Herbivore-induced infochemicals influence foraging behaviour in two intertidal predators

Area of Science:

• Marine ecology
• Chemical ecology
• Tritrophic interactions

Background:

• Herbivore-induced plant defenses are common in terrestrial ecosystems.
• These defenses can impact herbivore populations indirectly through natural enemies.
• Such tritrophic interactions have not been well-studied in marine environments.

Purpose of the Study:

• To investigate if herbivore-induced chemical changes in marine plants affect predator foraging behavior.
• To test for indirect effects of plant defenses on marine herbivores via predators.

Main Methods:

• Experiments used Ascophyllum nodosum (seaweed) with different prior treatments: control, mechanical damage, or herbivory.
• A novel flow-through flume served as a choice chamber to test predator responses.
• The foraging behavior of the crab Carcinus maenas and the fish Lipophrys pholis was observed.

Main Results:

• Infochemicals from herbivore-induced seaweed attracted predators.
• Lipophrys pholis was attracted to both feeding herbivores and herbivore-induced plant odors.
• Carcinus maenas was attracted to herbivore-induced plant odors, irrespective of herbivore presence.

Conclusions:

• This study demonstrates that herbivore-induced changes in marine plants can directly influence predator foraging behavior.
• These findings represent the first evidence of such indirect plant-herbivore interactions in marine systems.
• Induced plant defenses in marine environments may play a significant role in regulating herbivore populations.