Estimation of the dispersal distances of an aphid-borne virus in a patchy landscape

AbstractCharacterising the spatio-temporal dynamics of pathogensin naturais key to ensuring their efficient prevention and control. However, it is notoriously difficult to estimate dispersal parameters at scales that are relevant to real epidemics. Epidemiological surveys can provide informative data, but parameter estimation can be hampered when the timing of the epidemiological events is uncertain, and in the presence of interactions between disease spread, surveillance, and control. Further complications arise from imperfect detection of disease, and from the computationally intractable number of data on individual hosts arising from landscape-level surveys. Here, we present a Bayesian framework that overcomes these barriers by integrating over associated uncertainties in a model explicitly combining the processes of disease dispersal, surveillance and control. Using a novel computationally efficient approach to account for patch geometry, we demonstrate that disease dispersal distances can be estimated accurately in a fragmented landscape when disease control is ongoing. Applying this model to data for an aphid-borne virus (Plum pox virus) surveyed for 15 years over 600 orchards, we obtain the first estimate of the distribution of the flight distances of infectious aphids at the landscape scale. Most infectious aphids leaving a tree land beyond the bounds of a 1-ha orchard (50% of flights terminate within about 90 m). Moreover, long-distance flights are not rare (10% of flights exceed 1 km). By their impact on our quantitative understanding of winged aphids dispersal, these results can inform the design of management strategies for plant viruses, which are mainly aphid-borne.Author SummaryIn spatial epidemiology, dispersal kernels quantify how the probability of pathogen dissemination varies with distance. Spatial models of pathogen spread are sensitive to kernel parameters; yet these parameters have rarely been estimated using field data gathered at relevant scales. Robust estimation is rendered difficult by practical constraints limiting the number of surveyed individuals, and uncertainties concerning their disease status. Here, we present a framework that overcomes these barriers and permits inference for a between-patch transmission model. Extensive simulations show that dispersal kernels can be estimated from epidemiological surveillance data. When applied to such data collected from more than 600 orchards during 15 years of a plant virus epidemic our approach enables the estimation of the dispersal kernel of infectious winged aphids. This kernel is long-tailed, as 50% of the infectious aphids leaving a tree terminate their infectious flight within 90 m and 10% beyond 1 km. This first estimate of flight distances at the landscape scale for aphids–a group of vectors transmitting numerous viruses–is crucial for the science-based design of control strategies targeting plant virus epidemics.

Download Full-text

Comparing patterns and scales of plant virus phylogeography: Rice yellow mottle virus in Madagascar and in continental Africa

Virus Evolution ◽

10.1093/ve/vez023 ◽

2019 ◽

Vol 5 (2) ◽

Cited By ~ 4

Author(s):

Mbolarinosy Rakotomalala ◽

Bram Vrancken ◽

Agnès Pinel-Galzi ◽

Perle Ramavovololona ◽

Eugénie Hébrard ◽

...

Keyword(s):

Plant Virus ◽

Virus Disease ◽

Continuous Process ◽

Plant Viruses ◽

Mottle Virus ◽

Rice Yellow Mottle Virus ◽

Calendar Time ◽

Long Distance ◽

Transmission Potential ◽

Yellow Mottle

Abstract Rice yellow mottle virus (RYMV) in Madagascar Island provides an opportunity to study the spread of a plant virus disease after a relatively recent introduction in a large and isolated country with a heterogeneous host landscape ecology. Here, we take advantage of field survey data on the occurrence of RYMV disease throughout Madagascar dating back to the 1970s, and of virus genetic data from ninety-four isolates collected since 1989 in most regions of the country to reconstruct the epidemic history. We find that the Malagasy isolates belong to a unique recombinant strain that most likely entered Madagascar through a long-distance introduction from the most eastern part of mainland Africa. We infer the spread of RYMV as a continuous process using a Bayesian statistical framework. In order to calibrate the time scale in calendar time units in this analysis, we pool the information about the RYMV evolutionary rate from several geographical partitions. Whereas the field surveys and the phylogeographic reconstructions both point to a rapid southward invasion across hundreds of kilometers throughout Madagascar within three to four decades, they differ on the inferred origin location and time of the epidemic. The phylogeographic reconstructions suggest a lineage displacement and unveil a re-invasion of the northern regions that may have remained unnoticed otherwise. Despite ecological differences that could affect the transmission potential of RYMV in Madagascar and in mainland Africa, we estimate similar invasion and dispersal rates. We could not identify environmental factors that have a relevant impact on the lineage dispersal velocity of RYMV in Madagascar. This study highlights the value and complementarity of (historical) nongenetic and (more contemporaneous) genetic surveillance data for reconstructing the history of spread of plant viruses.

