Sometimes there is no more effective means of controlling an

Question

Sometimes there is no more effective means of
controlling an agricultural pest than giving free rein
to its natural predators. A case in point is the
cyclamen mite, a pest whose population can be
 (5)  effectively controlled by a predatory mite of the
genus Typhlodromus. Cyclamen mites infest
strawberry plants; they typically establish themselves
in a strawberry field shortly after planting, but their
populations do not reach significantly damaging
 (10)  levels until the plants’ second year. Typhlodromus
mites usually invade the strawberry fields during the
second year, rapidly subdue the cyclamen mite
populations, and keep them from reaching
significantly damaging levels.

(15)  Typhlodromus owes its effectiveness as a predator
to several factors in addition to its voracious appetite.
Its population can increase as rapidly as that of its
prey. Both species reproduce by parthenogenesis—a
mode of reproduction in which unfertilized eggs
 (20)  develop into fertile females. Cyclamen mites lay three
eggs per day over the four or five days of their
reproductive life span; Typhlodromus lay two or three
eggs per day for eight to ten days. Seasonal
synchrony of Typhlodromus reproduction with the
 (25)  growth of prey populations and ability to survive at
low prey densities also contribute to the predatory
efficiency of Typhlodromus. During winter, when
cyclamen mite populations dwindle to a few
individuals hidden in the crevices and folds of leaves
 (30)  in the crowns of the strawberry plants, the predatory
mites subsist on the honeydew produced by aphids
and white flies. They do not reproduce except when
they are feeding on the cyclamen mites. These
features, which make Typhlodromus well-suited for
 (35)  exploiting the seasonal rises and falls of its prey, are
common among predators that control prey
populations.

Greenhouse experiments have verified the
importance of Typhlodromus predation for keeping
 (40)  cyclamen mites in check. One group of strawberry
plants was stocked with both predator and prey mites;
a second group was kept predator-free by regular
application of parathion, an insecticide that kills the
predatory species but does not affect the cyclamen
 (45)  mite. Throughout the study, populations of cyclamen
mites remained low in plots shared with
Typhlodromus, but their infestation attained
significantly damaging proportions on predator-free
plants.

(50)  Applying parathion in this instance is a clear case
in which using a pesticide would do far more harm
than good to an agricultural enterprise. The results
were similar in field plantings of strawberries, where
cyclamen mites also reached damaging levels when
 (55)  predators were eliminated by parathion, but they did
not attain such levels in untreated plots. When
cyclamen mite populations began to increase in an
untreated planting, the predator populations quickly
responded to reduce the outbreak. On average,
 (60)  cyclamen mites were about 25 times more abundant
in the absence of predators than in their presence.  
 1 
 1. Which one of the following most accurately expresses the main point of the passage?

(A) Control of agricultural pests is most effectively and safely accomplished without the use of pesticides, because these pesticides can kill predators that also control the pests.
(B) Experimental verification is essential in demonstrating the effectiveness of natural controls of agricultural pests.
(C) The relationship between Typhlodromus and cyclamen mites demonstrates how natural predation can keep a population of agricultural pests in check.
(D) Predation by Typhlodromus is essential for the control of cyclamen mite populations in strawberry fields.
(E) Similarity in mode and timing of reproduction is what enables Typhlodromus effectively to control populations of cyclamen mites in fields of strawberry plants.

2 
 2. Based on the passage, the author would probably hold that which one of the following principles is fundamental to long-term predatory control of agricultural pests?

(A) The reproduction of the predator population should be synchronized with that of the prey population, so that the number of predators surges just prior to a surge in prey numbers.
(B) The effectiveness of the predatory relationship should be experimentally demonstrable in greenhouse as well as field applications.
(C) The prey population should be able to survive in times of low crop productivity, so that the predator population will not decrease to very low levels.
(D) The predator population’s level of consumption of the prey species should be responsive to variations in the size of the prey population.
(E) The predator population should be vulnerable only to pesticides to which the prey population is also vulnerable.

3 
 3. Which one of the following is mentioned in the passage as a factor contributing to the effectiveness of Typhlodromus as a predator?

