Does Herbivory Benefit Plants? A Review of the Evidence

The potential benefits of herbivory to plants have been debated over the last decade. Several investigators claim that removal of or damage to the productive, absorptive, or reproductive tissue of plants by herbivores benefits some plant species by increasing their net primary productivity, seed production, or longevity, and that these changes increase plant fitness and result in the evolution of herbivore-plant mutualisms. Although more than 40 papers have been cited as presenting experimental evidence in support of these benefits and mutualisms, strong evidence is lacking. Increased plant biomass as a result of tissue removal has been found only under growth-chamber conditions and in cultivated crops. Although herbivores may benefit certain plants by reducing competition or removing senescent tissue, no convincing evidence supports the theory that herbivory benefits grazed plants.