Mesostigmata
Taxonomic placing: Acari, Parasitiformes.
Common name: None.
Morphology: The Mesostigmata bear lateral, mid-body stigmata (hence the name of the suborder), located behind legs III (rarely legs II), and connected to forward-pointing peritremes. The chelicerae are long, chelate, with terminal scissor-like processes. In the male one of these processes is modified for transferring spermatophores to the female, whose genital apertures lie between or near legs III. The palpi are developed, usually five-segmented. The body is usually soft, milk-colored, covered by one or more weakly-sclerotized to brown shields (or plates), that bear mostly simple setae in transverse rows. Eyes absent. Adult body size ranges from 0.2 mm to about 2.0 mm. The legs are undifferentiated, usually with two claws and an empodium. In general the juveniles resemble the adults.The Mesostigmata is one of the two suborders in the order Parasitiformes, the other being the Metastigmata, or ticks, which are major pests of domestic and wild animals, but contain no plant pests.
Economic importance: All Mesostigmata that inhabit plants in the Middle East are predators of importance in the biological control (whether natural or humanly-instigated) of insect and mite pests. The most important species are the indigenous Amblyseius swirskii Athias-Henriot, Typhlodromus athiasae Porath and Swirski, and the introduced Phytoseiulus persimilis Athias-Henriot.
Life history: The terrestrial, non-parasitic Mesostigmata have a simple and uniform life history, developing through five stages, namely eggs, larvae, protonymphs, deutonymphs and adults. The duration of a generation can be one week or less. Reproduction may be sexual, arrhenotokous or (in the Phytoseiidae) by parahaploidy. Most species are free-living predators that roam the upper layers of the soil, live in decaying organic litter, and on plants. Others are parasitic on vertebrates (e.g. Dermanyssus on birds) and invertebrates (Varroa spp. on bees).
References
Beaulieu, F., Walter, D.E., Proctor, H.C., Kitching, R.L. and Menzel, F. 2006. Mesostigmatid mites (Acari: Mesostigmata) on rainforest tree trunks: arboreal specialists, but substrate generalists? Experimental and Applied Acarology 39: 25-40.
Gerson, U., R.L. Smiley and R. Ochoa. 2003. Mites (Acari) in Biological Control. Blackwell Science.
Hughes, A.M. 1976. The Mites of Stored Food and Houses. Her Majesty’s Stationery Office, London.
Koehler, H.H. 1999. Predatory mites (Gamasina, Mesostigmata). Agriculture, Ecosystems & Environment 74: 395-410.
Krantz, G.W. and Walter. D.E. (eds) 2009. A Manual of Acarology, 3rd Ed. Texas Tech University Press, Lubbock, Texas.