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

ACARIFORMES - PROSTIGMATA - I.M. Smith and E.E. Lindquist

Prostigmata is a large and extremely diverse group with representatives in virtually every type of habitat and community in the Montane Cordillera Ecozone. The Canadian fauna was discussed at the family level by Smith and Lindquist (1979). A summary of expected species diversity of families represented in the Montane Cordillera is presented in Table 6. Water mites (Hydrachnida) are one the best known groups of Prostigmata in the Montane Cordillera Ecozone, and are considered in more detail in a separate section below.

TABLE 6:EXPECTED SPECIES DIVERSITY OF FAMILIES OF PROSTIGMATA KNOWN FROM CANADA IN MONTANE CORDILLERA ECOZONE BASED ON RECORDS OF NAMED AND UNNAMED SPECIES IN CANADIAN NATIONAL COLLECTION OF ACARI

Pachygnathoidea. Several species of these mostly tiny, soft-bodied mites, representing 7 families, are commonly found in edaphic habitats and moss mats throughout the Montane Cordillera Ecozone.

Nicoletielloidea. Though not yet collected in the Montane Cordillera Ecozone, one species of the nicoletiellid genus Labidostomma probably occurs there. Members of this large, heavily sclerotized, predaceous species are common in the western United States, including Alaska.

Eupodoidea. Many soft-bodied species of these mites, representing fungivorous Eupodidae, predaceous Rhagidiidae and Penthalodidae with unknown feeding habits, occur in edaphic habitats in the Montane Cordillera. One species of penthaliid mite, Penthaleus major (Dugès), is an occasional pest of legume crops. A few species of Rhagidiidae are among the dominant predators in cavernicolous arthropod communities in the Ecozone.

Tydeoidea. Two families are well represented in the Montane Cordillera. Species of fungivorous Tydeidae are among the most common mites in soil and litter and members of other species are often very abundant on foliage. Most species of Ereynetidae found in the Ecozone are predators in edaphic habitats, but some are ectodermal cavity parasites of gastropods, amphibians, birds and mammals.

Bdelloidea. Species of at least seven genera of Bdellidae and five genera of Cunaxidae are among the common predatory mites in litter and herbaceous ground cover habitats in the Montane Cordillera. Some cunaxid species are primarily arboreal and may contribute to the regulation of populations of phytophagous mites.

Halacaroidea. A few species of freshwater Halacaridae occur in benthic and interstitial habitats in both streams and lakes in the Montane Cordillera. This family is unusual among Acari in that most of its species and clades are marine.

Tarsocheyloidea. A few species of the tarsocheylid genus Hoplocheylus are anticipated to inhabit subcortical and decaying wood habitats in the Montane Cordillera, just as they do in the northwestern United States. These mites probably prey on other microarthropods, but little is known of their habits.

Dolichocyboidea. A small number of fungivorous or possibly parasitoid species of the family Dolichocybidae are anticipated to occur in the Montane Cordillera. They are associated with subsocial and social insects, particularly beetles and ants, on which they are phoretic as adult females. In particular, at least one species of Acanthomastix probably occurs with bark beetles infesting coniferous trees in this ecozone.

Trochometridioidea. The trochometridiid genus Trochometridium has an intimate association with a variety of ground-nesting bees in North America (Cross & Bohart 1979). Although fungivorous, these mites may also function as egg parasitoids in a symbiotic relationship with the bees that has as yet not been fully clarified (Lindquist 1985, Kaliszewski et al. 1995). One species of this genus is associated with halictid bees in the Okanagan Valley. This is the most northern record of the family in North America, and is apparently near the northern limit of its distribution.

Pygmephoroidea. Fungivorous species of the families Siteroptidae and Pygmephoridae are expected to be well represented in the Montane Cordillera in litter habitats and nests of both social insects and mammals. These mites disperse as adult females on their hosts. Members of the siteroptid genera Siteroptes and Pediculaster, often associated with bark beetles and fungus- inhabiting flies, often manifest phoretic and non-phoretic female dimorphism. Members of the pygmephorid genus Pygmephorus commonly occur in the nest of small mammals, and are phoretic in the fur of the mammals or on insects frequenting their nests. Some 50 species of Pygmephorus have been described as phoretic adult females from the Northern Hemisphere, yet males of but two species are known and little is known of their way of life (Kaliszewski et al. 1995).

