Variation in Plant Defense Suppresses Herbivore Performance

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Science

Background:

• Plant defense variability influences herbivore communities and reduces herbivory.
• The precise mechanisms by which defense variability suppresses herbivores remain unclear.
• Two proposed mechanisms are nonlinear averaging and physiological tracking (time-dependent effects).

Purpose of the Study:

• To investigate how plant defense variability impacts herbivore performance and population growth.
• To differentiate the roles of nonlinear averaging and physiological tracking in herbivore suppression.
• To determine if defense variability can be a strategy for reducing herbivory.

Main Methods:

• Experimental manipulation of plant defense mean and variability.
• Assessment of herbivore performance and population growth rates under different defense conditions.
• Comparison of observed results with predictions from nonlinear averaging models.

Main Results:

• Defense variability significantly suppressed herbivore performance and population growth.
• The observed suppression was explained by physiological tracking effects, not nonlinear averaging.
• Variability decreased herbivore performance more than predicted by averaging the effects of constant defenses.

Conclusions:

• Plant defense variability is an effective mechanism for herbivore suppression.
• Physiological tracking constraints, rather than nonlinear averaging, drive this suppression.
• Increasing defense variability in crops can reduce herbivory at the individual herbivore scales.