14. The Zambezi Valley has been identified as one of the areas of very high potential erosion hazard in Zimbabwe (Whitlow, 1988). To date there is little evidence that environmental degradation is more severe here than elsewhere in Zimbabwe (World Bank, 1986; Whitlow, 1988), and indeed Whitlow (1988) points out that there is a very poor correspondence between potential and actual erosion at a national level. However, he asserts that the extension of settlement in the communal lands behind a retreating tsetse-fly frontier is likely to promote widespread degradation.
15. The environmental consequences of land use change following tsetse control in the Zambezi Valley are of deep concern not only to local conservation agencies (Greaves, 1985; Anon., 1987) but also to the Veterinary Department and the EEC, who are presently funding a Regional Tsetse and Trypanosomiasis Control Programme (RTTCP) covering Zimbabwe, Zambia, Mozambique and Malawi. This project was established in 1985 following an earlier feasibility study (PTA/Minster, 1983) with a view to the possible tsetse eradication in the common fly belt covering these four countries. In 1988 two land use studies 2 specifically relating to the RTTCP have been funded by the European Economic Community (EEC), one of which was jointly funded by the International Union for Conservation of Nature and Natural Resources (IUCN). It is understood that while neither consultancy considered that tsetse control should be discontinued in the Zambezi Valley, both underlined the need for greater attention to land use issues.
16. One of the central concerns is that, if overstocking with cattle were to occur in the Zambezi Valley, it could result in extensive environmental degradation. Land use plans recommend carrying capacities for different categories of land but commonly these stocking levels bear little relation to what communal farmers perceive as appropriate. Unless the difference between planned and desired cattle ownership can be reconciled, land use plans will require a level of control of communal farming which will be objectionable to farmers. Such plans may therefore prove impracticable, particularly in a political milieu where communities are being encouraged increasingly to make decisions for themselves.
17. In examining the case for and against tsetse control in support of rural development it should be borne in mind that tsetse control is not necessary to allow introduction of livestock: in much of the tsetse-infested communal areas farmers are already keeping cattle, goats and donkeys. In areas of low trypanosomiasis challenge farmers either accept the losses due to morbidity and mortality or use trypanocidal drugs on their cattle. Those areas where there are no cattle are largely areas where the Veterinary Department has prohibited cattle ownership for strategic reasons relating to animal disease control, or where trypanosomiasis challenge is very high.
18. While it cannot be argued that introduction of livestock into newly settled areas is dependent on tsetse control, it is certainly the case that removal of the tsetse fly promotes livestock production. Where there is a real concern about likely overstocking, then it may well be justified to argue against tsetse control until everything possible is being done to ensure that subsequent land use will be sustainable.
19. What is the evidence concerning the likely sustainability of traditional farming systems in the Zambezi Valley, and what are the alternatives to tsetse control in support of sustainable rural development? Sufficient consideration has not yet been given to the questions of whether overstocking will actually occur in the Zambezi Valley, and if so, what can be done about it.
