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Insights into the epidemiology and transmission of grapevine red blotch virus

Elizabeth Cieniewicz: Cornell University

<div>Red blotch is an emerging viral disease of <em>Vitis</em> spp. that threatens grapevine production. The causal agent, grapevine red blotch virus (GRBV) from the genus <em>Grablovirus</em> in the family <em>Geminiviridae</em>, is disseminated via infected propagation material and spread by at least one hemipteran insect vector- the three cornered alfalfa hopper (<em>Spissistilus festinus</em>). Our research is aimed toward understanding the factors mediating spread of GRBV by <em>S. festinus</em>. We modeled spatiotemporal attributes of a red blotch epidemic in a <em>V. vinifera </em>‘Cabernet franc’ vineyard in California over three years. Spatiotemporal analyses demonstrated predominantly localized, within-vineyard spread. We also described the seasonal and spatial distribution of <em>S. festinus</em> and additional potential vectors of GRBV in the ‘Cabernet franc’ vineyard. In parallel, hypothesizing a circulative transmission mode, we characterized the temporal GRBV retention by <em>S. festinus </em>on a non-host, described the gut morphology, determined GRBV tissue tropism in <em>S. festinus</em> using fluorescence <em>in situ</em> hybridization, and detected GRBV in dissected hemolymph, guts, and salivary glands from viruliferous <em>S. festinus</em> by multiplex polymerase chain reaction. A comprehensive understanding of the epidemiology and ecology of GRBV is crucial for the development of optimal disease and vineyard management recommendations.</div>