Petrobia

Superfamily Tetranychoidea

   Family Tetranychidae

      Subfamily Bryobiinae

        Tribe Petrobiini

          Genus Petrobia

Common names: brown wheat mite, legume mite, oxalis spider mite

Probability of Encounter: High

Quarantine importance: High.  The genus Petrobia contains more than 30 species often grouped into 3 subgenera of which several polyphagous species are important pests. 

• The brown wheat mite (also large brown wheat mite, garlic mite) P. (Petrobia) latens (Müller) attacks onion, galic, asparagus, strawberries, cucumber, spice crops, clover and other legumes, and a variety of grains.  P. latens is one of the few spider mites that is a proven vector, of barley yellow streak mosaic virus and probably carries the virus transovarially.

• P. (Mesotetranychus) tunisiae Manson feeds on grains and chrysanthemum in the Mediterranean region and Iran.

• The legume mite P. (Tetranychina) apicalis (Banks) attacks onions, peas, clover, vetch and other legumes in Europe and the USA.

• P. (Tetranychina) harti (Ewing) feeds on a variety of weeds, especially certain species of Oxalis, but also attacks citrus, tea, strawberry, apple, grape, sugarcane, clover and a variety of ornamentals and has been dispersed to most of the world.

Diagnosis:

• With reddish brown cuticle, dark body contents, and very long legs I.

• Claws pad-like; empodium hooked and with more than 1 pair of tenent hairs.

• Prodorsum with 3 pairs of setae (ve, sci, sce), without prominent lobes over gnathosoma.

• Paranal setae (h2-3) in a ventral position.

Similar taxa.  The true spider mites in the Tetranychinae do not have empodia with tenent hairs.  The claws are pad-like in other tribes of Bryobiinae.

References

 Baker EW & AE Pritchard.  1960.  The tetranychoid mites of Africa.  Hilgardia 29(11): 455-574.

 Baker EW & DM Tuttle.  1994.  A guide to the spider mites (Tetranychidae) of the United States.  Indira Pub. House, West Bloomfield, MI: 347 pp.

Bolland HR, J Gutierre  & CHW Flechtmann. 1998. World Catalogue of the Spider Mite Family (Acari: Tetranychidae). Brill: Leiden.

Helle W & MW Sabelis (eds.) 1985. Spider Mites, Their Biology, Natural Enemies, and Control, vol. 1A. Elsevier: New York.

Jeppson LR, HH Keifer & EW Baker. 1975. Mites Injurious to Economic Plants, University of California Press: Berkeley

Meyer, M.K.P. 1974.  A revision of the Tetranychidae of Africa (Acari) with a key to the genera of the world.  Dept. Agr. Tech. Serv. Mem. 36: 291 pp.

Meyer, M.K.P. Smith 1987.  African Tetranychidae (Acari: Prostigmata) - with reference to the world genera.  S. Afr. Dept. Agr. Water Supply, Entomol. Mem. No. 69: 175 pp.

Robertson NL & TW Carroll  1988.  Virus-like particles and a spider mite intimately associated with a new disease of barley.  Science 240: 1188-1190.

Smidansky ED & TW Carroll 1996.  Factors influencing the outcome of barley yellow streak mosaic virus-brown wheat mite-barley interactions. Plant Disease 80(2): 186-193.