Proteome Comparisons between Hemolymph of Two Honeybee Strains (Apis mellifera ligustica) Reveal Divergent Molecular Basis in Driving Hemolymph Function and High Royal Jelly Secretion

Hemolymph is vital for the immunity of honeybees and offers a way to investigate their physiological status. To gain novel insight into the functionality and molecular details of the hemolymph in driving increased Royal Jelly (RJ) production, we characterized and compared hemolymph proteomes across the larval and adult ages of Italian bees (ITbs) and Royal Jelly bees (RJbs), a stock selected from ITbs for increasing RJ output. Unprecedented in-depth proteome was attained with the identification of 3394 hemolymph proteins in both bee lines. The changes in proteome support the general function of hemolymph to drive development and immunity across different ages. However, age-specific proteome settings have adapted to prime the distinct physiology for larvae and adult bees. In larvae, the proteome is thought to drive temporal immunity, rapid organogenesis, and reorganization of larval structures. In adults, the proteome plays key roles in prompting tissue development and immune defense in newly emerged bees, in gland maturity in nurse bees, and in carbohydrate energy production in forager bees. Between larval and adult samples of the same age, RJbs and ITbs have tailored distinct hemolymph proteome programs to drive their physiology. In particular, in day 4 larvae and nurse bees, a large number of highly abundant proteins are enriched in protein synthesis and energy metabolism in RJbs. This implies that they have adapted their proteome to initiate different developmental trajectories and high RJ secretion in response to selection for enhanced RJ production. Our hitherto unexplored in-depth proteome coverage provides novel insight into molecular details that drive hemolymph function and high RJ production by RJbs.