Variable Chemistry and Herbivory of Ponderosa Pine Cones

We measured the terpenoid chemistry, cone insect distribution, and the relationship between these two parameters in the seed cones of ponderosa pine. Analyses of mono-, sesqui-, and diterpenes from four separate sites revealed high amounts of terpenoid diversity and variation. The majority of this variation occurred among trees within sites, but differences were also seen among sites and among cone clusters from individual trees. Cone insect distributions differed substantially in both time and space, with significant differences seen between two points in time and between five sites. Negative correlations existed between levels of cone insect herbivory and both a monoterpene and a diterpene factor at one site, indicating that these herbivores may be one reason that ponderosa pine maintains the high levels of chemical variation observed.