Location: Crops Pathology and Genetics Research
Project Number: 2032-22000-017-074-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2026
End Date: Aug 31, 2028
Objective:
1. Obtain evidence for the potential of Tortistilus albidosparsus, a treehopper frequently found in California vineyards, to transmit grapevine red blotch virus and study its life history.
Approach:
Membracid eggs laid on oak trees in vineyard landscapes by overwintering adult insects hatch in spring and the nymphs that drop on the floor will feed on vetch plants and develop into adults. As the vetch plants dry in late spring, the adults will migrate onto grapevines in the vicinity. Adult insects will be collected from vetch patches by the cooperator in late spring and released on into mesh cages on grapevines previously tested to be positive by the ARS group. After allowing insects, 5 to 10 days for virus access, the insects will be released into mesh cages on healthy grapevines previously tested to be free from GRBV. After allowing 5 to 10 days for inoculum access, some of the girdles formed on grapevines will be removed to test for the presence of GRBV and the grapevine will be monitored for systemic virus infection in the following months. Another cohort of tree hoppers will be subjected to feed onto sucrose solution through a membrane and the solution will be analyzed for the release of GRBV. Salivary glands of the insects will be dissected out by the cooperator and GRBV detection in the salivary glands will be attempted. Detection of GRBV by qPCR test will be done in the ARS lab and confirmation of amplicons as those of GRBV will be GRBV will be done by sequencing. The cooperator and ARS SY will analyze the results and prepare reports and publications on the outcome of the study.