今天上午我要给大家讲一个关于动植物关系的新发现。这是关于一种沙漠灌木,它的叶子能够射出一股六英尺远的有毒树脂。

你认为这会抵挡住所有昆虫的攻击吗?但是最近一项研究发现,有一种昆虫,甲壳虫可以通过切断植物向叶子输送毒液的主静脉,在这种植物的防御系统咀嚼出一条路来.这种主静脉切割法只是甲壳虫准备安全大餐的一种方式。另一种方法是切断通过树叶的路径以阻止毒液的流动.然后它们只管吃毒静脉之间的叶子.过去研究昆虫对植物防御系统适应性的科学家专注于化学反应,即,昆虫是如何中和或者改变植物制造的有毒物质。

 

这种咀嚼策略的独特之处是甲壳虫针对植物防御事实上表现出了行为反应而不是比较常见的化学反应。只有当甲壳虫经历过几次植物的树脂袭击并幸存下来,它才能学会如何避免中毒:通过咀嚼它要吞食的下一片叶子树脂输送静脉来为自己提供安全的食物。但是一只甲壳虫要花上一个半小时切断静脉为自己准备一小片只需几分钟就能吃掉的叶子。因此,尽管这个方法很有效,但不是很高效。

生词摘录:

1. 灌木 名词 shrub

2. 树脂 名词 resin

3. 甲壳虫 名词 beetle

4. 静脉 名词 vein

5. 中和 动词 neutralize

6. 改变 动词 alter

英文译文

This morning I want to tell you about a recent scientific discovery concerning the relationship between plants and animals.

It concerns a desert shrub whose leaves can shoot a stream of poisonous resin at a distance of six feet. You would think that it would be safe from all attacks by insects, but a recent study has discovered that a certain kind of beetle can chew past the plant's defense system by cutting the main vein that delivers the poison to the leaves. This vein cutting is just one method the beetles use to prepare a safe meal. Another is by cutting a path all the way across the leaves to hold the flow of chemicals. Then they simply eat between the veins of poison. In the past, scientists who studied insects' adaptation to plant defenses focused on chemical responses, that is, how the insects can neutralize or alter the poisonous substances plants produce.

What's unique about this chewing strategy is that the beetle is actually exhibiting a behavioral response to the plant's defenses rather than the more common chemical response. It is only after a beetle has survived several encounters with the plant's resin that it learns how to avoid the poison: by chewing through the resin transporting veins on the next leaf it eats, and thus gives itself a safe meal. However, it can take the beetle an hour and a half of careful vein cutting to prepare a small leaf that takes only a few minutes to eat. So, although the method is effective, it's not very efficient.