Scutacaroidea. Species of Microdispididae and Scutacaridae occur commonly in edaphic habitats and decaying wood in the Montane Cordillera. Most members of this superfamily have similar habits to pygmephoroid mites, and they are frequently associated with social insects, particularly ants. Many species of the group are phoretic as adult females, and dimorphism among the adult females is frequent, though a few species appear to have just one morph, the phoretic one (Ebermann 1991). A parasitoid association with insects has evolved at least twice in the family Microdispidae, though not among members of the genera that occur in the Montane Cordillera and elsewhere in north temperate and boreal regions of North America (Cross 1965).

Pyemotoidea. Adult females of Pyemotes, the only described genus of Pyemotidae, are parasitoids of Coleoptera, Lepidoptera, Hymenoptera, Diptera and Homoptera (Kaliszewski et al. 1995). With an intrinsic rate of population increase capable of a population-doubling time of 1.1 days, they have been estimated as the most fecund of arthropods yet known (Wrensch and Bruce 1991). High fecundity is achieved by a relatively short life cycle (suppression of active immature instars), a highly skewed sex ratio (females generally representing 80-95% of the progeny), and development of many eggs at approximately the same time, facilitated by extreme physogastry of the mother on a single host (Kaliszewski et al. 1995). The genus divides into two ecologically distinct groups, the scolyti-group and ventricosus-group. Species of the scolyti- group have narrow host ranges, usually as associates of bark beetles; their females are polymorphic, apparently non-venemous, and feed on the eggs, larvae and pupae, but usually not adults, of their hosts. Those of the ventricosus-group have wide host ranges as associates of insects in a wide variety of habitats; their females are monomorphic, highly venomous (to such an extent that they can cause severe dematitis on people handling infested material such as hay) , and attack all instars of their hosts. In the Montane Cordilleran Ecozone, several species of Pyemotes in the scolyti-group have been found associated with economically destructive bark beetles of the genera Ips, Scolytus, and Polygraphus. Adult females of Acarophenacidae, the sister family of Pyemotidae, are parasitoids strictly of insect eggs. Usually only one male is produced in a progeny, such that inbreeding has seemed to be unavoidable and has led to relatively high host specificity (Kaliszewski et al. 1995). All species of the genus Paracarophenax appear to be parasitoids of beetles, and one species is commonly associated with ipine bark beetles in the Montane Cordillera.

Tarsonemoidea. The ecologically diverse family Tarsonemidae is represented by numerous genera and species in the Montane Cordillera. Many tarsonemids are fungivorous, and some have interesting tritrophic associations with insects. In the Montane Cordilleran Ecozone, several species of Tarsonemus and Heterotarsonemus are known or anticipated associates of bark beetles in conifers (Lindquist 1969b, 1970). Adult females of these species are phoretic on the beetles, and both the mites and the beetles carry propagules of fungi, including the blue-staining fungi highly injurious to conifers, upon which the mites depend for sustenance and the beetles for pathogenically weakening their tree hosts (Bridges and Moser 1986). As many as nine species (six of them documented) of Iponemus, highly host-specific egg parasitoids of ipine bark beetles (Lindquist 1969a), occur in this Ecozone. The monospecificity of some species associated with pine-feeding ipines reflect the recognition of subspecies or closely related species of their hosts; for example, a different subspecies of Iponemus plastographus (Lindquist and Bedard) is associated with each of Ips plastographus plastographus (Leconte), Ips plastographus maritimus Lanier, and Ips integer (Eichhoff) sensu Lanier (1970). Two subspecies of Iponemus, each of a different species, I. plastographus integri Lindquist associated with Ips integer and I. confusus montani Lindquist associated with Ips montanus (Eichhoff), and two other species, I. spanus Lindquist associated with Ips woodi Thatcher, and I. striatus Lindquist associated with Ips latidens (LeConte), reach the northern limits of the distribution of their species and their hosts in this Ecozone. Iponemus calligraphi cordillerae Lindquist associated with Ips calligraphus (Germar) (=Ips ponderosae Swaine), known as far north as an unspecified locality in Montana, and I. plastographus subalpinus Lindquist associated with Ips plastographus plastographus (LeConte) sensu Lanier (1970), known from the Sierra Nevada and Cascades in northwestern United States, may also reach their northernmost limits in the Montane Cordillera. Two tarsonemid genera contain plant feeders capable of causing economic damage to plants in this Ecozone. The cyclamen mite, Phytonemus pallidus (Banks), damages a wide variety of herbaceous plants, particularly in greenhouses and nurseries, but also may be a major pest of strawberries wherever they are cultivated outdoors. Members of Steneotarsonemus, including several species in the Montane Cordillera, feed on wide variety of graminaceous plants (Lindquist 1986). Some species of Dendroptus are associated, apparently as predators, with free- living and gall-forming eriophyid mites on deciduous-leaved trees, including apple and pear orchards, in the Ecozone. Three species of Acarapis, all host-specific parasites of honey bees, have been introduced into the Ecozone along with their hosts. Two of them are external parasites that are not known to harm their hosts; however, the honey bee tracheal mite, A. woodi (Rennie), introduced into the Ecozone during the early 1980's, may be highly detrimental to bees, particularly in more northern areas. Members of the family Podapolipidae are all parasites of insects. Of the few species known as yet from Canada, one is anticipated to live under the elytra of carabid beetles in the Montane Cordilleran Ecozone.