(A) its ability to withstand most insecticides except parathion
(B) its lack of natural predators in strawberry fields
(C) its ability to live in different climates in different geographic regions
(D) its constant food supply in cyclamen mite populations
(E) its ability to survive when few prey are available

4 
 4. Suppose that pesticide X drastically slows the reproductive rate of cyclamen mites and has no other direct effect on cyclamen mites or Typhlodromus. Based on the information in the passage, which one of the following would most likely have occurred if, in the experiments mentioned in the passage, pesticide X had been used instead of parathion, with all other conditions affecting the experiments remaining the same?

(A) In both treated and untreated plots inhabited by both Typhlodromus and cyclamen mites, the latter would have been effectively controlled.
(B) Cyclamen mite populations in all treated plots from which Typhlodromus was absent would have been substantially lower than in untreated plots inhabited by both kinds of mites.
(C) In the treated plots, slowed reproduction in cyclamen mites would have led to a loss of reproductive synchrony between Typhlodromus and cyclamen mites.
(D) In the treated plots, Typhlodromus populations would have decreased temporarily and would have eventually increased.
(E) In the treated plots, cyclamen mite populations would have reached significantly damaging levels more slowly, but would have remained at those levels longer, than in untreated plots.

5 
 5. It can be inferred from the passage that the author would be most likely to agree with which one of the following statements about the use of predators to control pest populations?

(A) If the use of predators to control cyclamen mite populations fails, then parathion should be used to control these populations.
(B) Until the effects of the predators on beneficial insects that live in strawberry fields are assessed, such predators should be used with caution to control cyclamen mite populations.
(C) Insecticides should be used to control certain pest populations in fields of crops only if the use of natural predators has proven inadequate.
(D) If an insecticide can effectively control pest populations as well as predator populations, then it should be used instead of predators to control pest populations.
(E) Predators generally control pest populations more effectively than pesticides because they do not harm the crops that their prey feed on.

6 
 6. The author mentions the egg-laying ability of each kind of mite (lines 20–23) primarily in order to support which one of the following claims?

(A) Mites that reproduce by parthenogenesis do so at approximately equal rates.
(B) Predatory mites typically have a longer reproductive life span than do cyclamen mites.
(C) Typhlodromus can lay their eggs in synchrony with cyclamen mites.
(D) Typhlodromus can reproduce at least as quickly as cyclamen mites.
(E) The egg-laying rate of Typhlodromus is slower in the presence of cyclamen mites than it is in their absence.

7 
 7. Which one of the following would, if true, most strengthen the author’s position regarding the practical applicability of the information about predatory mites presented in the passage?

(A) The individual Typhlodromus mites that have the longest reproductive life spans typically also lay the greatest number of eggs per day.
(B) The insecticides that are typically used for mite control on strawberry plants kill both predatory and non predatory species of mites.
(C) In areas in which strawberry plants become infested by cyclamen mites, winters tend to be short and relatively mild.
(D) Typhlodromus are sometimes preyed upon by another species of mites that is highly susceptible to parathion.
(E) Typhlodromus easily tolerate the same range of climatic conditions that strawberry plants do.

8 
 8. Information in the passage most strongly supports which one of the following statements?

(A) Strawberry crops can support populations of both cyclamen mites and Typhlodromus mites without significant damage to those crops.
(B) For control of cyclamen mites by another mite species to be effective, it is crucial that the two species have the same mode of reproduction.
(C) Factors that make Typhlodromus effective against cyclamen mites also make it effective against certain other pests of strawberry plants.
(D) When Typhlodromus is relied on to control cyclamen mites in strawberry crops, pesticides may be necessary to prevent significant damage during the first year.
(E) Strawberry growers have unintentionally caused cyclamen mites to become a serious crop pest by the indiscriminate use of parathion.

Sajjad1994 · Answer

Explanation

6. The author mentions the egg-laying ability of each kind of mite (lines 20–23) primarily in order to support which one of the following claims?

Explanation

Why does the author mention the egg production? If we go back two sentences to  lines 17–18 , the author is talking about how the  Typhlodromus  mite population can increase as rapidly as that of the cyclamen mites. So, the egg production information is just support for that claim. That’s answer  choice (D).

