Ground beetles: Beller’s ground beetle (Agonum belleri)
(Arthropoda: Insecta: Coleoptera: Carabidae: Harpalinae) Profile prepared by Sarah Foltz, The Xerces Society for Invertebrate Conservation
Agonum belleri is a wetland-dependent ground beetle species endemic to the Pacific Northwest. It is known from sea level to high elevation mountain areas where it occurs in acidic Sphagnum bogs in forested regions, particularly floating mats of Sphagnum immediately adjacent to open water. Threats to this species include habitat destruction from urban development, logging, water-level alteration, peat-mining, pesticide application, and livestock grazing and trampling. Logging and development may be the most serious threats to individual populations of this species, as a substantial number of bogs have been destroyed by these two activities. Global climate change may also threaten populations by altering bog water levels and seasonal duration periods. Known sites of this species should be managed to protect water quality and quantity as well as the surrounding plant community.
A member of the Carabidae (ground beetle) family, this species is distinguished as follows: 6.0 – 7.5 mm (0.24 – 0.29 in.) in length; narrow body; metallic color, typically coppery-bronze, but may reflect green or blue; antennae densely pubescent; elytra striate, punctured and pubescent (Johnson 1979). The even covering of bristles on the dorsal surface is one of the most distinguishing characteristics to use when identifying this species in the field, and is most apparent when the insect is back lit, or held under a hand lens in oblique light (J. LaBonte in Martin 2003). Although there is another Agonum species possibly found in the region (A. melanarium), it is unlikely to be found sympatrically with A. belleri, as it prefers dryer habitats (Johnson 1979).
The technical description of this species is as follows: Above shining aeneous or virido-aeneous. Head impunctate; antennae black, pubescent from apical half of third segment; head through eyes wider than apex of pronotum. Pronotum nearly three-fifths as long as wide; side arcuate, feebly oblique behind; margin reflexed, narrowly so in front, more widely so behind; the foveae of hind angles large, their outer edge formed by the reflexed margin; pronotum smooth, impunctate, except for the side margin and the basal foveae which are densely rugose; mid-dorsal impressed line attaining neither base nor apex, crossed by an evident impressed line toward apex. Elytra very finely microreticulate with evident humeri, very feebly wider behind middle; the striae impressed, finely punctate; the first (sutural), third, fifth, and seventh interstriae more or less densely set with coarse seta-bearing punctures, the second interstriae with from four or five to a dozen punctures, the fourth interstria rarely with one or two punctures. Venter and legs viridescent, shining, finely alutaceous, impunctate; second to fifth visible abdominal sternites with single seta-bearing punctures on either side of the middle towards the hind margin. Protarsal segments feebly dilated and squamose beneath (male) or unmodified and simply setose beneath (female) (Hatch 1933).
Expert determination is suggested to confirm field identifications.
Adults breed in the spring, and lay eggs which hatch into larvae that complete development by late summer. Larvae have not been collected or studied. Adults are collected in spring and summer months, April through September. Adults probably live less than a year. Adults will eat seeds, scavenge plant and vegetable material, and prey on small invertebrates. Larvae probably do not eat seeds and may be more specialized on invertebrates (Bergdahl 1997). Invertebrates taken from Drosera may be an important food resource (Bergdahl 1997). The species is constantly brachypterous and flightless (Lindroth 1969), and is quite active on Sphagnum bogs. It overwinters in upland habitat around wetlands (Bergdahl 1997).
Range-wide: This Pacific Northwest species was historically known from approximately seven Sphagnum bogs in northern Oregon, western Washington, and southwestern British Columbia. An extensive 1997-1999 survey for this species in Sphagnum bogs between northwest Oregon and southwest British Columbia increased the number of known populations to ~25, including the first records in many Puget Sound counties, the mainland of British Columbia, and Vancouver Island (unpublished data, Bergdahl 2008, pers. comm.). Patches of suitable habitat are small and scattered throughout range, and abundance estimates are not available for existing sites.
Washington: Known records are from Skagit, Snohomish, King, Kitsap, and Mason Counties (Bergdahl 1997). Although the species was believed to be extirpated from the Washington type locality (Chase Lake) due to suburban residential development (Applegarth 1995), recent surveys (1996-1997) by James Bergdahl have revealed low numbers of this species (Bergdahl 2009, pers. comm.).
Oregon: In Oregon the species has been found at two sites: Bear Springs in Wasco Co. where the population may now be extinct, and Little Crater Lake in Clackamas Co. where the population faces serious threats from humans and livestock (Applegarth 1995, LaBonte 1995). The species may be more widely distributed in Oregon than is documented (Applegarth 1995), and surveys of potentially suitable habitat for new populations may be promising.
Federal Land: This species is documented on Mt. Hood National Forest (Bear Springs in Wasco County (one specimen collected in 1942), and Little Crater Lake Meadows near Timothy Lake, Clackamas Co. (1982)) (LaBonte 2006, pers. comm.). It is probably present on Mt. Baker/Snoqualmie National Forest, and possibly present on Olympic and Gifford Pinchot National Forests.
