Abstract
<jats:p>The interactions between phytophagous insects and plants are considered the main reason for the biodiversity of both taxa. The specialized and modular structure of their interaction networks is possibly driven by divergence in plant key attributes, but only a handful of economically important groups have been investigated in this direction. Neotropical tortoise beetles (Cassidinae s. str., Chrysomelidae, Coleoptera) are highly diverse phytophagous insects with strong host specialization; however, ecological studies on their host plant interactions are very scarce. Here, by using an ecological network approach with quantitative data from 28 months of fieldwork at Serra do Japi, an Atlantic Forest conservation unit, we describe the host specificity of a neotropical tortoise beetle assemblage and the patterns that arise from these interactions. By testing the phylogenetic signal of the host plant interactions, we also analyze the influence of host plants phylogenetic relationships on the structure of the network. We show that the tortoise beetle assemblage of Serra do Japi exhibit highly specialized feeding habits, producing a very modular and specialized network, with low niche overlap and connectance, across different taxonomic levels. We also show that closely related host plants are utilized by similar sets of tortoise beetles, with congeneric beetles tending to feed on the same plant taxa and on plants with similar growth forms. Our results indicate the importance of host plant traits in shaping the structure of such specialized insect-plant networks and improve the current knowledge of the host plant interactions of neotropical Cassidinae s. str.</jats:p>