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Following the recent detection of bois noir, X-disease and aster yellow (AY) in Canadian vineyards, a survey was conducted in 2006–2008 in vineyards located in Ontario (ON), British Columbia (BC) and Quebec (QC). PCR tests were used to detect phytoplasmas in grapevine cultivars and leafhopper species, and identify phytoplasma strains. The overall detection of phytoplasmas was <1% in BC, and ranged from 2.4% to 8.3% in ON and QC, respectively, with significant variability between years, cultivars and locations. A large proportion of phytoplasma-infected grapevines were symptomless and the cultivars merlot and pinot gris were the only two cultivars in which no phytoplasma were detected. Aster yellow phytoplasma strains belonging to the subgroups 16SrI-A, -B, and -C were detected in grapevines, with 16SrI-A being the most frequently found. Phytoplasma DNA was detected in 37 leafhopper species, out of which 11 are known vectors. Most leafhopper species in which phytoplasma DNA were detected are grass feeders, with the AY vector Macrosteles quadrilineatus constituting a strong potential candidate for AY transmission in ON and QC vineyards. Five new sequences of phytoplasma were found in grapevines, and 11 in leafhoppers: they were registered in GenBank. The possibility of phytoplasma transmission between leafhoppers and grapevines is discussed. [ABSTRACT FROM AUTHOR]

Leafhoppers (Hemiptera: Cicadellidae) are pests of many temperate crops, including grapevines (Vitis species). Uncontrolled populations can induce direct and indirect damage to crops due to feeding that results in significant yield losses and increased mortality in infected vineyards due to virus, bacteria, or phytoplasmas vectored by leafhoppers. The main objective of this work was to determine the diversity of leafhoppers found in vineyards of the three main Canadian production provinces, i.e., in British Columbia, Ontario, and Quebec. Approximately 18,000 specimens were collected in 80 commercial vineyards from 2006 to 2008. We identified 54 genera and at least 110 different species associated with vineyards, among which 22 were predominant and represented more than 91% of all the leafhoppers. Species richness and diversity were estimated by both Shannon's and Pielou's indices. For each province, results indicated a temporal variation in species composition. Color photographs provide a tool to quickly identify 72 leafhoppers commonly associated with vineyards., (This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.)