Smith, I.M., Lindquist, E.E., and V. Behan-Pelletier. 1998. Mites (Acari) in Smith, I.M., and G.G. Scudder, eds. Assessment of species diversity in the Montane Cordillera Ecozone. Burlington: Ecological Monitoring and Assessment Network, 1998

MITES (ACARI)

Ian M. Smith, Evert E. Lindquist and Valerie Behan-Pelletier
Biological Resources Program
Agriculture and Agri-food Canada
Central Experimental Farm
Ottawa, Ontario
K1A 0C6

INTRODUCTION

Mites (Acari) are the most diverse and abundant arachnids in the Montane Cordillera Ecozone. They are notable for their small size and often complex life histories. Mites rival insects in diversity of living habits and niches occupied, and are among the dominant arthropods in many soil, freshwater and plant-associated communities. They are permanent residents and integral components of these communities, typically exhibiting specific, obligate interactions with other groups of animals and plants as predators, phytophages, fungivores, saprophages, parasitoids, parasites or commensals. Nearly 10000 species of mites in over 700 genera and 250 families occur in Canada (Lindquist 1979), and we estimate conservatively that over 3000 of these species inhabit the Montane Cordillera. Soil and litter communities often contain as many as 100 species of mites, including detritivores, fungivores, predators and parasites, contributing substantially to the process of nutrient cycling and the regulation of prey and host populations. Freshwater communities may include as many as 50 species of water mites whose predatory adults and ectoparasitic larvae exploit various insect hosts and effectively regulate their populations. Communities associated with single host plants may contain up to 25 species of phytophagous, fungivorous and predatory mites. Plant-feeding species directly affect the growth and reproductive capacity of hosts, and may transmit pathogens that further reduce their vitality. Knowledge of the taxonomy, distribution and ecology of mites varies considerably among the various higher taxa. We have reasonably complete information at the species level for only a few of the families represented in the Montane Cordillera Ecozone.

Nearly all of our information on the distribution of mite species in the Montane Cordillera has resulted from collecting surveys carried out during the past 40 years and extensive information is available for only a few well studied sites. A considerable amount of data is associated with specimens in the Canadian National Collection but many of these records have yet to be reported in the literature. Distributions of species in relatively well known groups of Acari are often highly correlated with those of other arthropods, vertebrates or plants with which the mites are associated as predators, parasites or phytophages. Water mites (Hydrachnida), plant-feeding mites, ticks and some groups of gamasid and oribatid soil mites have been surveyed extensively in the Montane Cordillera. Distributional data for water mites and oribatids are currently being compiled in relational databases and available information for selected taxa of these groups is summarized and analysed.

Mites comprise the taxonomic subclass Acari of the class Arachnida which is also represented in the Montane Cordillera by scorpions (order Scorpionida), solifugids (order Solifugae), spiders (order Araneae), harvestmen (order Opiliones) and pseudoscorpions (order Pseudoscorpionida). Acari includes 2 orders, Parasitiformes represented in the Ecozone by the suborders Mesostigmata and Ixodides (Metastigmata) and Acariformes with 3 subordinal taxa, namely Prostigmata, Acaridida and Oribatida, in the Montane Cordillera.

TABLE OF CONTENTS