Queen pheromone was one of the first of honey bee substances of this nature to be identified. A pheromone is a chemical given off by one individual that controls the behavior of another of the same species. Much of the work on royal (queen) pheromone, sometimes called “queen substance,” was done by French researchers. Now another, Dr. Yves Le Conte (letter from France dated July 9, 1997), at the INRA station in Montfavet, has identified what he calls “brood pheromone.” Like royal pheromone, this is a “primer” chemical. That means it indirectly results in changes by influencing hormonal production of the endocrine system. It is the same process resulting in the irrevocable decision at the third day of larval life that determines whether it becomes a queen or worker.
Brood pheromone keeps workers from developing their ovaries (CR Acad. Sci. Paris, Sciences de la vie/Life Sciences, 317, pp. 511-5, 1994), something originally thought to be totally under control of royal pheromone. It also helps workers recognize queen cells (Chemoecology 5/6,1:6-12, 1994-5) and stimulates development of the worker hypopharyngeal glands that produce royal and worker jelly to feed larvae (CR Acad. Sci. Paris, Sciences de la vie/Life Sciences: 319, pp. 769-72, 1996).
Brood pheromone is a mixture of 10 simple fatty aliphatic esters. These are emitted by the brood in large amounts as the cells are capped, and in different concentrations varying with the age of the larva. Evidence has been found for specific actions for three of these chemicals. Methyl stearate produced best acceptance of queen cups, methyl lineolate caused more royal jelly to be deposited in queen cups, and methy palmitate produced heavier larvae (J Econ. Entomol. 88(4): pp. 798-804, 1995). The practical results of this include the possibilities of increasing the amount of royal jelly a colony provides during queen rearing. Placement of the queen rearing bar also affected the amount of jelly deposited; that closer to the comb bottom produced larger, heavier larvae.
At the present time, methyl palmitate is perhaps the ester of most significance in brood pheromone with reference to Varroa. It appears to be used by mites to find host larvae. Other work by Dr. Le Conte and his students include looking at mite pheromones within the Varroa population that might help control its population (see letter from France, March 23, 1997). More current information on brood pheromone exists on the World Wide Web.