A Fungal Endophyte Alters Poplar Leaf Chemistry, Deters Insect Feeding and Shapes Insect Community Assembly

Area of Science:

• Ecology
• Plant-Microbe Interactions
• Chemical Ecology

Background:

• Fungal endophytes in herbaceous plants confer anti-herbivore defenses.
• Limited knowledge exists on tree endophyte mutualisms and insect defense.

Purpose of the Study:

• Investigate the role of Cladosporium sp. in black poplar chemical defenses.
• Determine the impact on insect herbivore feeding, performance, and community assembly.

Main Methods:

• Assessed changes in constitutive and induced poplar defenses upon endophyte colonization.
• Monitored feeding preference and performance of Lymantria dispar larvae on infected vs. uninfected leaves.
• Observed insect community assembly under field conditions.

Main Results:

• Endophyte colonization significantly increased both constitutive and induced poplar defenses.
• Lymantria dispar larvae showed reduced preference and performance on endophyte-infected leaves.
• Higher concentrations of salicinoids and the alkaloid stachydrine were found in infected leaves.
• The endophytic fungus influenced insect community assembly, attracting aphids that excrete stachydrine.

Conclusions:

• Endophytic fungi are crucial for plant defense against diverse insect feeding guilds.
• These fungi play a significant role in structuring insect communities associated with trees.