A honey bee colony consists of a single queen, tens of thousands of ne
arly sterile female workers and usually a few hundred drones. The pres
ence of the queen inhibits rearing of new queens, stimulates foraging
and interaction of workers with the queen and, (along with the queen's
brood), inhibits the development of worker ovaries. Most or all of th
ese effects of the queen on the workers are mediated through primer ph
eromones secreted by the queen. An important component of the queen's
pheromone blend is 9-keto-(E) 2-decenoic acid (9-ODA). Workers also pr
oduce related substances which appear to function as nutrients and foo
d preservatives. A dominant component of the worker blend is a diacid
which is made from a precursor molecule hydroxylated at the omega carb
on atom rather than at the omega-1 carbon atom. The omega-1 precursor
is used by the queen which leads to the formation of a keto acid. One
might say that the fundamental difference between a queen and worker,
the essence of royalty is therefore, one keto group! The recently-eluc
idated caste-specific biosynthetic pathway for the production of these
pheromones permits two other speculations. One is that workers can be
thought of as being closer to the ancestral solitary condition and th
at queens can be thought of as a derived invention of sociality. The o
ther is that, compared to non-social species, social insects are espec
ially predisposed to evolve novel structures and characters as exempli
fied by the queen for example, through the process of evolution of gen
e duplication.