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Eradication of the tsetse fly Glossina palpalis gambiensis from the Niayes in Senegal

Place: senegal, Africa
Sustainable development of small rural communities Sustainable development of small rural communities
Total Budget: € 6.400.000,00 | Period: From January 2005 To

Summary

The aim of the project is to create a zone free of the tsetse fly Glossina palpalis gambiensis in the Niayes of western Senegal that would result in the sustainable removal of the debilitating livestock disease trypanosomosis. The removal of the tsetse fly and the disease would pave the way towards the development of more efficient livestock production systems. As the tsetse population of the Niayes proved completely isolated from the remainder of the tsetse belt in eastern Senegal, the Government of Senegal selected “sustainable eradication” as the strategic approach to reach that goal. The removal of the tsetse fly and the disease would greatly benefit the local farmer community as they would be able to replace their local unproductive cattle breeds by more productive exotic breeds. The benefits of the program for the local farmer community were estimated at Euro 2.8 million per year, concurrent to a 45% reduction of the cattle population and associated positive environmental impact.

Partnership

Directorate of Veterinary Services - Senegal

Lead applicant

Responsible for national animal health services using epidemiological surveillance, prophylactic and curative treatment of livestock diseases, application of the national animal health policy, liaison with regional and international institutes. For the project: DSV was involved in the initial discussions with the FAO/IAEA at the origin of the project. They pointed out the trypanosomoses problem in the Niayes area and the will of the Senegalese government to start a control project. They were then responsible for the overall coordination of the project and lead the monthly coordination meetings of the coordination unit. The veterinary staff of the DSV in the field was also involved in the preliminary studies (feasibility phase), the implementation of suppression and the monitoring of the impact of the project, including socio-economic and environmental impacts.

Senegal Institute for Agricutural Research - Senegal

Initiative partner

The mandate of the ISRA is the development and implementiton of research programmes on agriculture, forestry, animal health and rural economy. For the project, ISRA was included in the project at a very preliminary stage, and was responsible of the operational research component. It was part of the coordination team and participated in the implementation of adaptive management. It was responsible for most of the operations during the feasibility phase. ISRA also hosted the dispersal center for pupae and was responsible for the releases of sterile males and the monitoring of their impact. ISRA also produced scientific papers from the project activities.

French Agricultural Research Centre for International Development - France

Initiative partner

CIRAD is a public industrial and commercial enterprise (EPIC) under the joint authority of the Ministry of Higher Education and Research and the Ministry of Foreign Affairs. CIRAD works with the whole range of developing countries to generate and pass on new knowledge, support agricultural development and fuel the debate on the main global issues concerning agriculture. CIRAD is a targeted research organization, and bases its operations on development needs, from field to laboratory and from a local to a global scale. In the project CIRAD was involved in the training of staff, provided expertise, conducted operational research with ISRA. Moreover, CIRAD is a member of the coordination unit and provides statistics using the online relational database i.e. feedback from the monitoring systems. CIRAD is also hosting this database and participated to the dissemination of scientific and public information. One CIRAD staff (J. Bouyer) is based at ISRA since 2008 to support the operational research component of the project and a second one (G. gimmoneau) is based at ISRA since march 2014, with 50% of his time dedicated to the project.

Joint FAO/IAEA Division of Nuclear Technique in Food and Agriculture (International Atomic Energy Agency and Food and Agriculture Organisation of the United Nations) - Austria

Initiative partner

The Insect Pest Control Sub-programme of the Joint FAO/IAEA Division has the mandate to assist Member States with areawide control or eradication of major insect pests of crop and livestock by developing and integrating the Sterile Insect Technique with other methods. The aim is to reduce the use of insecticides, to reduce animal and crop losses, to protect the environment and to facilitate international trade in agricultural commodities

