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Dryad

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

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Jan 30, 2025 version files 820.79 KB

Abstract

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 at low phytochemical concentrations but diverged at high concentrations with the native plant showing low prevalence and the exotic plant hosting high prevalence. Altogether, our findings reveal that spatial proximity, ontogeny, larval host plant species, and phytochemistry are important in structuring infection risk and thus offer insight into causal drivers of disease prevalence in complex plant-insect systems.