Effects of Sucrose Feeding on the Quality of Royal Jelly Produced by Honeybee Apis mellifera L

Abstract

Royal jelly (RJ) is a highly nutritious secretion of the honeybees' hypopharyngeal glands (HPGs). During RJ production, colonies are occasionally subjected to manual interventions, such as sucrose feeding for energy supplementation. This study aimed to assess the impact of sucrose feeding on the composition of RJ. The results indicated that RJ obtained from sucrose-fed colonies exhibited significantly higher levels of fructose, alanine, glycine, tyrosine, valine, and isoleucine compared to the honey-fed group. However, no significant differences were observed in terms of moisture content, crude protein, 10-HDA, glucose, sucrose, minerals, or other amino acids within the RJ samples. Moreover, sucrose feeding did not have a significant effect on midgut sucrase activity, HPGs development, or the expression levels of MRJP1 and MRJP3 in nurse bees. Unsealed stored food samples from sucrose-fed bee colonies demonstrated significantly higher sucrose levels compared to sealed combs and natural honey. Additionally, natural honey exhibited higher moisture and Ca levels, as well as lower levels of Zn and Cu, in comparison to honey collected from bee colonies fed sucrose solutions. Based on these findings, we conclude that sucrose feeding has only a minor impact on the major components of RJ.

Keywords: Apis mellifera L.; nutritional compositions; royal jelly; stored food; sucrose feeding.

Figure 1

Effects of honey feeding and sucrose feeding on production of royal jelly (A) and the acceptance rate of queen cells (B). HF, honey feeding group; SF: sucrose feeding group. Values are means ± SD, n = 5. The independent samples t-test was adopted for comparisons between groups. ns, no significance (p > 0.05).

Figure 2

Proximate composition of the analyzed RJ samples obtained from honey feeding and sucrose feeding procedures (g/100 g, fresh weight). (A) The moisture content of RJ samples. (B) The crude protein content of RJ samples. (C) The 10-HDA content of RJ samples. (D) The fructose content of RJ samples. (E) The glucose content of RJ samples. (F) The sucrose content of RJ samples. HF, honey feeding group; SF, sucrose feeding group. Values are means ± SD. * p < 0.01 via independent samples t-tests, and ns, no significance (p > 0.05).

Figure 3

Comparison of proximate composition of stored food obtained from honey-fed and sucrose-fed colonies (g/100 g, fresh weight). (A) Sampling area diagram. (B) The moisture content of stored food samples. (C) The fructose content of stored food samples. (D) The glucose content of stored food samples. (E) The sucrose content of stored food samples. Honey, stored food obtained from honey-fed colonies; SSSF, stored food obtained from sealed combs of sucrose-fed colonies; and SUSF, stored food obtained from unsealed combs of sucrose-fed colonies. Values are means ± SD. Different lowercase letters indicate significant differences among treatments at the 0.05 level, according to Tukey’s HSD test.

Figure 4

The effects of different sugar diets on the activity of sucrose enzymes (A) the development of HPGs (B) and the expression of the MRJP 1 (C) and MRJP 3 (D). (a), Morphology of HPGs (SEM, ×250); (b), comparison of the development levels of HPGs. HF, honey feeding group; and SF, sucrose feeding group. Values are means ± SD. ** p < 0.01 by independent samples t-test, and ns, no significance (p > 0.05).