Report for period ending 6/30/18 During this reporting period we used EPG to study the behavioral changes in D. citri associated with different plant parts and the resulting effects of how long it takes to reach phloem, how long the psyllids stays in phloem to ingest, thereby influencing the risk of disease spread. D. citri feeding was recorded on the abaxial and adaxial surfaces of mature and immature citrus leaves. On abaxial surface of immature leaves, phloem salivation occurred after 11 h on average, but in a few rare instances, as short as 0.56 h. The corresponding values on mature leaves were 16 and 2.7h. In general, psyllids spent more time ingesting phloem sap on immature leaves than on mature leaves. Psyllids on abaxial surfaces spent more time ingesting from phloem, though the strength of this effect was less than for immature versus mature leaves. In contrast, xylem ingestion increased on mature leaves compared with young. Because imidacloprid and other soil applied neonics are known to move in the phloem (not xylem), our findings suggest that age of leaves on which psyllids are feeding may affect efficacy of insecticides. For example, psyllids feeding on young flush may be less affected by imidacloprid application because they will be feeding primary on phloem which is known to not contain imidacloprid. However, our observations of psyllids feeding on new flush has shown psyllids do suffer high rates of mortality when feeding on young flush, most liekly phloem and not xylem. To investigate this further, we extraced both phloem and xylem fluids from young trees treated with soil applied imiadcloprid in the greenhouse. We then analyzed the phloem and xylem sap collected for imidacloprid quantity. To our surprise, the levels of imidacloprid were significantly higher in the phloem compared to xylem. While we expected some low levels of imidcloprid to move into the phloem, the fact that imidacloprid levels were greater than in the xylem challenges the entrenched dogma that imidcloprid only moves in the xylem. We are at the end of our funding for this project, b ut this is something we will continue to better understand.