Extermination of wildlife
From 1951, tsetse control in the area of Bunyoro-Kitara in Uganda adopted radical methods, which instead of focusing on the flies, sought extermination of their mammalian hosts. The experiments initially involved shooting only large hoofed animals, while sparing smaller ones such as antelopes and pigs. Robertson and Bernacca12’ report that along a narrow strip of land between the Nile and Sezibwa in Uganda, the wild game killed included 293 buffalo, 69 hippopotami and 2,178 other animals. In Acholi in Uganda, the host of Q. morsitans is the rhino. Although shooting of these animals was initially resisted by the authorities, when eventually allowed, it was claimed that fly populations had dropped. Before this destruction of game in Acholi, the concentration of Q. moristans had extended for about 48 km from Gulu in northern Uganda; by 1945, the species had been eliminated from that part of the country at the cost of killing 855 buffalo and 10,128 smaller animals. The systematic destruction of the game resulted in the disappearance of Q. morsitans which had displaced human settlement from 305,775 of the 333,134 km2 of country in Tanganyika, and approximately 38,624 km2 in Uganda. Following further destruction of game in Shinyanga in Tanganyika, the adjoining Narok area of Kenya, and from Uganda, Q. swynnertoni and Q. morsitans were eradicated at least in the short term.124
From 1954, the Trypanosomiasis Research Committee was firm that there were no alternative methods to the destruction of game if the tsetse was to be controlled effectively. The systematic extermination of the game (large and small) had been completed by 1956.121 The report of the Commission was empathic that ‘the destruction of game should continue for at least a few years,’ and should be combined with greater control of development pro- grams in the tsetse-infested areas.126 Yet, what was being reported as ‘sue- cesses’ were short-term outcomes and, in the majority of cases, the situations were reverted with the return of the flies and the game to the areas from where they had reportedly been eliminated. Furthermore, tsetse control continued to frustrate the authorities. In January 1955, an official of the tsetse survey and control program reported his desperation as follows: ‘I fear that we will not achieve much by clearing.’12. The reasons given were the vastness of the areas, lack of funds, lack of staff, and the extensiveness of tsetse infestations beyond the riverine forests. Researchers and technical departments disappointed by the repeated bush clearing and game destruction, then placed their hopes in the application of pesticides for tsetse control.
The application of pesticides
In the area of Fort Victoria on the Kenyan side of the lake, the vegetation was subdivided into blocks to concentrate the flies; some blocks were sprayed with insecticide and the control areas were left without treatment. The costs of pesticide spraying between 1933 and 1943128 are shown in Figure 8.2. The spraying experiments were followed by tsetse fly catching by the ‘fly boys.’ The plots were repeatedly sprayed with DDT, which reduced the fly density and the catches then dropped in numbers.129 Increasing the dosage by 80 percent eliminated the flies. The implication was that in the short term, the use of insecticides was effective.1,0 However, considering that the pesticides entered the environment and passed along the food chain, their persistence in the ecology of the area and effects on biotic systems remained unknown.
Elsewhere in Africa, experiments with DDT had also been successful in controlling tsetse flies in the short term,131 by reducing their numbers considerably.132 In the Lake Victorian Basin, Q. palpalis was reduced by 99 percent. The spraying methods were costly, however, varying from £500 to £1,000 per km2. The costs of aerial spraying worked out at £200 to £300 per river kilometer in 1952.133 In Uganda, the Colonial Pesticide Unit sprayed the islands of Lake Victoria with DDT and benzene hexachloride, reducing the population densities of the tsetse. Aerial and ground spraying
Figure 8.2 Annual costs of aerial sprays of DDT for tsetse fly control.
of insecticides was used widely in sections of the Nyando River from 1952 to 1955. The sprays reduced the fly density but did not eliminate them.134 Meanwhile, the areas along the lake shore and the Yala River continued to experience tsetse infestations. Consequently, about 120 km of the vegeta- tion in these areas was sprayed. About 454 liters per km of Dieldrex was applied at a total cost of £2,430 for spraying only one-third of the planned area.135 In spite of all the efforts to eradicate it, the tsetse fly continued to have dire impacts on the pastoral economy.