Insect vectors and avian blood parasites with particular reference to insular Newfoundland

Coombs, Richard Frank (1974) Insect vectors and avian blood parasites with particular reference to insular Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

An extensive survey of 14,360 North American birds showing their parasite prevalence and a study of Newfoundland ornithophilic Diptera to determine the incidence of hematozoa in the local avifauna is presented. -- The overall infection rate of 55.6% within the North American birds is shown to be concentrated primarily in the passeriform birds and particularly in four families, i.e. Icteridae, Fringillidae, Parulidae and Turdidae. Similarly, the specific blood protozoa which are accountable for the bulk of the infected birds are Leucocytozoon and Haemoproteus. The incidence of Plasmodium, as determined from numbers of infected birds, is of secondary importance in this study. -- A stratification performed on the various bird families and species, based on their nesting sites, indicates that the bulk of the infection occurs in the mid canopy levels of the forest environment. A similar situation is observed in the marsh habitats in that there is a higher infection rate among birds whose nests are generally elevated above the marsh surface. -- Collections of ornithophilic Diptera (Simuliidae and Ceratopogonidae) from three test sites in Newfoundland verifies that the preferred habitats for these vectors is the 10-15 ft. strata in the woodland environment. Testing over a three year period (1970, 1971 and 1972) indicated a much reduced biting fly population in the Newfoundland area in comparison to Algonquin Park, Ontario where similar studies had been conducted. The numbers of vector species involved are also noted to be limited. The Hippoboscidae are not considered to be vectors of Haemoproteus in Newfoundland. -- Examination of the infected glands and hindguts of the ornithophilic Diptera indicated a relatively high incidence of Leucocytozoon transmission, a much lower incidence of Haemoproteus infection and an almost insignificant Plasmodium transmission. With the exception of hippoboscids all vectos were observed to harbour trypanosomes. -- A survey of the Newfoundland avifauna verified the parasite prevalence as determined from the laboratory examination of the glands and hindgut of the ornithophilic Diptera. The stratification of the birds supported the premise that most birds became infected in the mid canopy levels, despite some special characteristics of the Newfoundland situation. -- It is suggested that in Newfoundland there is a highly developed host-parasite-vector relationship of exceptional efficiency.

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