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The essential oil of Clausena anisum-olens (Blanco) Merr. showed strong contact toxicity and repellency against Lasioderma serricorne and Liposcelis bostrychophila adults. The components of the essential oil obtained by hydrodistillation were determined by gas chromatography-mass spectrometry. It was found that the main components were myristicin (36.87%), terpinolene (13.26%), p-cymene-8-ol (12.38%), and 3-carene (3.88%). Myristicin and p-cymene-8-ol were separated by silica gel column chromatography, and their molecular structures were confirmed by means of physicochemical and spectrometric analysis. Myristicin and p-cymene-8-ol showed strong contact toxicity against L. serricorne (LD50 = 18.96 and 39.68 μg per adult) and Li. bostrychophila (LD50 = 20.41 and 35.66 μg per adult). The essential oil acting against the two grain storage insects showed LD50 values of 12.44 and 74.46 μg per adult, respectively. Myristicin and p-cymene-8-ol have strong repellent toxicity to Li. bostrychophila.

Abstract:The chemical composition of the essential oil of Etlingera yunnanensis rhizomes and its contact and repellent activities against Tribolium castaneum (Herbst) and Liposcelis bostrychophila (Badonnel) were investigated. The essential oil obtained from E. yunnanensis rhizomes with hydrodistillation was performed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. The main components of the essential oil were identified to be estragole (65.2%), β-caryophyllene (6.4%), 1,8-cineole (6.4%), limonene (5.2%), and α-pinene (2.4%). It was found that the essential oil of E. yunnanensis rhizomes possessed contact toxicity against T. castaneum and L. bostrychophila (LD50 = 23.33 μg/adult and LD50 = 47.38 μg/cm against L. bostrychophila adults. Repellency of the crude oil was also evaluated. The essential oil and constituents possessed strong repellent activity against T. castaneum adults. The four individual constituents showed weaker repellent activity than the essential oil against L. bostrychophila adults. The results indicated that the essential oil of E. yunnanensis rhizomes and the individual constituents had the potential to be developed as a natural insecticide and repellent for the control of T. castaneum and L. bostrychophila.

The aim of this research was to determine the chemical constituents and toxicities of the essential oil derived from Alpinia blepharocalyx rhizomes against the cigarette beetle, Lasioderma serricorne (Fabricius). The essential oil of A. blepharocalyx rhizomes was obtained by hydrodistillation and was investigated by gas chromatography-mass spectrometry (GC-MS). A total of 46 components of the essential oil of A. blepharocalyx rhizomes were identified. The principal compounds in A. blepharocalyx essential oil were camphor (23.13 %), sabinene (11.27 %), α-pinene (9.81 %) and eucalyptol (8.86 %) followed by camphene (8.05 %), sylvestrene (5.61 %) and α-phellandrene (5.00 %). Among them, the four active constituents, predicted with a bioactivity-test, were isolated and identified as camphor, sabinene, α-pinene and eucalyptol. The essential oil of A. blepharocalyx possessed strong contact toxicity against the cigarette beetle with ad LD 50 value of 15.02 μg adult -1 , and exhibited strong fumigant toxicity against L. serricorne adults with an LC 50 value of 3.83 mg L -1 air. The results indicate that the essential oil of A. blepharocalyx shows potential in terms of contact and fumigant toxicities against stored product insects.