Trypanosomiasis in Zululand and the control of tsetse flies by chemical means

Abstract

1. The distribution of Nagana and its importance as a limiting factor in the development of the livestock industry in Africa are stressed. 2. The relationship between the tsetse fly belt within the Union of South Africa and those occurring in Portuguese East Africa is discussed, emphasis being laid upon the isolation of Glossina pallidipes in the Union. 3. Within Zululand the range of dispersion of G. pallidipes, G. brevipalpis and G. austeni, occupying approximately 7,000 square miles, have been plotted and the breeding areas accurately determined. 4. The bionomics of the Glossina spp., in Zululand and the dominant role of G. pallidipes in the causation of epizootics of Nagana are dealt with. 5. The cyclical appearance of Nagana epizootics at fairly regular intervals of approximately ten years and theories attempting to explain this phenomenon are considered. 6. Methods of survey for establishing the relative density of adult and immature flies are dealt with and their merits in arriving at a conception of the biotope of the different species discussed. 7. The preliminary investigations and the methods finally adopted for the application of DDT and BHC, together with the technique employed for the eradication of G. pallidipes over the entire, and G. brevipalpis in a localized area of Zululand, are described in detail. 8. The value of bush clearing as an important aid in the control of tsetse flies and the manner in which it was used in Zululand are pointed out. 9. Costs connected with the application of the procedures actually employed are compared and attention is drawn to the potentialities of the methods advocated following the experience gained. 10. The possible application of the methods used in Zululand to the eradication of at least some Glossina spp., in other parts of Africa is discussed. 11. In view of insufficient knowledge regarding methods of survey the practical eradication of G. austeni requires further investigation. Its elimination from the Union necessitates international co-operation, which would also be necessary in the case of G. brevipalpis on the international border with Portuguese East Africa. 12. The direct and indirect effects of mass applications of insecticides to extensive areas of bush upon the fauna and flora are considered.