Genetic and Biological Basis of High Royal Jelly-Producing Bees Apis mellifera ligustica: From Larval Signal Perception to Glandular Secretion

Royal jelly (RJ), the glandular secretion that determines honeybee caste, is also a high-value apicultural product. China supplies about 90% of the world production volume, almost entirely through high RJ-producing bees (RJBs) selected from Apis mellifera ligustica over four decades, or Chinese-selected a. m. ligustica population; these yield up to ten times more RJ per colony than ITBs. Here, we review and assemble the morphological, proteomic, genomic and behavioural evidence for that unusual selection response at four levels. RJ production may be dominated by a heritable polygenic trait whose acceptance and secretion components carry significant genotypic variance, and the selected candidate genomic architecture combines a large inversion with the tandem mrjp cluster. RJB nurses could detect larval volatiles more sensitively, and cross-fostering suggests that larval acceptance depends on the genotype of the nurse bees, not that of the larvae. RJB hypopharyngeal glands develop larger acini, delayed regression and reinforced protein synthesis, whereas mandibular glands up-regulate the fatty-acid pathway that may yield 10-HDA. An expanded nurse-stage neuropeptidome and a remodelled brain membrane proteome may tune larval recognition, water homeostasis and pollen collection. The proposed three coupled feedback loops and outline the experiments needed to test the model.