Control of tsetse and trypanosomiasis transmission in Uganda by applications of lambda-cyhalothrin

ABSTRACT

The pyrethroid insecticide lambda-cyhalothrin was evaluated in field trials against Glossina f.fuscipes and sleeping sickness transmission in Iyolwa sub-county; Tororo District; Uganda. The insecticide was applied selectively to the resting-sites of tsetse; by bush-spraying; using 10pc wettable powder (10WP) formulation at an application rate of 11.6 g a.i./ha over an area of 28 km2; or by a 2pc Electrodyn formulation (2ED) applied at 0.9 g a.i./ha over 30 km2. In a third trial area of 32 km2; 215 pyramidal traps treated with lambda-cyhalothrin 100 mg/m2 were set. The best impact was obtained with 10WP lambda-cyhalothrin which eliminated tsetse within 1-2 months; whereas G.f.fuscipes persisted at very low density in part of the area treated with 2ED lambda-cyhalothrin. In both treated areas the numbers of human sleeping sickness cases fell to no more than one per month; compared with four to twelve per month previously. The overall rate of cattle trypanosomiasis (T.brucei and T.vivax) was also reduced slightly. Insecticide-treated traps remained fully effective for at least 6 months under field conditions and catches were reduced 20-90-fold. These results in the control of tsetse and trypanosomiasis transmission lead us to recommend lambda-cyhalothrin for tsetse control operations