The sustained massive use of pesticides in farming has two effects tha

As the OA mentiones, the answer would be [B].
We can see that the question requires the effectiveness of the sustained massive use of pesticides to be extended. The paragraph above describe the destructive effects of the massive use of pesticides in farming which are:
1. kills off the pests' natural enemies in the area
2. gives rise to insecticide-resistant pests.

Now the first effect is not highlighted in any of the choices, but the second reason can be countered by continous change in the variety of insectiside so that the pests do not get acquainted with a given type of insectiside. The above argument is presented under the choice [B]. Rest of the choices can be eliminated for obvious reasons.

Hope this helps!

Regards,
Arpan

Argument:
Sustained massive use of pesticides in farming has two effects
1. it often kills off the pests' natural enemies in the area
2. it often unintentionally gives rise to insecticide-resistant pests , since those insects that survive a particular insecticide will be the ones most resistant to it, and they are the ones left to breed.

Pre thinking:
Sustained use kills natural enemies.
Sustained use of a particular pesticide wills make insects that survives as resistant to that pesticide.
So by using one pesticide for too long we are actually creating insects resistant to that pesticide. Hence a way to avoid this is not to use one particular pesticide for too long.

Analysis of answer choice
(Al Using only chemically stable insecticides
INCORRECT: Irrelevant as chemical stability is not a problem here.
(B) Periodically switching the type of insecticide used
CORRECT: Since using one particular pesticide makes insects resistant to it so a better approach would be to change pesticides so that insects which develops resistance against one type gets killed by other type of pesticides.

(C) Gradually increasing the quantities of pesticides used
INCORRECT: Argument already talks about sustained massive use which is not having effect on pesticide resistant insects.

(D) Leaving a few fields fallow every year
INCORRECT: It will not change the reasons which are causing the problem.

(E) Breeding higher-yielding varieties of crop plants
INCORRECT: higher yielding plants can still get affected by insects.

Let us examine the options.

Option A: Using only chemically stable insecticides.
Chemical stability of the insecticides is not mentioned anywhere in the passage. Irrelevant.
Hence Option A is incorrect.

Option B: Periodically switching the type of insecticide used.
It is given that insecticide-resistant pests arise due to breeding of the pests which survived a particular type of insecticide. Therefore it is a logical conclusion that by changing the insecticides there is a chance to reduce the incidence of insecticide-resistant pests thereby extending the effectiveness of sustained massive use of pesticides.
Hence Option B is correct.

Option C: Gradually increasing the quantities of pesticides used.
This doesn't help because pesticides are also responsible for killing off the pests' natural enemies in the area. Also this gradual increase can lead to an even stronger insecticide-resistant varieties among pests.
Hence Option C is incorrect.

Option D: Leaving a few fields fallow every year.
Irrelevant. This doesn't help increase the effectiveness of sustained massive use of pesticides.
Hence Option D is incorrect.

Option E: Breeding higher-yielding varieties of crop plants.
Breeding higher-yielding varieties of crop plants doesn't help with problem of pests. It doesn't, in anyway, increase the effectiveness of pesticides.
Hence Option E is incorrect.

So the correct answer is Option B.

Stmt structure :

Massive use of pest --> 1. Kill the natural enemy of pest --> 2. Resisted pest of the particular pesticide will breed. Hence the resisted pest will increase in the farming. This may not be good.

Pre-thinking: The resisted pest which can't be killed by a particular pesticide survives and breed.

a. Using only chemically stable insecticides - Nature of the pest is not discussed. can't be inferred.
b. Periodically switching the type of insecticide used - this is in alignment with prethinking. This will make sure that the survived pest may be killed if we use a diff one.
c. Gradually increasing the quantities of pesticides used - this can't be inferred.As the passage scope should be with in the usage of massive use of pesticides - and its reactions. Usage of more pest will not take any effect as it can be used only as much.
d. Leaving a few fields fallow every year - The passage scope is -- massive usage of pesticides and its effect. This option falls beyond its scope. Hence its incorrect.
e. Breeding higher-yielding varieties of crop plants - clearly irrelevant to the passage's scope.

Stmt structure :

Massive use of pest --> 1. Kill the natural enemy of pest --> 2. Resisted pest of the particular pesticide will breed. Hence the resisted pest will increase in the farming. This may not be good.