Download Full-text

RELATIONSHIPS BETWEEN COMMAND, MANAGEMENT, AND COMMUNICATIONS. TO CONTINUE IN DIFFERENT DIRECTIONS OR TO REMAIN IN SAME FIELD

Knowledge International Journal ◽

10.35120/kij28061887t ◽

2018 ◽

Vol 28 (6) ◽

pp. 1887-1891

Author(s):

Todor Kalinov

Keyword(s):

Data Exchange ◽

Content Management ◽

System Structure ◽

Power Comparison ◽

Long Distance ◽

Military Alliances ◽

Military Systems ◽

Military Command ◽

And Control ◽

The Military

Management and Command253 are two different words and terms, but military structures use them as synonyms. Military commanders’ authorities are almost equal in meaning to civilian managers’ privileges and power. Comparison between military command and the civilian management system structure, organization, and way of work shows almost full identity and overlapping. The highest in scale and size military systems are national ministries of defense and multinational military alliances and coalitions. Military systems at this level combine military command structures with civilian political leadership and support elements. Therefore, they incorporate both military command and civilian management organizations without any complications, because their nature originated from same source and have similar framework and content. Management of organizations requires communication in order to plan, coordinate, lead, control, and conduct all routine or extraordinary activities. Immediate long-distance communications originated from telegraphy, which was firstly applied in 19th century. Later, long-distance communications included telephony, aerial transmitting, satellite, and last but not least internet data exchange. They allowed immediate exchange of letters, voice and images, bringing to new capabilities of the managers. Their sophisticated technical base brought to new area of the military command and civilian management structures. These area covered technical and operational parts of communications, and created engineer sub-field of science, that has become one of the most popular educations, worldwide. Communications were excluded from the military command and moved to separate field, named Computers and Communications. A historic overview and analysis of the command and management structures and requirements shows their relationships, common origin, and mission. They have significant differences: management and control are based on humanities, natural and social sciences, while communications are mainly based on engineering and technology. These differences do not create enough conditions for defragmentation of communications from the management structures. They exist together in symbiosis and management structures need communications in order to exist and multiply their effectiveness and efficiency. Future defragmentation between military command and communications will bring risks of worse coordination, need for more human resources, and worse end states. These risks are extremely negative for nations and should be avoided by wide appliance of the education and science among nowadays and future leaders, managers, and commanders.

Download Full-text

Softening of Processed Plant Virus Infected Cucumis sativus Fruits

Agronomy ◽

10.3390/agronomy11081451 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1451

Author(s):

Anne-Katrin Kersten ◽

Sabrina Scharf ◽

Martina Bandte ◽

Peer Martin ◽

Peter Meurer ◽

...

Keyword(s):

Cucumis Sativus ◽

Plant Virus ◽

Plant Viruses ◽

Economic Losses ◽

Symptom Expression ◽

Considerable Influence ◽

Mechanical Inoculation ◽

Morphological Alterations ◽

Texture Properties ◽

Textural Changes

Texture softening of pickled cucumbers does not meet consumers’ quality expectations and leads to economic losses. The factor(s) triggering this phenomenon is still unknown. We investigated the importance of plant viruses such as Cucumber green mottle mosaic tobamovirus (CGMMV) and Zucchini yellow mosaic potyvirus (ZYMV) in the context of softening of pickles. Cucumber plants (Cucumis sativus) were infected by mechanical inoculation, grown under greenhouse conditions and tested positive for the viral infection by ELISA. The severity of virus infection was reflected in yield and symptom expression. Histological and morphological alterations were observed. All fruits were pasteurized, separately stored in jars and subjected to texture measurements after four, six and 12 months. CGMMV-infections were asymptomatic or caused mild symptoms on leaves and fruit, and texture quality was comparable to control. At the same time, fruits of ZYMV-infected plants showed severe symptoms like deformations and discoloration, as well as a reduction in firmness and crunchiness after pasteurization. In addition, histological alterations were detected in such fruits, possibly causing textural changes. We conclude that plant viruses could have a considerable influence on the firmness and crunchiness of pickled cucumbers after pasteurization. It is possible that the severity of symptom expression has an influence on texture properties.

