Laboratory Evaluation of some Eastern African Meliaceae as Sources of Larvicidal Botanicals for Anopheles Gambiae

Abstract

Root bark extracts of five Meliaceae species ( Turraea abyssinica Hochst., Turraea wakefeldii Oliv., Turraea mombassana Hiern ex C.DC., Trichilia roka (Forsk) Chiov. and Melia volkensii Guerke.) and different fractions thereof (following chloroform extraction and column chromatographic separation) were compared for their immediate toxicity and long-term effects on Anopheles gambiae Giles sensu stricto (Diptera: Culicidae). Larvicidal effects of the extracts appeared to be largely associated with limonoids of medium polarity with M. volkensii and T. mombassana extracts being more potent than those of the other Meliaceae. Long-term (6 – 8 days post-exposure) observations at lower doses showed that 100% cumulative mortality can be achieved with some extracts (particularly those of T. mombassana and M. volkensii ) with interesting growth-inhibition effects. Follow-up studies that are needed and practical implications of the results in terms of development of larval control strategies for African malaria vectors are discussed