Exploring the role of juvenile hormone and vitellogenin in reproduction and social behavior in bumble bees

Etya Amsalem*, Osnat Malka, Christina Grozinger, Abraham Hefetz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Background: The genetic and physiological pathways regulating behavior in solitary species are hypothesized to have been co-opted to regulate social behavior in social species. One classic example is the interaction between vitellogenin (an egg-yolk and storage protein) and juvenile hormone, which are positively correlated in most insect species but have modified interactions in highly eusocial insects. In some of these species (including some termites, ants, and the honey bee), juvenile hormone and vitellogenin levels are negatively correlated and juvenile hormone has shifted its role from a gonadotropin to a regulator of maturation and division of labor in the primarily sterile workers. The function of vitellogenin also seems to have broadened to encompass similar roles. Thus, the functions and molecular interactions of juvenile hormone and vitellogenin are hypothesized to have undergone changes during the evolution of eusociality, but the mechanisms underlying these changes are unknown.Bumble bees offer an excellent model system for testing how the relationship between juvenile hormone and vitellogenin evolved from solitary to social species. Bumble bee colonies are primitively eusocial and comprised of a single reproductive queen and facultatively sterile workers. In Bombus terrestris, juvenile hormone retains its ancestral role as a gonadotropin and is also hypothesized to regulate aggressive behavior. However, the function of vitellogenin and its interactions with juvenile hormone have not yet been characterized. Results: By characterizing vitellogenin RNA expression levels (vg) in B. terrestris we show that vg is not associated with task and only partially associated with worker age, queen presence, and caste (queen vs worker). The correlations of vg with ovarian activation were not consistent across experiments, but both vg and ovarian activation were significantly associated with levels of aggression experienced by workers. Treatment with juvenile hormone did not affect vg levels in queenless groups. Conclusions: We suggest that social interactions affect vg levels more strongly than a worker's reproductive physiological state, and that juvenile hormone and vg are uncoupled in this species. Thus, although juvenile hormone maintains its traditional role as gonadotropin in B. terrestris, vg has already been co-opted into a novel role, consistent with the model that Bombus represents an intermediate stage in the evolution of eusociality.

Original languageAmerican English
Article number45
JournalBMC Evolutionary Biology
Issue number1
StatePublished - 11 Mar 2014
Externally publishedYes

Bibliographical note

Funding Information:
We would like to thank Tracy Baumgarten from the Grozinger lab for assistance with the qRT-PCR experiments and Naomi Paz for editorial assistance. The work was supported by a grant from The Israel Science Foundation founded by the Israel Academy of Sciences (ISF grant no. 535/08) to A.H., and by a Prof. Rahamimoff travel grant for young scientists, which supported the travel of EA from Israel to US.


  • Aggression
  • Bombus terrestris
  • Reproduction
  • Social insects
  • Vitellogenin


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