The ecology of black flies (Diptera: Simuliidae) in the Scottish Highlands in relation to control
Black flies (Diptera: Simuliidae) are one of the most medically and economically important groups of insects. In Africa and Central America they are the primary vector for Onchocerciasis (River Blindness). In the holarctic region they cause significant losses in meat production and are a serious medical and nuisance problem due to their biting activities. In Britain the nuisance problem asssociated with black fly biting activity is localized to Dorset and the Scottish Highlands where this study was carried out to identify the pest species, investigate their ecology and to determine possible control measures. Four species were observed biting humans; Simulium reptans, S. tuberosum, S. argyreatum, and S. variegatum of which S. reptans was the most important. The factors affecting their distribution and abundance in the egg, larval, and adult stages were investigated in the field. Possible control measures derived from these field studies are discussed. Feeding biology was studied using video and microscope observations and enviromental factors affecting ingestion rates, and feeding behaviour noted. Bioassays using Bacillus thuringiensis var. israelensis were carried out in the laboratory using a trough maintenance system. The effect of various factors on the efficacy of this bacterial insecticide are discussed in relation to its possible use in the field.