| Summary: | 碩士 === 國立陽明大學 === 國際衛生碩士學位學程 === 100 === Mosquitoes are vectors of lethal pathogens to humans, therefore leading to public health impacts. There is a growing interest to search for alternative bioactive products to ultimately replace synthetic active ingredients most widely used in personal protection against insect biting, that have raised concerns in both environmental and human health.
Being the natural alternative, RAG essential oil is derived from the plant Acorus Gramineus (Sweetflag Rhizome) and used for medicinal purposes but in the scope of this thesis shall be investigated in its role to break the Dengue transmission through either repellency or ATSB (Attractive toxic sugar bait) methods against the vector, Aedes Aegypti. Screening of several essential oils was conducted through olfactometry, and RAG was found to be the most potential candidate. Following proper WHO Pesticide Evaluation Scheme guidelines for repellent testing, the arm-in-cage assay with the pure oil of RAG was found to give a complete protection time (cPT) of 4 hours or more. Furthermore, the addition of other natural essential oils such as Citronella, Aloe Vera, and Tea Tree oil provided an equal protection time requiring only 10% RAG, hence RACT was formulated. The 95% confidence interval for the estimated median cPT for the repellent RACT has boundaries of 240 +/- 1.96 6.6 minutes. This is more effective than the DEET 13% positive control with a cPT of 180 mins. Mosquito killing effects through sugar baits were evaluated, and RAG was shown to decrease the mosquito’s life span by as much as 23 days, and beta asarone giving 100% mortality as soon as Day 4. HPLC results revealed beta asarone to be the major component of RAG, along with alpha asarone as a minor one. Spatial repellency tests showed significant differences in mosquito counts (p=0.00, p=0.004), and feeding behavior (p=0.007); oviposition was also deterred.
In conclusion, with greater than 4-hours protection, Acorus gramineus may be a potential candidate for use in the development of commercial repellents that may be an alternative to conventional synthetic chemicals, and may holds applications in community vector control program.
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