Aspects of the biology of horse flies and deer flies (Diptera:Tabanidae) in subarctic Labrador : larval distribution and development, biology of host-seeking females, and effect of climatic factors on daily activity

• Main Author: McElligott, Paul Edward Kaye
• Other Authors: Lewis, David J. (advisor)
• Format: Thesis
• Language: English
• Published: McGill University 1992
• Subjects: Horseflies > Newfoundland > Labrador; Deerflies > Newfoundland > Labrador; Newfoundland; Subarctic
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41037

Larval tabanids were collected twice weekly from eight locations in Iron Arm fen, a peatland in subarctic Labrador near Schefferville, Quebec, June through August, 1990 and 1991. Of the 476 tabanid larvae collected, 82.7% were Chrysops (5 spp.), 17.0% were Hybomitra (5 spp.), and 0.3% were Atylotus sphagnicola Teskey; the most abundant species in the fen were C, zinzalus Philip (31%), and C. nigripes Zetterstedt (24%). Species- and genera-specific microhabitat preferences were apparent; in general Chrysops spp. preferred drier regions of the fen than did Hybomitra spp. Larvae of C. zinzalus and C. nigripes appear to require 3-4 years to complete their larval development in subarctic regions, based upon their patterns of seasonal growth. Adult horse flies and deer flies were collected using canopy and Malaise traps at two locations in the Schefferville area, Iron Arm fen and Capricorn fen, from late June until early August in 1990 and 1991. Seventeen tabanid species were collected, six Chrysops spp., 10 Hybomitra spp., one Atylotus sp.; Hybomitra spp. comprised 96% of collections. Adult abundance of different species varied markedly between the two study sites; in general Iron Arm fen had a more abundant and diverse tabanid fauna than Capricorn. For each of 10 tabanid species, samples of 10 flies were taken from daily trap catches for dissection and determination of parity, yolk deposition, and fat body deposition. In the Schefferville area, H. arpadi and H. aequetincta are obligately anautogenous, H. lurida and H. zonalis are facultatively autogenous, and H. pechumani, H. hearlei, H. frontalis (Walker), H. astuta (Osten Sacken), C. zinzalus and C. nigripes are obligately autogenous. Based upon gonotrophic age-grading of nulliparous individuaIs, the majority of H. aequetincta and H. arpadi females emerge either at the beginning of the flight season, midway through the season, or both, depending upon year and site. Most H. zonalis emerge midway through the flight season. Nulliparous female tabanids of anautogenous or facultatively autogenous species usually carry considerable amounts of fat body within their abdomens. The effect of meterological variables on tabanid daily activity was investigated using a canopy trap incorporating an electronic insect counter, a computerized data-logger, and sensors to measure air temperature, solar radiation, wind speed and direction, and relative humidity. (Abstract shortened by UMI.)