Field monitoring
The tolerance responses of E. annuus plants attacked by P. rufiventris were monitored in a field in Cheongju. Freshly girdledE. annuus plants and adjacent non-girdled E. annuus plants were labeled on the 15th and 17th, May 2020. The chlorophyll content of the 10th true leaf was measured using a SPAD meter (SPAD-502Plus, Konica Minolta, Japan) during the first two weeks of observation. SPAD values indicated the level of chlorophyll in the leaf samples. The numbers of branches longer than 15 cm and flowers were counted weekly until the monitored plants were senesced. A total of 30 flowers were randomly collected for diameter measurement on 17th July 2020 (nine weeks post-girdling).