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Zorluk: OrtaWeaken

Agronomist: In a three-year trial across several commercial groves, citrus orchards intercropped with sweet alyssum experienced a 45 percent reduction in parasitic aphid infestations compared to adjacent monoculture orchards. Alyssum blooms are known to attract hoverflies, whose larvae prey voraciously on aphids. Thus, intercropping sweet alyssum reduces aphid infestations in citrus orchards specifically by boosting populations of natural predatory insects.

Which of the following statements, if true, most seriously undermine the agronomist's reasoning? (Select TWO correct answers.)

  1. Sweet alyssum releases volatile organic compounds that directly deter adult aphids from landing on nearby citrus foliage, even in enclosures where predatory insects are entirely absent.Cevap
  2. B
    Hoverfly larvae reared in laboratory trials consistently consume dozens of aphids each day during their larval developmental stage.
  3. Adult hoverflies drawn to sweet alyssum lay their eggs almost exclusively on ground-level foliage and rarely migrate into the higher citrus tree canopies where the aphids reside.Cevap
  4. D
    Sweet alyssum requires significantly higher amounts of nitrogen fertilizer and irrigation than other companion groundcovers used in commercial agriculture.
  5. E
    The monoculture orchards evaluated during the trial suffered greater overall fruit drop than the orchards intercropped with sweet alyssum.

Cevap

The statements establishing that sweet alyssum directly repels aphids via chemical emissions and that hoverflies lay eggs only at ground level rather than in the citrus canopy.
The agronomist concludes that intercropping sweet alyssum reduces aphid infestations specifically by boosting populations of natural predatory insects. The option establishing that sweet alyssum directly repels aphids via chemical emissions provides an alternative explanation for the drop in pests, thereby undermining the predator hypothesis. The option showing that hoverfly larvae remain at ground level reveals that the predators do not reach the aphids in the tree canopies, directly breaking the proposed mechanism.

Adım Adım Çözüm

1
Identify the conclusion and supporting premises of the argument.
Premise: Alyssum intercropping reduced aphids by 45 percent, and alyssum attracts predatory hoverflies. Conclusion: Alyssum reduces aphids specifically by boosting natural predator populations.
To weaken an argument, one must locate the precise leap from the observed correlation to the specific causal conclusion.
2
Identify potential weaknesses in the causal claim.
The argument assumes that hoverfly predation is the sole driver of the aphid reduction and that the attracted hoverflies actually prey on the aphids in the citrus trees.
Causal claims can be undermined by providing an alternative cause or by breaking the chain between the alleged cause and the effect.
3
Evaluate the choices to find statements that independently undermine the causal link.
The statement showing direct chemical deterrence provides an alternative cause, while the statement showing hoverfly larvae stay at ground level demonstrates that the proposed mechanism does not reach the tree canopy pests.
Both findings directly cast doubt on the conclusion that increased predator activity caused the aphid decline.

Anahtar Kavram

Weaken via Alternative Cause and Broken Causal Mechanism
Tahmini Süre:1m 15s
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Konular

Weaken

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