Euscelidius variegatus (Kirschbaum) (Hemiptera: Cicadellidae) is widely distributed throughout Europe (Metcalf Reference Metcalf1967) and was probably introduced into North America prior to 1947 (Hamilton Reference Hamilton1983). At that point, it was only recorded to occur in western North America, notably in California (Hamilton Reference Hamilton1983), Washington, Oregon, and Utah in the United States of America (Young Reference Young1955).

Here, we report for the first time the presence of E. variegatus in Canada and in eastern North America. A first and single specimen was collected by T. West (full name and affiliation unknown) on 1 July 2002 in Port Colborne (Ontario, Canada) on a plant type not recorded (barcode index number BOLD: AAE0999, specimen CNCHF2114-12; www.boldsystems.org). In the fall of 2016, six commercial vineyards in Niagara-on-the-Lake (Ontario, Canada) were sweep netted on vines and on the surrounding vegetation once a week for eight weeks, and two more specimens of E. variegatus were collected directly on vines (Vitis vinifera Linnaeus (Vitaceae). The leafhoppers were identified by morphological comparison with specimens originating from Germany and the western United States of America, and using published information from Europe (Ribaut Reference Ribaut1952). The original specimen from Port Colborne (specimen database number CNC#HEM404049) and one of the specimens collected in Niagara-on-the-Lake (specimen database number CNC#603606) are now vouchers stored in the Canadian National Collection of Insects, Arachnids, and Nematodes in Ottawa, Ontario, Canada.

This finding is somewhat surprising considering the scale of recent collection efforts aiming to establish cicadellid diversity in Canadian vineyards. Saguez et al. (Reference Saguez, Olivier, Hamilton, Lowery, Stobbs and Lasnier2014) collected 18000 cicadellid specimens (110 species belonging to 54 genera) in 80 commercial vineyards in Ontario, Québec, and British Columbia, Canada. Olivier et al. (Reference Olivier, Saguez, Stobbs, Lowery, Galka and Whybourne2014) performed polymerase chain reaction analysis on 11 515 leafhopper specimens collected in Canadian vineyards for phytoplasma detection. Despite these collection efforts, E. variegatus remained undetected in Canada.

This could be explained by the low abundance of E. variegatus in and around vineyards in Canada. In 2016, we found only two E. variegatus specimens out of > 3500 cicadellid specimens collected. No other specimens of E. variegatus were found during weekly sweeps performed throughout the 2017 and 2018 growing seasons, despite having > 4000 cicadellid specimens collected per year from six commercial vineyards, including where they were found in 2016.

Furthermore, the abundance of E. variegatus remains low relative to Scaphoideus titanus Ball (Hemiptera: Cicadellidae), another native North American leafhopper species, which invaded western Europe in 1958. In Europe, S. titanus has become the main vector of flavescence dorée (Candidatus Phytoplasma vitis (Bacteria: Acholeplasmataceae)), a quarantine pathogen of cultivated grapevines in both the Palaearctic and Nearctic regions (Bonfils and Schvester Reference Bonfils and Schvester1960; Bressan et al. Reference Bressan, Clair, Sémétey and Boudon-Padieu2005). Given enough time however, the abundance of E. variegatus could increase to the point of it also becoming an important disease vector in North America. In actuality, E. variegatus has been reported as a vector of three phytoplasmas including flavescence dorée in grape, a quarantine pathogen of cultivated grapevines in western Europe, chrysanthemum yellows (Candidatus Phytoplasma asteris (Bacteria: Acholeplasmataceae)) in multiple plant species, and Western X-disease (Candidatus Phytoplasma pruni (Bacteria: Acholeplasmataceae)) in Prunus Linnaeus (Rosaceae) species (Jensen Reference Jensen1969; Bosco et al. Reference Bosco, Minucci, Boccardo and Conti1997; Bressan et al. Reference Bressan, Clair, Sémétey and Boudon-Padieu2005). Despite its ability to transmit flavescence dorée, the impact of E. variegatus in North America is unlikely to reach the scale of impact observed following the invasion of S. titanus into Europe. This is because flavescence dorée, which is prevalent across Europe, remains absent in North America. Nonetheless, as a potential vector of quarantine phytoplasma, this leafhopper will need to be continuously monitored, as it could have an important effect on the national wine and tree fruit industries.