Acaropathogenic fungi
Common name: None.
Many fungi may attack and kill mites (Acari), but only a few are specific. These include species of Hirsutella, Neozygites, Meira and Acaromyces. Hirsutella thompsoni Fisher, best known as an enemy of the citrus rust mite, Phyllocoptruta oleivora (Ashmead), also infects other eriophyoids as well as spider mites (Tetranychidae). The fungus invades the body of the mite, kills it and sporulates from the host quite rapidly, sometimes within 72 hours, but only if there are conditions of near-saturation humidities. In the field it may cause epizootics of pest mites, bringing about their complete control. In addition, the fungus secretes a toxic protein (Hirsutellin), which has been isolated and used to control various pests. Hirsutella kirchneri Minter, Brady and Hall and Hirsutella necatrix Minter, Brady and Hall, which also infect mites, are not as well known. These three species of Hirsutella can easily be mass-produced in the laboratory on conventional media (potato-dextrose-agar, usually abbreviated to PDA), and their spores obtained by centrifugation.
Neozygites floridana has a wide distribution and periodically, especially after heavy rainfall, causes large-scale epizootics of spider mites. The fungus invades the host wherein it reproduces by budding, killing the mite within 4-7 days. Under dry conditions the cadaver of the infected mite becomes mummified, and may thus preserve the fungus for many months. Natural infection in the field occurs only during periods of very high relative humidity. No method has yet been developed for its mass-production in the laboratory. Neither Hirsutella thompsoni nor Neozygites floridana are known to affect predatory mites of the family Phytoseiidae. Meira and Acaromyces are newly-discovered fungi that attack the citrus rust mite in the field and several spider mite pests in the laboratory. Little is known about their mode of action against the hosts. Both fungi can be mass-produced on PDA. Members of other genera, such as Aspergillus, Beauveria, Conidiololus, Paecilomyces, Tarichium, Tolypocladium and Verticillium have also been isolated from mites, but little is known about their effects on pest species.
References
Boekhout, T. (and 7 co-authors). 2003. New anamorphic mite-associated fungi belonging to the Ustilaginomycetes: Meira geulakonigii gen. nov., sp. nov., Meira argovae sp. nov. and Acaromyces ingoldii gen. nov., sp. nov. International Journal of Systematic and Evolutionary Microbiology 53: 1655-1664.
Chandler, D., Davidson, G., Pell, J.K., Ball, B.V., Shaw, K. and Sunderland, K.D. 2000. Fungal biocontrol of mites. Biocontrol Science and Technology 10: 357-384.
van der Geest, L.P.S. and Bruin, J. 2008. Diseases of mites and ticks: from basic pathology to microbial control - an introduction. Experimental and Applied Acarology 46: 3-6.
van der Geest, L.P.S., Elliot, S.L., Breeuwer, J.A.J. and Beerling, E.A.M. 2000. Diseases of mites. Experimental and Applied Acarology 24: 497-560.
Sztejnberg, A., Doron-Shloush, S. and Gerson, U. 1997. The biology of the acaropathogenic fungus Hirsutella kirchneri. Biocontrol Science and Technology 7: 577-590.
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