Species interdependence in nature confers many

  benefits on the species involved, but it can also become a

  point of weakness when one species involved in the rela-

  tionship is affected by a catastrophe. Thus, flowering

  (5) plant species dependent on insect pollination, as opposed

  to self-pollination or wind pollination, could be endan-

  gered when the population of insect-pollinators is depleted

  by the use of pesticides.

  In the forests of New Brunswick, for example,

  (10) various pesticides have been sprayed in the past 25 years

  in efforts to control the spruce budworm, an economi-

  cally significant pest. Scientists have now investigated

  the effects of the spraying of Matacil, one of the anti-

  budworm agents that is least toxic to insect-pollinators.

  (15) They studied Matacil’s effects on insect mortality in a

  wide variety of wild insect species and on plant fecun-

  dity, expressed as the percentage of the total flowers on

  an individual plant that actually developed fruit and

  bore seeds. They found that the most pronounced

  (20) mortality after the spraying of Matacil occurred among

  the smaller bees and one family of flies, insects that were

  all important pollinators of numerous species of plants

  growing beneath the tree canopy of forests. The fecun-

  dity of plants in one common indigenous species, the

  (25) red-osier dogwood, was significantly reduced in the

  sprayed areas as compared to that of plants in control

  plots where Matacil was not sprayed. This species is

  highly dependent on the insect-pollinators most vulner-

  able to Matacil. The creeping dogwood, a species similar

  (30) to the red-osier dogwood, but which is pollinated by

  large bees, such as bumblebees, showed no significant

  decline in fecundity. Since large bees are not affected by

  the spraying of Matacil. these results and weight to the

  argument that spraying where the pollinators are sensi-

  (35) tive to the pesticide used decreases plant fecundity.

  The question of whether the decrease in plant fecun-

  dity caused by the spraying of pesticides actually causes

  a decline in the overall population of flowering plant

  species still remains unanswered. Plant species dependent

  (40) solely on seeds for survival or dispersal are obviously

  more vulnerable to any decrease in plant fecundity that

  occurs, whatever its cause. If, on the other hand, vegeta-

  tive growth and dispersal (by means of shoots or runners)

  are available as alternative reproductive strategies for a

  (45) species, then decreases in plant fecundity may be of little

  consequence. The fecundity effects described here are

  likely to have the most profound impact on plant species

  with all four of the following characteristics: a short life

  span, a narrow geographic range, an incapacity for vege-

  (50) tative propagation, and a dependence on a small number

  of insect-pollinator species. Perhaps we should give special

  attention to the conservation of such plant species since

  they lack key factors in their defenses against the envi-

  ronmental disruption caused by pesticide use.

  1. Which of the following best summarizes the main point

  of the passage?

  (A) Species interdependence is a point of weakness for

  some plants, but is generally beneficial to insects

  involved in pollination.

  (B) Efforts to control the spruce budworm have had

  deleterious effects on the red-osier dogwood.

  (C) The used of pesticides may be endangering certain

  plant species dependent on insects for pollination.

  (D) The spraying of pesticides can reduce the fecundity

  of a plant species, but probably does not affect its

  overall population stability.

  (E) Plant species lacking key factors in their defenses

  against human environmental disruption will

  probably become extinct.

  2. According to the author, a flowering plant species whose

  fecundity has declined due to pesticide spraying may

  not experience an overall population decline if the plant

  species can do which of the following?

  (A) Reproduce itself by means of shoots and runners.

  (B) Survive to the end of the growing season.

  (C) Survive in harsh climates.

  (D) Respond to the fecundity decline by producing more


  (E) Attract large insects as pollinators

  3. The passage suggests that the lack of an observed

  decline in the fecundity of the creeping dogwood

  strengthens the researchers conclusions regarding

  pesticide use because the

  (A) creeping dogwood its a species that does not

  resemble other forest plants

  (B) creeping dogwood is a species pollinated by a

  broader range of insect species than are most

  dogwood species

  (C) creeping dogwood grows primarily in regions that

  were not sprayed with pesticide, and so served as a

  control for the experiment

  (D) creeping dogwood is similar to the red-osier

  dogwood, but its insect pollinators are known to be

  insensitive to the pesticide used in the study

  (E) geographical range of the creeping dogwood is

  similar to that of the red-osier dogwood, but the

  latter species relies less on seeds for reproduction

  4. The passage suggests that which of the following is true

  of the forest regions in New Brunswick sprayed with

  most anti-budworm pesticides other than Matacil?

  (A) The fecundity of some flowering plants in those

  regions may have decreased to an even greater

  degree than in the regions where Matacil is used.

  (B) Insect mortality in those regions occurs mostly

  among the larger species of insects, such as


  (C) The number of seeds produced by common plant

  species in those regions is probably comparable to

  the number produced where Matacil is sprayed.

  (D) Many more plant species have become extinct in

  those regions than in the regions where Matacil is


  (E) The spruce budworm is under better control in those

  regions than in the regions where Matacil is sprayed.

  5. It can be inferred that which of the following is true of

  plant fecundity as it is defined in the passage?

  (A) A plant’s fecundity decreases as the percentage of

  unpollinated flowers on the plant increases

  (B) A plant’s fecundity decreases as the number of

  flowers produced by the plant decreases.

  (C) A plant’s fecundity increases as the number of

  flowers produced by the plant increases.

  (D) A plant’s fecundity is usually low if the plant relies

  on a small number of insect species for pollination.

  (E) A plant’s fecundity is high if the plant can reproduce

  quickly by means of vegetative growth as well as by

  the production of seeds.

  6. It can be inferred from the passage that which of the

  following plant species would be LEAST likely to

  experience a decrease in fecundity as a result of the

  spraying of a pesticide not directly toxic to plants?

  (A) A flowering tree pollinated by only a few insect


  (B) A kind of insect-pollinated vine producing few


  (C) A wind-pollinated flowering tree that is short-lived

  (D) A flowering shrub pollinated by a large number of

  insect species

  (E) A type of wildflower typically pollinated by larger


  7. Which of the following assumptions most probably

  underlies the author’s tentative recommendation in

  lines 51-54?

  (A) Human activities that result in environmental

  disruption should be abandoned.

  (B) The use of pesticides is likely to continue into the


  (C) It is economically beneficial to preserve endan-

  gered plant species.

  (D) Preventing the endangerment of a species is less

  costly than trying to save an already endangered


  (E) Conservation efforts aimed at preserving a few well-

  chosen species are more cost-effective than are

  broader-based efforts to improve the environment.