أمراض العث Diseases of mites
أمراض العث
Diseases of mites
L.P.S. VAN DER GEEST1;, S.L. ELLIOT1, J.A.J. BREEUWER1 and
E.A.M. BEERLING2
Diseases of mites
Abstract. An overview is given of studies on diseases of mites. Knowledge of diseases of
mites is still fragmentary but in recent years more attention has been paid to acaropathogens,
often because of the economic importance of many mite species. Most research on mite
pathogens concerns studies on fungal pathogens of eriophyoids and spider mites especially.
These fungi often play an important role in the regulation of natural mite populations and are
sometimes able to decimate populations of phytophagous mites. Studies are being conducted
to develop some of these fungi as commercial acaricides.
Virus diseases are known in only a few mites, namely, the citrus red mite and the European
red mite. In both cases, non-occluded viruses play an important role in the regulation of
mite populations in citrus and peach orchards, respectively, but application of these viruses
as biological control agents does not seem feasible. A putative iridovirus has been observed
in association with Varroa mites in moribund honeybee colonies. The virus is probably also
pathogenic for honeybees and may be transmitted to them through this parasitic mite.
Few bacteria have been reported as pathogens of the Acari but in recent years research has
been concentrated on intracellular organisms such as Wolbachia that may cause distorted sex
ratios in offspring and incompatibility between populations. The role of these organisms in
natural populations of spider mites is in particular discussed. The effect of Bacillus thuringiensis
on mites is also treated in this review, although its mode of action in arthropods is mainly
due to the presence of toxins and it is, therefore, not considered to be a pathogen in the true
sense of the word.
Microsporidia have been observed in several mite species especially in oribatid mites,
although other groups of mites may also be affected. In recent years, Microsporidia infections
in Phytoseiidae have received considerable attention, as they are often found in mass rearings
of beneficial arthropods. They affect the efficacy of these predators as biological control agent
of insect and mite pests. Microsporidia do not seem to have potential for biological control of
mites.
Key words: Acari, mite pathogens, Hirsutella, Neozygites, Wolbachia, Microsporidia, acaropathogenic
fungi