Mentor: Deidra Jacobsen, Ph.D.

Neighboring plants can influence a plant’s likelihood of receiving insect damage, and this may depend on how closely related the plant species are and the number of shared herbivores.
Based on preliminary field observations at local field sites around Miami University, three plant species in the Solanaceae family—Solanum carolinense, Physalis longifolia, and Physalis heterophylla—have different levels of herbivory when they co-occur versus when occurring alone. These three species receive leaf damage from both generalist and specialist herbivores, including the specialist Solanaceous moth herbivore, Manduca sexta.
In order to better predict how insect damage is distributed in the field, we used greenhouse assays to examine differences in larval growth rate and M. sexta feeding preferences on leaves of these three host plant species. The results of feeding trials on individual leaves of these species indicated that M. sexta had a lower 24-hour growth rate when feeding on P. longifolia compared to S. carolinense and P. heterophylla. These results suggest that P. longifolia is more resistant to M. sexta herbivory. When given a leaf of each species in a 24-hour 3-way preference assay, M. sexta larvae mostly avoided P. longifolia and showed a preference for P. heterophylla and S. carolinense, with no preference between the two. With these results, the expected outcomes of upcoming summer 2025 field assays are that P. longifolia will receive lower levels of herbivory when co-occurring with S. carolinense and P. heterophylla, while these two species will show high levels of herbivory when occurring alone in the field.

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