Assessment of the insecticidal potency of neem (Azadirachta Indica) seed kernel methanolic and aqueous extracts on the malaria vector Anopheles gambiae

Abstract

The potency of aqueous and methanolic extracts of neem (Azadirachta indica A. Juss) seed kernel, in inhibiting and disrupting development of Anopheles mosquito was assessed in the laboratory. Different concentrations of aqueous and methanolic extracts were tested on eggs, larvae and pupae. Both extracts were found to cause mortality on the specimens used and the level of mortality was concentration dependent. Mortality increased as the concentration increased. Methanolic extract of the neem seed kernel caused significantly higher (P = 0.05) mortality than aqueous extract. Few adults emerged among those treated with lowest concentration of 1 %( wt./vol.) aqueous extract, whereas no larvae or pupae survived to next stage in methanolic extract of the same concentrations. At highest concentration of 5 % (wt/vol), both extracts caused 100% mortality of larvae although the methanolic extract gave a quicker kill (12 hours) than the aqueous extract (24 hours). No egg hatched in all concentrations of both extracts.