29 Chapter 3 Plant-feeding Mites of the Canadian Prairies Frédéric Beaulieu* and Wayne Knee Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri-Food Canada, 960 Carling Ave., K.W. Neatby bldg., Ottawa, ON, Canada, K1A 0C6 Email addresses: [email protected] (F. Beaulieu), [email protected] (W. Knee) *Author for correspondence: F. Beaulieu. Phone: 613 759 1789, Fax: 613 759 1927 Abstract. The diversity of plant-feeding mites of the Canadian Prairies Ecozone is reviewed using the literature and collection records. At least 101 species of strictly phytophagous mites (Trombidiformes: 57 Eriophyoidea, 41 Tetranychoidea, three Tarsonemidae) and fi ve presumed moss feeders (four Stigmaeidae, one Cryptognathidae) are present in the ecozone. In addition, species from at least two genera (Astigmata: Rhizoglyphus, Tyrophagus) that are primarily fungivorous can feed facultatively on plants, and approximately 40 species from several genera live in stored plant products, feeding on grains or associated fungi. A diversity of mites from at least 11 families in three orders (Mesostigmata, Trombidiformes, Sarcoptiformes) feed facultatively or obligatorily on fl oral products (pollen or nectar), including 15 species that are obligate associates of bees, mostly Bombus species. On the basis of records from the United States and the dearth of distribution and host association records for Canada, we predict the diversity of strict phytophages in the Canadian Prairies Ecozone to be at least 200 species. While many species (29) are associated with Poaceae (true grasses), we suspect that the poorer records for other plant families (e.g., Fabaceae (pea family), Asteraceae (aster or daisy family), Cyperaceae (sedges), Brassicaceae (crucifers)) common in the Prairies Ecozone merely refl ect a lower collecting effort. At least 11 species were recorded on fi eld cereal crops (including three fungivorous Siteroptes spp. (Siteroptidae), vectors of fungal pathogens), 11 on fruit crops, six from greenhouses (and three predicted to occur), six on weeds, nine on conifers, and 27 species on other hardwood trees and shrubs, including many urban ornamental plants. The biology and distribution of nearly all of these potential pests, and other species on native or naturalized hosts, are poorly documented. Their taxonomy is also poorly understood, since about two-thirds of the species are undescribed or have uncertain identities. Efforts targeting the taxonomy and biology of plant-feeding mites of the Canadian Prairies are needed to better understand, protect, control, and exploit the plant-associated mites of this region. Résumé. La diversité des acariens phytophages de l’écozone des Prairies canadiennes est revue en utilisant la littérature et les données de récoltes disponibles. Au moins 101 espèces d’acariens strictement phytophages (Trombidiformes : 57 Eriophyoidea, 41 Tetranychoidea, trois Tarsonemidae) et cinq qui se nourrissent présumément de mousse (quatre Stigmaeidae, un Cryptognathidae) sont présentes dans les Prairies. En outre, les espèces provenant d’au moins deux genres (Astigmata : Rhizoglyphus, Tyrophagus) principalement fongivores peuvent facultativement se nourrir de plantes, et environ 40 espèces appartenant à plusieurs genres vivent dans les produits végétaux entreposés, se nourrissant de grains ou de champignons qui leurs sont associés. Une diversité d’acariens appartenant à au moins 11 familles de trois ordres (Mesostigmata, Trombidiformes, Sarcoptiformes) se nourrissent facultativement ou obligatoirement de produits fl oraux (pollen ou nectar), dont 15 espèces qui sont strictement associées aux abeilles, principalement à des espèces de Bombus. D’après les données sur les espèces présentes aux États-Unis, et considérant le manque de données sur la répartition géographique et les plantes-hôtes pour les espèces canadiennes, nous estimons que la diversité des phytophages strictes dans l’écozone des Prairies canadiennes est d’au moins 200 espèces. Alors que de nombreuses espèces (29) sont associées à des Poaceae (graminées vraies), nous soupçonnons que le peu de données disponibles pour d’autres familles de plantes (par exemple les Fabaceae (famille des pois), Asteraceae (famille des asters et des marguerites), Cyperaceae (laîches), et Brassicaceae (crucifères)) communes dans l’écozone des Prairies ne font que refl éter un faible effort de Beaulieu, F. and W. Knee. 2014. Plant-feeding Mites of the Canadian Prairies. In Arthropods of Canadian Grasslands (Volume 3): Biodiversity and Systematics Part 1. Edited by H. A. Cárcamo and D. J. Giberson. Biological Survey of Canada. pp. 29-72. © 2014 Biological Survey of Canada. ISBN 978-0-9689321-6-2 doi: http://dx.doi.org/10.3752/9780968932162.ch3 30 F. Beaulieu and W. Knee