Forest species diversity reduces disease risk in a generalist plant pathogen invasion

• Published in: Ecology letters 2011-11, Vol.14 (11), p.1108-1116
• Main Authors: Haas, Sarah E., Hooten, Mevin B., Rizzo, David M., Meentemeyer, Ross K.
• Format: Article
• Language: English
• Subjects: Bayes Theorem; Bayesian hierarchical model; Biodiversity; California; Ecosystem; emerging infectious disease; forest ecosystem; Forests; Host Specificity; Host-Pathogen Interactions; Introduced Species; landscape epidemiology; Linear Models; Models, Biological; Phytophthora; Phytophthora - pathogenicity; Phytophthora ramorum; Plant Diseases - microbiology; Plant ecology; Plant pathology; Plant populations; Plants; Population Density; spatial autocorrelation; species diversity; sudden oak death; Trees - microbiology; zero‐inflation
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/j.1461-0248.2011.01679.x

Ecology Letters (2011) 14: 1108–1116 Empirical evidence suggests that biodiversity loss can increase disease transmission, yet our understanding of the ‘diversity‐disease hypothesis’ for generalist pathogens in natural ecosystems is limited. We used a landscape epidemiological approach to examine two scenarios regarding diversity effects on the emerging plant pathogen Phytophthora ramorum across a broad, heterogeneous ecoregion: (1) an amplification effect exists where disease risk is greater in areas with higher plant diversity due to the pathogen’s wide host range, or (2) a dilution effect where risk is reduced with increasing diversity due to lower competency of alternative hosts. We found evidence for pathogen dilution, whereby disease risk was lower in sites with higher species diversity, after accounting for potentially confounding effects of host density and landscape heterogeneity. Our results suggest that although nearly all plants in the ecosystem are hosts, alternative hosts may dilute disease transmission by competent hosts, thereby buffering forest health from infectious disease.