Let Emerging Plant Diseases Be Predictable

A prevalent concept for colonization and evolution among plant pathogens and their hosts stems from a post-Darwinian paradigm rooted in the formalized assumption of “specialized parasitism.” Seminal studies on rust fungi of socioeconomic importance integrated such an evolutionary perspective driven by the assumption of strict coevolution among pathogens and their plant hosts. Following this fundamentally unfalsifiable assumption, theories regarding host-switching for parasites were dismissed. If colonization occurred, this process would depend upon the origin of specific and novel mutations that allow infections of previously unexploited hosts or host groups, the acquisition of a broader host range. After a specific mutation arose, parasites and hosts would be locked into an eventual evolutionary dead end (e.g., codified under Dietel’s Law). Accordingly, if the parasites are highly specialized (one parasite, one plant), then new associations are rare or otherwise unpredictable. Similar schools of thought became dominant for animal pathogens and were established during the same period (i.e., Müller’s rule, Fuhrmann’s rule, and Fahrenholz’s rule). Other studies that focused on plant pathogens took the one host–one parasite idea for granted and only tentatively included evolutionary insights in subsequent development of plant pathogen scientific frameworks. Later, emerging from neo-Darwinian views, the paradigm of strict cospeciation was conflated with the gene-for-gene rule postulated in 1956 and which has persisted among phytopathologists even to the present day. In a parallel history, conceptual development among plant pathologists and parasitologists has assumed that colonization is rare and cannot be predicted, given the dependence on the origin of the elusive special mutation. In contrast, current impacts and increasing frequency of emerging pathogens and epidemics across the globe, which influence health and food security, suggest that this historical approach fails in describing a complex biosphere in dynamic change. The Stockholm paradigm (SP) provides a powerful alternative to what may be regarded as the standard model of coevolutionary diversification. The SP creates a theoretical workbench from which emergence of new associations can be evaluated and predicted. The SP provides a new perspective in exploring the dynamics among the phytoplasmas, an emergent group of plant pathogens with substantial risk for food security. New insights are examined, pushing for resolution of the internal conflicts generated by assumptions of the standard coevolutionary model, which has dominated the scientific reasoning for more than a century of plant pathology research

Contribution to the knowledge of the Auchenorrhyncha fauna of bogs and fens of Ticino and Grisons, with some new records for Switzerland: (Hemiptera: Fulgoromorpha et Cicadomorpha)

Beitrag zur Kenntnis der Zikadenfauna der Hoch- und Niedermoore des Tessin und Graubündens, mit einigen Neufunden für die Schweiz. Es werden 97 Zikadenarten aus 7 verschiedenen Familien von verschiedenen Feuchthabitaten der Kantone Tessin und Graubünden mitgeteilt. Das Material stammt aus zwei Arthropoden-Erfassungen aus den Jahren 1991-1998. Acht Arten waren neu für die Schweiz. Habitate, Wirtspflanzen, Generationenzahl und andere ökologische Ansprüche werden anhand der Literatur kurz diskutiert.97 species belonging to 7 different families of Fulgoromorpha and Cicadomorpha from various wetland areas of the Cantons of Ticino and Grisons are reported. Specimens were collected between 1991 and 1998 for two arthropod research projects. Eight species were new to Switzerland. The ecological significance of the recorded species is briefly discussed

A Field Synopsis, Systematic Review, and Meta-analyses of Cophylogenetic Studies: What Is Affecting Congruence between Phylogenies?

We conducted a field synopsis and systematic meta-analysis of studies that carried out cophylogenetic analyses using algorithms and available software. We evaluated the influence of three factors—namely, cophylogenetic method, association, and ecosystem type—on the outcome of the analyses, that is, the degree of congruence between phylogenies of interacting species. The published papers were identified using 4 different databases and 13 keywords; we included all studies for which statistical approaches to compare phylogenies (cophylogenetic analyses) of interacting lineages were used. After the initial screening, 296 studies were selected to extract response variable (outcome of the cophylogenetic analyses, i.e., congruent, incongruent, or both) and coded information of the three selected factors (method of analyses, association, and ecosystem type). The final dataset included 485 entries. The data were analyzed using the chi-square test and regression techniques. We provided evidence for the outcome to be strongly dependent on the method; in particular, we are confident in expecting that phylogenies in mutualistic associations are congruent when using global-fit methods and in parasitic associations are incongruent when using event-based methods. Using a mixed-model approach, the most parsimonious model includes a non-nested structure of two factors (method and association), with a higher probability for parasites, herbivores, and pollinators to provide incongruent results. We discuss the use of an alternative theoretical framework, the Stockholm paradigm (SP), to reanalyze published raw data, and the integration of the cophylogenetic analyses into a workbench (DAMA protocol, the policy extension of SP) aimed to anticipate emerging infectious diseases

