Multi‐scale patterns of human activity and the incidence of an exotic forest pathogen

Cushman, J. Hall; Meentemeyer, Ross K.

doi:10.1111/j.1365-2745.2008.01376.x

Cited by 61 publications

(53 citation statements)

References 57 publications

(136 reference statements)

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“…This experimental evidence well matches field observations describing significant infection only for oaks near an infectious host (23,71,77,82) and only in years when sporangial production is high due to the presence of rainfall in the late spring (72). Individual tanoaks and bay laurels do not require high inoculum loads for infection to occur.…”

supporting

confidence: 74%

Sudden Oak Death: Interactions of the Exotic Oomycete Phytophthora ramorum with Naïve North American Hosts

Garbelotto

Hayden

2012

Eukaryot Cell

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Ten years after a threatening and previously unknown disease of oaks and tanoaks appeared in coastal California, a significant amount of progress has been made toward the understanding of its causal agent Phytophthora ramorum and of the novel pathosystems associated with this exotic organism. However, a complete understanding of the ecology and epidemiology of this species still eludes us. In part, our inability to fully understand this organism is due to its phylogenetic, phylogeographic, phenotypic, and epidemiological complexities, all reviewed in this paper. Most lines of evidence suggest that the high degree of disease severity reported in California is not simply due to a generalized lack of resistance or tolerance in naïve hosts but also to an innate ability of the pathogen to survive in unfavorable climatic conditions and to reproduce rapidly when conditions become once again favorable.

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supporting

confidence: 74%

Sudden Oak Death: Interactions of the Exotic Oomycete Phytophthora ramorum with Naïve North American Hosts

Garbelotto

Hayden

2012

Eukaryot Cell

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“…and physiographic (e.g., soil type, slope, etc.) conditions can directly or indirectly drive pathogen transmission (Agrios 2005;Sacks et al 2003;Cushman and Meentemeyer 2008;Shapiro-Ilan et al 2012), thus influencing levels of disease. In gypsy moth populations, a baculovirus, Lymantria dispar nucleopolyhedrovirus; LdNPV), has long been known to cause epizootics that result in outbreak collapse (Alalouni et al 2013;McManus and Csóka 2007).…”

Section: Introductionmentioning

confidence: 98%

Replacement of a dominant viral pathogen by a fungal pathogen does not alter the collapse of a regional forest insect outbreak

2014

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Natural enemies and environmental factors likely both influence the population cycles of many forest-defoliating insect species. Previous work suggests precipitation influences the spatiotemporal patterns of gypsy moth outbreaks in North America, and it has been hypothesized that precipitation could act indirectly through effects on pathogens. We investigated the potential role of climatic and environmental factors in driving pathogen epizootics and parasitism at 57 sites over an area of ≈72,300 km(2) in four US mid-Atlantic states during the final year (2009) of a gypsy moth outbreak. Prior work has largely reported that the Lymantria dispar nucleopolyhedrovirus (LdNPV) was the principal mortality agent responsible for regional collapses of gypsy moth outbreaks. However, in the gypsy moth outbreak-prone US mid-Atlantic region, the fungal pathogen Entomophaga maimaiga has replaced the virus as the dominant source of mortality in dense host populations. The severity of the gypsy moth population crash, measured as the decline in egg mass densities from 2009 to 2010, tended to increase with the prevalence of E. maimaiga and larval parasitoids, but not LdNPV. A significantly negative spatial association was detected between rates of fungal mortality and parasitism, potentially indicating displacement of parasitoids by E. maimaiga. Fungal, viral, and parasitoid mortality agents differed in their associations with local abiotic and biotic conditions, but precipitation significantly influenced both fungal and viral prevalence. This study provides the first spatially robust evidence of the dominance of E. maimaiga during the collapse of a gypsy moth outbreak and highlights the important role played by microclimatic conditions.

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“…These studies, however, can only speculate about dispersal distances. A different approach correlates human movement with species distribution to postulate HMD (Buchan & Padilla 1999;Suarez et al 2001;Gilbert et al 2004;Cushman & Meentemeyer 2008), but such studies cannot demonstrate the dispersal mechanisms. In summary, we still lack detailed knowledge about the distances and frequencies achieved by HMD Bonn & Poschlod 1998).…”

Section: Introductionmentioning

confidence: 99%

Human-mediated dispersal of seeds over long distances

et al. 2008

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Human activities have fundamental impacts on the distribution of species through altered land use, but also directly by dispersal of propagules. Rare long-distance dispersal events have a disproportionate importance for the spread of species including invasions. While it is widely accepted that humans may act as vectors of long-distance dispersal, there are few studies that quantify this process. We studied in detail a mechanism of human-mediated dispersal (HMD). For two plant species we measured, over a wide range of distances, how many seeds are carried by humans on shoes. While over half of the seeds fell off within 5 m, seeds were regularly still attached to shoes after 5 km. Semi-mechanistic models were fitted, and these suggested that long-distance dispersal on shoes is facilitated by decreasing seed detachment probability with distance. Mechanistic modelling showed that the primary vector, wind, was less important as an agent of long-distance dispersal, dispersing seeds less than 250 m. Full dispersal kernels were derived by combining the models for primary dispersal by wind and secondary dispersal by humans. These suggest that walking humans can disperse seeds to very long distances, up to at least 10 km, and provide some of the first quantified dispersal kernels for HMD.

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Multi‐scale patterns of human activity and the incidence of an exotic forest pathogen

Cited by 61 publications

References 57 publications

Sudden Oak Death: Interactions of the Exotic Oomycete Phytophthora ramorum with Naïve North American Hosts

Sudden Oak Death: Interactions of the Exotic Oomycete Phytophthora ramorum with Naïve North American Hosts

Replacement of a dominant viral pathogen by a fungal pathogen does not alter the collapse of a regional forest insect outbreak

Human-mediated dispersal of seeds over long distances

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