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The Amomum villosum essential oil was obtained from hydrodistillation and was investigated by GC-MS. The main constituents were bornyl acetate (51.6%), camphor (19.8%), camphene (8.9%) and limonene (6.2%). Insecticidal toxicity of the essential oil was evaluated in this study. It showed that the essential oil possessed contact toxicity against Tribolium castaneum and Lasioderma serricorne (LD 50 = 32.4 and 20.4 μg/adult). Three monoterpenoids camphor, camphene and limonene showed strong fumigant toxicity against T. castaneum (LC 50 ＜ 2.3, LC 50 ＝ 6.2 and 6.2 mg/L air). In addition, repellency of the essential oil was also evaluated. Data showed that the essential oil and all four compounds had repellent activity against T. castaneum and L. serricorne at high concentration (78.63 nL/cm 2). But with the decrease of concentration, they showed a different degree of attractant properties.

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To develop natural product resources from the Clausena genus (Rutaceae), the essential oils (EOs) from four Clausena plants (Clausena excavata, C. lansium, C. emarginata, and C. dunniana) were analyzed by GC-MS. Their lethal (contact toxicity) and sublethal effects (repellency) against Liposcelis bostrychophila (LB) adults were also evaluated. Santalene sesquiterpene was the precursor substance of santalol, a valuable perfumery. It was found that plenty of α-santalol (31.7%) and α-santalane (19.5%) contained in C. lansium from Guangxi Province and α-santalene (1.5%) existed in C. emarginata. Contact toxicity of the four EOs was observed, especially C. dunniana (LD50 = 37.26 µg/cm2). Santalol (LD50 = 30.26 µg/cm2) and estragole (LD50 = 30.22 µg/cm2) were the two most toxic compounds. In repellency assays, C. excavate, C. lansium, and C. emarginata exhibited repellent effect at the dose of 63.17 nL/cm2 2 h after exposure (percentage repellencies were 100%, 98%, and 96%, respectively). Four Clausena EOs and santalol had an excellent potential for application in the management of LB. Clausena plants could be further developed to find more resources of natural products.

The objective of this study was to analyze six essential oils from Zanthoxylum genus (family Rutaceae) in China and evaluate their repellent activities against Tribolium castaneum and Lasioderma serricorne adults. Six essential oils from Zanthoxylum genus, including Z. armatum, Z. dimorphophyllum, Z. dimorphophyllum var. spinifolium, Z. piasezkii, Z. stenophyllum, and Z. dissitum, were obtained by hydrodistillation and their yields were ranging from 0.02% to 0.53%. Totally, there were 39 chemical components revealed by GC-MS. Among them, some components with high relative content existed in more than three Zanthoxylum species. For instance, both -cadinene (1.21%-17.15%) and spathulenol (0.36%-10.19%) appeared in essential oils of Z. dimorphophyllum, Z. piasezkii, Z. stenophyllum, and Z. dissitum which were found to have higher content of sesquiterpenoids. The repellent activities of six essential oil samples against T. castaneum and L. serricorne adults were investigated for the first time. Data demonstrated that six Zanthoxylum species had much stronger repellent activities against T. castaneum than L. serricorne adults, especially in 2 hours after exposure. The results indicate that these six essential oils from Zanthoxylum have significant potential to be developed into natural repellents to control insects in grains, food, and traditional Chinese medicinal materials.

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