The aim of the project is to create a zone free of the tsetse fly Glossina palpalis gambiensis in the Niayes of western Senegal that would result in the sustainable removal of the debilitating livestock disease trypanosomosis. The removal of the tsetse fly and the disease would pave the way towards the development of more efficient livestock production systems. As the tsetse population of the Niayes proved completely isolated from the remainder of the tsetse belt in eastern Senegal, the Government of Senegal selected “sustainable eradication” as the strategic approach to reach that goal. The removal of the tsetse fly and the disease would greatly benefit the local farmer community as they would be able to replace their local unproductive cattle breeds by more productive exotic breeds. The benefits of the program for the local farmer community were estimated at Euro 2.8 million per year, concurrent to a 45% reduction of the cattle population and associated positive environmental impact.

The main innovation was the extensive use of scientific principles to develop and implement a sound environmentally friendly eradication strategy following the phased conditional approach, i.e. the implementation of each phase of the project was conditional upon completing all the activities of the previous phase (1: Government strategic decision, 2: base-line data collection and feasibility studies, 3: pre-operational activities, 4: operational programme activities). A combination of tools such as remote sensing, geographic information systems, mathematical modelling, population genetics were used to assess very accurately the distribution, degree of isolation and the dynamics of the fly population.. It is expected that the concept of total population control will result in the sustainable eradication of the targeted tsetse fly population using a combination of 4 control tactics, including the sterile insect technique. 

Study on tsetse distribution The suitability of the vegetation for harbouring tsetse after a phytosociological study and wet areas as obtained from a supervised classification

Food security and safety remains a serious concern in Africa in general and in Senegal in particular. In the last century the human population in West-Africa has increased tenfold, and is expected to triple by 2050. The expansion of current agricultural production practices will not allow feeding this exploding population. The Niayes area is located along the Atlantic coast of Senegal and has particular meteorological and ecological characteristics that provide great potential for animal production. Intensified livestock production systems with improved breeds were only found on 1% of the farms before the project. Unfortunately, this microclimate also favours the presence of Glossina palpalis gambiensis, a riverine tsetse species that is a vector of African animal trypanosomosis. The permanent removal of the tsetse fly is considered the most efficient way of eliminating the disease and would remove the main obstacle for the development of more effective livestock production systems. 

Phase 4 of the project started in 2010 in the first, most northern of the 3 blocks of the target area. The tsetse population was reduced by 90% using insecticides on traps and livestock followed by weekly releases of sterile males, first from the ground and later by light aircraft (a gyrocopter). The last wild fly was trapped in April 2012 in this area and monitoring is to date still continuing. In late 2011, the project advanced to Block 2 where more than 1000 insecticide impregnated traps were deployed using a Maxent distribution model to select preferential habitat sites. Aerial releases of sterile males were started in January 2014 and are gradually expanding over Block 2. Fly population reduction in Block 2 is already > 95%. The drastic reduction of the fly population in Block 1 and 2 is evidenced by the prevalence of AAT in cattle: it has decreased from 40-50% before the project started to < 10% to date. 

Aerial release of sterile males The use of the newly developed aerial release machine installed in a gyrocopter for the aerial release of sterile male flies
Dispersal centre in Dakar The fly dispersal centre in Dakar receives every week thousands of sterile male pupae from Burkina Faso and Slovakia. The pupae emerge in the dispersal centre and are prepared for the release in the target area.
Insecticide impregnated trap These traps have been used in the project for prior suppression of the fly population. More than 1000 of these have been deployed in Block 2 of the target area.
Monitoring trap These traps have been used for sampling tsetse to assess their distribution, to assess their population dynamics and to monitor the progress of the project.

