From: ASSESSMENT OF SPECIES DIVERSITY IN THE MIXEDWOOD PLAINS ECOZONE

DRAGONFLIES AND DAMSELFLIES

P. M. Catling, R. Hutchinson and B. Ménard

3. RESEARCH BACKGROUND

3.1 General Information

3.1.1 Mixedwood Plains

A relatively good knowledge of the Odonata of this ecozone is attributable to the extensive works of R. Hutchinson (eg. Hutchinson & Larochelle 1977a, b), A. Larochelle (eg. 1978), B. Ménard (eg. 1996), A. Robert (eg. 1963) and E. M. Walker (eg. 1935, 1941, 1953, 1958; Walker & Corbet 1975). A complete outline of the contributions of University of Toronto Professor E. M. Walker is available in Wiggins (1966). Walker's work in Ontario, and particularly in southern Ontario provides a valuable benchmark for the evaluation of change (Catling 1997, Catling & Brownell 1997), but Walker (1935) also contributed to knowledge of Odonata in Quebec. Currently the growing interest in Odonata has resulted in the recognition of the need to make Walker's classic texts available through reprinting (Toronto Entomologist's Association). An Ontario atlas of his published Zygoptera records (Catling & Brownell 1997) has recently become available.

The compilation of Pilon et al. (1992) brought together a wealth of distributional data for the Quebec portion of the ecozone and provides a useful list of references. A list of references on dragonflies for Quebec from1871 to 1979 was produced by Hutchinson ( 1979). A publication concerning the dragonflies of Quebec is nearing completion. The simplifiesd identification manual produced by Hutchinson and Larochelle (1977) vastly increased the number of people able to contribute to research on Odonata in Quebec and surrounding regions. Dragonflies have been extensively treated in two journals originating from Quebec; "Cordulia" and "Fabreries". The former was produced by R. Hutchinson and A. Larochelle from 1975 to 1981 and featured work on dragonflies and other groups of insects such as carabid beetles, but with emphasis on the former. Fabreries, currently in its 23 volume, is the publication of the amateur entomologists of Quebec.

3.1.2 Surrounding US regions including the Mixedwood plains

The Mixedwood Plains extends into the adjacent states (from east to west) of Vermont,

New York, Pennsylvania, Ohio and Michigan. In most cases the knowledge of occurrence of damselflies and dragonflies is equivalent to that in Ontario. For Vermont the work of White and Morse (1973) covering the adjacent state of New Hampshire is useful. In addition for the New England area generally there is "Ode News" available on the web (http://www.capecod.net/~bnikula/onv4n1.htm). For New York the recent work of Donnelly (1992) provides a standard reference, which lists 177 species and subspecies including 54 damselflies and 123 dragonflies. With regard to Pennsylvania there is the older work of G.H. and A.F. Beatty (1968, 1969, 1971a, 1971b), with recent additions by C. Shiffer (eg. 1974).

The standard reference for the Odonata of Ohio is the recent report of Glozhober (1995a), which with recent additions (Glotzhober et al. 1995b), lists 156 species and subspecies including 50 damselflies and 106 dragonflies. The Ohio Odonata Survey was initiated in 1990 . By 1995 it had accumulated 15,000 records based on specimens in collections.

For Michigan Kormondy's catalogue is helpful, but even more useful and current is the "Michigan Odonata Survey Collector's Handbook" (O'Brien et al. 1997) which includes an introduction to the Michigan Odonata Survey, a list of references for the Great Lakes region, terminology and identification aids, as well as a current atlas which includes 42 damselflies and 113 dragonflies. The Michigan Odonata Survey web site is http://insects.ummz.lsa.umich.edu/michodo/mos.html. The Michigan Survey also has a specimen based database and produces the newsletter "Williamsonia".

3.1.3 General Information

The Dragonfly Society of the Americas (2091 Partridge Lane, Binghamton, New York 13903) produces the news journal "Argia" (9 volumes to 1997) and "Bulletin of Odonatology" (4 volumes to 1997), both of which contain valuable information. Argia in particular is an important communication network, and almost every issue includes important news and observations relating to the Mixedwood Plains ecozone. The international journals "Odonatologica" and "Notulae Odonatologicae" (the latter for shorter articles) are produced by International Dragonfly Society (Societas Internationalis Odonatologica or S.I.O, c/o the International Odonata Research Institute, P. O. Box 147100, Gainesville, Florida 32614-4700). To a lesser extent journals covering many aspects of entomology have included information on the Mixedwood Plains ecozone (Canadian Entomologist, Proceedings of the Entomological Society of Ontario, etc.). A comprehensive review of general biology of dragonflies is available in Corbet (1962, 1980).

