Abstract: 【Aim】 The purpose of this study is to reveal the diversity and population composition of the agromyzid leafminers attacking crops and their parasitoids in Baiyin, Gansu province, northwestern China. 【Methods】 The vegetables, flowers, and weeds damaged by the agromyzid leafminers were surveyed and sampled in fields by five-point sampling method, and the agromyzid leafminers and their parasitoids were identified by morphological and molecular methods. 【Results】 In total six species of agromyzid leafminers were found in the collected samples in Baiyin, Gansu province during 2016-2020, including native species Chromatomyia horticola and Liriomyza chinensis, and invasive species L. huidobrensis, L. trifolii, L. bryoniae, and L. sativae. Among them, C. horticola was the dominant species which damaged multi-family host plants. L. chinensis was only found on Allium fistulosum. L. huidobrensis occurred seriously on vegetables in the greenhouse. Furthermore, it was the first time to find L. trifolii in Baiyin. Besides, L. bryoniae and L. sativae had less damage than other agromyzid leafminers. In addition, the surveyed parasitoids included 24 species, 12 genera and 3 families, and the dominant species were Diglyphus isaea, Neochrysocharis formosa, D. wani, and Dacnusa sibirica. 【Conclusion】 On the one hand, monitoring and early warning of the occurrence of the invasive agromyzid leafminers should be strengthened in Baiyin. On the other hand, the parasitoids of the agromyzid leafminers are abundant in Baiyin and may play an important role in natural control of the main damage by the agromyzid leafminers in the field, so it is recommended to protect and apply of local parasitoids.

Key words:  Agromyzid leafminers, parasitoids, host plants, invasive species, native species