Induced plant responses and information content about risk of herbivory.

Plant defenses are plastic when a single genotype can produce different phenotypes depending upon the environment. Plastic responses might be favored by selection only if plants can respond appropriately to reliable information in their environments. Recent findings indicate that when information is accurate, plants can benefit by changing their defenses appropriately but, when information is inaccurate they produce inappropriate defenses and have lower fitness. Plants can potentially use a variety of cues to adjust their defensive phenotypes appropriately. The relationship between the information about risk of herbivory and plant defense can be evaluated by determining if the information available to plants is reliable enough to support the evolution of plastic-induced defenses.

The ecology and evolution of plant tolerance to herbivory.

The tolerance of plants to herbivory reflects the degree to which a plant can regrow and reproduce after damage from herbivores. Autoecological factors, as well as the influence of competitors and mutualists, affect the level of plant tolerance. Recent work indicates that there is a heritable basis for tolerance and that it can evolve in natural plant populations. Although tolerance is probably not a strict alternative to plant resistance, there could be inter- and intraspecific tradeoffs between these defensive strategies.

Induced responses to herbivory and increased plant performance

Plant resistance to herbivores was induced in a field experiment to evaluate the consequences of induced responses for subsequent herbivory and plant fitness. Induction early in the season resulted in halving of herbivory by chewing herbivores and a reduction in the abundance of phloem-feeding aphids when compared with controls. A correlate of lifetime plant fitness, seed mass, was enhanced by over 60 percent for individuals that were induced.