The main beneficiaries of the project are the many small holder farmers, the larger commercial farms and the consumers of meat and milk that would be able to consume a cleaner product. The expanding human population around the Dakar area is resulting in increased demands in meat and milk production, a need that currently cannot be satisfied by the local farmers. A socio-economic survey and benefit-cost analysis found that farms outside the tsetse-infested area produced 38% more milk, 64% more meat, and sold 2.8 times more livestock than similar farms in the tsetse-infested area. The survey estimated that there were 90,000 resident cattle in the Niayes area. After eradication of the tsetse, farmers will be able to replace their local breeds with exotic breeds at a rate of 2–10 % a year, and finally increase their annual income by Euro 2.8 million. In addition, it is expected that the number of cattle will be reduced by 45%, which will result in reduced environmental impacts.

Farmers that are the beneficiaries of the project Farmers will signficantly benefit from the removal of the tsetse fly from the Niayes
Heatlhy cattle Healthy cattle outside of the tsetse infested area in Western Senegal

The programme is implemented by the Division of Veterinary Services of the Government of Senegal (general manager: Dr Baba Sall) and employs 10 field staff, who are responsible for the implementation of the field monitoring, veterinary surveys, and the fly suppression activities. The project is scientifically supported by the Senegal Institute for Agricultural Research (Dr Momar Seck) to provide scientific advice, to operate the fly dispersal centre in Dakar (receipt of the sterile pupae, managing emerging flies) and to guide the aerial releases (5 staff). The project is technically and financially supported by the Joint FAO/IAEA Programme of Nuclear Techniques in Food and Agriculture (Dr Marc Vreysen) and the Department of Technical Cooperation of the IAEA (Ms Fatin Mohamed). The Centre de Coopération Internationale en Recherche Agronomique pour le Développement has deployed on site a tsetse ecologist (Dr Jeremy Bouyer) who provides scientific and technical support to the project.

Area-wide integrated pest management programme that have an SIT component are complex and management intensive undertakings. Their success depends upon continuous interactions between essential components of pest suppression. The main challenge in the programme in Senegal has been to ensure that all the elements of the project were properly planned, that ample training was given in the beginning of the programme, that ample time was taken to conduct and complete the base line and feasibility studies and that all the elements of the operational phase were implemented as scheduled. This required optimised interaction, daily communication, mutual understanding of problems, an attitude towards “problem solving”, the need to compromise, to prioritise etc. between all stakeholders of the project (DSV, ISRA, CIRAD and the FAO/IAEA). This was achieved through frequent email exchanges, telephone and video conferences, regular local and international meetings. 

The removal of the tsetse fly will have a very significant positive impact on the environment. Although insecticides are being used for fly suppression, they are applied for short periods on traps, nets and livestock, and are not spread into the environment. The release of sterile insects is one of the most environmentally friendly insect pest control tactics, as the target insect is being suppressed by sterile counterparts reared in the laboratory that have no offspring potential. Moreover, farmers are currently holding large numbers of unproductive cattle putting high pressure on a fragile ecosystem that is already fragmented. Replacing these with more productive breeds will result in fewer cattle kept per surface unit. The removal of trypanosomosis will eliminate the need for constant prophylactic treatments of the cattle with trypanocidal drugs, therefore reducing residues of these drugs in the dung, meat and milk. 

Tsetse habitat and small vegetable plots The ecosystem in the Niayes is very fragile and under severe pressure from many unproductive cattle. Much of the original vegetation has already disappeared. The elimination of tsetse will allow the introduction of more productive exotic cattle so that less cattle are required per surface unit.

The eradication of the tsetse population from the Niayes will be sustainable as population genetics studies have indicated that the Niayes population is isolated from the main tsetse belt in eastern Senegal. There is a gap of 100 km of sahelian vegetation, without any favourable habitat between the Niayes and the nearest tsetse population, so the potential of reinvasion is non-existing. The development and implementation of the eradication strategy following the phased conditional approach is a model example for other projects in Africa. This is especially relevant in view of the PATTEC (Pan Africa Tsetse and Trypanosomosis Eradication Campaign) initiative that was launched a decade ago by the African Heads of State. 

