How might beet leafhopper host plant preference mediate phytopathogen transmission risks?

The beet leafhopper, Circulifer tenellus (Hemiptera: Cicadellidae), is a potato pest which causes both direct and indirect damage through feeding and transmission of several phloem-limited plant pathogens, including a Curtovirus, Spiroplasma citri, and a phytoplasma which causes purple top disease. Beet leafhoppers are generalists with a wide host range which overlaps with phytopathogen hosts in the Columbia Basin of the Pacific Northwest. However, they have demonstrated both xylem and phloem ingestion behaviors on plants. We wondered, does the relative time spent in xylem vs. phloem vary across plant-host species? As the likelihood of acquisition or inoculation is related to the time spent ingesting or salivating into phloem, such variation could generate variation in relative host-plant-specific risks in phytopathogen epidemiology. To study this, we used electropenetrography (EPG) to record the feeding/probing behavior of infectious beet leafhoppers on various host-plant species and compared feeding/probing behavior and inoculation success.