Testing a ‘mix-and-match’ model of the winter honey bee transcriptome

Under adverse conditions, such as winter in temperate regions, many insect species enter a state of diapause, rapidly transitioning their behavior and physiology to facilitate a temporary reduction or complete arrest of physical activity, development, and reproduction. Honey bees evolved in the tropics but expanded into temperate regions where they were met with the challenge of adapting to winter conditions. In temperate regions, worker bees express a distinct behavioral and physiological state during winter, which has many of the hallmarks of diapause, but this has not been studied at the genome-wide scale. Furthermore, while most studies of diapause have focused on changes associated with reduced metabolism, the honey bee offers a unique opportunity to study the molecular underpinnings of this example of phenotypic plasticity, relegated to specific tissues. The winter bee phenotype has traditionally been considered to appear “nurse-like” in terms of developmental arrest and thus hypothesized to utilize similar gene expression and physiological pathways as nurses. However, the primary task of winter bees involves extensive use of their flight muscles, which is more consistent with a forager phenotype. Thus, we evaluated the transcriptional profile associated with the winter versus summer bee phenotypes in multiple tissues to test the hypothesis that winter bees are a ‘mix-and-match’ of nurse and forager gene expression patterns in a tissue specific fashion.