Many web sites feature a great deal of information on damselflies and dragonflies. These have been reported in a regular column in Argia called "Tramea" (a name of a genus of dragonflies that is derived from the latin meaning "web"). Some of the best sites (with numerous links and relevant to the Mixedwood Plains) include:

(a) The odonate information network: http://www.afn.org/~iori/

(b) Illinois Odonata database: http://www.museum.state.il.us/research/entomology/od_db.html

(c) Paulson's: http://www.ups.edu/biology/museum/UPSdragonflies.html

(d) Ohio: http://mcnet.marietta.edu/~odonata/species/odospec.html

(e) ODE News: http://www.capecod.net/~bnikula/onv4n1.htm

(f) Michigan: http://insects.ummz.lsa.umich.edu/michodo/mos.html

The Royal Ontario Museum (Toronto), Agriculture Canada in Ottawa (Biological Resources Division) and the International Dragonfly Society are able to assist researchers in locating and accessing information.

3.2 SPECIES

3.2.1 Systematics and identification

Some work has recently been done on the most perplexing taxonomic problems within the ecozone, but this has involved the US portion. With respect to Enallagma cyathigerum and Enallagma vernale, Donnelly (1989) decided that the latter cannot be considered more than an ecological and partly geographic subspecies of the former, but additional work is desirable (Donnelly 1996). Also notable is the classification of Enallagma westfalli as a subspecies of E. traviatum (Donnelly's 1973).A few new species have been discovered over the past few decades some of which potentially relate to Canada (eg. Vogt & Smith 1993), and even recently a new species of dragonfly was discovered in the Canadian Maritime Provinces (Neurocordulia n. sp.). The only recently described species that may occur in the Mixedwood Plains Ecozone is in the genus Zoreana (Carle 1983) and its status requires more study. The recently described Sympetrum janeae has been reported from ecoregion 133, the Frontenac Axis (Carle 1993), but is not admitted to our list pending further taxonomic study.

Also among other recent advances, are several descriptions of previously undescribed immature stages of rare and poorly known species such as Williamsonia fletcheri (Charlton & Cannings 1993) and several damselflies (Westfall & May 1996) including Coenagrion interrogatum (Cannings & Cannings 1980), Calopteryx amata (Tennessen 1984), and Lestes inaequalis (Westfall & Tennessen 1973.

Until a field guide (currently in production) is completed, the standard texts have to be used but a few simpler regional identification tools have been produced. The identification manual produced by Hutchinson and Larochelle (1977) is very useful for the more northern parts of the ecozone. A visual key for quick identification of Sympetrum species is available in Kielb (1996, appendix 3), and Carle (1993) has also produced a key to Sympetrum. Keys to American Octogomphines were produced along with the description of Lanthus vernalis (Carle 1980). Recently produced keys to adult and larval Ophiogomphus species (Cook & Daigle 1985, Carle 1992) are also relevant to workers in the Mixedwood Plains ecozone.

Lists for portions of the ecozone have been produced by several researchers (see below under "regions"). Some of these have also added several species to Walker's classic works and significant range extensions have also been reported individually (eg. Hutchinson 1989, Burke 1996).

3.2.2 Biodiversity patterns

Within the ecozone the three large ecoregions have a roughly similar number of species (Table 1), but composition does change substantially, the southern ecozones having southern species that do not range northward (Fig.2 & Fig.3), and the northern ecozone having northern species that do not range southward. The relatively small number of species listed for ecoregion 133 is probably mostly a result of inadequate data since a great diversity of habitats are available in this small area.

The number of species, presence and density of dragonflies at any particular site is controlled by complex patterns of predators and prey as well as other environmental factors such as pH and water quality. For example the presence or absence of fish has a significant effect on the presence and densities of species of dragonflies (Bendell & McNicol 1995). Some species such as the Azure Bluet (Enallagma aspersum) are largely confined to shallow ponds lacking fish and turtles, but the pH of their shallow pond habitats can vary from acid to alkaline (pers. obs). In a sample of 19 south-central Ontario lakes of variable pH, Pollard and Berrill (1992) found that the number of species of dragonflies present in a lake was not significantly correlated with lake pH. However, the assemblage of species was related to pH with 7 of 37 species restricted to lakes with a pH of less than 6.2. Some species such as Lestes unguiculatus are characteristic of temporary pools. Odonate biodiversity is evidently closely related to the diversity of water bodies in eastern Ontario townships where presence or absence of gravel pit ponds and rivers has a major effect.

Pilon et al. (1988) reported 37 species including 18 damselflies and 19 dragonflies from an old, abandoned gravel pit pond near Montreal. In a study of eastern Ontario gravel pits, Catling & Brownell (1998) reported 25 damselflies from a total of 41 pit ponds, this representing 70% of the eastern Ontario damselfly fauna. The relatively high diversity in pit ponds may be attributed to both the diversity of conditions found in gravel pit ponds and the generalized habitat requirements of many species. Although many damselflies and dragonflies are not narrowly specialized, at least 15-25% are, and notably several species in genera such as Gomphus, Stylurus, Ophiogomphus, and Somatochlora do have specialized habitats.

3.3 REGIONS

In the western portion of ecoregion 135, the Lake Erie lowland, in the counties of Essex, Kent and Lambton, Pratt (1997b) reported 37 damselflies and 61 dragonflies. Twenty damselflies were reported for Middlesex by Catling & Brownell (1997). Also in the western portion of the ecoregion, Stewart & Carmichael (1993) reported 29 damselflies and 30 dragonflies for Elgin County.

