Expression of Elongase- and Desaturase-Encoding Genes Shapes the Cuticular Hydrocarbon Profiles of Honey Bees.

Most terrestrial insects have a layer of cuticular hydrocarbons (CHCs) protecting them from desiccation and mediating chemical communication. The composition of these hydrocarbons is highly plastic and changes during their lifetime and with environmental conditions. How these changes in CHC composition are achieved is largely unknown. CHC profiles of Apis mellifera honey bees vary among castes, task groups and subspecies adapted to different climates. This makes A. mellifera an excellent model for studying the molecular mechanism underlying CHC biosynthesis. We correlated the expression of specific elongase- and desaturase-encoding genes with the CHC composition in bees performing different social tasks in two highly divergent A. mellifera subspecies. Elongases are enzymes that lengthen the hydrocarbon chain, while desaturases introduce double bonds in it. We evaluated the hypothesis that the expression of the genes encoding these enzymes determines CHC profiles of the worker bees. Our results revealed that the specificity of desaturases and elongases shapes the CHC profiles of worker bees performing different social tasks. Expression of the desaturase-encoding gene LOC100576797 and the elongase-encoding gene LOC550828 seemed to be strongly associated with the abundance of compounds that were characteristic of the CHC profile of nurse bees. In contrast, the compounds that characterised the CHC profiles of the forager bees seemed to be associated with the desaturase-encoding gene LOC551527 and the elongase-encoding gene LOC409638. Our data shed light on the genetic basis for task-specific CHC composition differences in social hymenopterans and paved the ground for unravelling the genetic underpinning of CHC biosynthesis.