Cheyletoidea. Several species of free-living predaceous Cheyletidae are common in litter and arboreal habitats in the Montane Cordillera. Numerous species representing 7 other families, all parasites of vertebrates, occur in the Ecozone, but have received very little attention. For example, although at least 250 species of syringophilid quill mites probably parasitize species of birds that reside or breed in the Montane Cordillera, there are no published records of the family from the Ecozone. Two species of Demodicidae, the follicle mites, Demodex follicularum (Simon) and D. brevis Akbulatova, infest the facial pores of a substantial percentage of the human population in Canada (Sengbusch and Hauswirth 1986).

Raphignathoidea. About half of the Canadian species of this superfamily, including members of all 8 families, inhabit the Montane Cordillera. Most of them are free-living predators in edaphic and herbaceous ground cover habitats, but species of the moderately large stigmaeid genus Eustigmaeus feed on mosses. Members of the small family Homocalligidae are at least semiaquatic and live in wet detritus at the edges of freshwater habitats.

Tetranychoidea. Both of the families Tetranychidae (Spider Mites) and Tenuipalpidae (False Spider Mites) are well represented in the Montane Cordillera, and the family Linotetranidae is expected to be represented by one species in this Ecozone. All species of Tetranychoidea are obligately phytophagous, and several of them reach the northern limit of their distribution along with their host plants in the Okanagan region of the Ecozone. Some species of Tetranychidae are important pests of various crops, ornamental plants and forest trees. The McDaniel mite, Tetranychus mcdanieli McGregor, is the most important mite pest of deciduous fruit trees in this Ecozone, and the European red mite, Panonychus ulmi (Koch), Brown mite, Byobia rubrioculus (Scheuten), and Two-spotted spider mite, Tetranychus urticae Koch, also are injurious to these, as well as a wide variety of other hosts. The Brown wheat mite, Petrobia latens (Müller), and Clover mite, Bryobia praetiosa Koch, injure grasses and herbaceous plants (Fig. 00). A few species in other genera of Tetranychidae, such as the Spruce spider mite, Oligonychus ununguis (Jacobi), on conifers, the Yellow spider mite, Eotetranychus carpini borealis (Ewing), on deciduous trees, and one of the willow spider mites, Schizotetranychus schizopus (Zacher), are occasionally significant pests in the Ecozone (Peterson and Hildahl 1969, Westigard and Berry 1970, Duncan and Lindquist 1989). A few species of Tenuipalpidae occasionally cause visible damage to their host plants in the Montane Cordillera. Pentamerismus canadensis McGregor and Pentamerismus erythreus (Ewing) are widespread on wild and ornamental cupressaceous plants, and heavy infestations may cause browning of foliage on ornamental shrubs and hedges. Brevipalpus lilium Baker and Brevipalpus obovatus Donnadieu, are anticipated to occur on a variety of broad-leaved hosts and to sometimes damage ornamentals such as rhododendron, privet and fuschia grown in southern areas of the Ecozone. Brevipalpus russulus (Boisduval) occurs on cacti and related succulents, and it not only damages them as ornamentals but also as range plants (Jeppson et al. 1975). One or two species each of the tenuipalpid genera Aegyptobia and Dolichotetranychus, and one species of the linotetranid genus Linotetranus are anticipated to occur on graminaceous hosts in subalpine meadow and open foothill areas of the Montane Cordilleran Ecozone.

