Spatial distribution of female Tabanidae and Simuliidae (Diptera) among different terrestrial habitats in central Newfoundland

Graham, Jeri L. (1992) Spatial distribution of female Tabanidae and Simuliidae (Diptera) among different terrestrial habitats in central Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

The spatial distribution of female Tabanidae and Simuliidae among terrestrial habitats was investigated during June-July of 1988 and 1989 in central Newfoundland. Tabanid collections from modified Manitoba and Box traps consisted predominantly of Chrysops species (>93%) with a much lower proportion of Hybomitra species. The four most common species in both years were C. excitans, C. frigidus, C. furcatus and C. zinzalus. In blackfly collections, sampled using dry-ice-baited sticky traps or a combination of landing counts and sweep netting, there was a predominance (>95%) of Eusimulium euryadminiculum, an ornithophilic species; Simulium venustum/verecundum complex and Prosimulium mixtum were also present. -- Tabanids were collected from five different habitat types: black spruce forest, fen, bog, regrowth and dirt road. Tabanid abundance was generally lowest on the bog and road, in 1988, and lowest on the regrowth and road in 1989. In both years, tabanids were most abundant in the fen. Factors affecting spatial distribution, including distance from larval habitat, dispersal ability of adults and presence of nectar sources or hosts in a habitat are discussed, as well as the effect of trapping methods on relative abundance and species composition. -- Of the four most common tabanid species, C. excitans and C. furcatus appeared to locate the traps more efficiently in open habitats while C. frigidus and C. zinzalus were trapped most often in a wooded habitat. Clearing of forested land during clear-cut logging operations will likely cause a shift in species composition from the preferentially sylvan species to those preferring open habitats. -- Blackflies were collected from three different habitats: fen, woods and regrowth area. These collections support the idea of habitat preferences for some species of biting flies, since blackflies, almost exclusively Eusimulium euryadminiculum, were trapped primarily in the fen and rarely in the woods.

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