Factors shaping community assemblages and species co-occurrence of different trophic levels

Species assemblages are the results of various processes, including dispersion and habitat filtering. Disentangling the effects of these different processes is challenging for statistical analysis, especially when biotic interactions should be considered. In this study, we used plants (producers) and leafhoppers (phytophagous) as model organisms, and we investigated the relative importance of abiotic versus biotic factors that shape community assemblages, and we infer on their biotic interactions by applying three-step statistical analysis. We applied a novel statistical analysis, that is, multiblock Redundancy Analysis (mbRA, step 1) and showed that 51.8% and 54.1% of the overall variation in plant and leafhopper assemblages are, respectively, explained by the two multiblock models. The most important blocks of variables to explain the variations in plant and leafhopper assemblages were local topography and biotic factors. Variation partitioning analysis (step 2) showed that pure abiotic filtering and pure biotic processes were relatively less important than their combinations, suggesting that biotic relationships are strongly structured by abiotic conditions. Pairwise co-occurrence analysis (step 3) on generalist leafhoppers and the most common plants identified 40 segregated species pairs (mainly between plant species) and 16 aggregated pairs (mainly between leafhopper species). Pairwise analysis on specialist leafhoppers and potential host plants clearly revealed aggregated patterns. Plant segregation suggests heterogeneous resource availability and competitive interactions, while leafhopper aggregation suggests host feeding differentiation at the local level, different feeding microhabitats on host plants, and similar environmental requirements of the species. Using the novel mbRA, we disentangle for the first time the relative importance of more than five distinct groups of variables shaping local species communities. We highlighted the important role of abiotic processes mediated by bottom-up effects of plants on leafhopper communities. Our results revealed that in-field structure diversification and trophic interactions are the main factors causing the co-occurrence patterns observed.Fil: Trivellone, Valeria. Swiss Federal Institute for Forest, Snow and Landscape Research; SuizaFil: Bougeard, Stephanie. French Agency for Food, Environmental and Occupational Health Safety; FranciaFil: Giavi, Simone. Swiss Federal Institute for Forest, Snow and Landscape Research; SuizaFil: Krebs, Patrik. Swiss Federal Institute for Forest, Snow and Landscape Research; SuizaFil: Balseiro, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Dray, Stephane. Université Claude Bernard Lyon 1; FranciaFil: Moretti, Marco. Swiss Federal Institute for Forest, Snow and Landscape Research; Suiz

Gebrauch biologischer Insektizide im Kampf gegen den Scaphoideus titanus, den Vektor von Flavescence dorée

Flavescence dorée and the mandatory control of its vector Scaphoideus titanus pose important problems in organic vineyards. The goal of our field studies conducted in the Ticino was to develop a pest control strategy conform to the guidelines of organic production. Insecticides containing pyrethrin were the only organic products showing an efficacy higher than 90% against the immature stages of S. titanus. However, these products had no effect on adult leafhoppers. Repeated applications of pyrethrin proved to be toxic against the predatory mite species Amblyseius andersoni. Despite this toxicity, the only efficient and recommended control strategy in organic vineyards is their application. Pyrethrin should be applied three times at an interval of ten days after the first appearance of individuals of the 3rd nymphal stage. Symptomatic plants must be eradicated from the vineyard to remove the phytoplasma inoculum

The 3P Framework: A Comprehensive Approach to Coping with the Emerging Infectious Disease Crisis

The COVID-19 pandemic is the latest example of the profound socioeconomic impact of the emerging infectious disease (EID) crisis. Current health security measures are based on a failed evolutionary paradigm that presumes EID is rare and cannot be predicted because emergence requires the prior evolution of novel genetic capacities for colonizing a new host. Consequently, crisis response through preparation for previously emerged diseases and palliation following outbreaks have been the only health security options, which have become unsustainably expensive and unsuccessful. The Stockholm paradigm (SP) is an alternative evolutionary framework that suggests host changes are the result of changing conditions that bring pathogens into contact with susceptible hosts, with novel genetic variants arising in the new host after infection. Host changes leading to EID can be predicted because preexisting capacities for colonizing new hosts are highly specific and phylogenetically conservative. This makes EID prevention through limiting exposure to susceptible hosts possible. The DAMA (Document, Assess, Monitor, Act) protocol is a policy extension of the SP that can both prevent and mitigate EID by enhancing traditional efforts through adding early warning signs and predicting transmission dynamics. Prevention, preparation, and palliation compose the 3P framework, a comprehensive plan for reducing the socioeconomic impact of EID. This article has been produced in support of and with appreciation for the efforts by Gábor Földvári of the Institute of Evolution, Centre for Ecological Research, and the Centre for Eco-Epidemiology, National Laboratory for Health Security (both located at 1121 Budapest, Konkoly-Thege Miklós út 29-33, Hungary). Through his untiring efforts, team building, and leadership, he has secured the first EU-wide team research grant. This work was supported by the National Research, Development and Innovation Office in Hungary (RRF-2.3.1-21-2022-00006) and the COST Action CA21170 “Prevention, anticipation and mitigation of tick-borne disease risk applying the DAMA protocol (PRAGMATICK),” which represent the first funded efforts to apply the principles of the DAMA protocol

