Abstract: 【Aim】 This study aims to explore the effects of altitude and seasonal changes on the composition and diversity of pollen-source plants of Apis cerana cerana. 【Methods】 Pollen-source plant DNA was extracted for PCR amplification targeting the ITS2 region by collecting the bee bread of A. c. cerana at various altitude gradients (500, 700, 900, 1 100 and 1 300 m) across different months (March, May, July, September and November) in Simian Mountain, Chongqing, southwestern China. Sequencing was performed using Illumina PE250 second-generation high-throughput sequencing technology. Bioinformatics methods were employed to analyze the composition, abundance and diversity of pollen-source plants of A. c. cerana. 【Results】 A total of 162 species belonging to 128 genera of 61 families across 30 orders were identified among the pollen-source plants of A. c. cerana in Simian Mountain, Chongqing, including 101 species of woody plants (accounting for 62.35%), 51 species of herbaceous plants (accounting for 31.48%) and 10 species of lianas (accounting for 6.17%). Among these pollen-source plants, the order Rosales exhibited the highest number of plant species (21), followed by Fagales and Astererales, which comprised 19 and 15 species, respectively. Analysis of the composition of pollen-source plants of A. c. cerana based on the operational taxonomic units (OTUs) indicated that there were 17 species of pollen-source plants accounting for over 1%, with the top five being Castanea seguinii (accounting for 18.9%), Eurya nitida (accounting for 11.3%), Rhus chinensis(accounting for 8.5%), Brassica oleracea (accounting for 6.3%) and Aralia chinensis (accounting for 5.3%). The results of alpha-diversity analysis showed that the diversity of pollen-source plants of A. c. cerana in Simian Mountain, Chongqing increased first and then decreased with the increase of altitude, and was the lowest in May and had no significant difference between the other months. 【Conclusion】 The pollen-source plant resources of A. c. cerana in the Simian Mountain region of Chongqing are abundant. The diversity of these pollen-source plants does not significantly vary by month, however, it exhibits a trend of initially increasing and then decreasing with altitudes. This study elucidates the characteristics of spatiotemporal variations in plant composition and diversity of pollen-source plants of A. c. cerana in Simian Mountain of Chongqing. The findings offer a novel perspective for further research and conservation efforts concerning A. c. cerana populations in this area, and provide valuable insights for local beekeepers in selecting appropriate apiary locations, ensuring a steady supply of pollen resources, enhancing honeybee survival rates, and ultimately increasing the yield of bee products.

Key words: Apis cerana cerana, pollen-source plants, pollen, spatiotemporal variation, highthroughput sequencing, Simian Mountain