The molecular bases of division of labor and reproduction in bumblebees

This project has been funded by BARD (in collaboration with Gene E. Robinson and Mark Band, UIUC)

Research problem. Bees are by far the most important pollinators in agricultural and natural ecosystems. The recent collapse of honey bee populations, together with declines in wild bee (including bumble bee) populations, puts their pollination services under severe threat. A promising strategy for circumventing this risk is the domestication and mass-rearing of non-Apis bees. This approach has been successfully implemented for several bumble bees including Bombus terrestris in Israel, and B. impatiens in the US.  In spite of their critical economic and environmental value, little is known about the physiology and molecular biology of bumble bees.

Objectives. 1) develop state-of-the-art functional genomics tools for B. terrestris. These resources will be then used to: 2) characterize genes and molecular pathways that are associated with reproduction, 3) characterize genes and molecular pathways associated with specialization in foraging or nursing activities, and  4) determine the extent to which juvenile hormone is involved in the regulation of reproduction and division of labor.

Methodology. We will use RNA-seq technology to sequence RNA from worker bees performing different tasks and at different reproductive states; quantitative RT-PCR will be used to identify genes and molecular processes in the brain and ovary that are associated with reproduction and division of labor. A protocol for RNAi mediated knockdown of gene expression will be developed for adult B. terrestris, using vitellogenin as a proof of concept, and will be adapted for testing the function of additional key genes. Finally, we will use allatectomy and replacement therapy to test the influence of juvenile hormone on reproduction, division of labor, and brain gene expression. Our proposed research is timely and will benefit from the publication of the B. terrestris genome that is expected to be available next year.

Recent publications stemming from this project.

  1. Wolschin F, Shpigler H, Amdam GV, Bloch G. (2012) Size-related variation in protein abundance in the brain and abdominal tissue of bumble bee workers. Insect Molecular Biology  21(3), 319–325.
  2. Woodard SH, Bloch G, Band M, Robinson GE (2013) Social regulation of maternal traits in nest-founding bumble bee (Bombus terrestris) queens. Journal of Experimental Biology 216: 3474-3482
  3. Shpigler H, Tamarkin M, Gruber Y, Poleg M, Siegel AJ, and Bloch G (2013) Social influences on body size and developmental time in the bumblebee Bombus terrestris. Behavioral Ecology and Sociobiology  67: 1601-1612.
  4. Amsalem E, Shpigler H, Bloch G, Hefetz A (2013) Dufour's gland secretion, sterility and foraging behavior: Correlated behavior traits in bumblebee workers. Journal of Insect Physiology 59: 1250-1255.
  5. Woodard SH, Bloch G, Band MR, Robinson GE (2014)  Molecular heterochrony and the evolution of sociality in bumblebees (Bombus terrestris). Proceedings of the Royal Society of London B 281: 20132419
  6. Shpigler H, Amsalem E,Huang ZY, Cohen M, Siegel AJ, Hefetz A and Bloch G (2014) Gonadotropic and physiological functions of juvenile hormone in bumblebee (Bombus terrestris) workers. PLoS One  9(6): e100650.
  7. Sadd BM, Barribeau SM, Bloch G, de Graaf DC, Dearden P, Elsik CG, et al.: (2015) The genomes of two key bumblebee species with primitive eusocial organisation. Genome Biology 16:623.
  8. Pandey A, Bloch G (2015) Juvenile hormone and ecdysteroids as major regulators of brain and behavior in bees. Current Opinion in Insect Science 12: 26-37
  9. Shpigler HY, Siegel AJ, Huang ZY and Bloch G (2016) No effect of juvenile hormone on task performance in a bumblebee (Bombus terrestris) supports an evolutionary link between endocrine signaling and social complexity. Hormones and Behavior
  10. Hamilton AR, Shpigler, H, Bloch, G, Wheeler DE, Robinson GE (2017) Endocrine Influences on Insect Societies. In: Pfaff, D.W and Joëls, M.(editors-in-chief), Hormones, Brain, and Behavior 3rd edition, Vol 2. Oxford: Academic Press; pp. 421–451.