Tissue Specificity in Social Context-Dependent Expression in Bumblebees.

Group living at high densities may result in the enhanced transmission of pathogens. Social insects are obligate group-living species, which often also exhibit high relatedness and frequent social interactions amongst individuals, resulting in a high risk of disease spread. Social species seem to exhibit immune systems that provide colonies of social insects with a certain level of flexibility for adjustment of immune activity according to the risk of disease spread. In bumblebees, , it was demonstrated that in group-kept individuals, immune component activity and immune gene expression is increased, potentially as a prophylactic adaptation. Here, I tested whether social environment influences the gene expression pattern of two genes, which are components of the antimicrobial response of the bumblebee. In addition, I tested gene expression activation in different tissues (gut, fat body). The analysis revealed that the gene, the density of individuals, the tissue, and the interaction of the latter are the main factors that influence the expression of genes. This is the first report of a tissue-specific response towards the social environment. This has implications for gene regulation, which must be responsive to social context-dependent information.