Abstract

Objective: To evaluate the larvicidal activity of essential oils derived from ten aromatic plants with special reference to Foeniculum vulgare (F. vulgare) against early fourth instar larvae of Culex quinquefasciatus (Cx. quinquefasciatus) Say (Diptera: Culicidae). Methods: Essential oils were extracted from plant materials through hydro distillation and efficacy was determined through bioassay method. Two of the effective oils were evaluated further for the determination of their LC 50 and LT50 values based on Probit analysis.Essential oils of one plant was analyzed through TLC and HPLC. Results: Most of the essential oils caused 100% mortality within 120 min at 250 ppm. Oil of Tagetes patula (T. patula) and F. vulgare gave more than 90% mortality within 40 min. LC 50 values calculated after 60 min of treatment were (84.80 暲 7.65) and (24.69 暲 1.24) ppm for T. patula and F. vulgare respectively. At the same exposure period positive control temephos yielded (22.13暲2.39) ppm LC50 value. At 50 ppm T. patula, F. vulgare and temephos exhibited LT 50 values (113.71 暲 10.29), (11.02 暲 3.31) and (38.15 暲 5.90) mins respectively. Presence of high quantity of trans anethole in the essential oils of F. vulgare was confirmed by TLC and HPLC results. Conclusions: Present study indicates that essential oils of spices/aromatic medicinal plants particularly F. vulgare and T. patula carry huge potential as a mosquito larvicide. This potential could be exploited for the development of safer and effective botanical mosquito larvicidal tool for the management of Cx. quinquefasciatus.

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