Preliminary studies on the biting flies (Nematocera-brachycera) attacking cattle in Newfoundland

McCreadie, John William (1983) Preliminary studies on the biting flies (Nematocera-brachycera) attacking cattle in Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

The seasonal occurrence and abundance, host-seeking activity, and blood-feeding behaviour of the species of biting flies attacking cattle in Newfoundland was investigated using a newly designed cattle-baited trap. A Trueman-McIver Segregating CO₂ trap was also employed to provide additional information during times when the cattle-baited trap was not in operation. -- A total of 19,682 female biting flies (26 species) were collected in the cattle-baited (11,407) and CO₂ (8, 275) traps, from May 25 to September 16, 1982. Simuliids were the most abundant family collected (cattle-baited trap = 10,747; CO₂ trap = 7773) comprising 94.1% of the total season’s catch. The remaining families of biting flies, mosquitoes, tabanids and sand flies, contributed little to the population, comprising only 5.9% of the total season’s catch. Sequentially mosquitoes (Family: Culicidae) and black flies (Family: Simuliidae) were the first to appear followed by the sand flies (Family: Ceratopogonidae) and finally the tabanids (Family: Tabanidae). -- Prosimulium mixtum, most common in June and S. venustum/verecundum complex, most numerous in July, were the two most abundant black flies collected and the only two biting flies taken in numbers sufficient to adequately study host-seeking activity and blood-feeding behaviour; limited information remaining species was obtained. The host-seeking activity of P. mixtum was usually restricted to the morning and afternoon, whereas S. venustum/verecundum complex was most active in the morning and evening. Preliminary results suggest that although the host-seeking activity of P. mixtum and S. venustum/verecundum complex was greatly suppressed by wind speeds, temperatures, saturation deficiences and light intensities outside of certain ranges, such factors do not account for most of the variation observed in the number of these simuliids collected in the cattle-baited trap. -- Mean temperature over the previous 24 hours appeared to greatly influence the blood-feeding behaviour of both groups, with changes in temperature showing a strong positive relation with changes in the proportion of blood-feds taken in the cattle-baited trap. The present temperature, mean temperature over the previous 24 to 48 hours, and light intensity might have had some influence on blood-feeding, but saturation deficit and wind speed appeared to have none. -- The cattle-baited trap designed for this study is an effective method for the study of host-seeking activity and blood feeding behaviour of at least simuliids under field conditions.

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