Insecticidal Activities of Chromolaena odorata and Vernonia amygdalina leaf extracts against Anopheles gambiae [Diptera: Culicidae]

Abstract

Female Anopheles mosquitoes are the vectors of human malaria. The use of chemical insecticides for vector control has hampered with environmental pollution and insect. This suggests the need for the development of more potent and environment-friendly insecticides for effective control of malaria.This research investigated the larvicidal, pupicidal and adulticidal activities of Chromolaena odorata and Vernonia amygdalina leaf extracts against, An. gambiae in the laboratory at ambient temperature of 28 ± 2 °C and 75 ± 5% relative humidity. Different concentrations of 20 mg/L, 40 mg/L, 80 mg/L, 120 mg/L and 160 mg/L were prepared and these aqueous solutions were used for the experiments. Larval, pupal and adult mortality of An. gambiae were tested after 24 hours of exposure. Results showed that there were significant differences (P < 0.05) in toxicity level of the two plant extracts on An. gambiae larvae, pupae and adults. Vernonia amygdalina extract was the most toxic to An. gambiae larvae at all tested concentrations of 20 mg/L, 40 mg/L, 80 mg/L, 120 mg/L and 160 mg/L causing 47.5%, 82.5%, 100%, 100% and 100% mortality after 24 hours of treatment, respectively.