More selective than most chemical
pesticides in that they ordinarily destroy
only unwanted species, biocontrol.
agents (such as insects, fungi, and
(5) 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
(10) 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.
(15) consequcnces 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
(20) 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 disrup-
(25) tions 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
(30) 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
(35) 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.
(40) so that it can feed on or otherwise harm
new hosts.
4
The passage suggests that the author would
be 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 evenfinally
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.
OA-E I find OA out of scope. Nowhere in the passage risks of non-native biocontrol agents is discussed.
pesticides in that they ordinarily destroy
only unwanted species, biocontrol.
agents (such as insects, fungi, and
(5) 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
(10) 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.
(15) consequcnces 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
(20) 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 disrup-
(25) tions 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
(30) 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
(35) 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.
(40) so that it can feed on or otherwise harm
new hosts.
4
The passage suggests that the author would
be 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 evenfinally
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.
OA-E I find OA out of scope. Nowhere in the passage risks of non-native biocontrol agents is discussed.
