Progress 02/15/05 to 02/14/07
Outputs
This proposal addressed three key questions: 1) Are larval cues regulating the suite of foraging behavioral traits that have been identified in honey bees? Our results clearly demonstrate that this is the case. Results of the experiments addressing this question are currently in preparation. 2) Are genetic differences in foraging behavior between strains of bees selected for their pollen foraging behavior a consequence of differences in sensitivity to larval cues? The answer to this question is more complex. The high and low pollen hoarding strains do respond differentially to changes in larval cues, as predicted, and this explains some of the differences observed. However, in the process of conducting these studies we discovered another difference between the strains, they have different sized ovaries, which led to additional experiments that revealed a more general causal structure. The larval cue study is in preparation, the ovary study was published in Nature (see
Amdam et al. 2006, below). 3) Does the biogenic amine octopamine modulate the suite of traits associated with foraging? Yes, and this is in preparation. 4) Do bees from the selected pollen foraging strains differ in brain titers of octopamine and other biogenic amines? Our experimental results show that they do not (see Schulz et al. 2004, below). 5) Do bees from the high and low pollen hoarding strains differ in their sensitivities to octopamine? Yes, and this is in preparation.
Impacts
These studies led to the fundamental discovery that division of labor and foraging specialization in worker honey bees is derived from an ancient reproductive regulatory network common to all insects. By understanding this, we can now pursue methods to alter the reproductive anatomy and physiology of bees and manipulate their foraging behavior for pollen and nectar.
Publications
- Schulz, D. J., T. Pankiw, K. Fondrk, G. E. Robinson, R. E. Page. 2004. Comparisons of juvenile hormone hemolymph and octopamine brain titers in honey bees (Apis mellifera) selected for high and low pollen hoarding. Annals of the Entomological Society of America 97: 1313-1319.
- G. J. Hunt, G. V. Amdam, D. Schlipalius, C. Emore, N. Sardesai, C. E. Williams, O. Rueppell, E. Guzman-Novoa, M. Arechavaleta-Velasco, S. Chandra, M. K. Fondrk, M. Beye, R. E. Page. 2007. Behavioral genomics of honeybee foraging and nest defense. Naturwissenschaften 94: 247-267.
- Amdam, G., A. Csondes, M. K. Fondrk, and R. E. Page. 2006. Complex social behaviour derived from maternal reproductive traits. Nature 439: 76-78.
- Page, R. E., R. Scheiner, J. Erber, and G. V. Amdam, 2006. The development and evolution of division of labor and foraging specialization in a social insect. Current Topics in Developmental Biology 74: 251-284.
- Page, R. E. and G. V. Amdam. 2007. The making of a social insect: developmental architectures of social design. Bioessays 29:334-343.
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Progress 02/15/05 to 02/14/06
Outputs
Effects of feeding octopamine on foraging behavior. Selected trains of bees that vary for pollen foraging behavior were tested for their sensitivity to the neuromodulator octopamine. Colonies were fed octopamine ad lib and foraging behavior was compared with unfed controls. High and low strain bees were co-fostered in treatment and control colonies. High strain bees were more sensitive to octopamine feeding as demonstrated by significant changes in foraging behavior. Low strain bees showed no effect. Effect of synthetic brood pheromone on foraging behavior: We tested the effects of synthetic brood pheromone on high and low strain bees. We found no consistent effects. Correlations of ovary size and vitellogenin on response to sucrose. High strain bees have more ovarioles than do bees of the low strain. An increased responsiveness to sugaris part of the pollen hoarding behavioral syndrome. We tested young wild type bees for their responses to sucrose solution and found
that bees with more ovarioles were more responsive, thus more closely linking ovary size with the pollen foraging behavior. We further showed that bees that were more responsive to sugar had higher titres of the egg protein vitellogenin in their blood.
Impacts
Understanding the physiological factors underlying foraging behavior may help us modify the behavior of bees making them more effective pollinators of economically important crops.
Publications
- Amdam, G.V, A. Cosondes, M.K. Fondrk, and R.E. Page. 2006. Complex social behavior derived from maternal reproductive traits. Nature 439: 76-78.
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