How the queen bee makes her pheromone.

Much of a queen honeybee's power over other hive members comes from a mix of chemicals called a primer pheromone. Scientists have identified the compounds in the pheromone, and beekeepers use a synthetic version in their hives. Now, researchers have figur ed out how the queen manufactures this potent scent, report Erika Plettner of Simon Fraser University in Burnaby, British Columbia, and her colleagues in the March 29 Science.

Primer pheromone in the air prevents workers from rearing a new sovereign and encourages them to care for the queen's brood. This perfume has more complex and longer lasting effects than other pheromones, such as compounds that simply attract potential ma tes (SN: 3/9/96, p. 159). Primer pheromones have been found in only one other animal, a goldfish.

Describing the natural synthesis of the bee's pheromone is "a significant development because of the pivotal role this substance plays in the regulation of social life," observes Gene E. Robinson of the Hebrew University in Jerusalem in a comment accompan ying the report.

The three steps involved in making the royal pheromone resemble closely the processes by which workers produce a substance they feed to larvae, reports Plettner's group.

Both processes begin with the stearic acid that worker and queen honeybees (Apis mellifera) produce in their mandibular glands. Enzymes cause the acid to add a hydroxyl group-an oxygen atom and a hydrogen atom-to its chain of 18 carbon atoms. This hydroxy l group attaches at or near the end of the carbon chain.

Other enzymes then clip most hydroxylated chains down to 10 carbon atoms. In queens, enzymes cut some chains to only eight carbon atoms. In worker bees, the enzymes target carbon chains that have a hydroxyl group at the end. In the queen, enzymes clip tho se with the hydroxyl near the end. Both groups then add an oxygen to their shortened hydroxylated chains. The workers end up with a compound to feed to the larvae, and the queen has her pheromone.

The team tracked the conversion of the acids by adding heavier than normal hydrogen atoms to stearic acid and putting this labeled substance into the bees' mandibular glands. Plettner and her colleagues then used a mass spectrometer to map the activities of the molecules.

"This is the first time that anyone has worked out the biosynthesis of a primer pheromone," Plettner asserts. The difference between the queen's pheromone and the product of the workers' mandibular acids is remarkably subtle, she says. The systems overlap in intriguing ways, agrees Robinson.