Livestock Disease Control and the Changing Landscapes of South-West Ethiopia, by Reid R.S., Thornton P.K. & Kruska R.L., 2001.
The book Agricultural Technologies and Tropical Deforestation (eds Angelsen, A. & Kaimowitz. D., 2001) CAB International, contains Chapter 15 (pp. 271-290), Livestock Disease Control and the Changing Landscapes of South-West Ethiopia, by R.S. Reid, P.K. Thornton and R.L. Kruska. The following is an extended summary of that chapter.
The chapter looks at the ways in which the control of trypanosomiasis in cattle and other livestock affects the rate of agricultural expansion and the areas affected. Given that the book of which this chapter is a part is concerned especially with deforestation, the authors point out that trypanosomiasis control and its effects cut across ecological zones, as well as vegetation types, and it can be argued that trypanosomiasis control can affect agricultural expansion in a variety of landscapes in the African scene.
While the emphasis is on Ethiopia, other locations are also referred to. It is believed that controlling trypanosomiasis can promote the expansion of agriculture, but in some places other additional factors come into play. It is suggested that there are six broad factors to be considered in this context: (i) the agroecological conditions and the strength of the disease constraint; (ii) land availability; (iii) the type of technology and its likelihood of adoption; (iv) accessibility and functioning of markets; (v) farmer characteristics; and (vi) culture.
A review of how trypanosomiasis has shaped African landscapes follows. It is pointed out that in the pre-colonial era, farmers would control the tsetse by burning late in the growing season; the people lived in dense settlements that had few or no fly. When the vagaries of the climate allowed tsetse to re-infest settled areas, migration of the cattle and their owners might be forced upon them, a situation that exists even today. The broad picture shows that people and their livestock settle in areas where tsetse are absent or few, avoiding the tsetse belts extending over great swaths of the land. In the case of Ethiopia, farmers keep away from the lower-lying areas and the riverine forests which are tsetse infested.
Ormerod argued strongly that tsetse control, leading to trypanosomiasis control, would lead to severe overgrazing of the Sahel, accelerating desertification and climate change. More recently, it has been argued that human population pressure, through bush clearing and the like, itself influences the rate of agricultural expansion, and is more important than trypanosomiasis control. More recently still, several studies have employed remote-sensing techniques and/or oral history/farmer recall to investigate how tsetse and trypanosomiasis control have influenced the extent of cropping and grazing.
Remote sensing techniques have several times revealed that tsetse and trypanosomiasis control was not the most important factor; such studies have been conducted in Nigeria (Lafia District), northern and central parts of Côte d'Ivoire, Galana Ranch and Nguruman in Kenya, and in the mid-Zambezi Valley. In contrast, a study in the Ghibe Valley in which several factors were allowed for, revealed that contraction of farmland was caused by the increased severity of trypanosomiasis at that location. Emigration of farmers from the area as well as the inability of the farmers to adequately plough the land, were also noted.
Oral history/farmer recall studies have been carried out especially in Ethiopia and Burkina Faso. According to interviews in Didessa Valley, and separately in Ghibe Valley, Ethiopia, increases in disease severity led to decline in cattle numbers, loss of land under cultivation, and decline in milk production. Oxen were more productive in tsetse-free areas compared with those in tsetse-infested ones. However, other factors can also be important in such situations and should be allowed for, such as changes in land tenure, drought, and changes in land settlement patterns. Allowing for these possibilities can be difficult in practice. In Somalia one study suggested that tsetse eradication had no effect on farmers' use of draught cattle. The type of livestock held can be influenced by trypanosomiasis; more cattle may be held in areas that have low disease risk, in comparison with the livestock kept in high risk areas; this has been shown in Ghibe Valley, Ethiopia, also in The Gambia and in Burkina Faso.
Trypanosomiasis control in Ghibe Valley
Suppression of trypanosomiasis in the Ghibe Valley, Ethiopia, and its effects, are now dealt with. There are three tsetse species present: Glossina morsitans submorsitans, G. pallidipes and G. fuscipes; the last species is regarded as being less important as a vector of cattle disease than the other two. The study area supports relatively little agriculture compared with the long-settled largely tsetse-free highlands. According to farmers' reports, tsetse appeared in the valley in the early 1980s, and aerial photographs showed that a high proportion of the cultivatable land was lost to agriculture after the advent of trypanosomiasis. Tsetse control started in 1990 with a small target campaign, later switching to a pour-on technique using a cypermethrin formulation. Tsetse control is regarded as a labour-saving, but capital-intensive, technology. If successful, it allows farmers to bring under cultivation larger tracts of land. Livestock production increases, and crop yields are increased due to greater effectiveness of the healthier draught cattle. By 1997, analysis of satellite imagery revealed that cultivation had expanded, mainly at the expense of wooded grassland. Loss of tree species and tree cover were not great, and would also be mitigated by later tree planting (hedgerows, woodlots) by farmers. Should farmers start to cut back the riparian forest, this would be expected to have a negative effect on wooded species abundance and diversity.
