title: A hyperparasite affects the population dynamics of a wild plant pathogen.
abstract: Assessing the impact of natural enemies of plant and animal pathogens on their host's population dynamics is needed to determine the role of hyperparasites in affecting disease dynamics, and their potential for use in efficient control strategies of pathogens. Here, we focus on the long-term study describing metapopulation dynamics of an obligate pathogen, the powdery mildew (Podosphaera plantaginis) naturally infecting its wild host plant (Plantago lanceolata) in the fragmented landscape of the Åland archipelago (southwest Finland). Regionally, the pathogen persists through a balance of extinctions and colonizations, yet factors affecting extinction rates remain poorly understood. Mycoparasites of the genus Ampelomyces appear as good candidates for testing the role of a hyperparasite, i.e. a parasite of other parasites, in the regulation of their fungal hosts' population dynamics. For this purpose, we first designed a quantitative PCR assay for detection of Ampelomyces spp. in field-collected samples. This newly developed molecular test was then applied to a large-scale sampling within the Åland archipelago, revealing that Ampelomyces is a widespread hyperparasite in this system, with high variability in prevalence among populations. We found that the hyperparasite was more common on leaves where multiple powdery mildew strains coexist, a pattern that may be attributed to differential exposure. Moreover, the prevalence of Ampelomyces at the plant level negatively affected the overwinter survival of its fungal host. We conclude that this hyperparasite may likely impact on its host population dynamics and argue for increased focus on the role of hyperparasites in disease dynamics.
authors.affiliation: Metapopulation Research Group, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), 00014, Helsinki, Finland.
authors.forename: C
authors.initials: C
authors.lastname: Tollenaere
authors.forename: B
authors.initials: B
authors.lastname: Pernechele
authors.forename: H S
authors.initials: HS
authors.lastname: Mäkinen
authors.forename: S R
authors.initials: SR
authors.lastname: Parratt
authors.forename: M Z
authors.initials: MZ
authors.lastname: Németh
authors.forename: G M
authors.initials: GM
authors.lastname: Kovács
authors.forename: L
authors.initials: L
authors.lastname: Kiss
authors.forename: A J M
authors.initials: AJ
authors.lastname: Tack
authors.forename: A-L
authors.initials: AL
authors.lastname: Laine
mesh_terms: D001203:Ascomycota / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity; D004271:DNA, Fungal / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005387:Finland; D054884:Host-Pathogen Interactions; D010935:Plant Diseases / Q000382:microbiology*; D010943:Plantago / Q000382:microbiology*; D011157:Population Dynamics
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer
keywords: disease; hyperparasite; metapopulation; molecular detection; plant pathogen; regulation