Drivers of emerging fungal diseases of forest trees

Biological invasions, resulting from deliberate and unintentional species transfers of insects, fungal and oomycete organisms, are a major consequence of globalization and pose a significant threat to biodiversity. Limiting damage by non-indigenous forest pathogens requires an understanding of their current and potential distributions, factors affecting disease spread, and development of appropriate management measures. In this review, we synthesize innate characteristics of invading organisms (notably mating system, reproduction type, and dispersal mechanisms) and key factors of the host population (namely host diversity, host connectivity, and host susceptibility) that govern spread and impact of invasive forest pathogens at various scales post-introduction and establishment. We examine spread dynamics for well-known invasive forest pathogens, Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz, Hosoya, comb. nov., causing ash dieback in Europe, and Cryphonectria parasitica, (Murr.) Barr, causing chestnut blight in both North America and Europe, illustrating the importance of host variability (diversity, connectivity, susceptibility) in their invasion success. While alien pathogen entry has proven difficult to control, and new biological introductions are indeed inevitable, elucidating the key processes underlying host variability is crucial for scientists and managers aimed at developing effective strategies to prevent future movement of organisms and preserve intact ecosystems.

Section: Introductionmentioning

confidence: 99%

Effects of Host Variability on the Spread of Invasive Forest Diseases

Prospero

Cleary

2017

“…For example, temperature affects pathogen metabolic activity as well as host predisposition in response to environmental stress [33]. Global change-driven range expansions or contractions could make disease emergence more, or less, likely due to changes in the abundance or spatial distribution of either biological component [3,19,34]. Physical host wounds that act as a de facto surmounting of host physical defenses play an important role in infection [1,22,35,36].…”

Section: Environmentmentioning

confidence: 99%

Tree Diseases as a Cause and Consequence of Interacting Forest Disturbances

Cobb

Metz

2017

Abstract:The disease triangle is a basic and highly flexible tool used extensively in forest pathology. By linking host, pathogen, and environmental factors, the model provides etiological insights into disease emergence. Landscape ecology, as a field, focuses on spatially heterogeneous environments and is most often employed to understand the dynamics of relatively large areas such as those including multiple ecosystems (a landscape) or regions (multiple landscapes). Landscape ecology is increasingly focused on the role of co-occurring, overlapping, or interacting disturbances in shaping spatial heterogeneity as well as understanding how disturbance interactions mediate ecological impacts. Forest diseases can result in severe landscape-level mortality which could influence a range of other landscape-level disturbances including fire, wind impacts, and land use among others. However, apart from a few important exceptions, these disturbance-disease interactions are not well studied. We unite aspects of forest pathology with landscape ecology by applying the disease-triangle approach from the perspective of a spatially heterogeneous environment. At the landscape-scale, disturbances such as fire, insect outbreak, wind, and other events can be components of the environmental 'arm' of the disease triangle, meaning that a rich base of forest pathology can be leveraged to understand how disturbances are likely to impact diseases. Reciprocal interactions between disease and disturbance are poorly studied but landscape ecology has developed tools that can identify how they affect the dynamics of ecosystems and landscapes.

“…A recent study attributed seven underlying drivers (alien pathogenic invasion, climate change, emergence of aggressive species or strains, rise in hybridization of fungi, latent and cryptic pathogens, establishment of novel links between pathogens and their vectors, adaptation of new crops and cultivation practices) of EIDs [61]. Often more than one driver may cause a rise in the range of pathogens, insects and ultimately infectious diseases.…”

Section: Pathogens and Pests Of Pine Nutsmentioning

confidence: 99%

“…According to Ghelardini et al [61], establishment of novel links between pathogens and their vectors, climate change, latent and cryptic pathogens are a few of the important factors identified that cause tip-blight of pines, also called dieback, due to Diplodia sapinea or D. pinea and its association with an adventive insect, Leptoglossus occidentalis Heidemann. Figure 2 shows the current presence of L. occidentalis in the world.…”

Section: Pathogens and Pests Of Pine Nutsmentioning

confidence: 99%

Pine Nuts: A Review of Recent Sanitary Conditions and Market Development

Awan

Pettenella

2017

Pine nuts are non-wood forest products (NWFP) with a constantly growing market notwithstanding a series of phytosanitary issues and related trade problems. The aim of this paper is to review the literature on the relationship between phytosanitary problems and trade development. Production and trade of pine nuts in Mediterranean Europe have been negatively affected by the spreading of Diplodia sapinea (a fungus) associated with an adventive insect Leptoglossus occidentalis (fungal vector), with impacts on forest management, production and profitability and thus in value chain organization. Reduced availability of domestic production in markets with a growing demand has stimulated the import of pine nuts. China has become a leading exporter of pine nuts, but its export is affected by a symptom caused by the nuts of some pine species: 'pine nut syndrome' (PNS). Most of the studies mentioned in the literature review concern PNS occurrence associated with the nuts of Pinus armandii. We highlight the need for a comprehensive and interdisciplinary approach to the analysis of the pine nuts value chain organization, where research on food properties and clinical toxicology may be connected to breeding and forest management, forest pathology and entomology, and trade development.