The impact of host biogeography, ecology, evolutionary history, and architecture on the structure of rolled-leaf beetle assemblages of Costa Rican Zingiberales

Abstract

Determining the factors affecting the structure of insect herbivore communities is a major challenge in ecology. Previous research demonstrated that plant defenses determine plant-herbivore associations. However, non-defensive variables may also explain why some plant species are associated with more diverse insect herbivore assemblages than others. Neotropical rolled-leaf beetles (Cephaloleia and Chelobasis) complete their life cycle inside the young rolled leaves of their host plants in the order Zingiberales. The diet breadth of each species in this assemblage is particularly well-known at our study site, La Selva Biological Station in Costa Rica. This study focused on the following non-defensive variables: host plant elevational and geographic range size, soil type, habitat, local abundance, plant size, and leaf size. Because plant characteristics among closely related plants are not independent, we analyzed these variables in a phylogenetic context. We detected a positive effect of leaf width on rolled-leaf beetle species richness (explaining 55% of the variation), abundance (28% of the variation and 57% when habitat is included in the model), diversity (37% of the variation), and community structure (6% of the variation, and 21%–26% when taxonomic family is included in the model). Our study demonstrates that Zingiberales leaf width influences positively rolled-leaf beetle species richness, abundance, and diversity. This effect varies among plant families. Our study shows that plant architecture plays an important role in structuring insect herbivore assemblages in Zingiberales. Our results highlight the importance of including variables beyond plant defenses to understand the ecology and evolution of plant-herbivore interactions.