MODERN FORESTS EXPERIENCE GREATER INSECT HERBIVORY THAN FOSSIL LOCALITIES (Invited Presentation)

Compression leaf fossils provide the longest running evidence for hyperdiverse plant-insect herbivore interactions through deep time. These relationships have been shown to have a strong link between environmental conditions such as temperature and precipitation but also insect herbivore diversity and feeding damage on leaves. Although this record has been highly studied within the geologic framework, it has yet to be compared to the modern era, which is characterized by intense anthropogenic environmental change. Here, we present estimates for damage frequencies and diversities on fossil leaves from the Late Cretaceous (66.8 Ma) through the Pleistocene (2.06 Ma) and compare these estimates to Recent (post-1955) leaves collected via paleobotanical methods from modern ecosystems: Harvard Forest, USA, Smithsonian Environmental Research Center, USA, and La Selva, Costa Rica. Total damage frequency, measured as the percent of leaves with any herbivore damage, within modern ecosystems is greater than any fossil locality within this record. This pattern is driven by increased frequencies across nearly all functional feeding groups within the Recent. Diversities of total, specialized, and mining damage types are elevated within the Recent compared to fossil floras. Our results demonstrate that plants in the modern era are experiencing unprecedented levels of insect damage despite widespread insect declines, likely driven by rate of global climate warming, influencing insect feeding and timing of life cycle processes, along with urbanization, insecticides, and the introduction of invasive plant and insect species may drive elevated herbivory. This research suggests that the strength of human influence on plant-insect interactions is not controlled by climate change alone, but rather the way in which humans interact with terrestrial landscape.