Isolation and identification of new components of the honey bee (Apis mellifera L.) queen retinue pheromone

Pheromones are chemicals used for communication between members of the same species. These semiochemicals can elicit either releaser or primer effects, changing the behavior or the physiology of the receiving organism respectively. The honey bee queen produces pheromones that function in both releaser and primer roles such as attracting a retinue of workers around her, attracting drones on mating flights, preventing workers from reproducing at the individual (worker egg laying) and colony (swarming) level, and regulating several other aspects of colony functioning. The queen mandibular pheromone (QMP), consisting of five synergistic components, is the only pheromone chemically identified in the honey bee (Apis mellifera) queen. However, this pheromone does not fully duplicate the pheromonal activity of a full queen extract. To identify the remaining unknown compounds for retinue attraction, honey bee colonies (Apis mellifera L.) were selectively bred to have low response to synthetic QMP and high response to a queen extract in a laboratory retinue bioassay. Workers from these colonies then were used in the bioassay to guide the isolation and identification of the remaining active components in the queen extract. Four new compounds have been identified that accounted for the majority of the difference in attraction between synthetic QMP and queen extract: methyl (Z)-octadec-9-enoate (methyl oleate), ( E)-3-(4-hydroxy-3-methoxyphenyl)-prop-2-en-1-ol (coniferyl alcohol), hexadecan-1-ol, and (Z9,Z12,Z15)-octadeca-9,12,15-trienoic acid (linolenic acid). Interestingly, these compounds were inactive alone or in combination, and only showed activity in the presence of QMP. There was still activity remaining in the queen extract that could not be attributed to any compound so far identified. The queen therefore produces a synergistic pheromone blend of at least ten compounds for retinue attraction, the most complex pheromone blend known for a single behavior in any insect.