The results of the campaign have been and continue to be disseminated through:
1. academic papers published in peer reviewed journals
2. The Insect Pest Control Newsletter
 http://www-naweb.iaea.org/nafa/ipc/public/IPC-NL-83.pdf
http://www-naweb.iaea.org/nafa/ipc/public/IPC-NL-81.pdf
http://www-naweb.iaea.org/nafa/ipc/public/IPC-NL-79.pdf
 

3. Websites and press releases

http://www-naweb.iaea.org/nafa/news/2014-tsetse-senegal.html
http://www.fao.org/news/story/en/item/211898/icode/
http://www.sciencedaily.com/releases/2014/07/140717094947.htm
http://www.parasitesandvectors.com/content/pdf/s13071-015-0869-3.pdf (published in Parasites & Vectors. This paper describe the methods developed to transport sterile males as pupae over long distance.

../file-system/small/pdf ../file-system/small/pdf Benefit-cost analysis of the tsetse eradication This paper published in PLOS NTD provides a cost benefit analysis of the eradication. It shows the potential increases of cattle sales as a result of tsetse elimination considering two scenarios, i.e. a conservative scenario with a 2% annual replacement rate from traditional to improved systems after tsetse elimination, and a more realistic scenario with an increased replacement rate of 10% five years after elimination. The final annual increase of cattle sales was estimated at ~€2800/km2 for a total cost of the elimination campaign reaching ~€6400/km2.
../file-system/small/pdf ../file-system/small/pdf Long distance transport of irradiated male Glossina palpalis gambiensis paper: “Long distance transport of irradiated male Glossina palpalis gambiensis pupae and its impact on sterile male yield” published in Parasites & Vectors
../file-system/small/pdf ../file-system/small/pdf Mating performance of Glossina palpalis gambiensis strains This paper, published in Entomologia experimentalis and applicata describes mating studies and confirms mating compatibility between the strain used for release (from Burkina Faso) and the target strain in Senegal.
../file-system/small/pdf ../file-system/small/pdf New aerial release machine This paper, published in the journal PLOS ONE describes a new aerial release machine specially designed for the release of chilled adult sterile males tsetse at low densities. The machine is now routinely used in Senegal for the aerial releases of tsetse.
../file-system/small/pdf ../file-system/small/pdf Population genetics of tsetse in Western Senegal This paper published in PLOS Neglected Tropical Diseases describes a study that used 3 different markers (microsatellite DNA, mitochondrial COI DNA, and geometric morphometrics of the wings) and revealed that the G. p. gambiensis populations of the Niayes were genetically isolated from the nearest proximate known population of Missira in eastern Senegal.
../file-system/small/pdf ../file-system/small/pdf Stratified entomological sampling This paper in the Journal of Medical Entomology describes the stratified sampling protocol that was used to assess the distribution of the tseste fly population in the Niayes, and provides the results of this study.
../file-system/small/pdf ../file-system/small/pdf The prevalence of African animal trypanosomosis in the Niayes This paper published in the journal Parasite describes the prevalence of the disease in the livestock population in the Niayes and its correlation with tsetse presence. The mean serological prevalence of the disease was 28% for Trypanosoma vivax and 4.4% for T. congolense.
../file-system/small/pdf ../file-system/small/pdf Tsetse flies: their biology and control This review paper was published in the Jounral of Invertebrate Pathology and provides an overview of the biology, control options and the principles of area-wide integrated pest management. It puts the entire Senegal project in a proper context.
../file-system/small/pdf ../file-system/small/pdf Using species distribution models to optimize vector control This paper published in PNAS describes a study using distribution models to optimize control operations. The probability of tsetse presence and habitat suitability was assesed using a regularized logistic regression and a Maxent model. Maxent predictions were then used to make operational activities of the eradication campaign in the Niayes more efficient in terms of the selection and deployment of ITT, the release density of the sterile males, and the location of monitoring traps used to assess programme progress.