Insect Herbivore Relationship to the State of the Host Plant: Biotic Regulation of Ecosystem Nutrient Cycling through Ecological Succession

Abstract

This paper provides a conceptual framework for increasing our understanding of the relationships between plant resistance to insect herbivores and insect herbivore influences on ecosystem nutrient cycling and succession. For a given plant species, adequate nutrient/light availability favors establishment and productivity; small insect herbivore populations regulated by plant biochemistry stimulate primary productivity and short-term nutrient cycling. As biomass and competition for nutrients and light increase during succession, plants become stressed as they approach their tolerance limits. Earlier successional plant species initially dominating the plant community have higher nutrient/light requirements and become stressed sooner than later successional plant species. Abundance and stress make the earlier plant species more apparent and susceptible, than later plant species, to insect herbivores. Insect herbivore populations increasing rapidly on stressed hosts tend to regulate long-term nutrient cycling patterns by accelerating changes in competitive relationships between plant species with different nutrient/light requirements.