Mosquito Larvicidal and Repellent Activities of Extractives from Cryptomeria japonica

• Main Authors: Hui-Jing Gu, 古惠菁
• Other Authors: Shang-Tzen Chang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/13115614581811795812

碩士 === 國立臺灣大學 === 森林環境暨資源學研究所 === 97 === Mosquito-transmitted diseases such as malaria, filariasis, yellow fever, dengue and Japanese encephalitis are very serious. Therefore, it is important to control mosquito vector population for preventing the spread of these diseases. Nature products offer an advantage over synthetic pesticides because of less toxic and easily biodegradable. The purposes of this study were to investigate the larvicidal activities of ethanolic extracts from Cryptomeria japonica against fourth-instar larvae of mosquitoes Aedes aegypti and Aedes albopictus and to evaluate the repellent activities of essential oil from C. japonica against adult of mosquitoes A. aegypti and A. albopictus. Results of mosquito larvicidal tests demonstrated that n-hexane soluble fraction of wood extract from C. japonica exhibited the best larvicidal activity against fourth-instar larvae of mosquitoes. Among fourteen subfractions (H1~H14) of n-hexane soluble fraction, H5 subfraction showed the best inhibitory activity against the mosquito larvae tested. In addition, nine compounds were isolated and identified from H5 subfraction, including ferruginol, epi-cubenol, 4-acetoxycryptomerione, sandaracopimaric acid, epi-cubebol, cubebol, β-eudesmol, isopimarol and phyllocladan-16α-ol. Comparison of the larvicidal activity of four major compounds (ferruginol, epi-cubebol, cubebol and isopimarol) revealed that cubebol and epi-cubebol exhibited the best activity against A. aegypti and A. albopictus. Comparison of repellent activity of essential oils from four plant parts of C. japonica revealed that leaf oil exhibited the best action against mosquitoes. In order to understand the relationship between volatile organic compounds and repellent activity, solid phase microextraction method (SPME) was employed to analyze volatile organic compounds of leaf oil. The SPME fiber used was coated with DVB/CAR/PDMS. The major volatile organic compounds in the box were 3-carene, α-terpinene, limonene, γ-terpinene and terpinolene at 0 min. Results of the tests demonstrated that the major volatile organic compound in the box was (-)-terpinen-4-ol at 20 min, 40 min and 60 min, respectively. Furthermore, the repellent activities of six compounds against adults of the mosquitoes were evaluated, results revealed that (-)-terpinen-4-ol exhibited the best repellent activity against A. aegypti and A. albopictus.