Larvicidal properties of some Tanzanian plant species against Anopheles gambiae s.s. Gile (Diptera:Culicidae) mosquitoes

Ethnobotanical survey was done among the Hehe community of central Tanzania to identify plants that can be used in the control of malaria transmitting mosquito vectors. Extracts from different plant parts wereanalysed for their larvicidal effects against Anopheles gambiae s.s mosquito by using the WHO (1996) protocols. The crude extracts that had highest larvicidal activity were the dichloromethane extract of the root barks of S. araliacea and L. viburnoides ssp. viburnoides var. kisi while the methanol extracts of the stem and root barks of Kotschya uguenensis showed low acute lethality but exhibited insect growth disruption activity. The extracts from Synadenium glaucensen were mildly active. Bisbenzocyclooctadiene lignans from S. araliaceae that had no lactone moiety exhibited higher larvicidal activity than the bisbenzocyclooctadiene lactone lignans. The high larvicidal potency of the three plant species S. araliacea, L. viburnoides ssp. viburnoides var. kisi and K. uguenensis indicates the importance of ethnobotanical criteria in selecting plant species having higher probability of possessing anti-mosquito compounds, a phenomenon that needs to be developed and incorporated in integrated mosquito vector management strategies