Abstract: 【Objective】To investigate the field occurrence dynamics of Frankliniella intonsa and its selectivity for different parts of sunflower plants,aiming to provide a theoretical basis for the control of F. intonsa in sunflower fields. 【Methods】Using sunflower variety SH361 as the test material,yellow and blue sticky traps were adopted to monitor the field occurrence dynamics of F. intonsa. With sunflower varieties SH363 and Sanrui No. 3 as test materials,seeds,ray florets,floral leaves,leaves,and disk florets were selected and placed in petri dishes with moist filter paper,followed by the introduction of F. intonsa. The feeding preference of F. intonsa was observed at 6,7,8,and 24 h respectively. In fields with severe F. intonsa infestation,seeds,ray florets,floral leaves,leaves,and disk florets were collected and adult F. intonsa were removed. After the samples were cultured in a climate chamber,the number of hatched nymphs and oviposition preference were observed,and the number of eggs laid was calculated. 【Results】The population trends of F. intonsa on yellow and blue sticky traps in sunflower fields were consistent,with the population showing a fluctuating change from late June to late August. Specifically,from 29 June to 13 July,the population initially increased and then declined,it reached a low point by late July,followed by a rapid increase in early August,peaking again on 17 August. Ray florets were the most preferred site for both feeding and oviposition of F. intonsa,and the oviposition preference for ray florets was significantly higher than that for other parts（P<0.05）,with the number of eggs laid of 5.17 and 2.50 individuals per petri dish on SH363 and Sanrui No. 3,respectively.【Conclusion】The population of F. intonsa increases sharply when sunflowers enter the flowering stage in mid-August,and ray florets are the most preferred site for both feeding and oviposition of F. intonsa.

Key words: Sunflower, Frankliniella intonsa, Occurrence dynamics, Feeding site, Oviposition