Trends in vector-borne transmission efficiency from coinfected hosts: Grapevine leafroll-associated virus-3 and Grapevine virus A

Grapevine leafroll-associated virus 3 (GLRaV-3) is the most prevalent and destructive virus species that contributes to grapevine leafroll disease, an economically damaging disease that affects vineyards globally. Grapevine virus A (GVA) is a virus species in the rugose wood complex and is associated with several vineyard diseases. Both virus species are transmitted by several mealybug species. Transmission efficiency is a major facet of pathogen spread and may be influenced by virus species interactions in the vector or host. We tested transmission efficiency of GLRaV-3 and GVA from nine field-collected source vine samples of Vitis vinifera cv Chardonnay by first instars of Planococcus ficus . Transmission of GLRaV-3 was 22% greater than transmission of GVA. Establishment of new mixed GLRaV-3/GVA infections did not differ significantly from single GLRaV-3 infections following inoculation by P. ficus . These results suggest that GVA may have a higher likelihood of establishing new infections in concert with GLRaV-3 than in single infections.