[Edited_by_A._Ciancio,_C.N.R.,_Bari,_Italy_and_K.(Bookos.org)

11
IPM POTENTIALS OF MICROBIAL PATHOGENS
AND DISEASES OF MITES
LEO P. S. VAN DER GEEST
IBED, Section Population Biology
University of Amsterdam,
1098SM
Amsterdam, The Netherlands
Abstract. 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.
1. INTRODUCTION
As other organisms, Acari may also be subject to disease, usually caused by
pathogenic microorganisms. Our knowledge on pathogens of mites, however, is still
fragmentary, in contrast to what we know about pathogens of insects. The rapid
development of invertebrate pathology in the second half of the twentieth century
has largely been due to the study of insect pathogens. Relatively few mite pathogens
are known, despite the large number of mite species. Approximately 48,000 species
have hitherto been described and it is estimated that this number represents only
10% of the total number of mite species.
That mite pathogens have been studied less comprehensively is not surprising:
their frequently small size renders disease diagnosis often difficult and
pathophysiogical studies almost impossible. From the other hand, the often large
249
A. Ciancio, K.G. Mukerji (eds.), Integrated Management of Arthropod Pests
and Insect Borne Diseases, Integrated Management of Plant Pests and Diseases 5,
DOI 10.1007/978-90-481-8606-8_11, © Springer Science+Business Media B.V. 2010