oa Journal of East African Natural History - Distribution and host-specificity of a number of fleas collected in South and Central Kenya
During the years 1963-1966 a collection of fleas was made by various members of the Department of Zoology of University College, Nairobi (UCN). This collection was mainly based on Dr. J. B. Foster's trapping of small mammals, and on the fieldwork of Dr. J. B. Sale with hyrax. Some specimens, however, were collected occasionally from road kills and other incidental mammalian hosts. The collection culminated with the work of the University College Mount Kenya Expedition in March 1966. The collection was mounted and identified by members of the Division of Insect-Borne Diseases (DIBD), Medical Department, Kenya, and a number of specimens were sent to Mr. F. G. A. M. Smit, Zoological Museum, Tring, England, for confirmation of identification. The present records of distribution and host-specificity are of interest for a variety of reasons. Fleas only spend their adult life in intimate contact with the mammalian host, the larva is a free living insect, feeding on proteinaceous detritus. It is, therefore, to be expected that fleas will be mainly found on those mammals which have permanent dwelling sites, and particularly on nest or den building animals. This is the immediate effect of the need of a freshly emerged adult flea to contact a new host. Flea eggs deposited in a nest or den have a much higher chance of developing into adults within the immediate reach of a new host than flea eggs deposited at random in the field. One other consequence of this necessity of the flea to locate a host within its life time after larval development away from the host, is a dependence on the climate. It is, thus, to be expected that within the fairly narrow geographical confines of Kenya a number of flea species will be restricted to particular altitudinal levels in response to a climatic adaptation, even when suitable hosts are available at other altitudes. Alternatively, one would expect to find fleas restricted to particular hosts at one altitude, and to other hosts at another altitude, this in response to the combined effect of climate and nesting habits of different hosts. This form of ecologically based isolation could well become the basis of speciation.
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