Location and Strength of Malvolio Expression in Chinese Honeybee Reveals Its Potential Role in Labor Division

The malvolio (mvl) gene plays an important role in the transition from nursing to foraging in honeybees (Apis mellifera). Apis cerana cerana (A. c. cerana) is a subspecies of the eastern honeybee, well-known for its pollinator role throughout China. Although A. c. cerana shares many characteristics with A. mellifera, it is unclear whether Acmvl plays a similar role to Ammvl in foraging behavior. In this study, Acmvl expression was quantified during the transition from nursing to foraging in A. c. cerana. Acmvl protein production was also characterized in different tissues in bees from three behavioral groups. Finally, in situ hybridization was used to describe Acmvl expression patterns in forager bee brains. Acmvl expression was low early in life but then showed a major peak, which suggests its role in labor division. Examination of tissue type revealed that Acmvl expression was highest in the thoraxes of nurse bees and the heads of forager bees. In bee brains, Acmvl was selectively expressed in the somata of Kenyon cells in the mushroom bodies, optic lobes and antennal lobes. Taken together, these findings suggest that Acmvl plays a role in the nurse–forager transition of A. c. cerana.