Pre-thinking: The resisted pest which can't be killed by a particular pesticide survives and breed.

a. Using only chemically stable insecticides - Nature of the pest is not discussed. can't be inferred.
b. Periodically switching the type of insecticide used - this is in alignment with prethinking. This will make sure that the survived pest may be killed if we use a diff one.
c. Gradually increasing the quantities of pesticides used - this can't be inferred.As the passage scope should be with in the usage of massive use of pesticides - and its reactions. Usage of more pest will not take any effect as it can be used only as much.
d. Leaving a few fields fallow every year - The passage scope is -- massive usage of pesticides and its effect. This option falls beyond its scope. Hence its incorrect.
e. Breeding higher-yielding varieties of crop plants - clearly irrelevant to the passage's scope.

The sustained massive use of pesticides in farming has two effects that are especially pernicious. First, it often kills off the pests' natural enemies in the area . Second, it often unintentionally gives rise to insecticide-resistant pests, since those insects that survive a particular insecticide will be the ones most resistant to it, and they are the ones left to breed.

Boil it down - 2 negative effects of pesticides - kills pest's natural enemies and gives rise to insecticide-resistant pests . The ones left will be resistant to pesticides .


From the passage above, it can be properly inferred that the effectiveness of the sustained massive use of pesticides can be extended by doing which of the following, assuming that each is a realistic possibility?

(Al Using only chemically stable insecticides - Irrelevant as per the argument the negative effects are for all kinds of pesticides
(B) Periodically switching the type of insecticide used - Correct - Suppose we use type A pesticide in first year and type B in second year , there is possibility that the pests that were resistant to type A might not be resistant to Type B .
(C) Gradually increasing the quantities of pesticides used - Incorrect
(D) Leaving a few fields fallow every year - Incorrect
(E) Breeding higher-yielding varieties of crop plants - Irrelevant

Answer B

Evaluation of a Plan

Situation Continued high-level pesticide use often kills off the targeted pests' natural enemies. In addition, the pests that survive the application of the pesticide may become resistant to it, and these pesticide-resistant pests will continue breeding.

Reasoning What can be done to prolong the effectiveness of pesticide use?
It can be inferred that the ongoing use of a particular pesticide will not continue to be effective against the future generations of pests with an inherent resistance to that pesticide. What would be effective against these future generations? If farmers periodically change the particular pesticide they use, then pests resistant to one kind of pesticide might be
killed by another. This would continue, with pests being killed off in cycles as the pesticides are changed. It is also possible that this rotation might allow some of the
pests' natural enemies to survive, at least until the next cycle.

A Not enough information about chemically stable insecticides is given to make a sound inference.

B Correct. This statement properly identifies an action that could extend the effectiveness of pesticide use.

C Gradually increasing the amount of the pesticides being used will not help the situation since the pests are already resistant to it.

D Continued use of pesticides is assumed as part of the argument. Since pesticides would be unnecessary for fallow fields, this suggestion is irrelevant.

E Breeding higher-yielding varieties of crops does nothing to extend the effectiveness of the use of pesticides.

The correct answer is B.

Argument: Sustained massive use of pesticides in farming has two effects:

1. Kills Pests
2. Gives rise to insecticide resistant pests

We are trying to look for a scenario which can help in overcoming or reducing the impact created by the second point.

(Al Using only chemically stable insecticides – Out of Scope, chemical stability not discussed.
(B) Periodically switching the type of insecticide used – Looks correct – Lets hold this
(C) Gradually increasing the quantities of pesticides used – This will worsen it more, incorrect
(D) Leaving a few fields fallow every year – Irrelevant
(E) Breeding higher-yielding varieties of crop plants – Does not solve the pesticide issue

Correct Answer is B

Get Major uses of pesticides, Plant growth Regulator And Major uses of biopesticide

Here is an official explanation:
Gradually increasing the amount of the pesticides being used will not help the situation since the pests are already resistant to it. Furthermore, while a rotation might allow some of the pests’ natural enemies to survive, at least until the next cycle, the method in C does not.

Are pesticides and insecticides the same?

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What the passage tells us.

Pesticides are used by farmers.
Continued and massive use of these pesticides lead to two very harmful side-effects
First, the usage often (most of the time) kills the natural enemies of these pests
(Here we can understand why this side-effect is harmful. If the natural enemies of the pests are also killed, then a natural way of getting rid of pests is eliminated leading to the abounding of the pests.)
Second, the usage often and without really intending to do so, leads to the growth of insecticide-resistant pests.
This happens because the insects that are not killed by a particular (not all but only one) insecticide (we can infer here that the insecticide does not always kill all the pests) are the ones that were able to resist is most.
And it is these insecticide-resistant pests that are left alive to breed more such insecticide-resistant pests,
(we can infer here that in future when the same {the same particular one used before} insecticide is again used {sustained and massive use}, then it is ineffective as now it is being used on insects that are resistant to it.)


