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.
Highlights
This study showed that the V. ovata methanolic extract might have larvicidal properties that can kill Ae. aegypti larvae
The crude extract of V. ovata used could be an innovative application as an alternative to synthetic chemical insecticides
Several authors have developed criteria to characterize mosquito larvicide potency for essential oils derived from plants, generally considered products with LC50 < 100 mg/L as exhibiting a significant larvicidal effect [17,18,19,20,21]
Summary
Aedes (Stegomyia) aegypti (Linnaeus, 1762), the principal vector of the dengue virus, is of great concern in various parts of the world, especially in tropical and subtropical countries [1]. In Malaysia, the number of dengue cases in 2019 was reported to be 127,407, with 176 deaths [3]. The increasing of this vector-borne disease is of great concern, as the incidence of dengue has increased 30-fold over the last 50 years [2]. Other than the dengue virus, Aedes (Stegomyia) aegypti s known to transmit yellow fever virus, chikungunya virus, and Zika virus, putting more than half of the world’s population at risk
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