Jason Hamilton presented an invited seminar entitled "Herbivory in a High CO2 World" at Rutgers State University of New Jersey on November 2004.
Human activity is rapidly altering the chemistry of the troposphere in ways that may have important effects on chemical composition of leaves. These changes in leaf chemistry will potentially affect the interactions between plants and insect herbivores. We are studying changes in herbivory in both agronomic and forested ecosystems using Free Air Concentration Enrichment (FACE) installations to increase [CO2] to levels expected for the year 2050. In soybeans, herbivory appeared to increased under elevated CO2. In July, elevated CO2 more than doubled the amount of leaf tissue consumed by herbivores (ambient losses 4.5 percent; elevated losses 10.6 percent). These results suggest that changes in tropospheric chemistry caused by human activities may increase crop damage by insect herbivores in the future. The findings are not general however, because a forested ecosystem with similar increases in CO2 shows a small decrease in insect herbivory.
Contributed by Nancy Pierce