(A)  The rates are not approximately equal. The  Typhlodromus  mites have a rate practically twice that of the cyclamen mites.

(B)  Reproductive life span is Out of Scope.  (C), (E)  Faulty use of Detail. The ideas of synchrony and slower reproduction in the absence of cyclamen mites don’t come up until later in  Paragraph 2 , when the author discusses a new factor in the relationship between the mites.

Answer: D

Sajjad1994 · Answer

Explanation

7. Which one of the following would, if true, most strengthen the author’s position regarding the practical applicability of the information about predatory mites presented in the passage?

Explanation

The author concludes that predatory control can be effective because of the predator’s ability to adapt its population to its prey’s population. However, for this argument to work, the author has to assume that there’s no practical factor that would negate the predator’s ability to do so in the real world. So, to strengthen this argument, we want to show that there’s nothing that negatively affects the Typhlodromus mite’s ability to survive and control cyclamen.

(A)  A correlation between life span and the number of eggs is irrelevant to the argument.

(B)  Opposite. If the insecticides also killed the prey, then there would be no need for the predators to keep prey in check.

(C)  According to the passage, winter is when cyclamen numbers dwindle and the Typhlodromus mites subsist on honeydew. The passage says nothing to indicate whether the winters in question are short and mild or long and frigid. So this doesn’t help the argument.

(D)  Irrelevant. Other species and insecticides are not factors in the application of predators to crop control.

(E)  One thing that could affect the Typhlodromus mite’s usefulness would be an inability to live in the environment where most strawberry plants grow. By saying that Typhlodromus mites can tolerate the same climate as strawberry plants, (E) rules out a potential weakener, thereby strengthening the argument. This is the correct answer.

Answer: E

8. Information in the passage most strongly supports which one of the following statements?

Explanation

Since there are no clues in the question stem, we need to check the answers one at a time remembering the overall topic, scope, purpose, and main idea.

(A)  The passage suggests that allowing Typhlodromus to thrive can be an effective solution to strawberry pests. No agricultural technique that destroyed the crop it was intended to help would be much of a solution. So, this is the correct answer.

(B)  Extreme. Cyclamen and Typhlodromus mites happen to have the same mode of reproduction, but the author does not go so far as to say that this is a reason for (let alone crucial to) the effectiveness of the control.

(C)  Other strawberry plant pests are Out of Scope.

(D)  Opposite. According to Paragraph 1, cyclamens don’t reach damaging levels until the second year.

(E)  The implied causality here is Out of Scope. We don’t know what actual strawberry growers have tried; we only have data from the greenhouse and field experiments.

Answer: A

Gaurav2896 · Answer

HI  AnirudhaS   VeritasKarishma ,

Shouldn't the answer to Q2 be A , which can be inferred from the line 
Seasonal synchrony of Typhlodromus reproduction with the
 growth of prey populations and ability to survive at
low prey densities also contribute to the predatory
efficiency of Typhlodromus.
In option D , relation between consumption level and population of prey is stated which can be inferred from increasing reproduction in predators .SO I think most direct answer should be A.

KarishmaB · Answer

(A) is the trap answer here.

2. Based on the passage, the author would probably hold that which one of the following principles is fundamental to long-term predatory control of agricultural pests?

(A) The reproduction of the predator population should be synchronized with that of the prey population, so that the number of predators surges just prior to a surge in prey numbers.

"synchronized" is correct but the use of the words "just prior" is not. The author doest not say or imply that the predator population should respond before the prey population surge. She just says that the two population sizes should be synchronised.

"Its population can increase as rapidly as that of its
prey."
"Seasonal
synchrony of Typhlodromus reproduction with the
(25) growth of prey populations and ability to survive at
low prey densities also contribute to the predatory
efficiency of Typhlodromus."

(D) The predator population’s level of consumption of the prey species should be responsive to variations in the size of the prey population.

From above, we know that predator population should respond to changes in prey population. So this is correct.

Answer (D)

Sajjad1994 · Answer

Explanation

4. Suppose that pesticide X drastically slows the reproductive rate of cyclamen mites and has no other direct effect on cyclamen mites or Typhlodromus. Based on the information in the passage, which one of the following would most likely have occurred if, in the experiments mentioned in the passage, pesticide X had been used instead of parathion, with all other conditions affecting the experiments remaining the same?

