?Milkweed grown with more carbon dioxide in the air supplies fewer toxins to monarch butterflies that need the toxins to fight off gut parasites.乳草生長過程中空氣里二氧化碳的含量越高,其毒素含量就越低,而這毒素正是帝王蝶抵抗腸道寄生蟲所必需的。 撰文/播音:Marissa Shieh 翻譯:張朵兒 審校:張清越 One of the delights of summer is to see monarch butterflies dancing through the air.?But it’s becoming harder to see them in certain locales—in some places the population has dropped by as much as 90 percent. And climate change may make life even more challenging for these charismatic insects. That’s because higher carbon dioxide levels can lower the amount of toxins in milkweed—the monarch caterpillar’s food. The caterpillars use those toxins to protect themselves from a deadly parasite that produces spores. 夏天的樂趣之一就是看帝王蝶在空中飛舞。但是在某些地方,越來越難看到它們的身影了——在一些區(qū)域,它們的數(shù)量減少了90%。氣候變化可能會讓這些充滿魅力的昆蟲生活更加艱難。這是因為較高的二氧化碳濃度可以降低乳草內(nèi)的毒素含量。毛蟲使用這些毒素來保護自己免受一種會產(chǎn)生孢子的致命寄生蟲傷害。 “When the caterpillars are really small…those spores get into the monarch’s gut and they break apart and they start drilling holes in the gut lining and reproducing and just doing nasty parasite things that are bad for the monarchs. “當(dāng)毛毛蟲還很小的時候......那些孢子進入它們的腸道,寄生蟲便離開孢子,開始在腸道襯里鉆孔并繁殖,做一些令人討厭的寄生蟲行為。 Leslie Decker, an ecologist at Stanford University. Decker and her colleagues raised hundreds of monarchs. They fed half of the caterpillars milkweed grown at current CO2 levels. The other half got milkweed grown at nearly double those CO2 levels. 斯坦福大學(xué)生態(tài)學(xué)家萊斯利?德克爾(Leslie Decker)和她的同事們培養(yǎng)了數(shù)百條帝王蝶幼蟲。他們給半數(shù)的毛毛蟲喂在目前二氧化碳濃度水平下生長的乳草。另一半喂生長在幾乎是兩倍二氧化碳濃度水平中的乳草。 “What we found is that elevated CO2 changes the medicinal quality of the milkweed in a way that makes monarchs sicker. They're less able to tolerate their pathogen, so the parasite becomes more hurtful…to them. And it also reduces their overall lifespan when they're infected in comparison to uninfected monarchs.” “我們發(fā)現(xiàn),二氧化碳濃度升高會改變乳草的藥用品質(zhì),使幼蟲病情加重。他們對病原體的耐受能力較差,因此寄生蟲會對他們造成更大的傷害。與未受感染的幼蟲的相比,受感染幼蟲的整體壽命會縮短。 The caterpillars that ate milkweed grown with more carbon dioxide grew into butterflies that died as much as a week earlier than the normal life span. 吃在較高二氧化碳濃度下生長的乳草的毛蟲,長成蝴蝶之后會比正常壽命早一周死亡。 “As a human, you think, oh, well that's not that meaningful. But then as an insect, or as an insect that needs to reproduce within a week, it's pretty important.” The study is in the journal Ecology Letters. [Leslie E. Decker et al., Elevated atmospheric concentrations of carbon dioxide reduce monarch tolerance and increase parasite virulence by altering the medicinal properties of milkweeds] “或許你會覺得,作為人類,這不是那么有意義。但作為一種昆蟲,或作為一種需要在一周內(nèi)完成繁殖的昆蟲,這一點非常重要。”這項研究發(fā)表在《生態(tài)快報》雜志上。 Decker say these findings are not just about butterflies and milkweed. 德克爾說,這些發(fā)現(xiàn)不只是關(guān)于蝴蝶和乳草。 “Many of our medicines come from plants…and so what this study is highlighting to us, or at least creating a red flag for, is the fact that the medicinal contents in those plants could be changing under elevated CO2. They could be going up or down, but it could mean that we lose the medicinal efficacy, the protective ability of that green pharmacy around us. “我們的許多藥物都來自植物......因此,這項研究向我們強調(diào)的是,至少作為一種警告,就是這些植物中的藥用成分可能會在二氧化碳濃度升高的情況下發(fā)生變化。這些成分或許會提高和下降,但這意味著我們可能會失去這些原本可以得到的藥效,失去了保護我們的綠色藥房。