Acidic Sphagnum bogs in forested regions are the primary habitat for this species. It tends to be found in floating mats of Sphagnum immediately adjacent to the open water of bogs and lakes (Johnson 1979). Marginal habitat includes small patches of Sphagnum at springs and in the backwaters of streams, as well as bogs that are in late stages of succession (becoming meadows) (Gray and Hatch 1941, Hatch 1953, Leech 1935, Lindroth 1969, LaBonte 2006, pers. comm., Kavanaugh 1992). In addition to Sphagnum species, such as S. magellanicum and S. sqaurrosum , this beetle is often found in association with certain plants, including Eriophorum polystachion, Drosera rotundifolia, Eriophorum polystachion , and Vaccinium oxycoccos (Johnson 1979, LaBonte 1995). The species is known from sea level to high elevation mountain areas (~1005m, 3300 ft.) (Applegarth 1995, LaBonte et al. 2001). At sites with a moisture range, individuals are only found in the wettest areas (Bergdahl 1997, Maynard 2004).
One example of A. belleri habitat is the Kings Lake Bog in Washington, which is surrounded by a forest of Acer macrophyllum, Alnus spp., Abies spp., Tsuga heterophylla, Thuja plicata and Pseudotsuga mensiesii . The ecotone consists of dense thickets of Ledum glandulosum and Kalmia occidentalis with sparse, short (less than 5 m tall) Thuja and Tsuga, and an understory of Sphagnum, reindeer lichen and associated plants including Sphagnum magellanicum, S. sqaurrosum, Eriophorum polystachion, Drosera rotundifolia, Vaccinium oxycoccos, and a few large rushes. The Sphagnum within a few meters of the water at this site is devoid of all but evenly distributed Eriophorum and abundant Drosera (LaBonte, 2006 pers. comm.).
Inventory: Conduct surveys in suitable habitat near known locations.
Management: Manage known sites to protect water quality and quantity as well as the surrounding plant community. Surveys of potentially suitable habitat for other populations, fencing of the sphagnum areas, manually eliminating or reducing encroaching meadow vegetation to retain open sphagnum, and conducting non-destructive demographic surveys of the Little Crater Lake population have all been recommended (LaBonte 1995).
Applegarth, J. S. 1995. Invertebrates of special status or special concern in the Eugene district. U.S. Department of the Interior, Bureau of Land Management. 126 pp.
Bergdahl, J. 2008. Personal communication with Sarah Foltz, Xerces Society for Invertebrate Conservation.
Bergdahl, J. 2009. Personal communication with Sarah Foltz, Xerces Society for Invertebrate Conservation.
Bergdahl, J.C. 1997. Endemic Sphagnum bog beetles from the Puget Sound Region: Kings Land and Snoqualmie Bogs, King Co., Washington. Unpublished report for Northwest Biodiversity Center.
Gray, B. and M.H. Hatch. 1941. The Coleoptera of Washington. (Carabidae: Agonini). University of Washington Publications in Biology. 10 (1,2,3,): 1-144.
Hatch, M.H. 1933. Notes on Carabidae. Pan-Pacific Entomologist. 9(3): 117-121.
Hatch, M.H. 1953. The beetles of the Pacific Northwest. Part I: Introduction and Adephaga. University of Washington Press, Seattle, 340 pp.
Johnson, P.J. 1979. Report on a survey for Beller’s ground beetle on the North Fork Snoqualmie River, King Co. WA. Report to the US Army Corps of Engineers. 19 pp.
Kavanaugh, D.H. 1992. Carabid beetles (Insecta: Coleoptera: Carabidae) of the Queen Charlotte Islands, British Columbia. Memoirs of the California Academy of Sciences. No. 16. 113 pp.
LaBonte, J.R. 1995. Possible threatened or endangered terrestrial predaceous Coleoptera of the Columbia River Basin. Report prepared for Bureau of Land Management and U.S. Forest Service, Upper Columbia River Basin Ecosystem Management Project. 31 pp.
LaBonte, J.R., D.W. Scott, J.D. McIver, and J.L. Hayes. 2001. Threatened, endangered, and sensitive insects in Eastern Oregon and Washington forests and adjacent lands. Northwest Science. 75: 185-198.
LaBonte, James. 2006. Personal communication with John Fleckenstein.
Leech, H.B. 1935. British Columbian records of Carabidae and Hydrophilidae. Pan-Pacific Entomologist. 11(3): 120-124.
Lindroth, C.H. 1969. The ground-beetles (Carabidae, excl. cincindelidae) of Canada and Alaska. Parts 1-6. Berlingska Boktryckeriet, Lund, Sweden. 1192 pp.
Martin, R. 2003. Final Report: Analysis Species Assessment: Beller’s Ground Beetle (Agonum belleri). Unpublished Work, Puget Sound Energy, Inc. Relicense study T-4, FERC Project No. 2150.
Maynard, C. 2004. Unpublished report on carabid beetles at Sheehan Lake. 11 pp.
NatureServe. 2008. “Agonum belleri.” NatureServe Explorer: An online encyclopedia of life [web application]. Feb. 2008. Version 7.0. NatureServe, Arlington, Virginia. 15 Dec. 2008 .