Movement and distribution of tsetse flies in Nguruman, South-western Kenya

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Siziya, Seter
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The work covered in this thesis was carried out between March 1988 and March 1991 in Kenya. The first 8 months of this 3-year study period was spent on compulsory course work and developing a research proposal under the African Regional Postgraduate Programme in Insect Science at the International Centre of Insect Physiology and Ecology. Field work commenced in November 1988 with a training on mark-release-recapture experiments.The study area is in the Rift Valley province of Kenya. It lies east of the Nguruman escarpment which runs down into woodland opening out into plains. Seasonal rivers run down the escarpment. The area north of the waterpipe line, hereafter called free or northern or uncontrolled zone, is the statistical control area; while the area in which flies are being continuously trapped, hereafter called suppression or controlled or southern zone, lies south of the waterpipe line.The project was aimed at studying the reinvasion of tsetse flies into a suppression zone in Nguruman, south-western Kenya. It was originally planned that the study should cover two suspected sources of reinvasion: the top of the escarpment and the northern area. The track leading to the top of the escarpment was almost impassable and we succeeded in reaching the top of the escarpment on only three occasions. Therefore, observations on reinvasion of tsetse flies into the suppression zone are mainly those on fly movement from the northern zone.Though detailed ecological studies were started for both Glossina pallidipes and G. longipennis with a view to modelling the movement and distribution of these two species at Nguruman, we have more confidence in the results for G. pallidipes than for G. longipennis. because catches of G. longipennis were generally very low. Partly the density of G. longipennis was low and partly the traps were inefficient for G. longipennis. The automated Delta-T weather station was only installed in July 1989. Climatic data for the period January 1989 to June 1989 was taken from the wet and dry, minimum and maximum thermometers and thermo-hydrograph kept in a Stevenson screen.Data entry, analysis and report writing was done on an IBM compatible personal computer using Lotus 123, dBase III, StatGraphics, SAS, CRIES and Microsoft Word.Should the reader wish to re-analyse the data, raw data of small data sets are presented in the appendix, and the rest of the data is available on request.