「殺手香料」 害蟲的剋星 | 環境資訊中心

「殺手香料」 害蟲的剋星

2009年08月19日
摘譯自2009年8月17日EN美國,華盛頓特區報導;張桂芳編譯;蔡麗伶審校

伊詩曼博士與用精油製作的環保殺蟲劑。圖片由 Martin Dee 攝,UBC 提供。正當業界嘗試滿足大衆對無施灑有毒化學品水果和蔬菜日益增長的需求情況下,廚房常見的香料如迷迭香、百里香、丁香和薄荷,暱稱為「殺手香料,」被公認為有機農業對抗昆蟲有效的殺蟲劑。

本月16日在華盛頓舉辦的美國化學學會全國會議開幕式上,來自英屬哥倫比亞大學的科學家提出了他們稱之為「精油農藥」的最新研究報告。

英屬哥倫比亞大學農業生態學教授,也是這次研究的發表人伊詩曼(Murray Isman)博士表示:「我們正在探索如何在精油的基礎上利用天然殺蟲劑──常用於食品和飲料中的調料。」

他還表示:「我們正在使用各種植物精油作為活性成分,嘗試開發殺蟲劑、殺蟎劑、殺菌劑和除草劑。」

一般而言,這類新的農藥將少量兩到四個不同的香料稀釋在水中混合而成。部份農藥用途為殺死昆蟲,而其他則為驅除昆蟲用。

研究顯示,香料油透過干擾昆蟲的神經系統,或破壞其細胞膜而導致死亡。

伊詩曼表示,天然殺蟲劑的好處是不需要經過冗長與繁複監管部門的批准,並且隨處可得。另外一個優點是,昆蟲不太容易發展出抗藥性 -- 能夠擺脫一次性有效的毒素。此外,天然殺蟲劑對常與農藥接觸的高風險農場工人也比較安全。

但是,使用新農藥也有缺點。由於精油往往蒸發速度快,在陽光下分解也快。因此,比起傳統農藥,農民必需更常對作物施灑以天然香料為主的農藥,原因是部份農藥的藥性只有幾小時。而與傳統農藥相比,藥效則可持續幾天甚至幾個月的時間。

伊詩曼表示,天然農藥的藥性一般來説比傳統農藥的藥性弱,因此,為達到相當程度蟲害控制的效果就必須使用高濃度的農藥。研究人員目前正在設法找尋一種讓天然殺蟲劑能更持久和更有效的方法。

據美國環保署表示,75%的美國家庭每年至少使用一種室內殺蟲劑產品。同時80%的一般民衆接觸殺蟲劑的機會都是在室內。

一些科學家正在探索薰衣草、羅勒、佛手柑、廣藿香油,以及至少十幾種其他在中國的外來種植物,其對付昆蟲的可能性。

'Killer Spices' Fatal to Insect Pests
WASHINGTON, DC, August 17, 2009 (ENS)

Common kitchen spices such as rosemary, thyme, clove, and mint, nick-named "killer spices," are proving effective as pesticides in organic agriculture's battle against insects as the industry tries to meet the growing demand for fruits and vegetables that are free of toxic chemicals.

In a study presented Sunday at the opening day of the American Chemical Society's national meeting in Washington, scientists from the University of British Columbia presented new research into what they are calling "essential oil pesticides."

"We are exploring the potential use of natural pesticides based on plant essential oils - commonly used in foods and beverages as flavorings," said study presenter Murray Isman, PhD, a professor of agroecology at UBC.

"We are developing insecticides, miticides, fungicides and herbicides using various plant essential oils as the active ingredients," he said.

The new pesticides are generally a mixture of small amounts of two to four different spices diluted in water. Some kill insects, while others repel them.

Research indicates that the spicy oils act by interfering with insects' nervous systems or by breaching their cell membranes, causing death.

To their credit, the natural pesticides do not require extensive regulatory approval and are readily available. An additional advantage is that insects are less likely to evolve resistance - the ability to shrug off once-effective toxins - Isman says. They are also safer for farm workers, who are at high risk for pesticide exposure, he says.

But there are also drawbacks to using the new pesticides. Since essential oils tend to evaporate quickly and degrade rapidly in sunlight, farmers need to apply the spice-based pesticides to crops more frequently than conventional pesticides. Some last only a few hours, compared to days or even months for conventional pesticides.

As the natural pesticides are generally less potent than conventional pesticides, they also must be applied in higher concentrations to achieve acceptable levels of pest control, Isman says. Researchers are now seeking ways of making the natural pesticides longer-lasting and more potent.

According to the U.S. Environmental Protection Agency, at least one pesticide product is used indoors by 75 percent of U.S. households each year and that 80 percent of the average person's exposure to pesticides occurs indoors.

Other scientists are exploring the insect-fighting potential of lavender, basil, bergamot, patchouli oil, and at least a dozen other oils from exotic plant sources in China.