Parasites and pathogens of mites.

Mites are an ancient group of arachnids that have had some 400 million years to adapt to a variety of conditions on Earth. Microorganisms have had the same amount of time to form symbiotic relationships with mites, with results ranging from phoresy to parasitism. This review covers the still fragmentary information on the groups of parasites and pathogens that are associated with mites. The known mite-associated bacteria, rickettsiae, fungi, Protozoa, viruses, and nematodes represent the tip of the iceberg, and few details of their host-parasite relationships have been recorded. Mites offer an opportunity to investigate new pathogens and new types of associations. Pathogens can be a boon when they affect mites that are detrimental to crops, livestock, or ourselves, and the diseases they cause probably play an important role in controlling mites, at least under certain conditions. However, pathogens can also cause crop failure and economic loss when they occur in biological control agents of pests.