GWD-24 Q3 TO 6生物防除剂的风险分析,求指导

autumn1015

More selective than most chemical pesticides in that they ordinarily destroy only unwanted species, biocontrol. agents (such as insects, fungi, and viruses) eat, infect, or parasitize targeted plant or animal pests. However, biocontrol agents can negatively affect nontarget species by, for example, competing with them for resources: a biocontrol agent might reduce the benefits conferred by a desirable animal species by consuming a plant on which the animal prefers to lay its eggs. Another example of indirect negative consequences occurred in England when a virus introduced to control rabbits reduced the amount of open ground (because large rabbit populations reduce the ground cover), in turn reducing underground ant nests and triggering the extinction of a blue butterfly that had depended on the nests to shelter its offspring. The paucity of known extinctions or disruptions resulting from indirect interactions may reflect not the infrequency of such mishaps but rather the failure to look for or to detect them: most organisms likely to be adversely affected by indirect interactions are of little or no known commercial value and the events linking a biocontrol agent with an adverse effect are often unclear. Moreover, determining the potential risks of biocontrol agents before they are used is difficult, especially when a nonnative agent is introduced, because, unlike a chemical pesticide, a biocontrol agent may adapt in unpredictable ways, so that it can feed on or otherwise harm new hosts.

Q4

The passage suggests that the author wouldbe most likely to agree with which of the following statements about the use of biocontrol agents?

A.Biocontrol agent should be used only in cases where chemical pesticides have proven ineffective or overly dangerous.

B.Extinctions and disruptions resulting from the use of biocontrol agents are likely to have increasingly severe commercial consequences.

C.The use of biocontrol agents does not require regulation as stringent as that required by the use of chemical pesticides.

D.The use of biocontrol agents may even finally supersede the use of chemical pesticides in controlling unwanted species.

E.The risks of using native biocontrol agents may be easier to predict than the risks of using nonnative biocontrol agents.

此题选E. 对照原文应该是mark成红色的部分，可是我不太理解这句话的含义，特别是when a nonnative agent is introduced，这里的nonative agent是biocontrol agent的一个subcategory嘛？与native agent对应嘛？那两者之间有什么且别呢？biocontrol agent不是包含such as insects, fungi, and viruses，这些不都应该是native的嘛，没有nonnative的呀。不能理解呀，我怎么觉得这道题是需要背景知识呢？那位大NN帮忙解释一下？

autumn1015

自己顶一下。大牛在那里？

西米露77

不要想的那么复杂
前面半句说BA这东西在用之前是很难预测他会带来的潜在风险的，尤其是nonnative的BA
所以就可以infer出nonnative的比native的更难预测