Hymenoptera) of the Canadian Prairies Ecozone: a Review
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317 Chapter 9 Ichneumonidae (Hymenoptera) of the Canadian Prairies Ecozone: A Review Marla D. Schwarzfeld* Department of Biological Sciences, CW 405 Biological Sciences Centre, University of Alberta, Edmonton, AB, T6G 2E9 Email: [email protected] Abstract. The parasitoid family Ichneumonidae is the largest family in the order Hymenoptera. This chapter provides a checklist of 1,160 ichneumonid species (299 genera) known from the Canadian Prairies Ecozone. The list is primarily drawn from literature records and also includes 35 newly recorded species from the ecozone. The number of species on the list is a vast underestimate of the number of ichneumonid species present, as many genera lack revisions and few biodiversity surveys have been conducted. Most species recorded from this ecozone are only known from the Nearctic region, but are not restricted to the Prairies Ecozone. Little is known about the ecology, habitat requirements, or host associations of most ichneumonid species, with 43% of the species on the checklist lacking any host records. Future research should include revisions of the many genera that have not been studied in the Nearctic region, as well as biodiversity surveys in prairie habitats, rearing of potential host species, and the creation of user-friendly identification resources. Résumé. Les guêpes parasitoïdes de la famille des Ichneumonidae forment la plus grande famille de l’ordre des hyménoptères. Le présent chapitre dresse la liste des 1 160 espèces de cette famille, réparties en 299 genres, présentes dans l’écozone des prairies. Cette liste, établie principalement à partir de sources documentaires, fait état de 35 nouvelles mentions provenant de l’écozone. Elle sous-estime cependant très largement le nombre d’espèces d’ichneumonidés présentes puisque de nombreux genres n’ont toujours pas fait l’objet d’une révision et que les études sur la biodiversité restent peu nombreuses. La plupart des espèces recensées dans cette écozone ne sont connues que dans la région néarctique, mais ne sont pas limitées à l’écozone des prairies. On sait peu de choses sur l’écologie, les besoins en matière d’habitat ou les hôtes des ichneumonidés, et la liste n’a aucune information à fournir sur les hôtes de 43 % des espèces répertoriées. Les recherches futures devraient inclure des révisions des nombreux genres qui n’ont toujours pas été étudiés dans la région néarctique, l’étude de la biodiversité dans les habitats des prairies, l’élevage d’espèces hôtes possibles et la création de ressources documentaires d’identification facile à utiliser. Introduction Ichneumonidae is the largest family within the order Hymenoptera and may be among the largest insect families on earth (Gauld 1991). It consists of at least 24,268 described species (Yu et al. 2012) and has an estimated world total of over 100,000 species (Gauld 2002). The family is monophyletic and is one of two families (with Braconidae) that make up the superfamily Ichneumonoidea (Sharkey and Wahl 1992; Schwarzfeld M. D. 2014. Ichneumonidae (Hymenoptera) of the Canadian Prairies Ecozone: A Review. In Arthropods of Canadian Grasslands (Volume 4): Biodiversity and Systematics Part 2. Edited by D. J. Giberson and H. A. Cárcamo. Biological Survey of Canada. pp. 317-397. © 2014 Biological Survey of Canada. ISBN 978-0-9689321-7-9 doi: http://dx.doi.org/10.3752/9780968932179.ch9 Species checklist available at http://dx.doi.org/10.5886/5r772nsm *Current address: University of Northern British Columbia,3333 University Way, Prince George, BC, V2N 4Z9 318 M. D. Schwarzfeld Belshaw et al. 1998). Ichneumonoidea has been hypothesized to be the sister group of Aculeata (Rasnitsyn 1988; Dowton and Austin 1994); more recent studies, however, have not supported this relationship. Instead, strong evidence suggests that the superfamily is sister to Proctotrupomorpha (Heraty et al. 2011; Sharkey et al. 2012), or to Aculeata + Proctotrupomorpha (Sharanowski et al. 2010). According to the most recent taxonomically comprehensive analysis, 38 subfamilies are currently recognized within Ichneumonidae (Quicke et al. 2009). Their boundaries and relationships are still highly unresolved, however, and several subfamilies are currently paraphyletic (Quicke et al. 2009). Parasitoids are insects that are free-living as adults, but whose larvae live and feed entirely on or in a single host arthropod, ultimately killing it (Godfray 1994). With the exception of a few species that are predators on spider eggs (Fitton et al. 1987) and a very few that may be partly herbivorous (Gauld 1983), all ichneumonids are parasitoids (Gauld and Bolton 1988). Within this basic lifestyle, however, there is a wide range of life histories. Most species