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

PARASITIFORMES - MESOSTIGMATA - E.E. Lindquist

The suborder Mesostigmata, also known as Gamasida, is a large group of mites that are adapted to highly diverse habitats in the Montane Cordillera, as they are elsewhere in terrestrial ecosystems. The majority of these mites are free-living predators, though many species are external or internal parasites of mammals, birds, reptiles, or invertebrates (Krantz 1978). The suborder includes 2 supercohorts, Monogynaspida and Trigynaspida. Monogynaspida contains 4 cohorts, namely, Sejina, Gamasina, Diarthrophallina and Uropodina. Trigynaspida comprises the 2 cohorts Cercomegistina and Antennophorina. The Canadian fauna of the various cohorts was treated at the family level by Lindquist (1979), Ainscough (1979) and Funk (1979). A summary of expected species diversity of families represented in the Montane Cordilleran Ecozone is presented in Table 1. This is based on the results of collecting surveys in areas at the southeastern and southwestern extremes of the Ecozone (Waterton Lakes National Park in the Northern Continental Divide Ecoregion and Manning Provincial Park in the Okanangan Range Ecoregion, respectively) and in other areas that represent ecoregional disparity in this Ecozone, including southern and northern extremities of the Okanagan Valley (Thompson-Okanagan Plateau and Okanagan Highlands Ecoregions, respectively), a southern part of the Columbia Highlands (Columbian Mountains and Highlands Ecoregion), and the Kananaskis area and Banff National Park (Northern Continental Divide Ecoregion). Voucher material from these surveys is deposited in the Canadian National Collection of Insects and Arachnids, maintained by Research Branch, Agriculture and Agri-Food Canada.

Sejina - Sejoidea. The only superfamily of Sejina has 2 families represented in the Montane Cordilleran Ecozone. These mites live in litter and decaying wood, some in association with wood-boring beetles.

Gamasina. This large group includes 6 superfamilies and and an anticipated 28 families represented in the Montane Cordilleran Ecozone. Most are free-living predators, but some are parasites and a few genera in 2 families are fungivores.

Epicrioidea. Species of 3 families occur in the Montane Cordillera. Many species of the family Zerconidae occur commonly in litter and decaying wood. One species each of the small families Epicriidae and Arctacaridae have been found in litter. The arctacarid, collected from the Northern Continental Divide Ecoregion, represents an apparently undescribed species in a group otherwise known from subarctic or arctic localities.

Parasitoidea. These generally large, predatory mites occur in various edaphic habitats in the Montane Cordillera. The family Veigaiidae is represented by relatively few species compared to the fauna of the eastern Mixedwood Plains. Many species of Parasitidae are associated with animal nests, carrion and dung; their deutonymphs disperse by phoresy on mammals and more commonly on insects, on which they were mistaken as parasites (hence the family name) in early observations.

Rhodacaroidea. Representatives of 4 families occur in the Montane Cordillera. Members of Rhodacaridae, Ologamasidae and Halolaelapidae, and some of Digamasellidae are predators in soil and compost habitats and belowground nests of insects and mammals. Other digamasellid species inhabit subcortical insect galleries or accumulations of organic matter such as manure. Phoretic deutonymphs of many species of Halolaelapidae and Digamasellidae disperse on their insect associates, and those of a few Ologamasidae disperse on their mammalian nidicolous associates.

Eviphidoidea. Species of 4 families occur in the Montane Cordillera. Members of Eviphididae, Macrochelidae, Pachylaelpidae and Parholaspidae are predators in edaphic habitats. Some species of Macrochelidae are prevalent in compost, manure and carrion, where they are associated with insects that act as carriers during a phoretic stage of the mite’s life cycle. Certain macrochelid species have been investigated as indicators in the chronology of decomposition in forensic studies or as beneficial predators of the larvae of pestiferous flies in synanthropic habitats.

