BISC 121 - Article on Plants Responding to Chewing Sounds - Midterm 3

What did Appel and Cocroft (2014) discover about plants and sound?

Plants can detect and respond to vibrations caused by insect chewing.

Why did researchers study chewing vibrations instead of music or random sounds?

Chewing vibrations are natural, ecologically relevant cues from herbivores.

What plant species was used in the experiments?

Arabidopsis thaliana.

What insect species produced the chewing vibrations used in the study?

Pieris rapae (cabbage white butterfly caterpillar).

What was the main hypothesis of the study?

Plants use herbivore chewing vibrations as warning signals to trigger or prepare chemical defenses.

What kind of defenses did Arabidopsis increase after exposure to chewing vibrations?

Glucosinolates and anthocyanins.

What are glucosinolates?

Defensive chemicals that deter herbivores.

What are anthocyanins?

Pigments with defensive and antioxidant properties.

What is meant by “priming” in plant defenses?

Preparing a plant to respond faster or more strongly to future attacks.

What is “direct induction” in plant defenses?

A defense response that occurs immediately after a stimulus without needing further attack.

What did Experiment 1 test?

Whether chewing vibrations could trigger higher chemical defenses after herbivory.

What did Experiment 1 find?

Plants exposed to chewing vibrations produced more glucosinolates after feeding.

Were the effects of chewing vibrations local or systemic?

Both; nearby leaves also showed increased defenses.

What did Experiment 2 test?

Whether plants respond specifically to chewing vibrations and whether responses are direct or primed.

What did Experiment 2 find?

Chewing vibrations primed anthocyanin production; wind and insect song did not.

Did vibrations alone trigger defenses?

No, defenses increased only after herbivory occurred, showing priming not direct induction.

What types of non-chewing vibrations were used as controls?

Wind-induced vibrations and leafhopper mating song.

Why is the ability to distinguish vibration types important for plants?

It helps plants avoid wasting energy responding to non-threatening vibrations.

What relationship was found between vibration strength and defense levels?

Stronger chewing vibrations led to higher glucosinolate induction.

What signaling pathways are likely involved in vibration detection?

Jasmonate and ethylene hormone pathways.

What molecules or ions help transmit the vibration signal inside the plant?

Calcium ions (Ca2+), reactive oxygen species (ROS), and hydrogen ions (H−).

What structures might detect mechanical vibrations in plants?

Mechanosensors in the cell wall or plasma membrane.

How fast can mechanical vibrations travel through plants?

10–100 meters per second.

What are the potential benefits of vibration-based signaling?

Rapid within-plant communication and early detection of herbivory.

Can vibrations travel between plants?

Possibly, through connecting roots, stems, or closely touching leaves.

How do chewing vibrations differ from wind vibrations?

Chewing includes both low and high frequencies; wind is mostly low frequency.

How do chewing vibrations differ from leafhopper song?

Chewing has short, repeated bursts; leafhopper song is continuous.

What does the ability to respond to chewing vibrations suggest about plants?

They can sense and process mechanical information from their environment.

What is the ecological significance of this study?

Plants can use vibrations as a new, rapid signaling mechanism to defend against herbivores.

How might vibration-based detection complement other signaling methods?

It works alongside chemical, electrical, and phloem-borne signals to coordinate defenses.