Emily Meineke, Postdoctoral Fellow
Harvard University

Topic: Herbivory through the ages: Revealing effects of climate on insect herbivory with herbarium specimens

Host Lab: Davis

Abstract:
Herbivory by phytophagous insects is ubiquitous and has effects that cascade from damage to individual plants to altered nutrient cycling through ecosystems. Yet, how herbivory has responded to anthropogenic environmental change remains unclear, because historical monitoring of insect herbivores and herbivory is sparse over time and space. We quantified herbivory on 591 herbarium specimens from four plant species from across the northeastern USA—an area that has experienced rapid climate warming and varying levels of urbanization—to examine the effects of environmental change over the past 110 years. Herbarium specimens collected within the past 10 years were 13% more likely to be damaged by leaf-feeding herbivores than those collected in the early 1900s. Trends across latitude and temperature provide evidence that these increases are due in large part to climate warming. Climate occupancy models implicate winter temperature as a key driver of insect herbivore presence and/or abundance. In contrast, human population densities were negatively associated with herbivory and occupancy for the majority of herbivores, indicating that urban development may disrupt the effects of climate change on insect diversity, with downstream consequences for plant-insect interactions.