In the coastal Niayes zone of Senegal, meat and dairy production is set to increase substantially in the coming years. This is a boon for the region, which is home to 80% of the country's population. It is thanks to the eradication of the infamous tsetse fly, due to be officially announced on Saturday 8 December by Senegalese President Macky Sall. CIRAD was invited to the ceremony, having been involved in the eradication alongside ISRA, Senegalese veterinary services, the Senegalese Ministry of Agriculture and the Joint FAO-IAEA Programme Nuclear Techniques in Food and Agriculture.
An obstacle to development of the livestock sector
Tsetse flies transmit parasitic diseases: trypanosomiases. In humans, they cause "sleeping sickness", which can be fatal if left untreated. In cattle, the infection causes reduced fertility, weight loss and sometimes death. Tsetse flies are a substantial obstacle to development of the livestock sector throughout sub-Saharan Africa, including in Senegal, where 80% of the milk consumed is imported.
The stages of eradication
The target zone for eradication operations covered 1000 km² of the Niayes region. Before operations began, the genetic isolation of the tsetse fly population had to be proved and their presence mapped in detail. "A previous programme in the 1970s began when only half the infested areas had been pinpointed. This doomed it to fail", says Jérémy Bouyer, a veterinary surgeon and entomologist with CIRAD currently posted to the IAEA, who has been working on the project since 2007. The methods developed by researchers from ISRA and CIRAD have enabled substantial progress, including a 90% reduction in sampling costs.
Pedal of the gyrocopter used to release sterile male tsetse flies on zebus during small-scale transhumance between baobabs in the Niayes zone (Senegal) © CIRAD, J. Bouyer
The sterile insect technique
The project used socioeconomic studies and herd surveys to draft its eradication strategy. The operational phase then began in 2012. Installing insecticide traps and treating cattle reduced tsetse fly population levels, and releasing radiation-sterilized males wiped out the last remaining wild flies. The pupae (fly nymphs) used came from the Bobo-Dioulasso insectarium and the Centre International de recherche-développement sur l'élevage en zone subhumide (CIRDES, Bobo Dioulasso, Burkina Faso). This sterile insect technique has proved itself as a way of controlling many insect pests and vectors, such as fruit flies. At the start of the project, we were capturing up to 100 tsetse flies per trap, per day at some sites", Jérémy Bouyer recalls. "By July, we were finding one or two per month. We're now down to ze ro!"
An annual gain of 2.8 million euros
Eradicating tsetse flies will allow farmers to switch from disease-resistant cows, which are less productive, to more productive races. The resulting increase in production should generate around 2.8 million euros a year, according to the impact study conducted alongside the project. There is already another visible spin-off: a reduction in the areas cultivated by livestock farmers, a major issue given current levels of land pressure.
How about extending to Sine Saloum?
Buoyed by the eradication programme's success, the Senegalese authorities are planning to extend it to a 5000-km² zone of Sine Saloum. The tsetse fly problem is even more acute there, since they transmit two species of trypanosomes, one of which is much more virulent.
PATTEC: a pan-African eradication campaign
The results in Senegal fit into a vast pan-African tsetse fly eradication campaign (PATTEC), launched in 2001. CIRAD supported three national programmes, in Burkina Faso, Guinea and Senegal. "CIRAD played a role in knowledge production, training, and capacity-building, as well as in fostering a multi-partner network including policy-makers", says Sylvie Lewicki, CIRAD Regional Director for West Africa- Dry Zone.