Multiannual infestation patterns of grapevine plant inhabiting Scaphoideus titanus (Hemiptera: Cicadellidae) leafhoppers

The Nearctic leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae) was accidentally introduced in Europe, where it became the vector of the ‘Candidatus Phytoplasma vitis' phytoplasma causing the ‘Flavescence dorée' disease of grapevine plants. A time-varying distributed delay model, simulating the successive occurrences of egg hatching, nymph presence, and adult emergence, is extended here to represent multi-generation infestation patterns of grapevine plants inhabited by eggs, nymphs, and adults. The model extension includes intrinsic mortality, mortality caused by plant dormancy, and low temperatures, development of diapausing and post-diapausing eggs, fecundity rates, and adult longevity. Field observations and published data were used to estimate parameters. The model was validated with five years canopy infestation data from five vineyards not subjected to insecticide treatments and found to have satisfactory explicative and predictive qualities. The model output is most sensitive to a 10% variation in the upper threshold and in the shape parameters of the survivorship function and least sensitive to a 10% variation in the shape parameters of the development function and the survivorship level. Recommendations are made to take into account other factors than temperature and plant phenology and include a wider geographical area in further model developmen

Stepping-stones and Mediators of Pandemic Expansion—A Context for Humans as Ecological Super-spreaders

Humans represent ecological super-spreaders in the dissemination and introduction of pathogens. These processes, consistent with the dynamics of the Stockholm paradigm, are exemplified in the origin and globalized distributions of SARS-CoV-2 since initial recognition in central Asia during 2019 and 2020. SARS-like viruses are not widespread in mammals but appear widespread in chiropterans. Bats are isolated ecologically from most other assemblages of mammals in terrestrial systems. Humans may be the stepping-stone hosts for broad global dissemination and wider infection (given the opportunity) among diverse assemblages of mammals in which host and viral capacity are compatible. Human globalization mediated insertion in global ecosystems along primary and secondary pathways initially with localized to regional circulation across continents. Origins and persistence of cycles involving variants and viral transmission among other mammals and the potential for secondary exposure (retrocolonization) of people occurs on multidirectional pathways. Humans were responsible for the initial breakdown in ecological isolation of the virus that facilitated colonization events from chiropterans to other mammals. In the absence of these human drivers, environmental or ecological interfaces (boundary zones among habitats) limiting the distribution of SARS-CoV-2 are unlikely to have been crossed, leaving a diverse assemblage of SARS-like viruses (Sarbecovirus) remaining relatively hidden and isolated in southeast Asia

Kritische Artenliste der Zikaden der Schweiz: (Hemiptera: Auchenorrhyncha)

Eine kommentierte Liste aller für die Schweiz gemeldeten Zikadenarten wurde zusammengestellt. Es wurden nur publizierte Daten berücksichtigt; zusätzlich werden 10 Arten hier zum ersten Mal für die Schweiz gemeldet: Hyalesthes luteipes Fieber, Calligypona reyi (Fieber), Kelisia confusa Linnavuori, Xanthodelphax flaveola (Flor), Macropsis haupti Wagner, M. remanei Nickel, Erythria cisalpina Dworakowska, Euscelis distinguendus (Kirschbaum), Metalimnus steini (Fieber) und Proceps acicularis Mulsant & Rey. Die Artenliste der Schweiz zählt aktuell insgesamt 561 bestätigte Arten (davon wurden allerdings rund 40 nicht mehr in den letzten 50 Jahren nachgewiesen). Zusätzlich wurde eine Liste mit insgesamt 173 weiteren Arten erstellt, die geografisch und ökologisch zu erwarten sind. 17 Arten aus der Literatur wurden wegen Fehldetermination oder taxonomischer Probleme nicht in die Liste aufgenommen