Within smaller areas of a few to several square kilometers, similar to somewhat smaller numbers have been encountered. A compilation of the records for Cook Bay, Lake Simcoe, based on data collected over almost 50 years by E.M. Walker, whose summer cottage was located at De Grassi Point, included 28 species of damselflies (Catling & Brownell 1997). Pratt (1997a) found 20 damselflies and 31 dragonflies in the Ojibway Prairie complex south of Windsor. Falls (1996) recorded 18 damselflies and 28 dragonflies from Long Point on the central north shore of Lake Erie.

The first list of dragonflies for the Ottawa area (central Ottawa valley) in the northwestern arm of ecoregion 132, was published in 1908 (Walker 1908). It remains one of the best known areas of the Mixedwood Plains Ecozone. Currently there are 119 species including 32 damselflies and 87 dragonflies (listed by Ménard 1996, including Enallagma aspersum and E. civile recently discovered). A few of the species may be more characteristic of the adjacent uplands of the Mixedwood Shield and drift down fast-flowing rivers into the lowland areas of the Mixedwood Plains.

Although Algonquin Park is north and west of the boundary of the Mixedwood Plains Ecozone, it is not far outside. It is however, a region of higher elevation and is much more boreal in character. The dragonflies of this region are relatively well known and it provides an interesting comparison for the Mixedwood Plains, especially the portion to the south. Holder (1996) listed 85 species, including 20 damselflies and 65 dragonflies, but there have been a few recent additions. The second Algonquin Park Odonate count took place on 6 July 1997. It involved 27 observers and a 15 mile diameter count circle centered on Rutter Lake in Sproule Twp. A total of 3157 individuals were recorded including 55 species (Jones 1997, 1998). Sixty species have been recorded within the count area.

3.4 BIOLOGY AND ECOLOGY

3.4.1 General

Over the past several years research mostly conducted in the eastern Ontario part of the ecozone has extended knowledge of odonate biology and also provided new insights into other research areas, particularly host-parasite interactions (e.g. Forbes & Baker 1990, 1991). Parasitism of Enallagma ebrium males by water mites was found to have the effect of reducing male competitiveness for access to females which is energetically expensive (Forbes 1991). In another study covariation of factors was found to lead to reduced fitness of parasitized individuals (Forbes & Baker 1991)

Research on colour morphs has also produced interesting results. Green as well as blue females of E. boreale have been associated with the advantage of avoidance of harassment by males of E. ebrium (Forbes 1991). Occurrence of male-like female morphs of N. irene was found to be positively correlated with density of males (Forbes et al. 1995). Other studies have shown that female colour may be a selectively neutral trait (Forbes &Teather 1994).

Several studies have increased our knowledge of the behaviour and ecology of certain poorly known species, such as the work of Hutchinson & Ménard on Erythemis simplicicollis (1993a), Libellula incesta (1994a), Neurocordulia yamaskensis (1994c), Ophiogomphus anomalus (1994b), Stylogomphus albistylus (!993b), Stylurus spiniceps (1992), and the work of Hutchinson on Argia moesta (1993), Dromogomphus spinosus (1993), Erythemis simplicollis (1991a), Gomphus furcifer (1991b), and Stylurus spiniceps (1993). Pilon and others have reported on several ecological studies relating various factors to activity of different species (e.g. Pilon et al. 1989, Pilon & Pilon 1994). Trottier (eg. 1967, 1971) has documented the effects of temperature on certain migratory species. Species concentrating in large numbers at various locations on the north shore of Lake Erie during an apparent late summer southward movement were discussed by Corbet & Eda (1969). True migration of dragonflies has also received attention with some interesting results (eg. Dumont & Hinnekint 1973). Bick & Bick (1980) produced a useful bibliography reproductive behaviour in North American Zygoptera.

Studies in adjacent US portions of the ecozone have also contributed substantially to knowledge of the biology of the Odonata. For example Duffy's (1994) study of the demography of Lestes disjunctus disjunctus contains a great deal of data and provides a useful basis for further demographic work. McMillan (1996) recently made some interesting observations on tandem oviposition in Sympetrum vicinum in New York State and speculated that it may be interpreted as a strong mate investment where males face intense competition for females. A prolonged pre- copulatory tandem phase supports this hypothesis, but there are other possibilities (Catling & Brownell 1997b).

3.4.2 Importance of Odonata

The importance of dragonflies and damselflies as an essential layer of the predator-prey food pyramid is well known, but they are an important group in many other ways as evidenced by the attention focussed on them by protective agencies such as the Nature Conservancy. Recent studies have shown that Odonate larvae are an important food for ducks, particularly on acidic lakes (e.g. Bendell & McNicol 1995b). Although acidity of water bodies is not as much of an issue in the Mixedwood Plain as it is in the Canadian Shield region to the north, species of Enallagma and Ischnura are considered to be acid-tolerant (e.g. Rutherford & Mallow 1994).

Dragonfly and damselfly nymphs may be of substantial value as indicators of water quality as more information on their distribution and biology becomes available.