Predictions
To predict agricultural expansion, a simple model was devised based on farmers' preferences for the different land-use options available, and the resulting economic returns that might be expected, based on expected production, input costs and location (distance from market, infrastructure). Farmers stated that they preferred to live at higher elevations, to avoid tsetse and mosquitoes, even though the greater fertility of the lower soils was recognised; the government in 1986 relocated farmers into small villages; farmers preferred slightly sloping land as the soil is easier to work by hand. These were the main factors determining farmers' preferences. On the hypothesis that the distribution of land use could be predicted on the basis of the physical nature of the landscape as well as farmers' preferences, three simulated land use models were drawn up for 1973, 1993 and 1997, for the Gullele/Toley area, and compared with the actual land use. These simulations were linked in the following way. Land use was modelled for the situation in 1973; then these results were used to predict the land use pattern in 1993, taking into account important government policy shifts in the meantime, which pushed people away from the forest margins and the riparian forest; finally the land use pattern was predicted for 1997, taking into account the changes brought about by the control of trypanosomiasis. For the 1997 model in particular, it is now possible to see the way in which successful tsetse control encouraged people to move into land at relatively low elevation, and to penetrate points closer to the rivers.
Lesson learned
We now return to the six main factors mentioned at the outset that tend towards extending land use in the direction of agriculture, following successful trypanosomiasis control:
Agroecological conditions and the strength of the disease constraint
In south-western Ethiopia, the main constraint on the opening up of more agricultural land is animal traction; on these grounds one can expect trypanosomiasis control to be beneficial to the process. The effect may be greatest in areas of heavy soil, for which animal traction is specially required. In contrast, in an area of south-western Burkina Faso, migrant farmers were mainly driven by the search for pasture and water.
Land availability
It can be conjectured that technological progress (in this instance, trypanosomiasis control) in land-extensive systems leads to agricultural expansion, whereas the same type on progress in the context of land-intensive systems may not lead to such expansion, though it may bring about greater productivity.
Type of technology and benefits
Pour-on techniques are not labour-intensive, and have both public and private benefit to farmers. Use of therapeutic drugs requires little labour input and gives private benefits to farmers, but drug resistance reduces its effectiveness. Traps and targets are more labour-intensive and deliver mainly public benefits. Aerial and ground spraying campaigns are beneficial to the farming community but expensive for the government. It is suggested that the most successful control programmes take the form of pour-ons with or without input from other techniques.
Accessibility and functioning of markets
In the Ghibe Valley, farmers are able to respond quickly to the opportunities to increase the area under cultivation by using increased levels of animal traction made available by trypanosomiasis control. Animal traction can itself be traded, thus opening opportunities for widespread increases in ploughing. In areas where these conditions do not prevail, increase in agriculture following trypanosomiasis control may be less marked. In yet other areas, it may be immigrant farmers who are the first to introduce the ploughing of land freed by trypanosomiasis control. Unfortunately, marketing may be poorly developed in such areas, reducing the positive effects of disease control.
Farmer characteristics
In general, poorer farmers will be less able that richer ones to respond to the opportunities presented by disease control.
Cultural practices
Tradition is important in determining the ways in which the farming community will respond to new opportunities. Pastoralists will increase the size of their herds; mixed farmers will plough more land; those without relevant traditions of settled agriculture may in contrast be slower to seize the chance to use oxen to plough more land.
Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture and FAO/IAEA Agriculture and Biotechnology Laboratory, Siebersdorf: Notice of some recent and forthcoming events and projects
Fourth and Final Research Co-ordination Meeting, "Application of genetics to improve the SIT for tsetse" 23-27 June, 2003. Edmonton, Alberta, Canada.
Consultants' meeting on "Development of guidelines for verification of tsetse fly free areas", August, 2003. Vienna, Austria.
Regional East Africa Training Course on Establishing National GIS Capacity for Ongoing and Planned Tsetse/Trypanosomosis Intervention Campaigns, February/March 2003 Addis Ababa, Ethiopia.
First Research Co-ordination Meeting relating to a new Co-ordinated Research Project (CRP) "Improved and Harmonized Quality Control for Expanded Tsetse Production, Sterilization and Field Application", 15-19 September 2003. Montpellier, France. This new CRP is designed to meet the requirements for the harmonization and improvement of existing ad hoc measures for the rearing of tsetse flies in colonies. One result of the CRP should be the production of a quality control manual similar to the one that has been published for the rearing of tephritid fruit flies. It is anticipated that the research will be concerned with seven areas: quality control protocols for reproductive behaviour; colony maintenance; tsetse fly diet; fly handling, transporting and release; field quality control protocols for released flies; and standardised facilities, equipment and materials for quality control. The CRP is expected to run for five years, 2003-2007.
The Entomology Unit, Seibersdorf, Austria, report the following developments in tsetse research and development. Mating compatibility tests were conducted between two strains of the tsetse species Glossina pallidipes. One of the strains was a recently initiated laboratory line from Ethiopia, and the other was a well established Seibersdorf line from Uganda. There was no indication of any mating incompatibility between these two strains; shipments of the Uganda strain were made from Seibersdorf to the breeding facilities in Tanga, with a view to building up a large colony for future transfer to Ethiopia.