What we need to do

Question Stem - From the passage above, it can be properly inferred that the effectiveness of the sustained massive use of pesticides can be extended by doing which of the following, assuming that each is a realistic possibility?

Let us suppose that each of the options presents a practical possibility. In that case, based on the information given in the passage, which of these can be used to increase the effectiveness of continuous and massive use of pesticides.

Choice B

Understand the choice

The choice says that no one type of insecticide should be used continuously. Rather the type of insecticide used should be changed at regular periods.

Analyze in the context of the passage and the question stem

One of the causes of the harmful side effects of pesticides given in the passage is its sustained use. That is, using the same pesticide continuously. The harmful effect is that when a particular (not all but a specific one) insecticide is used, it give rise to insects that are resistant to that particular (that same specific one) insecticide. This happens when the insects that are not killed by that particular insecticide (because they must have been the ones that were able to most resist that particular insecticide) remain alive to breed more of the same insecticide-resistant breed. Now, when the same insecticide is used again (sustained use), then the insects that are now resistant to that particular insecticide cannot be killed.

The above choice offers a logical solution to this part of the cause. If we do not use the same insecticide again then the new insecticide will now act upon the insects that are resistant to the previous insecticide but not to this new one. In this manner, it will be possible to continue to use insecticides without leading to growth of insecticide -resistant insects and also killing the existing ones.

Hence, this choice offers a practical solution to the given problem in the passage

Pesticides are chemicals that may be used to kill fungus, bacteria, insects, plant diseases, snails, slugs, or weeds among others. ... Insecticides are a type of pesticide that is used to specifically target and kill insects. Some insecticides include snail bait, ant killer, and wasp killer.

The sustained massive use of pesticides in farming has two effects that are especially pernicious. First, it often kills off the pests' natural enemies in the area. Second, it often unintentionally gives rise to insecticide-resistant pests, since those insects that survive a particular insecticide will be the ones most resistant to it, and they are the ones left to breed.

From the passage above, it can be properly inferred that the effectiveness of the sustained massive use of pesticides can be extended by doing which of the following, assuming that each is a realistic possibility?

-Sustained massive use of Pesticides has the opposite effect of what it was intended to do. Because it kills threats to pests and it creates a stronger species of pests.
We have to find an answer which extends the effectiveness of the use of pesticide. This is important to know as the question isn't asking us for alternatives to pesticides, which we can often infer because of our biases.

(A) Using only chemically stable insecticides

- Out of scope, we don't have any conversation about the stability of pesticides used.

(B) Periodically switching the type of insecticide used

- This is a good option, if pests have become immune to one type of pesticide, we can keep switching these to have a stronger impact.

(C) Gradually increasing the quantities of pesticides used

- This seems like a good option too, but increasing quantities of pesticides won't help kill the immune pests.

(D) Leaving a few fields fallow every year

- This is out of scope, we have to show effectiveness of Pesticides used.

(E) Breeding higher-yielding varieties of crop plants

- The question has asked us to figure out how to reduce the no. of pests. Not how to increase yield.

GMATNinja nightblade354 - while I understand why B is the OA, I do want to clarify something regarding the OA

Would you agree, option B only refers to the 2nd pernicious point mentioned in the red.

Option B doesn't seem to be referring to the 1st pernicious point highlighted in blue ?

I was ideally hoping for a OA that "HITS" both pernicious points mentioned (in the red and in the blue)

Just curious on your thoughts

Thank you

It’s definitely true that (B) helps reduce the likelihood of creating insecticide-resistant pests, and (B) may or may not limit the first pernicious effect. The important thing is that it really doesn’t matter.

The question doesn’t ask for an answer choice that limits both pernicious effects. It merely asks for an answer choice that will extend the effectiveness of the sustained massive use of pesticides.

So the most valuable takeaway from this question is really not whether (B) limits the first effect. It’s more that we need to be careful not to pre-think and try to come up with what we feel the right answer should do, without looking at the answer choices. This is particularly relevant because we’re asked to find the BEST answer choice and NOT the right answer choice.


I hope that helps!

GMATNinja

Can you please help me understand the impact of option D.
In my opinion, if the a few fields are left fallow, pesticides won't be used because there are no crops. And since the pesticide usage gets a break, wouldn't such a scheme reduce the pesticide resistance?

Regards,
Niyati