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honey bees live in populous colonies consisting of a single fertile female -- the queen -- tens of thousands of sterile female workers and, usually, a few hundred drones. Perhaps the most fascinating aspect of honey bee colonies is the differentiation of the bees into a sterile worker caste and a fertile queen caste (Current Science, Vol 71, No 12).
In a colony, the queen is always surrounded by an ever-changing retinue of about 10 workers at a time who feed and lick her. The queen affects the workers in several ways. Her presence normally prevents the workers from rearing new queens. Also, it inhibits the development of the workers' ovaries; in the event of the death of the queen, however, workers do develop their ovaries and lay a small number of unfertilised haploid eggs. They resort to emergency queen-rearing by enlarging some of the cells containing young larvae and feeding the chosen larvae with 'royal jelly', and thus channelling them into a developmental pathway leading to the formation of queen.
Most of the effects of the queen on workers are mediated through pheromones secreted by the queen. Pheromones are chemicals which serve to elicit behavioural or physiological responses and operate as chemical messengers. Important components of the queen's pheromone blend are 9-keto-2-decenoic acid (9-oda) and 9-hydroxy-2-decenoic acid (9-hda). Workers also produce related pheromones that are added to the brood food and may serve as preservatives and nutrients. They secrete 10-hda. Besides, instead of the queen's 9-oda, workers secrete the diacid (combination of two monovalent acid radicles) derived from their 10-hda. That is, queens and workers differ essentially only in the position of the carbon atom that is hydroxylated (addition of a hydroxyl, oh, group).
The dominant component of the worker blend, diacid, is made from a precursor molecule hydroxylated at the 10th carbon atom rather than at the 9th carbon atom. This 9th precursor which is used by the queen 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.
These results demonstrate how, in social insects, caste-determined biosynthesis of different forms of the same compound (isomeric compound) can markedly produce different pheromones that result in functional differences between queens and workers. The caste-specific biosynthetic pathway for the production of these pheromones also leads to two other speculations. One is that workers can be thought of being closer to the ancestral solitary conditions and the queens can be thought of as a derived invention of sociality. The other is that, compared to non-social insects, social ones are especially pre-disposed to evolve novel structures and characters as shown by the queen. This is done through the process of gene duplication, in which duplicate copies of genes accumulate mutations without killing the organism and eventually give rise to novel genes which then form novel structures.