Food jellies of honey bees – the role of major royal jelly proteins and sterols

• Applicant: Dr. Anja Buttstedt
• Subject Area: Animal Physiology and Biochemistry
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 534955761

Honey bees (Apis spp.) do not feed their larvae directly with the collected pollen and honey, but with a special food jelly that is produced in two head glands of the feeding workers. Although all larvae receive food jelly up to a certain age, almost all our knowledge concentrates so far on queen food jelly (royal jelly) of the Western honey bee Apis mellifera. Studies on food jelly from worker and drone larvae as well as on food jelly from one of the other eight honey bee species are almost completely missing. Royal jelly fulfils in all honey bee species another task besides pure nutrition: Queen larvae are raised in a special queen cell at the lower edge of the comb. The queen larva literally hangs in the cell that is open at the bottom and the larva is glued to the cell ceiling by its royal jelly. Thus, in all honey bee species, royal jelly prevents the queen larva from falling out of the cell and thus ensures the survival of the entire colony. The necessary viscosity of royal jelly in A. mellifera is adjusted by a protein-sterol complex (formed by major royal jelly protein 1 (MRJP1), apisimin and 24-methylenecholesterol (24MC)), which forms fibrillar structures in the acidic environment of royal jelly (pH 4.0) thereby increasing royal jelly viscosity. Among other things, the various honey bee species differ, in the and weight of their queens and the physical properties of royal jelly, which in A. mellifera are determined by the protein-sterol complex, have certainly influenced the evolution of size and weight of the different honey bee species. In the context of this proposal, I will: 1) investigate the properties of royal jelly of four other Apis species (Apis florea, Apis andreniformis, Apis cerana & Apis dorsata) and elucidate the role of MRJP1, apisimin and 24MC in these royal jellies. 2) extend the studies on food jelly of A. mellifera to worker and drone food jelly. For this purpose, food jelly samples from the entire natural range of A. mellifera will be investigated with regard to their protein and lipid content, again with a focus on MRJP1, apisimin and 24MC. 3) determine the importance of A. mellifera MRJP1, apisimin and 24MC for complex and subsequent fibril formation. It will be investigated whether 24MC and MRJP1 can be replaced by any other plant sterol or any other of the major royal jelly proteins found in royal jelly. If complex and fibril formation is indeed only possible in the presence of MRJP1, apisimin and 24MC, all three components would be essential for queen rearing in A. mellifera.

• DFG Programme: Research Grants