Tolerance to insect herbivory increases with progressing plant development

Area of Science:

• Plant ecology
• Insect-plant interactions
• Plant physiology

Background:

• Plants exhibit varying capacities to tolerate or compensate for tissue loss from herbivory.
• Plant tolerance is influenced by the developmental stage at which damage occurs and the amount of tissue removed.
• Understanding plant responses to herbivory is crucial for predicting population dynamics and community structure.

Purpose of the Study:

• To investigate how ontogenetic stage and herbivory intensity affect plant fitness correlates in annual brassicaceous species.
• To determine the extent to which different developmental stages (vegetative, budding, flowering) influence compensation for tissue loss.
• To assess the impact of herbivory on seed germination and subsequent generations.

Main Methods:

• Three annual brassicaceous species were exposed to feeding by Pieris brassicae caterpillars at varying intensities.
• Plant fitness correlates, including biomass and seed germination, were measured at different ontogenetic stages.
• The study compared responses across vegetative, budding, and flowering stages.

Main Results:

• Fitness costs associated with herbivory decreased as the plant's ontogenetic stage progressed.
• Damage to meristem tissues in vegetative and budding plants hindered compensation, while flower damage led to compensation or overcompensation in some species.
• Herbivory promoted seed germination in the subsequent year, shifting generational contribution from the seed bank to the next generation.
• Species-specific differences in response to herbivory intensity were observed, affecting reproductive output differently.

Conclusions:

• Annual plant species demonstrate resilience to herbivory, but tolerance is strongly dependent on the attacked ontogenetic stage.
• Herbivore-induced changes in seed germination can alter the balance between seed bank persistence and immediate generational contribution.
• Plant responses to herbivory are complex and species-specific, impacting long-term fitness and population dynamics.