Explanation

For this question, we have to revisit the experiments mentioned in the passage. Both experiments included one plot treated with pesticide and one without. The one with pesticide killed the predators, leading to dangerous levels of cyclamen mites. The one without saw cyclamen population kept in check by the predators.

This time, the question wants us to consider a different pesticide—one that doesn’t affect the predator but instead slows the reproduction of the cyclamen mites. In that case, based on the details of the second paragraph, the Typhlodromus mites should be able to adjust its population to the new, slower reproducing cyclamen. So with the new pesticide, the cyclamen’s population should be kept in check. And since the untreated plot doesn’t change, we would experience controlled pest populations in both cases. That’s what answer  choice (A)  says.

(B)  If the Typhlodromus mites were absent, there would be no predators to eat the cyclamen mites. So, even if pesticide slowed cyclamen reproduction, there would still be no predators to keep the population in check and, in that case, it is likely that the cyclamen population would ultimately be higher, not lower.

(C)  The way seasonal synchrony is described in Paragraph 2, the slowed reproduction would have no effect on Typhlodromus mites. Typhlodromus mites would still be able to reproduce faster should the cyclamen population increase. And with slowed reproduction, the Typhlodromus mites should still be able to subsist on honeydew during times of dwindled cyclamen population.

(D)  With a slower reproduction rate for cyclamen, it might make sense that Typhlodromus populations would decrease initially. But, according to Paragraph 2, Typhlodromus mites only reproduce when they’re feeding on cyclamen mites. If the cyclamen reproduction is slowed, there’s no reason to expect the Typhlodromus mites to increase again after decreasing to match the cyclamen.

(E)  Again, with a slower reproduction rate for cyclamen, it makes sense that damaging population levels would take longer to achieve. However, nothing suggests this dangerous level would last any longer than if reproduction rate was normal. In either case, the damaging level might last only until they’d eaten up all the strawberries.

Answer: A

PS: As this is an LSAT passage one might not see such a hard and LSAT-only question in the real GMAT.

Cheers

napolean92728 · Answer

Question 2: 
 Based on the passage, the author would probably hold that which one of the following principles is fundamental to long-term predatory control of agricultural pests?

Correct Ans:   
 (D) The predator population's level of consumption of the prey species should be responsive to variations in the size of the prey population.
This principle is shown in the passage through how Typhlodromus effectively controls cyclamen mite populations. Specifically: 
 
  The passage notes in lines 24-27 that "Seasonal synchrony of Typhlodromus reproduction with the growth of prey populations and ability to survive at low prey densities also contribute to the predatory efficiency of Typhlodromus."  
  Lines 32-34 state that the predatory mites "do not reproduce except when they are feeding on the cyclamen mites," showing how their reproduction is directly tied to prey consumption.  
  Lines 57-60 describe how "When cyclamen mite populations began to increase in an untreated planting, the predator populations quickly responded to reduce the outbreak," demonstrating the responsiveness that makes predator control effective.

Reasons to eliminate other options:   
 (A) The reproduction of the predator population should be synchronized with that of the prey population, so that the number of predators surges just prior to a surge in prey numbers. 
 
 The passage indicates synchrony is important (lines 24-27), but it doesn't state predators should surge "prior to" prey numbers increasing. Instead, it shows predators responding to increases in prey. 
 Lines 57-60 explicitly state that "when cyclamen mite populations began to increase...the predator populations quickly responded," indicating the response follows the increase, not precedes it.  
 (B) The effectiveness of the predatory relationship should be experimentally demonstrable in greenhouse as well as field applications. 
 
 This describes a scientific validation method, not a principle of predatory control itself. 
 The passage mentions experiments to verify effectiveness, but doesn't suggest demonstrability is fundamental to the control mechanism.  
 (C) The prey population should be able to survive in times of low crop productivity, so that the predator population will not decrease to very low levels. 
 
 This reverses the relationship described in the passage. 
 The passage emphasizes the predator's ability to survive when prey populations are low (lines 25-32), not the other way around.  
 (E) The predator population should be vulnerable only to pesticides to which the prey population is also vulnerable. 
 
