Chemical Constitution And Insecticidal Activities Against Mosquitoes Of Essential Oil From Eucalyptus Urophylla×Eucalyptus Grandis (Guanglin9)

The chemical composition, extraction technology, repellent and insecticidal activitiesof the essential oil from leaves of Eucalyptus Urophylla×Eucalyptus Grandis (Guanglin9)were investigated. The main research findings in the paper were as follows:(1) The essential oil from leaves of Eucalyptus Urophylla×Eucalyptus Grandis(Guanglin9) were obtained by steam distillation. Due to find the conditions of theextraction, the influence factors as extraction time, soak time and solid-liquid ratio wereinvestigated. Orthogonality experiments showed that the ideal extraction technologyconditions were follow: extracting time more than70min, soaking time over6h, ratio ofmaterial to liquid at8:1.(2) The extraction yield and annual changes of the essential oil were investigated bycollecting the leaves of the Eucalyptus every month from Feburary2011to Janury2012.The highest extraction efficiency from leaves of Eucalyptus featured in May2011,reached to0.40mL/(100g fresh foliage), while the lowest happened in October2011, only0.24mL/(100g fresh oliage), annul average value was0.32mL/(100g fresh foliage). Thevolatile components of the essential oil from leaves of Eucalyptus Urophylla×EucalyptusGrandis were analyzed and identified by Gas Chromatography-Mass Spectrometry(GC-MS) method. The principal constituents were1,8-cineole (36.165%～42.267%),α-pinene (20.135%～38.873%), α-terpineol(2.528%～5.589%), α-terpinyl acetate(3.513%~6.503%), borneol (0.781%~3.038%), trans-Pinocarveol (0.842%~4.152%) andfenchol (0.294%~1.180%). Annual average of the principal constituents were as follow:1,8-cineole (40.477%), α-pinene (28.713%), α-terpineol(4.444%), α-terpinyl acetate(4.852%), borneol (2.157%), trans-Pinocarveol (2.200%and fenchol(0.831%).(3) The essential oil and its principal components (1,8-cineole, α-pinene, α-terpineoland phytol) were tested for repellent against Culex quinquefasciatus referencing thenational standard (GB/T139179.9-2009). Assays indicated that the effective protectiontime against Culex quinquefasciatus of the essential oil (cellected in December2010) was30min,60min and210min when the concentration was12.5%,25.0%and50.0%respectively. While the effective protection time of the essential oil (cellected in June2011) was0min,60min and120min when the concentration was12.5%,25.0%and50.0%, respectively. The repellent avtivity of the principal constituents showed differentabilities. The repellency avtivity of phytol was the most power, the effective protectiontime for human was60min,330min and480min when its concentration was12.5%,25.0%and50%, respectively. The repellency avtivity of α-pinene and α-terpineol wereless than that of Eucalyptus oil.(4) Fumigating insecticidal activity of the essential oil from EucalyptusUrophylla×Eucalyptus Grandis (Guanglin9) was investigated by airtight fumigation inconical flask. The median lethal concentration (LC50) of the essential oil (collected in December2010) against Culex quinquefasciatus was1.822%,1.635%,1.141%,2.677%,2.403%and0.748%after applied0.5h,1h,2h，4h,8h,24h, respectively. While to theplant collected in June2011, the case was changed, the value of LC50was3.188%,3.269%,2.502%,2.148%,2.637%and1.853%, respectively. Fumigating insecticidalactivity of the principal constituents in the essential oil (α-terpineol,1,8-cineole, α-pinene,β-carypohyllene, phytol) against Culex quinquefasciatus was remarkable difference. Afterapplied24h, The LC50of them was1.962%,0.542%,0.190%,0.491%and0.212%,respectively.(5) At the concentration of6.4%, the median lethal time (LT50) of the essential oilfrom Eucalyptus Urophylla×Eucalyptus Grandis (Guanglin9) collected in Decenmber2010against Culex quinquefasciatus was6.479min; The LT50of essential oil collected inJune2011was14.058min. And at the same concentration, the LT50of1,8-cineole,α-terpineol, α-pinene, β-carypohyllene, phytol was5.698min,6.152min,10.608min,30.629min and18.444min, respectively. As see from the value of median lethal time(LT50), the Fumigating insecticidal activity of5principal constituents against Culexquinquefasciatus ranked as1,8-cineole> α-terpineol> α-pinene> phytol> β-carypohy-llene.