Introduction

Acarology Unit, Research Branch, Agriculture and Agri-Food Canada,
Central Experimental Farm, Ottawa,
Ontario, Canada K1A 0C6

Introduction

Oribatida, (also called Cryptostigmata) are one of the most numerically dominant arthropod groups in the organic horizons of most soils, where their densities can reach several hundred thousand individuals per square meter (Norton 1990). Undisturbed soils can easily yield examples of 50-100 species. Oribatid mites have five active postembryonic instars: larva, 3 nymphal instars and the adult. All these stages feed on a wide variety of material including living and dead plant and fungal material, lichens and carrion, some are predaceous; but none is parasitic; and feeding habits may differ between immatures and adults of the same species (Siepel 1990). Oribatid mites generally have low metabolic rates, slow development and low fecundity. Species are iteroparous with adults living a relatively long time (Norton 1994), for example, estimates of development time from egg to adult vary from several months to two years in temperate forest soils (Luxton 1981).

Oribatida influence decomposition and soil structure by shredding and feeding on fungi and dead organic matter. Their faecal pellets provide a large surface area for primary decomposition by bacteria and fungi, and are in turn an integral component of soil structure. Oribatida also disperse bacteria and fungi, both externally on their body surface, or by feeding, with subsequent survival of spores during passage through their alimentary tracts. Many oribatid species sequester calcium and other minerals in their thickened cuticle. Recent reviews on the role of Oribatida in decomposition and nutrient cycling include those of Seastedt (1984) and Norton (1986), and their role as bioindicators in agriculture has been reviewed by Behan-Pelletier (1999).

Astigmata, now considered highly derived Oribatida (Norton 1998), are not treated in this review because their life-history traits differ from those of other Oribatida (Norton 1994).

Review of Recent Research

Danks' (1979) review of Canada's arthropod fauna has played a pivotal role in expanding awareness of the state of knowledge of Canadian mites: various experts conducted a census and provided a baseline against which to measure growth in our knowledge of taxonomy, biogeography, evolutionary biology and ecology. Information on the taxonomy and distribution of Oribatida in Canada to 1986 is easily accessible in the excellent catalogue of the Oribatida of the United States and Canada (Marshall et al. 1987). Distributions of species shown in these pages are based on this work, subsequent published taxonomic revisions, and faunistic and ecological studies listed in the References. Data on distribution are summarized by province.

Oribatida are the soil mite group for which most taxonomic, chorological and ecological data are available, yet, we estimate we still know only a quarter of the Canadian fauna at the species level. Recent ecological studies on these groups in Canada, although limited, are much more extensive than for any other non-pest soil arthropods.

We provide illustrated regional lists for each province and territory. The Image Library may be useful as an identification guide.Check boxes are found beside the species names throughout the Image Library and beside several of the species in the provincial lists. By clicking these boxes and then clicking on the bar at the bottom of each page, enlarged images of the selected species will be displayed on a new page. A maximum of 45 species can be selected at one time.

References and further reading

  • Battigelli, J.P., Berch, S.M. and Marshall, V.G. (1994): Soil fauna communities in two distinct but adjacent forest types on northern Vancouver Island, British Columbia. - Can. J. For. Res., 24(8): 1557-1566.
  • Behan-Pelletier, V. M. 1986. Ceratozetidae (Acari: Oribatei) of the western North American subarctic. Can. Ent. 118: 991-1057.
  • Behan-Pelletier, V. M. 1987a. Suborder Oribatida (or Cryptostigmata). Pp. 30-39 in The insects, spiders and mites of Cape Breton Highlands National Park. Biosystematics Research Centre Report 1. 302pp.
  • Behan-Pelletier, V. M. 1987b. Redefinition of Ametroproctus (Acari: Oribatida) with descriptions of new species. Can. Ent. 119: 505-536.
  • Behan-Pelletier, V. 1987c. Oribatida of the Haynes Lease Ecological Reserve, B.C. Arthropods of Canadian Grasslands Newsletter 4: 4,5.
  • Behan-Pelletier, V. M. 1988a. Systematic relationships of Ametroproctus, with modified definition of Cymbaeremaeidae (Acari: Oribatida). Pp. 301- 307 in Channabasavanna, G. P. and C. A Viraktamath, (Eds.) Progress in Acarology Vol. 1 Oxford and IBH Publishing Co. PVT. Ltd., New Delhi. 523pp.
  • Behan-Pelletier, V.M. 1988b. Redefinition of Zachvatkinibates (Acari: Mycobatidae), with description of a new species. Can. Ent. 120: 797-813.
  • Behan-Pelletier, V. M. 1989a. Limnozetes (Acari: Oribatida: Limnozetidae) of northeastern North America. Can. Ent. 121: 453-506.
  • Behan-Pelletier, V.M. 1989b. Description of Scapuleremaeus kobauensis gen. nov. sp. nov. (Acari:Oribatida: Cymbaeremaeidae) from western Canada. Can. Ent. 121: 507-513.
  • Behan-Pelletier, V.M. 1990. Redefinition of Megeremaeus (Acari: Megeremaeidae) with description of new species, and nymphs of M. montanus Higgins and Woolley. Can. Ent. 122: 875-900.
  • Behan-Pelletier, V.M. 1993a. Eremaeidae (Acari:Oribatida) of North America. Mem. ent. Soc. Canada 168: 193 p.
  • Behan-Pelletier, V.M. 1993b. Diversity of soil arthropods in Canada: systematic and ecological problems. Mem. ent. Soc. Canada 165:11-50.
  • Behan-Pelletier, V.M. 1994a. Mycobates (Acari: Oribatida: Mycobatidae) of North America. Can. Ent. 126: 1301-1361.
  • Behan-Pelletier, V.M. 1994b. Feature species: Diapterobates notatus: an arctic oribatid mite. Arctic Insect News, 5:15-16.
  • Behan-Pelletier, V.M. 1997a. Naiazetes reevesi n.g., n. sp., (Acari: Oribatida: Zetomimidae) from semi-aquatic habitats of eastern North America. Acarologia, 37:345-355.
  • Behan-Pelletier, V.M. 1997b. The semi-aquatic genus Tegeocranellus (Acari: Oribatida: Ameronothroidea) of North and Central America. Canadian Entomologist 129:537-577.
  • Behan-Pelletier,V.M.1998. Oribatid mites (Acari: Oribatida) of the Yukon. Pp. 115-149 in H. V. Danks and A. D. Downes (eds.) Insects of the Yukon. Biological Survey of Canada Monograph Series No. 2.
  • Behan-Pelletier, V. M. 1999. Oribatid mite biodiversity in agroecosystems: role for bioindication. Agriculture, Ecosystems and Environment. 74:411-423.
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  • Behan-Pelletier, V. M. and B. Eamer, 2003. Zetomimidae (Acari: Oribatida) of North America. Book chapter in Smith, I. M. (Ed.). An Acarological Tribute to David Cook. Indira Publishing House. 21-56.
  • Behan-Pelletier, V. M. and N. A. Ryabinin, 1991. Taxonomy and biogeography of Proteremaeus (Acari: Oribatida: Eremaeidae). Can. Ent. 123:559-565.
  • Behan-Pelletier, V.M. and N.A. Rjabinin, 1991. Description of Sacculozetes filosus gen. nov., sp. nov. and Guatemalozetes danos sp. nov.(Acari: Oribatida) from grassland habitats. Can. Ent. 123:1135-1147.
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For more information, contact Valerie M. Behan-Pelletier and Barbara Eamer.