Download Full-text

Novel Functional Genomics Approaches: A Promising Future in the Combat Against Plant Viruses

Phytopathology ◽

10.1094/phyto-03-16-0145-fi ◽

2016 ◽

Vol 106 (10) ◽

pp. 1231-1239 ◽

Cited By ~ 10

Author(s):

Vincent N. Fondong ◽

Ugrappa Nagalakshmi ◽

Savithramma P. Dinesh-Kumar

Keyword(s):

Functional Genomics ◽

Plant Virus ◽

Reverse Genetics ◽

Plant Viruses ◽

Micro Rna ◽

Viral Genomes ◽

Virus Control ◽

Local Lesions ◽

Short Palindromic Repeat ◽

Interfering Rna

Advances in functional genomics and genome editing approaches have provided new opportunities and potential to accelerate plant virus control efforts through modification of host and viral genomes in a precise and predictable manner. Here, we discuss application of RNA-based technologies, including artificial micro RNA, transacting small interfering RNA, and Cas9 (clustered regularly interspaced short palindromic repeat–associated protein 9), which are currently being successfully deployed in generating virus-resistant plants. We further discuss the reverse genetics approach, targeting induced local lesions in genomes (TILLING) and its variant, known as EcoTILLING, that are used in the identification of plant virus recessive resistance gene alleles. In addition to describing specific applications of these technologies in plant virus control, this review discusses their advantages and limitations.

Download Full-text

An introduction to the collection of plant viruses at the American Type Culture Collection and a review of the literature on plant virus preservation

Cryobiology ◽

10.1016/0011-2240(73)90079-5 ◽

1973 ◽

Vol 10 (5) ◽

pp. 469

Author(s):

J.W. Blizzard

Keyword(s):

Plant Virus ◽

Plant Viruses ◽

Culture Collection ◽

American Type Culture Collection ◽

Review Of The Literature

Download Full-text

Individuality, self and sociality of vascular plants

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2019.0760 ◽

2021 ◽

Vol 376 (1821) ◽

pp. 20190760 ◽

Cited By ~ 2

Author(s):

František Baluška ◽

Stefano Mancuso

Keyword(s):

Action Potentials ◽

Vascular Plants ◽

Kin Recognition ◽

Flowering Plants ◽

Theme Issue ◽

Long Distance ◽

Self Recognition ◽

Seed Dispersers ◽

And Control

Vascular plants are integrated into coherent bodies via plant-specific synaptic adhesion domains, action potentials (APs) and other means of long-distance signalling running throughout the plant bodies. Plant-specific synapses and APs are proposed to allow plants to generate their self identities having unique ways of sensing and acting as agents with their own goals guiding their future activities. Plants move their organs with a purpose and with obvious awareness of their surroundings and require APs to perform and control these movements. Self-identities allow vascular plants to act as individuals enjoying sociality via their self/non-self-recognition and kin recognition. Flowering plants emerge as cognitive and intelligent organisms when the major strategy is to attract and control their animal pollinators as well as seed dispersers by providing them with food enriched with nutritive and manipulative/addictive compounds. Their goal in interactions with animals is manipulation for reproduction, dispersal and defence. This article is part of the theme issue ‘Basal cognition: multicellularity, neurons and the cognitive lens’.

Download Full-text

Body Flexibility Enhances Maneuverability in the World’s Largest Predator

Integrative and Comparative Biology ◽

10.1093/icb/icy121 ◽

2018 ◽

Vol 59 (1) ◽

pp. 48-60 ◽

Cited By ~ 8

Author(s):

P S Segre ◽

D E Cade ◽

J Calambokidis ◽

F E Fish ◽

A S Friedlaender ◽

...

Keyword(s):

Open Ocean ◽

The Body ◽

Long Distance ◽

Active Surfaces ◽

Aquatic Locomotion ◽

And Performance ◽

And Control ◽

Blue Whales ◽

Control Surfaces ◽

Complex Trajectories

Abstract Blue whales are often characterized as highly stable, open-ocean swimmers who sacrifice maneuverability for long-distance cruising performance. However, recent studies have revealed that blue whales actually exhibit surprisingly complex underwater behaviors, yet little is known about the performance and control of these maneuvers. Here, we use multi-sensor biologgers equipped with cameras to quantify the locomotor dynamics and the movement of the control surfaces used by foraging blue whales. Our results revealed that simple maneuvers (rolls, turns, and pitch changes) are performed using distinct combinations of control and power provided by the flippers, the flukes, and bending of the body, while complex trajectories are structured by combining sequences of simple maneuvers. Furthermore, blue whales improve their turning performance by using complex banked turns to take advantage of their substantial dorso-ventral flexibility. These results illustrate the important role body flexibility plays in enhancing control and performance of maneuvers, even in the largest of animals. The use of the body to supplement the performance of the hydrodynamically active surfaces may represent a new mechanism in the control of aquatic locomotion.

