Passage 3 | Entomology
Decline of Wild Bee Populations
At one time, wild bee populations – with the help of other natural pollinators like birds, butterflies, and bats—were sufficient to pollinate food crops, transferring pollen 5 from what is referred to as the male part of the flower (the anther) to the female part (the stigma), in a crucial part of plant reproduction that enables crops to produce fruits and vegetables. Although agricultural production o has grown too large to rely solely on wild bees for pollination, these pollinators still play a role in crop pollination and, in some cases, are more effective than the domesticated bees that are used in U.S. agriculture. Therefore, s it is alarming that wild bee populations are shrinking.
Wild bees are threatened by a number of factors, including habitat degradation, pesticides, and parasites. Habitat degradation o is a serious problem for wild bee populations. When land is cleared for logging or farming purposes, ecological diversity in the area decreases, and this may cause food-supply and habitat losses for the species that once lived in the area. For example, the loss of hardwood blossoms and hollow trees results in a loss of wild bees. Over the course of a fourteen-year period, habitat degradation in Costa Rica caused the number of wild bee ¡o species to drop from seventy to thirty-seven. All over the world, human activities threaten the natural habitats of wild bees.
- TOEFL IBT Reading Practice Test 11 from IVY’s Reading Actual Test
- TOEFL IBT Reading Practice Test 10 from IVY’s Reading Actual Test
- TOEFL IBT Reading Practice Test 09 from IVY’s Reading Actual Test
- TOEFL IBT Reading Practice Test 08 from IVY’s Reading Actual Test
- TOEFL IBT Reading Practice Test 13 Solution & Explanation
[A] The effect of pesticides has been an environmental issue for decades, and many species have been harmed by agricultural chemical spraying. [B] Although both commercial and wild bees play a role in crop pollination, commercial bees remain in pesticide-sprayed fields only long enough to o pollinate them, but wild bees inhabit those fields and spend all their time there. [C] For example, native bumblebees that feed on the blossoms of cotton crops receive large, harmful doses of pesticides as cotton fields s are sprayed with chemicals while the bees are feeding on the blooming flowers. [D] During the 1970s, pesticide spraying in Canada was so harmful to bee populations that the yields from blueberry crops —pollinated by native o bees—were reduced for four years.
Parasites and diseases have become more of a threat as international trade spreads foreign pests to places where native species have developed no resistance to or defense s against the invaders. In the American South, fire ants imported from South America in the early twentieth century have caused problems by destroying wild bee populations that make their nests in the ground. Some diseases, like foulbrood and chalkbrood, have recently spread internationally, and parasites like the African hive beetle and the Varroa mite have traveled beyond the continents of their origins.
Of all the threats to wild bees, the s greatest is the parasitic mite Varroa destructor. The Varroa mite, originally from Asia, has had an alarmingly damaging impact on the Western honeybee. When contact is made, adult female Varroa mites fasten themselves to the bee between its abdominal segments, an ideal site that makes their detection very difficult and allows the mites to easily suck the blood of their hosts. Varroa mites assault bees at every stage of development, from 5 formative stages to adulthood. Female mites lay their eggs with bee larvae so that the young bees will become hosts for the mites. Consequences for the hosts include deformed abdomen, abnormal wings, and misshapen legs. In colonies of Western honeybees, Varroa mite infestations, if untreated, generally cause the death of the colony. In the United States, Varroa infestations have nearly eradicated wild honeybee colonies.
Unfortunately, if the problems currently threatening wild bee populations are not resolved, there may be troubling results. If the number of wild bees continues to dwindle, it is likely that some of the fruits and vegetables d being enjoyed today may simply vanish from supermarket shelves in the not-too-distant future.
29. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
(A) Fruit and vegetable plants no longer require the assistance of wild bees and other flying animals to become pollinated.
(B) Birds, butterflies, bats, and bees are used in agricultural operations to help pollinate food crops.
(C) Wild bees were once able to move enough pollen to ensure the reproduction of food crops.
(D) Pollination is the process of transferring pollen from male flower parts to female flower parts.
30. The word solely in the passage is closest in meaning to
31. Why does the author mention the change in the number of wild bee species in paragraph 2?
(A) To show that wild bee species exist in the same habitats as humans
(B) To give an example of reasons why people clear forests
(C) To show the effect of land degradation on wild bees
(D) To demonstrate that the habitat of wild bees has recently changed
32. It can be inferred from paragraph 2 that hardwood blossoms and hollow trees
(A) are not destroyed when a forest is cleared for farming purposes
(B) are used by wild bees as food and shelter
(C) are found in all regions of the world
(D) are abundant in Costa Rica
33. What can be inferred from paragraph 3 about commercial bees?
(A) Their populations are larger than wild bee populations.
(B) They have evolved a resistance to agricultural chemicals.
(C) They are not harmed by pesticides as much as wild bees.
(D) They play a minimal role in crop pollination.
34. Why does the author mention the Canadian blueberry crops in paragraph 3?
(A) To show the importance of wild pollinators in Canadian agriculture
(B) To explain the commercial value of wild pollinators
(C) To indicate the effect of pesticides on wild bees
(D) To demonstrate the effectiveness of chemical pesticides
35. The word defense in the passage is closest in meaning to
36. According to paragraph 4, why is international trade problematic for wild bees?
(A) They seldom survive overseas journeys.
(B) They are vulnerable to diseases from overseas.
(C) There are few international laws to protect endangered species.
(D) They are exported to places with unsuitable habitats.
37. The word their in the passage refers to
(A) Varroa mites
38. The word assault in the passage is closest in meaning to
39. According to paragraph 5, Varroa mites affect bees by
(A) causing physical defects
(B) spreading lethal diseases
(C) impairing their reproductive capabilities
(D) destroying their food sources
40. The word dwindle in the passage is closest in meaning to
41. Look at the four squares  that indicate where the following sentence could be added to the passage.
Wild bees are particularly susceptible to the damages caused by pesticides because of their constant exposure to agricultural chemicals.
Where would the sentence best fit?
42. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Wild bee populations are declining because they are facing several serious threats.
(A) By depriving them of food and shelter, loss of habitat has severely reduced the number of wild bee species in some areas.
(C) Bumblebees are poisoned by pesticides because the cotton fields they live in are heavily sprayed with chemicals.
(E) Fire ants from South America have endangered ground-nesting bees in the southern United States.
(B) Pesticides endanger wild bees because they are constantly exposed to the chemicals that are applied to crop fields.
(D) Blueberries are a crop that requires
significant amounts of pesticides in order to thrive.
(F) Parasites and diseases are a very severe problem for wild bee populations, which have nearly been destroyed by this menace.