Which leaf mechanical traits correlate with insect herbivory among feeding guilds?

Area of Science:

• Plant biology
• Ecology
• Entomology

Background:

• Leaf mechanical traits are known to deter insect herbivores.
• Understanding which specific traits defend against different feeding guilds is crucial for plant-herbivore interaction studies.

Purpose of the Study:

• Investigate the contribution of multiple leaf mechanical traits (shear, punch, tear) to herbivore deterrence across various feeding guilds.
• Determine the relative importance of mechanical traits versus nutrient and chemical defenses in influencing insect feeding.

Main Methods:

• Assessed visible damage from miners and external chewers, and sucker feeding density in mature leaves of 20 forest plant species.
• Conducted cafeteria trials with a generalist chewing insect (Epiphyas postvittana).
• Compared herbivore damage with leaf mechanical traits, nutrient content, and chemical defenses.

Main Results:

• Leaf mechanical traits, particularly specific work to shear, significantly deterred external chewers and the generalist larva.
• Mining damage did not correlate with mechanical traits, suggesting avoidance by miners.
• Nutrients strongly influenced diet selection in controlled trials, while mechanical traits were more predictive of field chewing damage.

Conclusions:

• Leaf mechanical traits differentially affect insect feeding guilds based on their life history and feeding modes.
• Specific work to shear is a key mechanical trait predicting damage by external chewers.
• Understanding these trait-guild interactions is vital for comprehending plant-herbivore relationships.