Honeydew Microbes Shape Plant-Herbivore Interactions via Defense Signaling

Area of Science:

• Plant-insect interactions
• Microbial ecology
• Chemical ecology

Background:

• Hemipteran insects excrete honeydew, rich in carbohydrates and microbes, influencing plant-herbivore dynamics.
• The role of honeydew-associated microbes in mediating these interactions and plant defense responses remains unclear.

Purpose of the Study:

• Investigate the impact of honeydew from Phenacoccus solenopsis on herbivore fitness.
• Elucidate the mechanisms by which honeydew and its associated microbes affect plant defense.

Main Methods:

• Application of crude and sterilized honeydew to cotton plants.
• Isolation and identification of honeydew-associated bacteria using 16S rRNA sequencing.
• Exogenous application of bacterial isolates to cotton leaves and assessment of herbivore performance and plant defense gene expression.

Main Results:

• Crude honeydew reduced weight gain and phloem ingestion in P. solenopsis and Helicoverpa armigera.
• Sterilized honeydew suppressed H. armigera growth but not P. solenopsis, indicating microbial contribution.
• Honeydew and isolated bacteria (Acinetobacter, Bacillus) activated jasmonic acid (JA) and salicylic acid (SA) pathways, enhancing plant resistance.

Conclusions:

• Honeydew-associated microbes are key players in plant-herbivore interactions.
• These microbes act as exogenous elicitors, activating plant defense mechanisms against insect feeding.
• Understanding these microbial roles can lead to novel strategies for pest management.