本篇文章共分 8 段，將害蟲與殺蟲劑之間的關係藉由梨圓介殼蟲為例做一介紹，從介殼蟲的出現與對其進行的早期殺蟲劑控制、昆蟲產生抗藥性、科學家研究找出變化原因、到新式殺蟲劑問世與其後失效一一加以整理說明。

本篇考題英文原文與對應之中文翻譯整理如下。練習作答解題時若有對語意不清楚之處，請仔細查閱對照，以提升閱讀理解能力。

Pests and Pesticides 害蟲和殺蟲劑

1. 梨圓介殼蟲

   Around 1870, a little fruit-eating insect arrived in San Jose, California, on some nursery stock shipped from Asia. The pest, which became known as the San Jose scale, quickly spread through the United States and Canada, killing orchard trees as it went. Farmers found that the best way to control the scale was to spray their orchards with a mixture of sulfur and lime. Within a few weeks of spraying a tree, the insect vanished completely.

   大約在 1870 年，一種吃水果的小昆蟲附在一些從亞洲運來的苗木上來到了加利福尼亞的聖荷西。這種害蟲，被稱為梨圓介殼蟲 (San Jose scale)，迅速在美國和加拿大傳播，在它所到之處殺死了果園樹木。農民們發現，控制這種介殼蟲的最好方法是用硫磺和石灰的混合物噴灑他們的果園。在噴灑樹木的幾個星期內，這種昆蟲就完全消失了。

2. 硫磺石灰殺蟲劑失效

   Around the turn of the century, however, farmers began to notice that the sulfur-lime mixture was not working all that well. A handful of scales would survive a spraying and eventually rebound to their former numbers. In Clarkston Valley in Washington State, orchard growers became convinced that manufacturers were adulterating their pesticide. They built their own factory to guarantee a pure poison, which they drenched over their trees, yet the scale kept spreading uncontrollably. An entomologist named A. L Melander inspected the trees and found scales living happily under a thick crust of dried spray.

   然而，在本世紀初，農民們開始注意到硫磺-石灰混合物的效果並不理想。少數介殼蟲會在噴藥後存活下來，並最終反彈到以前的數量。在華盛頓州的克拉克斯頓谷，果園種植者認為製造商在他們的殺蟲劑中摻雜了雜質。他們建立了自己的工廠，以保證毒性純正，他們把這些毒素淋在他們的樹上，但介殼蟲仍然不受控制地蔓延。一位名叫 A.L. Melander 的昆蟲學家檢查了這些樹木，發現介殼蟲在噴劑乾燥後形成的厚厚外殼下快樂地生活著。

3. 昆蟲抵抗力

   Melander began to suspect that adulteration was not to blame. In 1912, he compared how effective the sprays were in different parts of Washington. In Yakima and Sunnyside, he found that sulfur-lime could wipe out every last scale on a tree, while in Clarkston between 4 and 13 percent survived. On the other hand, the Clarkston scales were annihilated by a different pesticide made from fuel oil, just as the insects in other parts of Washington were. In other words, the scales of Clarkston had a peculiar resistance to sulfur-lime.

   梅蘭德開始懷疑，問題並不是摻假的藥劑。1912 年，他比較了華盛頓州不同地區噴霧劑的效果。在雅基馬和桑尼塞德，他發現硫磺石灰可以消滅樹上的每一隻介殼蟲，而在克拉克斯頓，有 4% 到 13% 的介殼蟲倖存。另一方面，克拉克斯頓的介殼蟲被一種由燃料油製成的不同的殺蟲劑消滅，就像華盛頓州其他地區的昆蟲一樣。換句話說，克拉克斯頓的介殼蟲對硫磺石灰有一種特殊的抵抗力。

4. 抗藥性出現

   Melander wondered why. He knew that if individuals eat small amounts of certain poisons, such as arsenic, they can build up an immunity. But San Jose scales bred so quickly that no single scale experienced more than a single spray of sulfur-lime, giving them no chance to develop immunity.

