Quantitative Neuropeptidome Analysis Reveals Neuropeptides Are Correlated with Social Behavior Regulation of the Honeybee Workers

Neuropeptides
play vital roles in orchestrating neural communication
and physiological modulation in organisms, acting as neurotransmitters,
neuromodulators, and neurohormones. The highly evolved social structure
of honeybees is a good system for understanding how neuropeptides
regulate social behaviors; however, much knowledge on neuropeptidomic
variation in the age-related division of labor remains unknown. An
in-depth comparison of the brain neuropeptidomic dynamics over four
time points of age-related polyethism was performed on two strains
of honeybees, the Italian bee (Apis mellifera ligustica, ITb) and the high royal jelly producing bee (RJb, selected for
increasing royal jelly production for almost four decades from the
ITb in China). Among the 158 identified nonredundant neuropeptides,
77 were previously unreported, significantly expanding the coverage
of the honeybee neuropeptidome. The fact that 14 identical neuropeptide
precursors changed their expression levels during the division of
labor in both the ITb and RJb indicates they are highly related to
task transition of honeybee workers. These observations further suggest
the two lines of bees employ a similar neuropeptidome modification
to tune their respective physiology of age polyethism via regulating
excretory system, circadian clock system, and so forth. Noticeably,
the enhanced level of neuropeptides implicated in regulating water
homeostasis, brood pheromone recognition, foraging capacity, and pollen
collection in RJb signify the fact that neuropeptides are also involved
in the regulation of RJ secretion. These findings gain novel understanding
of honeybee neuropeptidome correlated with social behavior regulation,
which is potentially important in neurobiology for honeybees and other
insects.