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Difficulty: MediumCommand of Evidence: Textual

Lima bean plants (*Phaseolus lunatus*) release volatile organic compounds (VOCs) when damaged by herbivorous spider mites. While some scientists suggest these emissions function primarily as a general warning signal to alert neighboring plants of impending danger, ecologist Dr. Sandra Keller hypothesizes that the plants actively customize the chemical profile of their VOCs to recruit predatory mites (*Phytoseiulus persimilis*), which prey on spider mites.

Which finding, if true, would most directly support Keller’s hypothesis?

  1. A
    Healthy neighboring lima bean plants exposed to the VOCs of spider-mite-infested plants immediately begin synthesizing defensive compounds to deter potential herbivore attacks.
  2. B
    Predatory mites possess highly sensitive olfactory receptors that enable them to detect plant emissions from farther away than neighboring plants can detect them.
  3. C
    Plants infested with spider mites release a lower volume of VOCs overall compared to plants experiencing mechanical damage, reducing the likelihood that neighboring plants will detect the signal.
  4. Predatory mites are strongly attracted to the specific combination of VOCs emitted by plants infested with spider mites, but they do not respond to the VOCs emitted by plants experiencing mechanical damage or infestation by non-prey insects.Answer

Answer

Predatory mites are strongly attracted to the specific combination of VOCs emitted by plants infested with spider mites, but they do not respond to the VOCs emitted by plants experiencing mechanical damage or infestation by non-prey insects.
The correct answer supports Keller's hypothesis by demonstrating that the chemical emissions of the lima bean plants are specifically tailored to attract predatory mites. If the predatory mites respond to the unique VOC blend of spider-mite-infested plants but not to generic damage or other pests, it confirms that the plant's response is a customized signal to recruit a specific predator rather than a general distress call.

Step-by-Step Solution

1
Identify the hypothesis to be supported.
Keller's hypothesis is that lima bean plants customize their VOC chemical profiles to actively recruit predatory mites (*Phytoseiulus persimilis*), rather than just releasing a generic warning signal.
To support this hypothesis, we need evidence demonstrating that the chemical signal is specific to attracting these predatory mites and is not just a general response.
2
Evaluate the evidence provided in the choices.
The statement about predatory mites being attracted to the specific combination of VOCs from spider-mite-infested plants (and not to other damages) shows the required specificity.
This directly connects the customized chemical profile of the VOCs to the successful recruitment of the specific predator.

Key Concept

Command of Evidence: Textual
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