Larvicidal Effect of Vitex ovata Thunb. (Lamiales: Lamiaceae) Leaf Extract towards Aedes (Stegomyia) aegypti (Linnaeus, 1762) (Diptera: Culicidae)

Abstract

According to the WHO there are more than 700,000 deaths every year involving vector-borne diseases such as malaria, dengue, Chagas disease, yellow fever and Japanese encephalitis. Aedes aegypti, the principal vector of the dengue virus, is of great concern in various parts of the world, especially in tropical and subtropical countries. Vector control through insecticide application is one of the best ways to control the disease’s transmission. Thus, insecticide resistance in Ae. aegypti poses a significant threat to public health worldwide. The use of plant natural product-based insecticides that are less harmful to the environment, and without known resistance development, constitutes an alternative to chemical insecticides. Given this, a methanolic extract from Vitex ovata plants was prepared and tested for its larvicidal effect against Ae. aegypti. A susceptibility test on Ae. aegypti larvae was conducted using the standard WHO method. Results showed that the methanolic extract of V. ovata had larvicidal activity against Ae. aegypti with LC50 values of 2114 mg/L, and achieved 84% mortality with the highest concentration at 10,000 mg/L. This study showed that the crude extract of V. ovata bioactive molecules could be potentially developed as biolarvicides for Aedes mosquito vector control. This study recommends future research on using different solvents in the isolation of active ingredients from V. ovata, identification of phytochemicals with larvicidal properties, a toxicity study and lastly, an evaluation of the effectiveness of controlling Aedes in small-scale field trials for environmentally safe botanical insecticide intervention.