DOI: 10.5061/dryad.79vg007
title: Data from: Pathogen dynamics under both bottom-up host resistance and top-down hyperparasite attack

description: 1. The relative importance of bottom-up versus top-down control of
 population dynamics has been the focus of much debate. In infectious
 disease biology, research is typically focused on the bottom-up process of
 host resistance, wherein the direction of control flows from the lower to
 the higher trophic level to impact on pathogen population size and
 epidemiology. However, the importance of top-down control by a
 pathogen's natural enemies has been mostly overlooked. 2. Here, we
 explore the effects of, and interaction between, host genotype (i.e.
 genetic susceptibility to pathogen infection) and infection by a
 hyperparasitic fungus, (Ampelomyces spp.) on the establishment and
 early-epidemic growth and transmission of a powdery mildew plant pathogen
 (Podosphaera plantaginis). We used a semi-natural field experiment to
 contrast the impacts of hyperparasite infection, host-plant resistance and
 spatial structure to reveal the key factors that determine pathogen
 spread. We then used a laboratory-based inoculation approach to test
 whether the field experiment results hold across multiple pathogen-host
 genetic combinations, and to explore hyperparasite effects on the
 pathogen's later life-history stages. 3. We found that hyperparasite
 infection had a negligible effect on within-host infection development and
 between-host spread of the pathogen during the onset of epidemics. In
 contrast, host-plant resistance was the major determinant of whether
 plants became infected, and host genotype and proximity to an infection
 source determined infection severity. 4. Our laboratory study showed that,
 while the interaction between host and pathogen genotypes was the key
 determinant of infection outcome, hyperparasitism did, on average, reduce
 the severity of infection. Moreover, hyperparasite infection negatively
 influenced the production of the pathogen's overwintering structures.
 5. Synthesis and applications: Our results suggest that while host
 resistance affects pathogen spread, efficient top-down control of powdery
 mildew pathogens is dependent on which pathogen life history stage is
 targeted. Further, while hyperparasitism in this system can reduce early
 pathogen growth under stable laboratory conditions, this effect is not
 detectable in a semi-natural environment. Considering the effects of
 hyperparasites at multiple points in pathogen's life history will be
 important when considering hyperparasite-derived biocontrol measures in
 other natural and agricultural systems.
description: Parrattt_&_Laine_LabExpt1_dataResponse and independent variable used to analyse the effect of hyperparasite infection and host genotype on pathogen growth in the laboratory.Parratt_&_Laine_second_expt_dataResponse and independent variable used to analyse the effect of hyperparasite infection on pathogen resting structure productionParratt_&_Laine_Field_Recipient_Plant_DataData used to analyse the effect of spatial structure, host genotype and hyperparasite infection on the between-plant spread of powdery mildewParratt_&_Laine_Source_Plant_DataData used to analyse the effect of ampelomyces on within-host growth in the fieldParratt_&_Laine_metadataMetadata file for each of the data files in this submission