Ascoidea. This large, diverse group is abundantly represented in the Montane Cordillera by members of 4 families. Predatory mites of the relatively well known family Phytoseiidae are the dominant arboreal Mesostigmata in the Montane Cordillera, as elsewhere in temperate regions of the Northern Hemisphere. Certain species are important regulators in integrated pest management of spider mite populations, including those in fruit orchards in the Okanagan Valley. Other species of Phytoseiidae occur in forest and open field litter. Members of the most disparate family, Ascidae, are mostly predators in edaphic, subcortical, arboreal, nidicolous and subaquatic habitats. Species of this family are often closely associated with insects and disperse by phoresy as adult females on these hosts. One species of the genus Mucroseius occurs with its sawyer beetle hosts, Monochamus spp., on conifers in the Montane Cordillera. Its females are phoretic on adult sawyers, and they may have a tritrophic association with their hosts and the potentially highly destructive pine wood nematode, Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle, which the sawyers also carry from infected to healthy conifers (Lindquist and Wu 1991). Whether these mites prey on the nematodes or on the sawyer’s immature instars in their galleries has not been determined. The related genus Proctolaelaps is represented by many species in this Ecozone. Although most of its species appear to prey on nematodes in subcortical and edaphic habitats, members of one species group, represented by 2 species in the Montane Cordillera, are specialized as pollen-feeding associates of bumble bees (Lindquist and Evans 1965). These mites disperse on adult bumble bees, and they develop in the bees’ nests, where they feed on pollen. The only known species of another related genus, Mycolaelaps, lives on bracket fungi attached to dead or dying conifers in this Ecozone and adjacent regions. The slender, elongate-bodies of all instars of this mite are adapted for living inside the lumen of bracket fungus pores, where they apparently feed on fungal tissue (Lindquist 1995). An undescribed genus and species of the ascid subfamily Arctoseiinae is known to date only from 2 collections of a few adults in the Montane Cordillera. A few adult females were found phoretic on bark beetles of the species Dryocoetes affaber (Mannerheim) in Banff National Park; this beetle attacks a wide variety of pines, spruces and other conifers transcontinentally and north to treeline in Canada (Bright 1976). Both females and males were collected from an old bracket fungus on spruce in the Kananaskis area of the Northern Continental Divide Ecoregion. This mite probably undergoes development in subcortical habitats of dead conifers on which bracket fungi may be present. At least 1 species of the unusual family Otopheidomenidae, parasites in the tympanic cavities of moths, probably occurs in this Ecozone. These mites infest the 'ears' of their hosts in such a way as not to impair the moths from sensing the echolocating sounds of bats and taking evasive actions to avoid being consumed by them. Representatives of several species of the family Ameroseiidae occur in litter, bracket fungi and nidicolous habitats in the Montane Cordillera. As with a few species of Ascidae, these mites are atypical among Mesostigmata in that they feed on fungal spores and pollen grains.

Dermanyssoidea. This group is also diverse and well represented in the Montane Cordillera. The family Laelapidae (including the subfamily Hypoaspidinae which is sometimes treated as a separate family) includes both predatory species in edaphic and nidicolous habitats, where they are free living or associated with social and subsocial insects, and parasitic species on birds and mammals. Species of Haemogamasidae live in edaphic nidicolous habitats where they are facultative or obligatory parasites on birds and mammals. The parasitic bee mite, Varroa jacobsoni Oudemans, has probably invaded the Ecozone recently in association with its introduced host, the honey bee Apis mellifera L., as it has in other regions where the honey bee occurs from coast to coast. The varroa mite is a devastating parasite that usually wipes out entire hives of honey bees unless preventive measures are taken. Parasitic species of 8 other dermanyssoid families are anticipated to occur on their reptilian, avian or mammalian hosts in the Montane Cordillera; however, other than 1 record of the family Spinturnicidae on the bat Myotis lucifugus (LeConte) in the southern Fraser Plateau Ecoregion near 100 Mile House (Smith 1981), comprehensive surveying for parasitic mites on their vertebrate hosts has not been undertaken in this Ecozone.

Uropodina. Saprophagous and predaceous members of 4 families of tortoise mites occur commonly in edaphic, nidicolous and decaying wood habitats in the Montane Cordillera. Most species are associated with insects and disperse as phoretic deutonymphs on their hosts. One species of Uroobovella (Fuscuropoda) is known to be a predatory pest in commercial earthworm cultures (Stone and Ogles 1953).

Trigynaspida. A few species representing perhaps 5 families and 4 superfamilies of this group are anticipated to be associated with myriapods and insects, particularly bark beetles, in the Montane Cordillera. These mites are thought to be near the northern limits of their distribution in southern ecodistricts of this Ecozone.