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This paper analyzed the chemical constituents of the essential oil (EO) of Kaempferia rotunda L. and the bioactivities of the predominant compounds. Results obtained from GC/MS analysis indicated 14 compounds, which accounted for 96.66% of the total extract. Among them, the most abundant compound was benzyl benzoate (81.13%), followed by bornyl acetate (4.51%). EO from the medicinal plant K. rotunda inhibited the potent toxicity of Lasioderma serricorne and Liposcelis bostrychophila (LD50=17.1μg/adult and 18.6 μg/adult). K. rotunda oil also exerted strong repellency against three target insects at high concentrations. Based on the theory of the grey correlation analysis, EO from K. rotunda performed better than benzyl benzoate but worse than bornyl acetate on the repellency against Tribolium castaneum. Benzyl benzoate possessed excellent contact toxicity with three target insects. Meanwhile, the binary mixture of two main compounds (benzyl benzoate and bornyl acetate) was evaluated for contact toxicity with T.castaneum for the first time. The synergistic effect in natural ratios has been observed, suggesting that unique mechanisms of action should be responsible for EO toxicity. Plant-derived insecticides appear suitable for developing control means against stored product insects. [ABSTRACT FROM AUTHOR]

Alpinia zerumbet cv. 'Variegata', as a special spice, has attracted social attention for its potential to replace synthetic chemicals as insecticides and repellents in food protection. In this work, the essential oils (EOs) from different organs of Alpinia zerumbet cv. 'Variegata' (stem and leaf, flower, and rhizome) were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). The contact toxicities and repellent activities of the extracted EOs, along with their common components, against three insect species (Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila) were evaluated. GC-MS analysis identified 25 components, and eucalyptol and camphor were the common primary components in the three EOs. The result showed that EOs and the main components (eucalyptol and camphor) exhibited varying degrees of contact toxicity and repellent activity against three insect species. Camphor exhibited more obvious contact toxicity than eucalyptol against both insect species (L.serricorne and L.bostrychophila), but the toxic effect was opposite for T.castaneum. The gray relation analysis explained that REOA had the strongest repellency against L.serricorne, with a coefficient of 0.52. The results in this study suggest that EOs of A.zerumbet cv. 'Variegata' have the potential to be developed into botanical insecticides and repellents to control stored-product insects. [ABSTRACT FROM AUTHOR]