Data from: Plant spines deter herbivory by restricting caterpillar movement

The spines of flowering plants are thought to function primarily as a defense against mammalian herbivores; however, we previously reported that feeding by Manduca sexta caterpillars on the leaves of horsenettle plants (Solanum carolinense) induces increased development of internode spines on new growth. To determine whether and how these spines impact caterpillar feeding, we conducted assays with three Solanaceous plant species that vary in spine numbers (S. carolinense, S. atropurpureum, and S. aethiopicum) and also manipulated spine numbers within each of these species. We found that M. sexta caterpillars were able to locate experimentally isolated target leaves much more quickly on plants with experimentally removed spines compared to plants with intact spines. Moreover, it took caterpillars longer to defoliate species with relatively high spine numbers (S. carolinense and particularly S. atropurpureum) compared to S. aethiopicum, which has fewer spines. These findings suggest that spines may play a significant role in defense against insect herbivores by restricting their movement and increasing the time taken to access feeding sites, with possible consequences including longer developmental periods and increased vulnerability or apparency to predators.