Abstract
Purpose: To evaluate the larvicidal activity of the essential oil of Dipsacus asper Wallich ex Candolle (Dipsacaceae) roots against the larvae of Aedes aegypti L. and Culex pipiens pallens Coquillett.Methods: Essential oil was extracted from D. asper roots by hydrodistillation and analyzed for its composition by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The oil was evaluated for larvicidal activity, using World Health Organization (WHO) procedures, against the fourth larvae of A. aegypti and C. pipiens pallens within 24 h, and activity was recorded for various concentrations of the oil ranging from 12.5 – 200.0 μg/mL.Results: A total of 34 components of the essential oil of D. asper were identified. The major compounds of the essential oil were caryophyllene oxide (13.29 %), caryophyllene (9.14 %), cubebene (7.87 %), β-gurjunene (6.43 %), carvone (5.38 %), 1,8-cineole (5.29 %), and calamenene (5.05 %). The oil exhibited larvicidal activity against A. aegypti and C. pipiens pallens at median lethal concentrations (LC50) of 56.29 μg/mL and 47.49 μg/mL, respectively.Conclusion: The essential oil of D. asper roots has potentials for use in the control of A. aegypti and C. pipiens pallens and may be useful in the search for new, safer and more effective natural larvicides.Keywords: Dipsacus asper, Aedes aegypti, Culex pipiens pallens, Essential oil, Larvicidal activity, Caryophyllene, Cubebene, β-Gurjunene, Carvone
Highlights
The mosquitoes, Aedes aegypti L. and Culex pipiens pallens Coquillett (Diptera: Culicidae) are two worldwide insects causing dreadful nuisance and transmitting many dangerous diseases [1,2]
In China, A. aegypti is considered one of the major vectors for the transmission of dengue fever and C. pipiens pallens is the primary vector of wuchereriasis and epidemic encephalitis B [1,2]
Repeated and injudicious application of these synthetic insecticides have caused disrupt of the natural biological control systems and sometimes resulted in the widespread development of resistance as well as undesirable effects on non-target organisms, toxic residues in food, workers’ safety, and high cost of procurement [4]. Essential oils and their constituents have been suggested as alternative sources for conventional mosquito larvicides [57]
Summary
The mosquitoes, Aedes aegypti L. and Culex pipiens pallens Coquillett (Diptera: Culicidae) are two worldwide insects causing dreadful nuisance and transmitting many dangerous diseases [1,2]. Synthetic insecticides and insect growth regulators are widely applied to control larval mosquitoes [3]. Repeated and injudicious application of these synthetic insecticides have caused disrupt of the natural biological control systems and sometimes resulted in the widespread development of resistance as well as undesirable effects on non-target organisms, toxic residues in food, workers’ safety, and high cost of procurement [4]. Essential oils and their constituents have been suggested as alternative sources for conventional mosquito larvicides [57]. During the present author’s mass screening program for new agrochemicals from wild plants and Chinese medicinal herbs, the essential oil of Dipsacus asper Wallich ex Candolle (Family: Dipsacaceae) roots, was found to possess larvicidal activity against the larvae of A. aegypti and C. pipiens pallens
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