 Contradicted by the passage, which specifically notes parathion "kills the predatory species but does not affect the cyclamen mite" (lines 43-45). 
 The passage actually uses this differential vulnerability to demonstrate why pesticide use is harmful.

Question 5:  
  5.    It can be inferred from the passage that the author would be most likely to agree with which one of the following statements about the use of predators to control pest populations?

Correct Ans:  
  (C) Insecticides should be used to control certain pest populations in fields of crops only if the use of natural predators has proven inadequate. 
The passage strongly advocates for using natural predators (Typhlodromus mites) over insecticides (parathion) for controlling cyclamen mite populations. The author explicitly states in lines 50-52: "Applying parathion in this instance is a clear case in which using a pesticide would do far more harm than good to an agricultural enterprise." 
 
The author demonstrates through experiments that natural predation is highly effective, with cyclamen mites being "about 25 times more abundant in the absence of predators than in their presence" (lines 59-60). The entire passage builds a case for the effectiveness of natural predation as the preferred control method. 
 
Option C aligns with this position by suggesting insecticides should be used only as a fallback when natural predation proves inadequate - which matches the author's preference for natural solutions first.

Reasons to eliminate other options:   
  (A) If the use of predators to control cyclamen mite populations fails, then parathion should be used to control these populations.  
 
  The passage specifically argues against using parathion, calling it a "clear case in which using a pesticide would do far more harm than good" (lines 50-52).  
  There's no suggestion that parathion would be appropriate even if predator control failed.   
  (B) Until the effects of the predators on beneficial insects that live in strawberry fields are assessed, such predators should be used with caution to control cyclamen mite populations.  
 
  The passage doesn't mention concerns about effects on other beneficial insects.  
  The author presents predator control as clearly beneficial without expressing caution.   
  (D) If an insecticide can effectively control pest populations as well as predator populations, then it should be used instead of predators to control pest populations.  
 
  Directly contradicts the author's position, which strongly favors natural predation over insecticides.  
  The passage shows that parathion did control both populations but resulted in worse outcomes.   
  (E) Predators generally control pest populations more effectively than pesticides because they do not harm the crops that their prey feed on.  
 
  While the passage shows predators are more effective, it doesn't attribute this to predators not harming crops.  
  The effectiveness is attributed to factors like reproductive capabilities, seasonal synchrony, and ability to survive at low prey densities.

Question 8:   
  Information in the passage most strongly supports which one of the following statements?

Correct Ans:    
  (A) Strawberry crops can support populations of both cyclamen mites and Typhlodromus mites without significant damage to those crops. 
This statement is strongly supported by the passage, which shows that when both species coexist, the strawberry crops remain healthy. Key evidence includes: 
 
  Lines 42-49 describe an experiment where plants with both predator and prey mites had low cyclamen mite populations and avoided significant damage, while predator-free plants suffered "significantly damaging proportions" of infestation.  
  Lines 52-56 confirm similar results in field plantings, where cyclamen mites reached damaging levels when predators were eliminated but "did not attain such levels in untreated plots" (where both species coexisted).  
  The overall data showed cyclamen mites were "about 25 times more abundant in the absence of predators than in their presence" (lines 59-60), indicating that strawberry crops can indeed support both species without significant damage when the natural predator-prey relationship is maintained.

Reasons to eliminate other options:  
  (B) For control of cyclamen mites by another mite species to be effective, it is crucial that the two species have the same mode of reproduction.   
 
  While the passage mentions both species reproduce by parthenogenesis (lines 18-20), it doesn't state this similarity is crucial for effective control.  
  The passage attributes effectiveness to other factors like voracious appetite, rapid population growth, seasonal synchrony, and survival ability at low prey densities.   
   (C) Factors that make Typhlodromus effective against cyclamen mites also make it effective against certain other pests of strawberry plants.   
 
  The passage doesn't mention Typhlodromus controlling any pests other than cyclamen mites.  
  While it mentions Typhlodromus consuming honeydew from aphids and white flies during winter, it doesn't indicate this controls those insects.   
   (D) When Typhlodromus is relied on to control cyclamen mites in strawberry crops, pesticides may be necessary to prevent significant damage during the first year.   
 
