線香艾草真的能驅蚊！昆蟲系研究證實 傳統宗教常用煙霧能忌避埃及斑蚊
你知道嗎？燒香除了祭祀也能驅蚊！台大昆蟲系助理教授薛馬坦與學生研究發現，台灣傳統宗教中常用的線香及艾草，燃燒過後的煙霧其實對埃及斑蚊有一定的擊倒（knockdown）作用，不過效果微弱、範圍有限，且線香、蚊香等物品含有多種對人體有害的化學物質，因此仍不建議作為主要驅蚊工具。
焚燒植物產生大量濃煙是一種傳統的驅蚊方式，且在世界各地被廣泛使用，而台灣許多傳統宗教儀式也有類似做法，例如鹽水蜂炮的起源最早是因為當地霍亂疫情嚴峻，百姓為祈求平安的儀式。
來自美國的薛馬坦對這些宗教儀式頗感興趣，因此好奇，這些宗教儀式會不會其實真的可以消除疾病？即使只是間接驅離病媒昆蟲（蒼蠅或蚊子）？某些歷史悠久的廟宇日漸香火鼎盛，有沒有可能是因為這些信眾在參拜時不易被蚊蟲叮咬，也因此較不易得到如登革熱等傳染病？
為了驗證這項假說，薛馬坦與學生使用登革熱媒介昆蟲埃及斑蚊為實驗材料，測試宗教上常使用的各種資材，如沉香木、宣紙紙錢和艾草等，焚燒後的煙霧對埃及斑蚊是否有忌避效果。
研究團隊將受測蚊子放置於大蟲箱中，箱子的一邊是悶燒中的資材，另一邊則沒有燃燒，並觀察蚊群是否會被煙霧被驅離。此外，團隊還收集上述各式資材的煙霧並且透過台大「氣相層析質譜分析研究室」分析煙霧的化學組成，以了解這些物質對人體的影響。
研究結果顯示，線香確實可以持續驅趕蚊子，但效果不大；艾草葉也具有微弱的驅蚊效果，甚至有些蚊子在吸入艾草煙後會直接死亡；而紙錢則不具有忌避蚊子的效果，甚至會因為燃燒時產生大量的二氧化碳和水蒸汽吸引蚊子前來。
不過，這樣的結果並不代表人們應該要在登革熱季節點線香和燃燒艾草作為驅蚊的手段。薛馬坦指出，此研究中最強的蚊蟲忌避劑是線香，但可以發現即使台灣的廟宇每天都燃燒大量線香，登革熱仍然存在。此外，線香的煙對蚊子忌避效果不大，甚至比市售的防蚊液還弱許多，保護力範圍也有限，倘若離開煙霧瀰漫範圍，蚊子就有可能找上你。
研究也指出，這些物品燃燒後產生的煙霧都會人體有害，無論是線香、蚊香、紙錢或是蠟燭都具有害化學物質，恐對肺部造成損害。而該研究所使用的煙霧更包含超過100種化學物質，如苯、苯甲醛、苯乙烯和甲苯等。
研究表示，對於避免蚊蟲叮咬的最好方式依然是穿長袖或使用含有敵避的防蚊液，會比對肺部造成危害的煙霧來得更安全，而市面上仍有許多具忌避效果的線香，可以在蚊蟲盛行的夏季提供一點額外保護。
上述研究結果已發表於「泛太平洋昆蟲學家（The Pan-Pacific Entomologist）」期刊中。
研究全文：https://doi.org/10.3956/2021-97.2.67
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台灣傳統宗教儀式中常用的艾草、線香燃燒後煙霧具微弱驅蚊效果，但紙錢不但沒有，還可能吸引蚊子。
The effects of Taiwanese ritual smoke on Dengue mosquitoes
Smoke from burning plants is used around the world as a traditional mosquito repellent. Smoke is also used worldwide in ritual worship, from burning incense to lighting firecrackers. What if the two are related? Many rituals are related to fighting disease, such as the Yanshui beehive rocket festival that began after the successful end of a cholera epidemic. What if one reason certain smoke-related rituals are popular is that they really did eliminate disease, albeit indirectly by repelling disease-vectoring flies and mosquitoes? What if certain incense-filled temples historically became popular because worshippers were less likely to be bitten by mosquitoes there and catch diseases like dengue? This creative hypothesis was tested in a recent publication by National Taiwan University entomologist, Prof. Matan Shelomi (薛馬坦).
Using Aedes aegypti, the mosquito that transmits dengue, his students tested the repellent effects of smoke from three different sources: agarwood incense sticks, rice paper ghost money, and Asiatic wormwood leaves (Artemesia argyi, 艾草) of the kind used during the dragon boat festival. Mosquitoes were put in a large cage, with smoldering, smoky material on one side and un-burnt material on the other. Mosquitoes were checked to see if they flew away from the smoke or not. Samples of smoke were also collected using special tools and their composition tested at the National Taiwan University gas chromatography-mass spectrometry laboratory. The results were recently published in the Pan-Pacific Journal of Entomologist. Incense repelled mosquitoes consistently but weakly. Wormwood leaves were weak repellents, and some mosquitoes seemed to die from inhaling the smoke. Ghost money did not repel mosquitoes, with some actually attracted to the fire, likely due to the carbon dioxide and water vapor it releases.
Do these results mean you should use incense and burning wormwood as a mosquito repellent during dengue season? Not so fast! Incense, the strongest repellent from this study, is burned daily in Taiwan, yet Dengue still exists. The effects of the smokes were weak–far weaker than smoke from commercial mosquito repellent coils. Smoke also only provides protection within a certain space: once you leave the smoky area, the mosquitoes will find you. Lastly, none of the smokes are healthy. All smoke, whether from incense or mosquito coils or ghost money or candles, is damaging to the lungs and contains noxious chemicals. The smokes in this study contained over 100 different chemicals like phenol, benzaldehyde, styrene, and toluene. The best protection against mosquitoes is still the protection you carry with you, like long-sleeved clothing or mosquito repellents containing DEET, which is far safer for your skin than smoke is to your lungs. Still, the possibility does exist that more repellent versions of incense could be made to provide a little extra protection during the summer months!
Ching-Yu Shu, Hsueh-Lien Lai, Pei-Yin Lin, Kevin Chi-Chung Chou, and Matan Shelomi "Preliminary studies on the effects of Taiwanese ritual smoke on Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae)," The Pan-Pacific Entomologist 97(2), 67-74, (30 July 2021). https://doi.org/10.3956/2021-97.2.67
Asiatic wormwood leaves, agarwood incense sticks and rice paper ghost money.
