Fungal endophytes are increasingly recognized for their extraordinary diversity, their role mediating plant-insect interactions and their cryptic contributions to biodiversity. However, little is known about fungal endophyte communities outside of agricultural systems. Using a tropical shrub, we investigated: 1) how plant chemical diversity influences fungal endophyte communities, 2) the vertical transmission of these communities in a common garden experiment, and 3) whether herbivory is influenced by these interactions. To test specific hypotheses related to these questions, we chose Piper sancti-felicis because it is characterized by a diverse herbivore community, it is well defended with a high diversity of defensive compounds, and it is a fast-growing shrub which can be cloned. We quantified plant chemistry using standard natural products approaches as well as a 1H-NMR metabolomics approach to characterizing phytochemical diversity. We also documented herbivory of both parents and offspring from a common garden experiment using ImageJ.
Our study adds support to the hypothesis that fungal endophyte community variation can be influenced by plant chemical profiles. We also found that herbivory was influenced both by plant chemical diversity and characteristics of associated fungal endophyte communities. Overall, our study shows how fungal endophyte communities can interact with their host plants to scale up and influence plant-herbivore interactions. Fungal endophytes are a cryptic layer of diversity which have previously been under-documented and can play significant roles in plant-insect communities, which are among the most abundant types of ecological interactions.