Abstract: 【Aim】 This study aims to screen genes highly expressed in the hypopharyngeal glands (HGs) of Apis mellefera foragers, and to provide a basis for further studying the genes related to honey bee foraging behavior.【Methods】 Differentially expressed genes (DEGs) in the HGs were screened based on the previously sequenced HGs transcriptome data of the 3-day-old workers (3 d_W), 10-day-old nurses (10 d_N), 10-day-old foragers (10 d_F), 21-day-old nurses (21 d_N), 21day-old foragers (21 d_F) and the DEGs highly expressed in the HGs of the 10-day-old foragers and 21-day-old foragers of A. mellefera were subjected to GO and KEGG enrichment analysis. Meanwhile, the expression levels of four highly expressed DEGs (LOC409889, LOC406114, LOC408453 and LOC100578735) in the HGs of foragers in different developmental stages (egg, larva, pupa, newly emerged workers, 10-day-old nurses and 21-day-old foragers) and tissues (abdomen, thorax, antenna, mandibular gland, hypoharyngeal gland, sting, leg, gut, wing and brain) of the 21-day-old foragers of A. mellefera were examined using qPCR.【Results】Comparative transcriptome result showed that the expression levels of 164 up-regulated DEGs in the HGs of the 21-day-old foragers were obviously increased as compared with those of the 3-day-old workers, 10-day-old nurses and 21-day-old nurses, and those of the 10-day-old foragers were also higher than those of the 10-day-old nurses. While the expression trend of the 105 down-regulated DEGs was opposite with that of the above 164 DEGs. GO analysis result showed that the 164 highly expressed DEGs in the HGs of the 10-/21-day-old foragers were enriched significantly in sulfate transmembrane transporter activity, sulfur compound transmembrane transporter activity, iron ion binding and oxidoreductase activity, and the 105 down-regulated DEGs were enriched significantly in ribosome, intracellular ribonucleoprotein complex and ribonucleoprotein complex. KEGG pathway analysis result revealed that the 105 down-regulated DEGs were significantly enriched in two pathways ribosome, and starch and sucrose metabolism. qPCR detection result indicated that the expression levels of LOC409889, LOC406114, LOC408453 and LOC100578735 were the highest in the 21-day-old foragers, and those of LOC406114 and LOC100578735 were the highest in the HGs of the 21-day-old foragers and showed low expression level or no expression in other tissues.【Conclusion】 The highly expressed DEGs identified in the HGs of A. mellifera forager were screened in this study via comparative transcriptome, which provides a valuable source of data for the function study of forager HGs, and also provides a new perspective for further studying the foraging behavior of A. mellefera and the molecular breeding selection of bee species with strong foraging ability.

Key words: Apis mellifera, hypopharyngeal glands, differentially expressed genes, alpha-amylase, pyruvate dehydrogenase E1 component subunit alpha