IS INSECT DAMAGE DIVERSITY CORRELATED WITH INSECT DIVERSITY? PRELIMINARY RESULTS FROM THE PANAMA CANOPY CRANES AND IMPLICATIONS FOR PLANT-INSECT ASSOCIATIONAL DIVERSITY IN THE FOSSIL RECORD

Insect feeding marks on leaf compression fossils have provided substantial information on the extent and intensity of past phytophagy and the responses of terrestrial food webs to past climate change and extinction events. A crucial, uninvestigated aspect of interpreting fossil damage-type (DT) diversity is its relation to actual insect diversity: are there quantitative correlations between leaf damage and insect diversity that can be applied to reconstructing the latter through time? Even though leaf-damage richness has been widely used as a proxy for insect diversity in the fossil record, more confident use of this proxy requires establishing an empirical association between damage and insect diversity within modern communities.

Canopy crane systems provide direct access to the foliage and insect communities of dominant trees in forest assemblages. Two lowland tropical forests in Panama, Parque Natural Metropolitano and Parque Nacional San Lorenzo (a seasonally dry and a moist forest, respectively), were surveyed for phytophagous insects during the wet seasons of 2008 and 2009, using the canopy crane facilities of the Smithsonian Tropical Research Institute. Thirteen species of the most dominant trees, as well as lianas and palms, at each site were intensively surveyed for feeding insects. These were captured and fed fresh leaves of the plant species they consumed in order to isolate and record the specific DTs made by each insect. A total of 520 individual insects showed feeding activity, leaving one or more DTs on the leaves. Rarefaction curves for overall damage types plateaued for each site and host plant species; however, insect species richness curves did not. Although insect and damage diversity correlate to some extent, insect mouthpart design constraints seem to set a limit to the sensitivity of insect damage diversity to actual insect richness. Further analysis of this new dataset will improve understanding of the relationship among plant, insect and leaf damage diversities and provide further actualistic groundtruthing for the relationship between plant, insect, and associational diversity in the fossil record.