Abstract: Bumblebees are effective pollinators for many natural plants and crops and have great value in economy and ecology. Bumblebees’ complex growth process and high eusociety make them become outstanding model organisms in sociobiology research. The reproductive division of labor based on caste differentiation in social insects is of great significance in evolution. Many important findings about honeybee caste differentiation have been obtained, and the mechanisms underpinning this process are well elucidated. Compared with honeybees, the system of bumblebees’ eusociety has not been thoroughly studied. Recently, it is evident that the feeding frequency or the feeding amount may induce bumblebee caste differentiation. Juvenile hormone and ecdysteroid are associated with the development of bumblebee larvae and play an important role in caste differentiation. Some genes involved in the regulation of honeybee caste differentiation were also found to be differentially expressed between bumblebee castes. In addition, the caste interaction and competition are found to be key factors causing bumblebee caste differentiation. In this article, we reviewed the mechanisms of bumblebee caste differentiation from nutrition, hormonal regulation, community development and interaction, and also proposed several directions for future studies in these areas.

Key words: Bumblebee, caste differentiation, nutrition, community interaction, juvenile hormone (JH), ecdysteroid (Ecd)