As insects feed on plants, they leave specific trace marks that reflect their mouthpart morphology and feeding behavior. These trace marks, or leaf damage, can range from simple, generalized piercing and leaf-chewing marks, to complicated and highly specific leaf mines and galls. Leaf damage is beautifully preserved in plant fossils and is a direct evidence of ecological interactions in ancient forests.

Host-specific damage, such as most leaf mines and many galls, usually reflect a single herbivore species feeding on a single host. How do generalized chewing-marks reflect on past insect communities?

In order to test whether damage richness reflects the richness of culprit herbivores, I collected and experimentally fed insects to record their damage. Over 100 species of leaf-chewing insects were collected from the canopies of 24 dominant tropical trees and lianas using the canopy crane facilities at the Smithsonian Tropical Research Institute.

Turns out that the numbers of distinct damages induced by insects on any given plant host, are correlated with the number of insect species that created them… This means that the numbers of distinct damage traces on a plant is actually reflecting the relative number of insects that fed on it!

This observation adds value and robustness to quantifying leaf damage on fossil leaves… After all those bite-marks are a lot more common than the insects themselves.

Right now, I am exploring the extent to which damage differs from one plant to the next, may actually reflect the extent to which different insect communities feeding on them differ. More soon...