predatory mites, may also be infected by microorganisms (bacteria, viruses, microsporidia), resulting in poor performance of the predator. Prospects for the application of pathogens in IPM systems are discussed.