Pseudococcus maritimus (Hemiptera: Pseudococcidae) and Parthenolecanium corni (Hemiptera: Coccidae) Are Capable of Transmitting Grapevine Leafroll-Associated Virus 3 Between Vitis x labruscana and Vitis vinifera

The grape mealybug, Pseudococcus maritimus (Ehrhorn), and European fruit lecanium scale, Parthenolecanium corni (Bouche), are the predominant species of Coccoidea in Washington State vineyards. The grape mealybug has been established as a vector of Grapevine leafroll-associated virus 3 (GLRaV-3) between wine grape (Vitis vinifera L.) cultivars, elevating its pest status. The objective of this study was to determine if GLRaV-3 could be transmitted between Vitis x labruscana L. and V. vinifera by the grape mealybug and scale insects. Three transmission experiments were conducted with regard to direction; from V. vinifera to V. x labruscana L., from V. x labruscana L. to V. x labruscana L., and from V. x labruscana L. to V. vinifera. Each experiment was replicated 15 times for each vector species. Crawlers (_rst-instars) of each vector species were allowed 1-wk acquisition and inoculation access periods. The identities of viral and vector species were con_rmed by reverse transcription-polymerase chain reaction, cloning, and sequencing of species-specific DNAfragments. GLRaV-3wassuccessfully transmittedbyboth species in all experiments, although Ps. maritimus was a more efficient vector under our experimental conditions. To the best of our knowledge, this study represents the first documented evidence of interspecific transmission of GLRaV-3 between two disparate Vitis species. It also highlights the potential role of V. x labruscana L. in the epidemiology of grapevine leafroll disease asasymptomlesssourceofGLRaV-3inoculum.