Repellency Effect Of 22 Essential Oils Against Aedes Albopictus And Formulation Research

Mosquitoes, an important disease vector, can spread malaria, yellow fever, dengue, and other epidemics, which is a serious threat to human health. Currently, the most common commercial mosquito repellent is DEET, of which side effects on the human have caused public concern. This study evaluated the repellent activity of 22 kinds of essential oils against Aedes albopictus, in order to find efficient, low toxic, and environmentally friendlybotanical repellents. The results are as follows:(1) The repellent activity of 22 kinds of essential oils against Aedes albopictus was evaluated by Y olfactometer. Twelve essential oils had percent repellency higher than 50%with the amount of 0.5 μL. among these essential oils, the litsea cubeba oil and mentha arvensis oil had percent repellency with 100% and 80.48%, respectively. Meanwhile, six essential oils had percent repellency higher than 60% when applied with the amount of 2.0μL. The mentha arvensis oil, litsea cubeba oil, geranium oil, thyme oil, lauric oil and ginger oil had percent repellency with 91.66%, 73.94%, 71.21%, 67.94%, 65.00% and 64.85%,respectively.It can be concluded that the repellent activity of essential oils was not always positively related to the concentration. So when screeningfor repellent activity of essential oils against mosquito, we should pay attention to examine the effection of different amounts of reagents on the repellent activity, to evaluate the effectiveness ofessential oils for mosquito control comprehensively.(2) Combined effect of mentha arvensis oil and litsea cubeba oil against Aedes albopictus were studied following GB/T 13917.9-2009. The binary mixture of mentha arvensis oil and litsea cubeba oil exhibited a combined effect than the single component and the percent repellency could keep a period of 2h. Through recipe optimization, the best formulation ingredients(10%litsea cubeba oil+10%mentha arvensis oil+5%tween80+synergistic agent C)have been developed. The optimized formulation had the protection efficacy with 4h, showing potential for asbotanical repellent developmentfor mosquito control.(3) The main ingredients of litsea cubeba oil,mentha arvensis oil and lauric oilwereanalyzed by GC/MS. The main ingredients of litsea cubeba oilwere cinnamonene(36.69%),terpinolene(9.26%), cinene(7.04%). The main ingredients of menthaarvensis oil wereterpinolene(17.52%),D-limonene(14.92%),2-methyl-5-isopropyl-bicyclo[3.1.0]hexane-2-alkoxy(9.93%),pinene(8.43%),menthone(3.34%).The main ingredientsof lauric oils were vinyloxymethyl-3-cyclohexyl(24.47%),(1α,2β,5α)-2,6,6-trimethyl-bicyclo[3.1.1]heptane(16.75%),2-nonynoic(15.80%),1-Lsopropyl-2,3-dimethyl-1-cyclopentene(11.02%).Through analysis of the essential oil components, these compounds could be major active ingredients for oil repellent activity. Further discussion on the active components and their synergic relationship may provide reference and basis for in-depth study of the repellent activity of essential oils, and guidance for the development, production and application of plant essential oil repellent.