Abstract

Larvicidal effects of plant extracts against larvae of Anopheles gambiae were studied in the malaria entomology laboratory at Mendefera. The aim of the study was to evaluate ethanol and hot water extracts from leaves of seven different plants, viz., Azadirachta indica, Eucalyptus globulus, Tagetes minuta, Datura stramonium, Lantana camara, Ricinus communis and Jatropha curcas, as natural larvicides against third instar larvae of An. gambiae. Insecticidal susceptibility tests were carried out using WHO standard method and the mortality was observed after 24 and 48 h (h) of exposure. The experiment was conducted in complete randomized design in three replications. Data were collected on mortality of mosquito larvae in all the treatments and then subjected to statistical analysis using one-way ANOVA. Most of the tested extracts showed more than 50% mortality. J. curcas (100±0.00%) and R. communis (99.44±0.56) gave significantly higher larval mortalities at 1000 ppm concentration after 48 h of exposure. The experiment also showed that ethanol extracts gave higher larval mortality than hot water extracts and the efficiency of the extracts increased with an increase in the exposure period of the larvae.

Key words: Mosquito vector, malaria, larvicidal activity, leaf extracts