plant-insect interactions

The relationship between plants and insects is one of the most consequential ecological partnerships in the history of life on Earth. Plants have evolved an extraordinary diversity of physical and chemical defenses against herbivores, while insects have repeatedly evolved novel strategies to overcome them — a dynamic that has played out across hundreds of millions of years and left a rich record in both the fossil record and living ecosystems. A central interest of the Swain Lab is in understanding this relationship across timescales, using deep-time and contemporary approaches as complementary windows into the same long-running ecological story.

In the fossil record, leaf damage morphologies — the traces left by feeding insects on fossil leaves — serve as proxies for herbivore community diversity, diet breadth, and the ecological consequences of environmental change. Published work has shown that plant–insect interaction networks can be reconstructed from the fossil record with meaningful ecological fidelity, that temperature is a key driver of herbivory intensity across both modern and ancient ecosystems, and that landscape-level variability in herbivore pressure — familiar from modern forests — is also detectable in deep time. The discovery of endophytic leaf mining in the Late Carboniferous has pushed back the origins of one of the most intimate forms of plant–insect interaction, suggesting that the ecological diversification of herbivorous insects began far earlier than previously recognized. Alongside fossil herbivory, the lab works on the chemical ecology of plants and insects, examining how elemental stoichiometry varies across the insect tree of life and how plant defensive strategies — including the evolution of wood as a stoichiometric barrier — have shaped herbivore communities over geological time.

In contemporary ecosystems, the lab studies plant–insect interactions in the field, examining thermogenic pollination — where plants generate heat to attract and reward pollinators — and insect phenology, asking how the seasonal timing of plant–insect interactions is shifting under contemporary climate change. Together, these threads connect the deep evolutionary history of plant–insect relationships to the ecological dynamics playing out in living systems today.