Natural Polyesters: Dufour's Gland Macrocyclic Lactones Form Brood Cell Laminesters in Colletes Bees
Bees in the genus Colletes make their brood cells in the ground and coat them with a highly resistant, waterproof, transparent membrane. This membrane is a polyester constructed mainly from 18-hydroxyoctadecanoic acid and 20-hydroxy-eicosanoic acid, which are stored as their corresponding lactones in the Dufour's gland of the bee. When lining the cells, the bee secretes its glandular content, and the membrane is apparently a product of polycondensation reaction of its contents. This appears to be the first report of a naturally occurring linear polyester. The term laminester (lamina ≃ layer + ester) for this class of compounds is proposed.