Host choice experiment
One potted knotweed plant of each species was placed into a rearing cage equidistant from each other in a randomly assigned position in each cage. Each cage was randomly assigned to receive one of four psyllid treatments (Hokkaido, Kyushu, F2 FemKYU, or F2 FemHOK), with six replicate cages set up for each treatment for a total of 24 cages. Using a manual aspirator, 25 females and 25 males about 14 days old of the corresponding psyllid population were collected in a 33 mL polystyrene vial and then released at the center of the cage. The inoculation period for this experiment was 72 hours, after which all adult psyllids were removed from the cage. The knotweed plants were also removed, and the number of eggs on each plant was counted by visually inspecting the surface of the leaves using a 10x magnification hand lens. Once the eggs were counted each plant was covered individually by a mesh cage (1 m tall x 40 cm wide) that was secured to the rim of the pot by an elastic band and labeled with the treatment and replication number. Individually covered plants were placed in the greenhouse (21 °C ± 5, RH 50% ± 10, 16L: 8D) where knotweeds were grown. After 50 days the number of emerged adults from each plant was recorded.