the Biological Survey
About the Canadian Fauna
ÉTAT ET BESOINS DES RECHERCHES SUR LES ARTHROPODES TERRICOLES DU CANADA
Cette communication fait remarquer que la connaissance des arthropodes terricoles du Canada est étonnamment insuffisante. Bien que la faune terricole soit relativement riche, surtout dans les habitats septentrionaux caractéristiques de notre pays, on sait très peu de chose sur les groupes typiquement terricoles, et en particulier sur leur taxonomie.
La faune terricole est abondante et importante au point de vue écologique, surtout pour la décomposition et le recyclage des éléments nutritifs, donc d'un intérêt immédiat pour les activités qui, comme l'agriculture et la sylviculture, dépendent de la fertilité des sols. Certaines espèces d'arthropodes terricoles ont une importance directe comme animaux nuisibles et d'autres servent d'espèces indicatrices, d'agents de contrôle biologique ou d'aides pédagogiques.
Les lacunes qu'accusent les connaissances à ce sujet se manifestent principalement au sujet des formes immatures, en particulier chez les groupes qui rassemblent de nombreuses espèces, comme les acariens, les podures et les mouches; cependant, moins de la moitié de nos espèces terricoles - qu'on estime du nombre de 18 000 ou davantage - sont décrites, même pour la phase adulte. Ces lacunes résultent du peu d'appui que reçoit généralement l'étude des arthropodes terricoles à l'heure actuelle. Le manque de compétences taxonomiques est un problème fondamental qui entrave grandement le travail écologique. Cette communication tente d' ouvrir la voie aux initiatives et aux démarches visant à améliorer cette situation que permettront les circonstances.
The Biological Survey of Canada (Terrestrial Arthropods) develops and coordinates national initiatives in taxonomic and ecological entomology on behalf of the National Museum of Natural Sciences and the Entomological Society of Canada. Several active projects have been selected for special emphasis because of their particular scientific importance. The arthropods of the soil were readily recognized as an area of particular concern, but an active project could not be developed in this case because resources are inadequate; instead the importance of soil forms is indicated in this brief, which thus points out a significant deficiency in the national entomological effort. The brief is intended to provide general support for the development of appropriate studies in the future.
The enormous gap in our knowledge of soil animals has been recognized for over a decade, as the following statement for invertebrates other than insects (Lindsey et al. 1970) demonstrates: "Canada has no basic faunal studies of invertebrates compared to the extensive and well-illustrated series of books 'Fauna of the U.S.S.R.'. The abortive 'Canadian Fauna' series of the Fisheries Research Board, started some 40 years ago, has been discontinued. Except for molluscs, there is no check list of Canadian species in any major invertebrate group (and in the mollusc check list perhaps 50% of the identifications are erroneous)... Taxonomy of Canadian freshwater and land invertebrates is not in much better shape. Earlier remarks concerning the state of knowledge of spiders [Araneae], mites [Acari] and nematodes are particularly applicable to Canada. A list of groups for which there are no adequate keys to Canadian species would include most Orders and most Families of the invertebrates."
Canadian arthropod groups that have been well documented are mainly not permanent soil forms. They include: the fleas (Holland 1949, (and in press)), ticks (Gregson 1956), dragonflies (see Corbet 1979), specific groups of insects and spiders in the recent (since 1977) handbook series from the Biosystematics Research Institute (including crab spiders), centipedes (Kevan 1979), and orthopteroids (Vickery and Kevan, in press). The knowledge of collembolans has been greatly improved by a recent treatment for North America (Christiansen and Bellinger 1980), but is still deficient. However, for the majority of true soil forms the situation today has changed little since 1970, and perhaps for the worse, when compared to other advanced countries. This is difficult to understand, because the soil arthropod fauna is ubiquitous, abundant, diverse and ecologically important.
Nature of the soil arthropod fauna
Abundance and diversity
Densities of 200,000 arthropods/m should be common in Canadian soils, and 1,000,000 individuals/m were obtained from a black spruce stand in southern Quebec (Behan et al. 1978). Over 8,000 species have been recorded from our soils and more than this number still remain to be discovered. The estimate of uncollected species is very conservative. Dondale (1979) estimated that there were five species of Pseudoscorpionida (Arachnida), but emphasized that the group was inadequately collected in Canada. We now know that over 50 species of pseudoscorpions occur in Canada (D. K. McE. Kevan, pers. comm.). Similarly, the eight species of Protura estimated by Tomlin (1979) is small compared to the 40 known from Japan. Other comparable examples could be cited .
On the human time scale, soil is our most precious non-renewable resource. Canada is seriously lacking in the study of many phases of soil science, and particularly in sub-disciplines dealing with the fauna of the soil.
