Abstract: 【Aim】 Thisstudyaimstoscreenhighlyexpressed genes in the mandibular glands of Apis mellifera foragers, so as to provide the basis for further screening and study of genes related with the foraging behavior of honey bees. 【Methods】 Differentially expressed 
genes (DEGs) in the mandibular glands of foragers were screened based on previously sequenced transcriptome data of mandibular glands of five kinds of workers of A. mellifera with different tasks (3-day-old worker bees, 10-day-old nurse bees, 10-day-old forager bees, 21-day-old nurse bees and 21-day-old forager bees), and GO and KEGG analyses of these DEGs were performed. qRTPCR was used to detect the expression levels of eight randomly selected DEGs in the mandibular glands of 10dayold nurse bees and 
10dayold forager bees, and two key DEGs including Δ-1-pyrroline-5-carboxylate synthase gene Amp5cs and cytochrome P450 9e2 gene CYP9Q3 in different developmental stages of workers and tissues of foragers. 【Results】 The expression levels of 22 DEGs in the mandibular glands of 21-day-old foragers were significantly higher than those of 3-day-old workers, 10-day-old nurses and 21-day-old nurses. Meanwhile, the expression levels of the above 22 DEGs in the mandibular glands of 10-day-old foragers of A. mellifera were also significantly higher than those of 10-day-old nurses. GO and KEGG enrichment showed that these DEGs were mainly enriched in cholesterol metabolism, galactose metabolism, starch and sucrose metabolism, arginine and proline metabolism, apoptosis-fly, and biosynthesis of amino acids. qRT-PCR results showed that the expression patterns of eight 
DEGs (LOC100576395, LOC411983, LOC410235, LOC725581, LOC410527, LOC406131, LOC408453 and 
LOC410253) were consistent with those of the transcriptome data. Two key DEGs Amp5cs and CYP9Q3 were expressed in various developmental stages of workers, with the highest expression level in foragers. The expression levels of Amp5cs in abdomen, thorax, 
mandibular glands and antennae of foragers were higher, and those of CYP9Q3 were significantly higher in antennae and legs than those in other tissues of foragers. 【Conclusion】 In this study, 22 highly expressed DEGs in the mandibular glands of A. mellifera foragers were screened under the condition of decreasing the interference of day-age. And these DEGs may be mainly involved in the physiological development of mandibular glands of forager bees, as well as metabolic pathways including energy supply, detoxification of exogenous substances, and nectar transformation, affecting the foraging behavior of honey bees. These results not only provide a theoretical reference for the functional study of mandibular glands of A. mellifera, but also lay a foundation for the cultivation of new lines with strong foraging ability.

Key words: Apis mellifera, mandibular glands, foraging behavior; Δ-1-pyrroline-5-carboxylate synthase, cytochrome P450 9e2