Vector-Borne Pathogens and Disease Development

Factors affecting the spatial spread of vector-borne diseases include vector movement and aggregation, wind direction affecting aphid dispersal, the presence of alternate hosts around the fields, and disease gradients estimated from observed frequencies at different distances from the source plant.

The 'multiple infection transformation' is used to estimate the number of inoculations by transforming the observed disease frequencies close to the source plant. It is represented by the equation $ln[1/(1-x)]$, where x is the proportion of diseased plants or diseased area.

Control methods for vector-borne diseases depend on the pathogen, vector, and host. Prevention of vector landing on the crop, host plant resistance, reflective mulches, and a combination of different control tactics are recommended. Spraying of the vector may not always be effective, especially for non-persistent vectors.

<p>The spatial spread of black currant reversion virus transmitted by aphids is observed and then transformed using the 'multiple infection transformation' to estimate the number of inoculations close to the source. The solid line represents the observed spread, while the dotted line represents the transformed spread.</p> Signup and view all the answers

<p>Roguing of infected plants may be effective in controlling vector-borne diseases, especially when the incubation period is short. It is dependent on the stage of disease development of the rogued plants, and roguing of infectious symptomatic and asymptomatic plants can be effective.</p> Signup and view all the answers

<p>The incidence of tomato yellow leaf curl, transmitted by Bemisia tabaci whiteflies, is lower when a barrier with insecticide is used compared to a barrier without insecticide, as shown by the solid line with barrier being below the dotted line without barrier.</p> Signup and view all the answers

<p>Roguing of symptomatic plants has a significant impact on the incidence of cassava mosaic virus, as indicated by the difference in incidence over time between the group with no roguing (closed dots) and the group with roguing (open dots).</p> Signup and view all the answers

<p>A combination of different control tactics is needed to reduce epidemic development of vector-borne diseases because control methods depend on various factors such as the specific pathogen, vector, host, and the presence of other means of dispersal. Additionally, spraying of the vector may not always be effective, and prevention of vector landing on the crop, host plant resistance, and reflective mulches are among the recommended control methods.</p> Signup and view all the answers

<p>Pathogen population size, or the number of propagules, can influence disease development by affecting the likelihood of successful transmission to a host plant and the establishment of infection.</p> Signup and view all the answers

<p>Vector relationships, including specificity and persistence, play a crucial role in disease development as they determine the ability of the pathogen to be transmitted and maintained within the vector population.</p> Signup and view all the answers

<p>The level of virulence, replication, and movement inside plants, as well as ecological factors such as soilborne or foliar survival, are key characteristics of pathogens that can significantly influence disease development.</p> Signup and view all the answers

<p>Spores of plant pathogenic fungi can be transmitted to flowers by thrips and various pollinators, or to the bark and wood of trees by bark boring beetles.</p> Signup and view all the answers

<p>For many plant virus diseases, the epidemiologically important propagule is often the vector. The same is true for phloem-limited bacteria or mollicutes.</p> Signup and view all the answers

<p>Insects belonging to the order Homoptera, such as aphids, whiteflies, psyllids, planthoppers, and leafhoppers, are the main insect vectors that transmit viruses, bacteria, and mollicutes.</p> Signup and view all the answers

<p>Trap design affects catch by influencing the effectiveness of the trap in capturing specific insect species, with factors such as size, color, height, location, and position playing crucial roles in the quantification process.</p> Signup and view all the answers

<p>Real-time quantitative PCR methods and amplicon sequence specific and non-specific methods are utilized for identifying and quantifying viruses in plants or vectors.</p> Signup and view all the answers

<p>Vector relationships encompass specificity and persistence, with specificity referring to the transmission by particular species or non-specifically, and persistence affecting epidemic development based on non-persistence, semi-persistence, circulative persistence, or circulative persistence and propagative traits.</p> Signup and view all the answers

<p>The five steps in vector transmission include acquisition, movement inside the vector, multiplication, inoculation, and movement/replication in the host plant, and they play a crucial role in disease spread and epidemic development.</p> Signup and view all the answers

<p>Factors affecting transmission and epidemic development include the proportion of infected source plants, pathogen content, vector density, vector aggregation, vector movement, and the presence of alternate hosts.</p> Signup and view all the answers

<p>Plant virus infection can affect vector multiplication rate and may also lead to vectors being more attracted to diseased plants, indicating co-evolution between the virus and the vectors.</p> Signup and view all the answers