Disease from leaves to landscapes: Viral hotspots are determined by spatial arrangement and phytochemistry of host plants in specialist caterpillars

Although infectious diseases play a critical role in population regulation, the drivers of disease prevalence in insects have most often been investigated in isolation, thus our knowledge of disease dynamics for insects is severely limited. We conducted a field study on Baltimore checkerspots (Euphydryas phaeton) to investigate the roles of host plants, phytochemistry, ontogeny, and larval spatial associations in determining viral prevalence at the landscape scale. We analyzed individuals for viral presence and loads, and quantified secondary phytochemistry from their native and novel host plants. We found caterpillar groups that were more proximate had greater similarity in infection prevalence, with areas of high prevalence indicating the presence of viral hotspots. Post-diapause caterpillars had higher infection rates than other developmental stages. We found that infection prevalence was linked to phytochemistry for both plants; infection prevalence was similar on both host plants a..., , , # Disease from leaves to landscapes: Viral hotspots are determined by spatial arrangement and phytochemistry of host plants in specialist caterpillars

[https://doi.org/10.5061/dryad.qnk98sfrf](https://doi.org/10.5061/dryad.qnk98sfrf)

## Description of the data and file structure

Project description: This database contains R scripts and data files for the project including data analysis for all reported results, and figure

creation using ggplot2. This project involved two main analytical approaches: the first used multiple regression on distance matrices

to examine the relative impacts of spatial distances and differences in underlying host plant chemistry to predict

viral prevalence in the larvae of Baltimore checkerspot butterflies. The second involved using natural history traits of the caterpillars

and their host plants to predict viral prevalence and viral loads.  Additionally, there are two analyses included in the SI for the article, one where there is a site-level MRM cond...