| Tropical infectious diseases such as Dengue Fever are majorly transmitted by Aedes albopictus Skuse and Aedes aegypti Linnaeus. Its incidence had risen so sharply in the recent decades, still now no safe and effective vaccine for prevention of dengue fever had been invented. Therefore its vectors Aedes mosquitoes had been paid more attention. Among the whole management methods, using repellent is always an effective and safe way to control mosquito. Due to some adverse reports about the golden repellent DEET, more and more researcher had chosen the natural sourced repellent such as plant Essential Oils as the future products to protect human from mosquito biting. In this study, we had used Aedes as the object, 24 plant essential oil had been assessed their mosquito repellency. The major research contents are as follows:1. The improvement of raising Aedes mosquito in the lab. Optimized our method to raising mosquito better in the lab. Self-constructed one set of Blood Feeding System in the lab to replace the animal as the blood source. At the same time this System can be used as the in vitro method called Hemotek Membrane System to assess potential mosquito repellent.2. To grope the in vitro method for repellency assessment. Based on the review most of Bioassay to assess repellent, K&D Module, Wind-tunnel Module, Y-tube Olfactory Module had been constructed here. The better landing space for the mosquito was Parafilm Membrane which got 66.7% attractant. And the best air speed was 0.3 L/min, and the best stable recoeding time was 135s,195s, and 255s with 83% attractant rate.3. To assess plant Eos efficacy as mosquito repellent.24 Essential Oils (Eos) as mosquito repellent had been assessed by using γ-tube olfactory test.10 Eos including H oil, Clove bud oil, and Patchouli oil had showed a great potential to be a repellent. Next used Hemotek membrane system to assess H oil repellent rate compared with DEET which got 100% protection rate in 3-mins. For other 9 Eos, Human-arm/hand in cage method had been cited here to determine their mosquito repellency against Aedes Albopictus. The best one was 30% Clove bud oil which showed 130 min to completely protect human from mosquito biting. The next one was 25% Patchouli oil which was just 90 mins. The ED50 of Clove bud oil was just 0.002μg/cm2 [95%,0.000-0.005] which was significantly lower than Patchouli oil 2.496μg/cm2 [95%,0.504-5.068]. The results showed that the best one was Clove bud oil which can protect human from mosquito biting by using a lower But the Median CPT for the Clove bud oil was 60 min, Patchouli was 36 min which were too short than DEET.4. To verify the idea that the idle Eos would protected human from biting longer than fresh one. Assessed 9 Eos old oils VS fresh oils, Ginger oil CPT was longer for 8 times changing from 15 min to 120 min. Also Patchouli oil had been extremely significantly longer than the fresh one.5. To measure the Aedes albopictus antenna physiological response to 5 different Eos including 3H Eos, Clove bud oil and Patchouli oil by combined with GC-MS and GC-EAD method. A few active chemicals such as Linalool coming from Eos had been proved big response in mosquito antenna which indicating that these chemicals maybe responsed for the repellency in the Eos.In all, Y-tube olfactory method, Hemotek Membrane System, Human arm in cage method (GB2009 and WHO2009) were all good method to assess plant Eos repellency which suited for different ways. As for 24 kinds of Eos, Clove bud oil and Patchouli oil is the good choice as mosquito repellent, and H oil can also a very potential mosquito repellent against Aedes. By using the GC-MS and GC-EAD physiological method, the terpenes which got obvious strong antenna response can be a good source for us to analysis as active leading chemical to use for repellent. Therefore this study here will support more evidence to explore a new generation of plant-base repellent against mosquito, at last this will help a lot for the prevention of Dengue fever disease. |
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