Here, we provide the first insights into the transmission dynamics of the bacteriumXylella fastidiosaby the meadow spittlebugPhilaenus spumarius, gathered through DC EPG (electrical penetration graph)-assisted transmission tests and comparative observations of the probing and feeding behavior of infective versus non-infective vectors on healthy olive plants. Bacterial cells binding toP. spumarius’ foregut occurred at a very low rate and in a time as short as 15min spent by the insect in xylem ingestion or activities interspersed with xylem ingestion (interruption during xylem ingestion and resting).P. spumariusinoculation of bacterial cells into the xylem was exclusively associated with an early (ca. 2 to 7min after the onset of the first probe) and occasional behavior, provisionally termed waveform Xe, presumably related to egestion regulated by pre-cibarial valve fluttering. Infective spittlebugs compared to non-infective ones exhibited: (i) longer non-probing and shorter xylem ingestion; (ii) longer duration of single non-probing events; (iii) fewer sustained ingestions (ingestion longer than 10min) and interruptions of xylem activity (N); and (iv) longer time required to perform the first probe. These observations suggest difficulties in feeding of infectiveP. spumariusprobably caused by the presence ofX. fastidiosawithin the foregut. Overall, our data indicate that likely short time—few minutes—is required forX. fastidiosatransmission byP. spumarius; thus, vector control strategies should aim at preventing spittlebug access to the host plant. Furthermore, our findings represent an important contribution for further research on the disruption of spittlebug–bacterium interactions.