Download Full-text

Genetic Variation and Possible Mechanisms Driving the Evolution of Worldwide Fig mosaic virus Isolates

Phytopathology ◽

10.1094/phyto-05-13-0145-r ◽

2014 ◽

Vol 104 (1) ◽

pp. 108-114 ◽

Cited By ~ 19

Author(s):

Jeewan Jyot Walia ◽

Anouk Willemsen ◽

Eminur Elci ◽

Kadriye Caglayan ◽

Bryce W. Falk ◽

...

Keyword(s):

Genetic Variation ◽

Mosaic Virus ◽

Rna Virus ◽

Plant Viruses ◽

Long Distance ◽

Evolutionary Mechanisms ◽

Plant Materials ◽

Genomic Rnas ◽

Fig Trees ◽

Fig Mosaic Virus

Fig mosaic virus (FMV) is a multipartite negative-sense RNA virus infecting fig trees worldwide. FMV is transmitted by vegetative propagation and grafting of plant materials, and by the eriophyid mite Aceria ficus. In this work, the genetic variation and evolutionary mechanisms shaping FMV populations were characterized. Nucleotide sequences from four genomic regions (each within the genomic RNAs 1, 2, 3, and 4) from FMV isolates from different countries were determined and analyzed. FMV genetic variation was low, as is seen for many other plant viruses. Phylogenetic analysis showed some geographically distant FMV isolates which clustered together, suggesting long-distance migration. The extent of migration was limited, although varied, between countries, such that FMV populations of different countries were genetically differentiated. Analysis using several recombination algorithms suggests that genomes of some FMV isolates originated by reassortment of genomic RNAs from different genetically similar isolates. Comparison between nonsynonymous and synonymous substitutions showed selection acting on some amino acids; however, most evolved neutrally. This and neutrality tests together with the limited gene flow suggest that genetic drift plays an important role in shaping FMV populations.

Download Full-text

The attainment of herd immunity with a reducing risk of contact infection in modelling

10.21203/rs.3.rs-289776/v4 ◽

2021 ◽

Author(s):

Kian Boon Law ◽

Kalaiarasu M Peariasamy ◽

Hishamshah Ibrahim ◽

Noor Hisham Abdullah

Keyword(s):

Infectious Disease ◽

Disease Transmission ◽

Herd Immunity ◽

Sir Model ◽

Mixed Population ◽

Transmission Model ◽

Force Of Infection ◽

Initial Stage ◽

And Control ◽

Model Features

Abstract The risk of contact infection among susceptible individuals in a randomly mixed population can be reduced by the presence of immune individuals and this principle forms the fundamental of herd immunity. The conventional susceptible-infectious-recovered (SIR) model features an infection-induced herd immunity model, but does not include the reducing risk of contact infection among susceptible individuals in the transmission model, therefore tends to overestimate the transmission dynamics of infectious diseases. Here we show that the reducing risk of contact infection among susceptible individuals can be achieved by incorporating the proportion of susceptible individuals (model A) or the inverse of proportion of recovered individuals (model B) in the force of infection of the SIR model. We numerically simulated the conventional SIR model and both new SIR models A and B under the exact condition with a basic reproduction number of 3·0. Prior to the numerical simulation, the threshold for the eradication of infectious disease through herd immunity was expected to be 0·667 (66·7%) for all three models. All three models performed likewise at the initial stage of disease transmission. In the conventional SIR model, the infectious disease subsided when 94·0 % of the population had been infected and recovered, way above the expected threshold for eradication and control of the infectious disease. Both models A and B simulated the infectious disease to diminish when 66·7% and 75·6% of the population had been infected, showing herd immunity might protect more susceptible individuals from the infectious disease as compared to the projection generated by the conventional SIR. Our study shows that model A provides a better framework for modelling herd immunity through vaccination, while model B provides a better framework for modelling herd immunity through infection. Both models overcome the insufficiency of the conventional SIR model in attaining the effect of herd immunity in modelling outputs, which is important and relevant for modelling infectious disease, such as the COVID-19 in a randomly mixed population.

Download Full-text