Abstract

Background & objectives: Natural products of plant origin possess larvicidal potential against mosquitoes with safety. Presently research studies have been undertaken to test the larvicidal activity of plants. The aim of the present study was to test the larvicidal efficacy of fruits of Emblica officinalis and leaf of Eucalyptus citriodora against third instar larvae of Aedes aegypti.
Methods: The plant powder was sequentially extracted using various solvent from non polar to polar solvents such as hexane, dichloromethane (DCM), ethanol, methanol and water. Each crude extract was dissolved in dimethyl sulfoxide (DMSO) and acetone (1:1v/v) and test concentration was prepared. Larvicidal bioassay was carried out and mortality data were analysed by log probit regression analysis to calculate 50% lethal dose (LD50) at 95% fiducial limit.
Results: The bioassays with crude extracts of both plants revealed that the dichloromethane extract of E. officinalis and E. citriodora exhibited higher larvicidal effect than other solvent extracts of both plant after 24 hours of exposure period and LD50 values were 166.64 ppm and 176.29 ppm respectively. Hexane, ethyl acetate, methanol and aqueous extracts of E. officinalis had higher larvicidal activity against third instar larvae of Ae. aegypti than the same extracts of E. citriodora.
Interpretation & conclusion: The findings of present study suggest that DCM extract of E. officinalis and E. citriodora exhibited higher larvicidal potential against Ae. aegypti. Further study is warranted to isolate and purify the novel bioactive molecule from the dichloromethane extract of E. officinalis and E. citriodora.