Eriophyoidea. Most species of perennial vascular plants in the Montane Cordillera are host to one or more species of these tiny phytophagous mites. Most eriophyoids are highly host specific, and their feeding often causes characteristic symptoms on the host ranging from discolouration of foliage to production of striking galls or erineal secretions on foliage, flowers or fruits. Some Phytoptidae, especially species of the genera Trisetacus and Nalepella, are significant pests of conifers and may seriously damage plantations throughout the Ecozone. The most conspicuous phytoptid species in the Montane Cordillera are Trisetacus gemmavitians Styer et al. which distorts and damages buds on a variety of pines and Trisetacus chamaecyparis Smith and T. neoquadrisetus Smith which feed on seeds in the cones of Yellow Cedar and Rocky Mountain Juniper, respectively. Several Eriophyidae are pests on crop and ornamental plants and infestations of some of these species occasionally cause serious economic losses. The widespread orchard pests Aculus schlectendali Nalepa and A. cornutus (Banks) cause rusting on foliage of apple and peach, respectively. A population of Eriophyes insidiosus Wilson and Keifer, the peach mosaic vector mite, has recently been discovered in the Creston Valley. This species has been implicated in the transmission of mosaic virus among various rosaceous hosts , including both cherries and pecan as well as peach. The pear leaf blister mite, Eriophyes pyri Pagenstecher occurs throughout the southern orchard lands of the Ecozone, damaging both the foliage and buds of pears and apples. One species of Diptilomiopidae, the big-beaked plum mite Diptacus gigantorhynchus (Nalepa), is frequently encountered on both native and cultivated species of Prunus.

Anystoidea. The most conspicuous members of this superfamily in the Montane Cordillera are species of the anystid genera Anystis, Chausseria and Tarsotomus. These mites, known as whirligig mites, are highly active predators of phytophagous and other soft-bodied mites in edaphic, herbaceous ground cover and arboreal habitats. Members of 2 other families, Barbutiidae and Paratydeidae, are predators in litter and soil habitats. Species of these families are rarely collected in the Montane Cordillera and appear to reach the northern limit of their distributions in the Ecozone.

The remaining 11 superfamilies of Prostigmata present in the Montane Cordillera belong to the subcohort Parasitengona. Mites of this well defined clade share an essentially holometabolous life history pattern with ectoparasitic larvae, active and predaceous deutonymphs and adults, and quiescent protonymphal and tritonymphal instars.

Calyptostomatoidea. One species of the worldwide genus Calyptostoma is commonly found in wet edaphic habitats in the Montane Cordillera. Larvae of these mites are parasitic on adult crane flies (Tipulidae).

Erythraeoidea. Species of Erythraeidae are common in litter and herbaceous ground cover habitats, and are among the dominant arthropod predators in the grasslands and deserts in the southern ecoregions of the Montane Cordillera. Their larvae typically parasitize various insects, but those of the erythraeid genus Leptus are also frequently found on other arachnids. Larvae of Balaustium are atypical among Parasitengona in having secondarily become predaceous on other mites and aphids in arboreal habitats and also in being capable of feeding on pollen.

Trombidioidea. Species of 4 families are among the most conspicuous mites in litter and edaphic habitats in the Montane Cordillera. Larvae of Johnstonianidae, Trombellidae and Trombidiidae parasitize a wide variety of insects, while those of Trombiculidae are the infamous chigger mites that parasitize vertebrates and occasionally attack humans. Adult johnstonianids and trombellids prefer wet litter and moss habitats near bodies of water, but trombidiids (velvet mites) and trombiculids are also found on various other substrates in woodlands, savannahs and fields.

Stygothrombidioidea. Several undetermined species of this enigmatic group occur in hyporheic aquatic habitats in the Montane Cordillera. Larvae parasitize stoneflies (Plecoptera) and the elongate, vermiform deutonymphs and adults are predators in subterranean water. These mites appear to have affinities with both trombidioid taxa and true water mites, considered below, but precise relationships have not yet been worked out.