récolte. Au moins 11 espèces ont été recensées sur des cultures de céréales (y compris trois espèces de Siteroptes (Siteroptidae) fongivores, vectrices de pathogènes fongiques), 11 sur des cultures fruitières, six dans les serres (et trois autres possibles pour la région), six sur des mauvaises herbes, neuf sur des conifères et 27 espèces sur d’autres arbres et arbustes feuillus, dont de nombreuses plantes ornementales en milieu urbain. La biologie et la distribution de la quasi-totalité de ces ravageurs potentiels sont peu connues, ainsi que celles d’autres espèces sur des hôtes indigènes ou naturalisées. Leur taxonomie est également mal comprise, puisqu’environ le deux tiers des espèces sont non décrites ou ont une identité incertaine. La recherche portant sur la taxonomie et la biologie des acariens phytophages des Prairies canadiennes doit être favorisée davantage afi n de mieux comprendre, protéger, contrôler et exploiter les acariens associés aux plantes de cette région. Introduction The Prairies Ecozone of Canada comprises a diverse set of habitats, where roughly 1,300 vascular and non-vascular plant species occur, either naturally or after unintentional introduction or escape from cultivation (Looman and Best 1987). Essentially all of these plants have mites using their leaves, stems, fl owers, buds, bark, and roots as their foraging, reproducing, and sheltering grounds for part or all of their life cycle. Plant-associated mites include fungivores, saprophages, predators, parasites, phytophages, and omnivores and are a diverse group, though less diverse taxonomically than the mite faunas of soil and litter (Walter and Proctor 1999; Walter 2004). Phytophagy1 evolved independently in several mite lineages (Krantz and Lindquist 1979; Lindquist 1998). However, major evolutionary radiations of phytophagy on vascular plants occurred in only two lineages of mites, both within the order Trombidiformes (Prostigmata): the Tetranychoidea and the Eriophyoidea. Each superfamily comprises about 2,000 and 4,000 described species, respectively, which are all presumed to be strict phytophages, or “plant parasites” (Walter 2004; Mesa et al. 2009; de Lillo and Skoracka 2010; Migeon and Dorkeld 2013). Other prostigmatic mite taxa include essentially obligate phytophagous species: at least seven genera of Tarsonemidae, two genera of Penthaleidae, and one genus of Stigmaeidae. Representatives of all of these taxa occur in the Canadian Prairies Ecozone. Feeding on live plant tissues is exceptional in other mite groups and is mostly restricted to fungivorous or predatory forms that feed facultatively on plant tissues or on fl oral products—pollen and nectar.1 Mites can be detrimental to agriculture. They include pests of pome and stone fruits , berries, cereals, stored grains and other food products, vegetables, and ornamentals, as well as parasites that can drastically affect the health and populations of livestock (e.g., cattle ticks) or key pollinators (e.g., varroa mites on honey bees) (Helle and Sabelis 1985b; Lindquist et al. 1996; Sammataro et al. 2000; Lysyk 2011). Fortunately, many mites are also benefi cial to agriculture, either directly or indirectly, by contributing to terrestrial and aquatic food chains and to nutrient cycling (Behan-Pelletier 1999), or by acting as biocontrol agents of crop pests and of weeds (Gerson et al. 2003). In sustainable agriculture systems based on the moderate use of softer (less toxic) chemical pesticides, predatory mite communities may play an important role in biological control, although 1 Phytophagy is here defi ned as feeding on a live plant substrate rather than consuming whole plants or plant parts (herbivory; Krantz and Lindquist 1979) (analogous to a parasite feeding on an animal host). In addition, we consider feeding on pollen and nectar to be a form of phytophagy in the broad sense, though distinct from feeding on live plant tissues. Although trombidiform and sarcoptiform mites commonly feed on microscopic algae, lichen, and especially fungi, this is not considered phytophagy here, nor is it treated in any detail, except where pests (of fi eld crops or stored products) are concerned. Plant-feeding Mites of the Canadian Prairies 31 they are not often well understood or exploited (Bostanian et al. 2006; Beaulieu and Weeks 2007). Similarly, phytophagous mites that attack crop plants or weeds are understudied and often overlooked. Mites therefore may affect plants, particularly crops, more than we think because the symptoms produced are often subtle and overlooked, or mistaken for a nutrient defi ciency or disease (Kane et al. 2012), and because mites are too small to be readily associated with observed symptoms. Even with fairly obvious symptoms, mites may still