Intraspecific differences in plant defense induction by fall armyworm strains

Area of Science:

• Entomology
• Plant Science
• Molecular Biology

Background:

• Insect herbivore adaptation to specific host plants is crucial for their survival and evolution.
• Understanding the molecular mechanisms underlying insect-plant interactions is key to developing sustainable pest management strategies.

Purpose of the Study:

• To investigate how different fall armyworm (Spodoptera frugiperda) strains induce plant defenses.
• To determine the role of herbivore-induced defenses in the host plant association of fall armyworm strains.
• To explore the impact of these interactions on caterpillar fitness.

Main Methods:

• Assessing the expression of defense-related genes in maize and Bermuda grass.
• Measuring the activity of plant defensive proteins (proteinase inhibitors, trypsin inhibitors) after herbivory.
• Analyzing the activity of salivary phospholipase C in different fall armyworm strains.

Main Results:

• Fall armyworm strains differentially induced proteinase inhibitors and trypsin inhibitor activity in maize and Bermuda grass.
• The rice strain induced higher levels of plant defenses compared to the corn strain.
• Differences in plant defense induction were linked to variations in salivary phospholipase C activity.
• Higher plant defense levels correlated with reduced caterpillar growth, indicating a fitness cost.

Conclusions:

• Specific salivary compounds from fall armyworm strains trigger differential plant defense responses.
• These plant defense responses significantly impact caterpillar growth and fitness.
• The composition of salivary elicitors plays a critical role in shaping host plant associations for insect herbivores.