Similarly, mating compatibility tests were conducted between strains of Glossina palpalis gambiensis, one from Bobo-Dioulasso and the other from the Niger River Basin in Mali. It was concluded that there was mating compatibility between the males of the Bobo-Dioulasso strain and females of the Niger River Basin strain.
Improvements are being tested for a transportable fly rearing system that can be manufactured in advance and rapidly installed where it might be needed. Injection-moulded netting cages are also being tested for use in the tsetse production units.
A consultant has been appointed to investigate the effect of the salivary gland hypertrophy virus on colony performance. The transmission and distribution of the virus will be followed, with a view to establishing a virus free strain of Glossina pallidipes.
Possible effects of high-frequency sound made by the male G. pallidipes on mating success are to be investigated. Wild and laboratory-bred insects will be used, and the study will be extended to other tsetse species.
The extent of multiple mating by female tsetse flies is under investigation, as multiple mating might have an adverse effect on the sterile insect method of control. Females of three species were given a second chance of mating two days after the first, and immediately thereafter dissected for the presence of a spermatophore, and the levels of sperm from the first mating recorded. Rates of remating were found to be very low.
DFID-AHP meeting on "Tsetse Control - The Next 100 Years", 9-10 September 2002, Edinburgh, Scotland
The reaction of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture to this important meeting is summarised in the following paragraphs, which are necessarily of a provisional nature, given that at the time of their publication is ahead of the publication of the official conclusions by the meeting organizers (see Insect and Pest Control Newsletter No. 60, January 2003).
The majority of participants reached general consensus on various issues, namely:
1. That "eradication" basically stands for the long-term political vision and the strategy for implementation will aim at initiating tsetse and trypanosomosis intervention in identified priority areas with high potential for sustainable agriculture and rural development.
2. That initial "small-scale" (20 000-35 000 km2) efforts at creating tsetse fly free zones in the PAAT/PATTEC identified priority intervention areas will likely result in highest possible benefits and should therefore be supported.
3. That the two unique features of SIT as a component of area-wide Integrated Pest Management are widely recognised viz. firstly that it is the only technique with no known adverse effects on non-target organisms, and secondly that it has greater efficiency when used against lower target population densities, and it is best applied following other intervention techniques.
Serious levels of Sleeping Sickness in Uganda
Tsetse flies have spread to 70 percent of the territory of Uganda, putting 5.1 million people at risk of catching sleeping sickness. This was revealed by the Minister of State for Animal Industry Mary Mugenyi when she opened a one-day sensitization workshop for district leaders in Kampala, according to a report from the Monitor Newspaper. Mugenyi said in her written speech that the tsetse flies and the diseases they cause are spreading to areas that were formerly free of such diseases, adding that sleeping sickness and nagana were spreading to Kumi, Soroti and Kaberamaido districts in the eastern part of the country, where they had not been known before.
The human disease is fatal if it is untreated and causes abortions, sterility, and other gynaecological problems among women, the Minister said. She said 40 percent of cattle in Uganda are at risk of catching nagana, adding that the government is fighting the disease, but is being hampered by lack of sufficient funds.
A communication of the PAAT Secretariat announces that at the meeting of the Programme Committee of PAAT held November 2002 at the WHO headquarters, Geneva, the process to replace Professor Peter Holmes as Chairman, which started in Nairobi at the PAG meeting in September, was concluded with the unanimous election of Professor Albert Ilemobade as the new Chairman. Professor Ilemobade was first introduced to Tsetse and Trypanosomiasis (T&T) in 1969 by the Dutch group of scientists in Ahmadu Bello University, Zaria, immediately following his appointment to the Faculty. His research interest has spanned the areas of epidemiology and chemotherapy of animal trypanosomiasis as well as tick-borne diseases. For many years, he served nationally on Nigeria's highest Livestock Development Committee and continues to be involved in research and field programmes on T&T, having attracted research funds for work on tick-borne diseases and animal trypanosomiasis from EU and other international organizations. Professor Ilemobade has served on several Expert Panels of FAO relating to research on tick-borne diseases and vectors, education, and the ecological and technical aspects of the Programme for the Control of African Animal Trypanosomiasis and Related Development. He has also served as Special Adviser to the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases and as Consultant to the IAEA on T&T. In 1987, Professor Ilemobade was elected Chairman of ISCTRC having served on the Executive Committee since 1979. From November 1988 he was Vice-Chancellor of the Federal University of Technology, Akure, retiring from this post in January 1996. For the last three years Professor Ilemobade has served as Senior PAAT Adviser.
In the same communication from the PAAT Secretariat, the Secretariat thanks Peter Holmes for his immense contributions to the nurturing, growth, sustenance and success of PAAT. In recognition of this and in an effort to keep benefit from his good services, the PAAT Chairman and the members of the PAAT Secretariat have agreed that Professor Peter Holmes remains on PAAT as Senior Programme Adviser.
