The insecticidal effect of extracts from the bark and leaves of B. dalzielii was tested on adults of A.
gambiae. A series of five mass concentrations of active material was prepared: 0.5 g/m2 ; 1.5 g/m2 ; 2.5
g/m2; 3.5 g/m2 and 5 g/m2
. For each concentration, 20 adult anopheles were introduced into the cone -
WHO. The lethal concentration 50 (LC50) and the lethal hour 50 (LH50) of the extracts were determined.
The LC50s of B. dalzielii were 3.05 g/m2 and 3.94 g/m2 respectively for bark and leaves. The LH50s were 7
h 46 min 08 sec and 9 h 52 min 25 sec respectively for bark and leaves. The extracts of the bark showed a
rather high toxicity compared to that of the leaves. However, a non - significant difference (α > 0.05) was
recorded between the toxicity of the two extracts. Long - acting Insecticide Impregnated Mosquito Net
(LLIN) showed a low LH50 (2 h 11 min 13 sec) compared to those of the B. dalzielii extracts. The results
of this article have shown that there are local ways to chase or to kill mosquitoes in Far North Region
Cameroon.