Table 1 points out several important deficiencies related to soil arthropods. There is a strong need for studying immature forms, especially in large taxa such as the Acari, Collembola and Diptera. Inadequate taxonomic knowledge also extends to adults, since more than half of our soil arthropods are still undescribed. This lack of taxonomic knowledge greatly hampers ecological work. The following quotation sums up this difficulty (Entomological Society of Canada 1974):
Coupled with these inadequacies of taxonomic knowledge is the lack of Canadian specialists for many groups of soil arthropods. Seven of the groups (Tardigrada, Pauropoda, Diplopoda, Symphyla, Protura, Diplura, and some "other arachnids") are not being studied by Canadian taxonomists. In the recent compendium, Canada and its Insect Fauna (Danks 1979), sections on the tardigrades, pauropods, diplopods and symphylids were written by non-Canadian authors. Even where taxonomists are available, they are too few to cope with the formidable array of soil arthropod species. For example, fewer than 4 person-years in Canada are devoted to the taxonomy of soil mites and dipterous larvae combined, although each group contains thousands of soil-dwelling species.
The Canadian soil arthropod fauna is an important heritage that deserves more study than it has received in the past. The greatest need is increased taxonomic information; this is a prerequisite to ecological studies focussed on nutrient cycling and relationships with the soil microflora, indicator species of soil conditions, pests, biological control, and environmental impact studies. There is, of course, also a need for studies in other areas, including physiology, morphology, and behaviour.
Our fragmentary knowledge of soil arthropods has been obtained chiefly over the past two decades, primarily from a small group of universities, and Canada Departments of Agriculture and Environment. Attempts should be made to strengthen such incipient "centres of specialization", and to encourage other agencies to include soil arthropod research as part of their future programs. Agencies that fund research should also be made aware of this major deficiency in the study of the Canadian fauna, so that the problem may be addressed through soil zoology working groups, "strategic" research support, solicited or unsolicited proposals, or other specific vehicles.
Behan, V.M., S.B. Hill, and D.K. McE. Kevan. 1978. Effects of nitrogen fertilizers, as urea, on Acarina and other arthropods in Quebec black spruce humus. Pedobiologia 18: 249-263.
Christiansen, K. and P. Bellinger. 1980. The Collembola of North America north of the Rio Grande. Grinnell College, Iowa. iv + 1322 pp.
Corbet, P.S. 1979. Odonata. pp. 308-311 in H.V. Danks (Ed.), Canada and its insect fauna. Mem. ent. Soc. Can. 108. 573 pp.
Danks, H.V. (Ed.). 1979. Canada and its insect fauna. Mem. ent. Soc. Can. 108. 573 pp.
Dondale, C.D. 1979. Opiliones, Pseudoscorpionida, Scorpionida, Solifugae. pp. 250-251 in H.V. Danks (Ed.), Canada and its insect fauna. Mem. ent. Soc. Can. 108. 573 pp.
Entomological Society of Canada. 1974. A biological survey of the Insects of Canada. Suppl., Bull. ent. Soc. Can. 6(2). 16 pp.
Finnegan, R.J. 1977. Establishment of a predacious red wood ant, Formica obscuripes (Hymenoptera: Formicidae) from Manitoba to eastern Canada. Can. Ent. 109: 1145-1148.
Ghilarov, M.S. 1965. [Zoological methods of soil diagnostic.] Moscow, Nauka. 278 pp. (In Russian, English summary).
Gregson, J.D. 1956. The Ixodoidea of Canada. Can. Dep. Agric. Pub. 930. 92 pp.
Holland, G.P. 1949. The Siphonaptera of Canada. Can. Dep. Agric. Tech. Bull. 70. 306 pp.
Kevan, D.K. McE. 1979. Chilopoda. pp. 296-298 in H.V. Danks (Ed.), Canada and its insect fauna. Mem. ent. Soc. Can. 108. 573 pp.
Lindsey, C.C., E.L. Bousfield, and I.A. McLaren. 1970. Animal systematics exclusive of insects. pp. 1-60 in K.C. Fisher (Ed.), Panel reports of the study of basic biology in Canada. Biol. Counc. Can. and Sci. Counc. Can., Feb. 1970: Panel 4.
McNeil, J.N., J. Delisle, and R.J. Finnegan. 1978. Seasonal predatory activity of the introduced red wood ant, Formica lugubris (Hymenoptera: Formicidae) at Valcartier, Quebec, in 1976. Can. Ent. 110: 85-90.
Rocket, C.L. 1980. Nematode predation by oribatid mites (Acari: Oribatida). Int. J. Acarol. 6: 219-224.
Tomlin, A.D. 1979. Protura. pp. 299-300 in H.V. Danks (Ed.), Canada and its insect fauna. Mem. ent. Soc. Can. 108. 573 pp.
Vickery, V.R. and D.K. McE. Kevan. (in press). The orthopteroid insects of Canada and adjacent territories. The insects and arachnids of Canada, Part. Agric. Can. Pub.
This brief was developed by a
subcommittee of the Biological Survey: V. G. Marshall (Chairman), D. K. McE. Kevan,
Published by The Entomological Society