parasitize Holometabola, in particular Lepidoptera and Symphyta, but a wide range of hosts is known, including several species that attack Araneae (Fitton et al. 1987; Gauld and Bolton 1988). Ichneumonidae species can be classified as either idiobionts (parasitoids that prevent their hosts from developing further) or koinobionts (parasitoids that allow the host to continue to develop) (Askew and Shaw 1986). Within each of these strategies, they can be further classified as ectoparasitoids or endoparasitoids. All host life stages (egg, larval, pupal, and rarely, adult) are prone to attack by different species of Ichneumonidae. Finally, ichneumonids can be primary parasitoids and either obligate or facultative hyperparasitoids (Gauld and Bolton 1988; Gauld 1991). Some ichneumonid species are highly host specific, whereas others are generalists. In general, koinobionts are thought more likely to be host specialists because of being highly physiologically intertwined with their hosts, whereas idiobionts may have a wider host range (Askew and Shaw 1986; Gauld 1988a), but are often specific in a particular niche (e.g., hosts in silk, or hosts in woody material) (Gauld 1988a; Godfray 1994). Summary of Taxonomic and Biodiversity Studies in the Canadian Prairies Ecozone Despite the abundance, diversity, and ecological importance of Ichneumonidae, there is a dearth of ecological studies or biodiversity surveys on them in general, and a near absence of such studies in the Canadian Prairies. The information contained within this chapter is thus almost entirely drawn from taxonomic studies. In particular, a great many Nearctic groups were revised by H. K. Townes and C. E. Dasch, though many other workers made great contributions to the knowledge of Nearctic species. A preliminary list of the natural enemies of Canadian agricultural pests was drawn from the literature by Graham (1965), though no localities beyond province were provided. Bradley (1974, 1978) compiled lists of forest Lepidoptera parasitoids in three ichneumonid subfamilies (Ichneumoninae, Metopiinae, Pimplinae) from rearings and museum collections. Although these species were examined in the context of forest pest enemies, many records are from the Prairies Ecozone. Sharkey et al. (1987) studied the parasitoids associated with sunflower in Alberta and Saskatchewan. Finnamore (1994) conducted a survey of the Hymenoptera of Wagner Natural Area, a spring fen within the Aspen Parkland Ecoregion, which included an estimated 665 species of Ichneumonidae. Ichneumonidae (Hymenoptera) of the Canadian Prairies Ecozone: A Review 319 Extensive collecting by E.H. Strickland led to the publication of his checklist of Alberta Ichneumonoidea (1946, 1952), with many records from the Prairies Ecozone. In Manitoba, many ichneumonid species (as well as other taxa such as Carabidae; see Chapter 1, this volume) are known from the collecting efforts of N. Criddle and associates around Aweme. In this chapter, I provide a checklist of all Ichneumonidae species recorded from the Canadian Prairies Ecozone, with localities and a summary of host records. This list consists primarily of published records, with the addition of 35 new records for the region. I also summarize the biogeographical and ecological patterns of these species in the Canadian Prairies and discuss the gaps in our current knowledge. Approach Region The Canadian Prairies Ecozone extends across the southern portions of Alberta, Saskatchewan, and Manitoba. It includes seven ecoregions, most of which are grassland dominated (Shorthouse 2010). Greater amounts of tree cover are found in the Aspen Parkland Ecoregion, which is a transitional zone between prairie grasslands and boreal forest; in the Cypress Upland Ecoregion; and in the Southwest Manitoba Uplands Ecoregion (Shorthouse 2010). This chapter lists all ichneumonid species that have been recorded from the Prairies Ecozone. Since habitat associations were not given for the vast majority of records, locality was used as the criterion for whether a species should be included in the checklist. When in doubt, I erred on the side of including species. For example, many records are from Waterton Lakes National Park, Alberta, with no further data. Since the park includes the ecologically important Fescue Grassland Ecoregion (Shorthouse 2010), I included these records, although they are equally likely to have come from non-prairie habitats at higher elevations. I also used a relaxed northern border; since the Aspen Parkland Ecoregion has been highly altered by agriculture, and this agricultural land extends beyond what would have historically been parkland habitat and into the boreal, I used the current agricultural limit as an approximate northern boundary. This limit is arbitrary since few species appear to be restricted