*2.2. Bee Pollen Sample Collection*

Fifteen CBP samples were collected from Anhui, Fujian, Jiangsu, Sichuan, and Zhejiang Provinces in China (*n* = 3 for each), while fifteen non-CBP samples were obtained from five botanical plants (*n* = 3 for each; Table S1), i.e., rose (*Rosa rugosa* Thunb.), apricot (*Prunus armeniaca* L.), lotus (*Nelumbo nucifera* Gaertn.), rape (*Brassica campestris* L.), and wuweizi (*Frucus Schisandra chinensis*). To guarantee their authenticity, these samples were collected by professional beekeepers from their apiaries of *Apis mellifera* L. colonies using pollen traps, and were then identified using a scanning electron microscope (S-4800, Hitachi, Tokyo, Japan). Dead bee parts and other hive debris were removed manually. All samples were freeze-dried and stored at −80 ◦C until analysis.
