Differential Proteomics in Dequeened Honeybee Colonies Reveals Lower Viral Load in Hemolymph of Fertile Worker Bees

Dries Cardoen,Ulrich R Ernst,Matthias Van Vaerenbergh,Bart Boerjan,Tom Wenseleers,Dirk C De Graaf,Peter Verleyen,Liliane Schoofs,Anna Maria Delprato

doi:10.1371/journal.pone.0020043

Abstract

The eusocial societies of honeybees, where the queen is the only fertile female among tens of thousands sterile worker bees, have intrigued scientists for centuries. The proximate factors, which cause the inhibition of worker bee ovaries, remain largely unknown; as are the factors which cause the activation of worker ovaries upon the loss of queen and brood in the colony. In an attempt to reveal key players in the regulatory network, we made a proteomic comparison of hemolymph profiles of workers with completely activated ovaries vs. rudimentary ovaries. An unexpected finding of this study is the correlation between age matched worker sterility and the enrichment of Picorna-like virus proteins. Fertile workers, on the other hand, show the upregulation of potential components of the immune system. It remains to be investigated whether viral infections contribute to worker sterility directly or are the result of a weaker immune system of sterile workers.

Highlights

Honeybees have fascinated scientists for hundreds of years because of the highly evolved eusocial organization of their colonies in which labor is divided on several levels
The queen monopolizes egg laying, while thousands of female workers perform all other tasks in the colony. This extreme form of worker altruism involves the sterility of the vast majority (99.9%) of the worker bee caste, with only very few exceptions [1]
The proximate mechanisms, which cause the inhibition of worker bee ovaries, remain partially unknown; as are the factors which cause the activation of worker ovaries upon the loss of queen and brood in the colony

Summary

Introduction

Honeybees have fascinated scientists for hundreds of years because of the highly evolved eusocial organization of their colonies in which labor is divided on several levels. [6] we compared the hemolymph proteome profiles of age matched fertile and sterile workers collected from the same hopelessly queenless colony by means of 2D-DIGE. Only 18 out of 847 detected and matched spots were found to be differentially expressed, 9 of which were relatively upregulated in the hemolymph of sterile worker bees and 9 were more abundant in the fertile worker bees (Table 1).

Results

Conclusion