  Contradicted by the passage, which states cyclamen mites "typically establish themselves in a strawberry field shortly after planting, but their populations do not reach significantly damaging levels until the plants' second year" (lines 7-10).  
  This suggests pesticides aren't necessary in the first year since damage isn't significant then.   
   (E) Strawberry growers have unintentionally caused cyclamen mites to become a serious crop pest by the indiscriminate use of parathion.   
 
  Not supported by the passage, which only discusses parathion in controlled experiments.  
  The passage presents cyclamen mites as an existing pest problem, not one created by pesticide use.

Sunsh · Answer

Can you please explain why the answer is not C? as in the next line the word synchronised use to show that they are aligned in numbers. Not as quickly, as technically in the terms of day  Typhlodromus takes more time. It is just after one reproduction cycle they are aligned.

StuffMob · Answer

Please explain the first passage

guddo · Answer

6. The author mentions the egg-laying ability of each kind of mite (lines 20–23) primarily in order to support which one of the following claims?

The passage says Typhlodromus is effective partly because its population can increase as rapidly as the population of its prey. The egg-laying details support that point: cyclamen mites lay more eggs per day, but for fewer days; Typhlodromus lay slightly fewer eggs per day, but for more days.  So the overall reproductive capacity of Typhlodromus is at least comparable  to that of the cyclamen mites.

(A) Mites that reproduce by parthenogenesis do so at approximately equal rates.

This is too broad. The passage compares these two mite species, not all mites that reproduce by parthenogenesis.

(B) Predatory mites typically have a longer reproductive life span than do cyclamen mites.

This is not the main point. The passage gives reproductive-life-span details, but only to show that Typhlodromus can keep up with cyclamen mite population growth.

(C) Typhlodromus can lay their eggs in synchrony with cyclamen mites.

This is tempting because the passage later mentions seasonal synchrony, but the egg-laying numbers themselves support reproductive speed, not timing.

(D) Typhlodromus can reproduce at least as quickly as cyclamen mites.

This is correct. The egg-laying comparison shows that Typhlodromus can increase its population quickly enough to control the cyclamen mites. That is the claim the details primarily support.

(E) The egg-laying rate of Typhlodromus is slower in the presence of cyclamen mites than it is in their absence.

This is unsupported. The passage says Typhlodromus reproduce when feeding on cyclamen mites; it does not say their egg-laying rate becomes slower in their presence.

Answer: (D)

guddo · Answer

1. Which one of the following most accurately expresses the main point of the passage?

The passage explains that cyclamen mites can damage strawberry plants, but Typhlodromus mites naturally control them. It then explains why Typhlodromus is effective and gives experimental evidence showing that when Typhlodromus is removed, cyclamen mite populations become much worse.  So the main point is that this predator-prey relationship shows how natural predation can control an agricultural pest .

(A) Control of agricultural pests is most effectively and safely accomplished without the use of pesticides, because these pesticides can kill predators that also control the pests.

This is too broad. The passage does show that parathion is harmful in this case, but it does not claim that all agricultural pests are best controlled without pesticides.

(B) Experimental verification is essential in demonstrating the effectiveness of natural controls of agricultural pests.

This is too focused on method. The experiments support the passage’s main point, but the passage is not mainly about the importance of experimentation.

(C) The relationship between Typhlodromus and cyclamen mites demonstrates how natural predation can keep a population of agricultural pests in check.

This is correct. It captures the whole passage: Typhlodromus naturally controls cyclamen mites, and the experiments confirm that this predator keeps the pest population low.

(D) Predation by Typhlodromus is essential for the control of cyclamen mite populations in strawberry fields.

This is too strong. The passage shows Typhlodromus is highly effective, but “essential” goes beyond the passage. There may be other possible control methods.

(E) Similarity in mode and timing of reproduction is what enables Typhlodromus effectively to control populations of cyclamen mites in fields of strawberry plants.

This is too narrow. Reproduction is one factor, but the passage also mentions appetite, survival at low prey densities, and experimental evidence.

Answer: (C)

Sometimes there is no more effective means of controlling an

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