A strategy to decrease vectorial competence of dengue mosquito Aedes aegypti by alteration of its gut microbiota using Indian traditional medicinal plants

Abstract

In the present study, the sensitivity of the gut microbes of dengue fever mosquito Aedes aegypti to Indian traditional medicinal plants was evaluated. The microbes were isolated from the midgut of laboratory-reared fourth instar larvae of Ae. aegypti and grown on Luria-Bertini agar plates at an optimum temperature of 27oC. The microbial colonies were differentiated based on their characteristics such as size, shape, opacity, elevation, consistency, and rate of growth. The axenic culture of different strains was obtained by streaking method. Ten different types of microbial clones were identified up to species level using Biolog’s advanced phenotypic technology. Five Indian traditional plants: Ocimum sanctum, Azadirachta indica, Catharanthus roseus, Curcuma longa, and Syzygium aromaticum and an invasive obnoxious weed Lantana camara were used in the present study. The extracts of the specific parts of individual plants were prepared in ethanol and hexane using ‘Soxhlet apparatus’. The extracts were screened for their antimicrobial activities by disc diffusion assay. The results indicate that the plants used in the present study possessed antimicrobial activities against gut microbes of Ae. aegypti. However, the sensitivity of different microbes to the extracts varied. The zone of inhibition observed after 24 h of incubation revealed that ethanol extract of A. indica has the most potent antibacterial activity; followed by that of S. aromaticum, C. longa and O. sanctum. L. camara and C. roseus were least effective against gut microbes of Ae. aegypti.