Decline of Glossina morsitans ugadensis in Gambella, Ethiopia.

Gambella is the only area where sleeping sickness is endemic in Ethiopia. Four species of Glossina had been reported from Gambella out of the five species found in the country in surveys made before 1985. These are Glossina morsitans ugadensis, G. pallidipes, G. fuscipes and G. tachinoides. A tsetse fly survey was carried out in parts of Gambella owing to the fact that the area is undergoing ecological changes due to massive deforestation (because of resettlement and development programmes), poaching, and introduction of domestic animals into tsetse infested parts of Gambella after 1985. Tsetse populations were sampled for one year, March 1993-April 1994, using biconical traps and hand catches. The survey has reported all Glossina spp which were previously reported except G. morsitans ugadensis. It seems that a combination of factors, such as, lack of host and increase in human population have forced G. morsitans ugadensis to decline. This study has consolidated the fact that tsetse flies of the morsitans group specially G. morsitans, are easily affected by human interference while the palpalis group is resistant to this factor. In addition, this study has also indicated, villagization and rural development could be practised where G. morsitans is the only species in a certain area to alleviate pressure on already impoverished land in parts of Africa.