The capping pheromones and putative biosynthetic pathways in worker and drone larvae of honey bees Apis mellifera

In honey bees (Apis mellifera), methyl palmitate (MP), methyl oleate (MO), methyl linoleate (ML), and methyl linolenate (MLN) are important pheromone components of the capping pheromones triggering the capping behavior of worker bees. In this study, we compared the amounts of these four pheromone components in the larvae of workers and drones, prior to be capped, in the process of being capped and had been capped. The amounts of MP, MO, and MLN peaked at the capping larval stage, and ML was highest at capped larvae in worker larvae, whereas in drone larvae, the amounts of the four pheromone components were higher overall and increased with aging. Furthermore, we proposed de novo biosynthetic pathways for MP, MO, ML, and ML, from acetyl-CoA. Besides, stable isotope tracer C-13 and deuterium were used to confirm that these capping pheromone components were de novo synthesized by larvae themselves rather than from their diets.