Common name: None.
Morphology: The Astigmata are usually slow-moving, whitish mites with a soft cuticle. They can be recognized by lacking stigmata and peritremes, by possessing chelate or dentate chelicerae, by their claw-like or sucker-like empodia and by never bearing tenent hairs. Some astigmatids have a heteromorphic deutonymph, the hypopus. It is strongly sclerotized, usually dark in color, lacks mouth parts but endowed with caudal suckers or claspers that serve as adhering organs. The Astigmata is one of the three suborders in the acarine order Acariformes.
Life history: Most free living Astigmata feed on fungi and various live and dead organic materials, often living in the nests or on the bodies of invertebrates and vertebrates (which also serve to disperse them). The free-living species usually have six stages, namely eggs, larvae, three nymphal stages and adults, and their reproduction is sexual (both males and females are diploid). The life cycle is often rapid, a generation being completed in about two weeks. After exposure to harsh conditions (e.g. low relative humidities and/or lack of food) the protonymph of some species molts into a hypopus. This stage is often the dispersal unit, due to its phoresy on various vertebrates and invertebrates, and to its dark integument that protects it from radiation. Molting from the hypopus to the tritonymph is triggered by a return to more humid conditions, and by environmental chemical cues.
Economic importance: Only a few free-living astigmatids are plant pests. Rhizoglyphus robini Claparede and its relatives injure bulb crops in the field and in storage, and Acarus siro (L.) and its relatives are major pests of stored grains and fruit in many parts of the world. In addition, the suborder contains many medical and veterinary pests, such as the scabies mite, Sarcoptes scabiei (Linnaeus), the cattle scab mite Psoroptes equi (Hering) and the house dust mites, Dermatophagoides farinae Hughes and D. pteronyssinus (Trouessart). On the other hand, Hemisarcoptes coccophagus Meyer is an important natural enemy of armored scale insects (Diaspididae).
Hughes, A.M. 1976. The Mites of Stored Food and Houses. Her Majesty’s Stationery Office, London.
Izraylevich, S. and Gerson, U. 1995. The hypopus of Hemisarcoptes coccophagus Meyer: distribution and apolysis. Acarologia, 36 333-339.
Krantz, G.W. and Walter. D.E. (eds) 2009. A Manual of Acarology, 3rd Ed. Texas Tech University Press, Lubbock, Texas.
OConnor, B.M. 1982. Astigmata. In: Synopsis and Classification of Living Organisms (ed. by Parker, S.P., pp. 146-69. McGraw-Hill, N.Y.