Abstract

Objective: To identify the chemical composition and larvicidal activity of Acorus calamus (A. calamus) rhizome essential oil against the filarial vector mosquito, Culex quinquefasciatus (Cx. quinquefasciatus). Methods: Essential oil was isolated by hydro-distillation and the chemical composition of the oil was analysed by gas chromatography and gas chromatography mass spectroscopy analysis. The larvicidal activity of the essential oil was analysed at different concentrations, viz., 12.5, 25.0, 50.0, 100.0 and 200.0 mL/L. Early 4th instar larvae were used for the larvicidal assay. The larval mortality was calculated after 24 h of the exposure. Results: The gas chromatography and gas chromatography mass spectroscopy analysis showed that the essential oil extracted from the rhizome of A. calamus contained 20 chemical compounds representing about 99.99% of the total oil. Beta-asarone (33.36%), cis-beta-terpineol (23.44%), limonene (13.08%), carvone (5.64%) and amyl isovalerate (4.92%) were identified as the major chemical compounds. The essential oil had promising larvicidal effect against the early 4th instar larvae of Cx. quinquefasciatus with LC 50 value of 63.43 mL/L and LC90 value of 145.95 mL/L. Conclusions: The essential oil of A. calamus rhizome can be used as a natural larvicidal agent against the larvae of filarial vector mosquito, Cx. quinquefasciatus.

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