   梅蘭德想知道為什麼。他知道，如果個人吃了少量的某些毒藥，如砒霜，他們可以建立起一種免疫力。但是梨圓介殼蟲繁殖得如此之快，以至於沒有一隻介殼蟲經歷過超過一次以上的硫磺石灰噴灑，因而使它們沒有機會產生免疫力。

5. 突變與抗藥性增生

   A radical idea occurred to Melander. Perhaps mutations made a few scales resistant to sulfur-lime. When farmers sprayed their trees, these resistant scales survived, as did a few nonresistant ones that hadn’t received a fatal dose. The surviving scales would then breed, and the resistant genes would become more common in the following generations. Depending on the proportions of the survivors, the trees might become covered by resistant or nonresistant scales. In the Clarkston Valley region, farmers had been using sulfur-lime longer than anywhere else in the Northwest and were desperately soaking their trees with the stuff. In the process, they were driving the evolution of more resistant scales.

   梅蘭德想到了一個極端的想法，也許突變使一些介殼蟲對硫磺石灰有抵抗力。當農民給他們的樹木噴灑硫磺石灰時，這些有抵抗力的介殼蟲就會存活下來，而一些沒有抵抗力的介殼蟲也沒有受到致命的劑量。然後，倖存的介殼蟲會進行繁殖，抗性基因會在接下來的幾代中變得更加普遍。根據倖存者的比例，樹木可能被抗性或非抗性介殼蟲覆蓋。在克拉克斯頓山谷地區，農民使用硫磺石灰的時間比西北其他地方都長，他們拚命地用這種東西浸泡他們的樹木。在這個過程中，他們正在刺激更多抗性介殼蟲的進化。

6. DDT 問世

   Melander offered his ideas in 1914, but no one paid much attention to him; they were too busy discovering even more powerful pesticides. In 1939 the Swiss chemist Paul Muller found that a compound of chlorine and hydrocarbons called DDT could kill insects more effectively than any previous pesticide had. DDT was cheap and easy to make, it could kill many species of insects, and it was stable enough to be stored for years. It could be used in small doses, and it didn’t seem to pose any health risks to humans. Between 1941 and 1976, 4.5 million tons of DDT were produced. DDT was so powerful and cheap that farmers gave up old-fashioned ways of controlling pests, such as draining standing water or breeding resistant strains of crops.

   梅蘭德在 1914 年提出了他的想法，但是沒有人注意他；他們忙於發現更強大的殺蟲劑。1939 年，瑞士化學家保羅．穆勒發現，一種名為 DDT 的氯和碳氫化合物可以比以前的任何殺蟲劑更有效地殺死昆蟲。DDT 便宜而且容易製造，它可以殺死許多種類的昆蟲，而且穩定到可以儲存多年。它可以小劑量使用，而且似乎不會對人類造成任何健康風險。從 1941 年到 1976 年，共生產了 450 萬噸 DDT。 DDT 的威力如此之大，價格如此之低，以至於農民放棄了老式的控制害蟲的方法，如排乾積水或培育具抗性的作物品系。

7. DDT 大量使用

   DDT and similar pesticides created the delusion that pests could be not merely controlled but eradicated, so farmers began spraying pesticides on their crops as a matter of course, rather than to control outbreaks. Meanwhile, public health workers saw in DDT the hope of controlling mosquitoes, which spread diseases such as malaria.

   DDT 和類似的殺蟲劑造成了一種錯覺，即害蟲不僅可以被控制，而且可以被消滅，因此農民開始在他們的作物上理所當然地噴灑殺蟲劑，而不是為了控制疾病的爆發。同時，公共衛生工作者從 DDT 中看到了控制蚊子的希望，因為蚊子會傳播諸如瘧疾等疾病。

8. DDT 失效

   DDT certainly saved a great many lives and crops, but even in its early days, some scientists saw signs of its doom. In 1946 Swedish scientists discovered houseflies that could no longer be killed with DDT. Houseflies in other countries became resistant as well in later years, and soon other species could withstand it. Melander’s warning was becoming a reality. By 1992 more than 500 species were resistant to DDT, and the number is still climbing. As DDT began to fail, farmers at first just applied more of it; when more no longer worked, they switched to newer pesticides.

   DDT 確實拯救了很多人的生命和莊稼，但即使在它的早期，一些科學家也看到了它的末日跡象。1946 年，瑞典科學家發現了無法被 DDT 殺死的家蠅，後來其他國家的家蠅也出現了抗藥性，很快其他物種也能承受 DDT。梅蘭德的警告逐漸成真。到 1992 年，有 500 多個物種對 DDT 產生了抗藥性，而且這個數字還在不斷攀升。當 DDT 開始失效時，農民們起初只是施用更多的 DDT；當更多的 DDT 不再起作用時，他們就改用更新的殺蟲劑。