Exocrine secretions of bees : IV. Macrocyclic lactones and isopentenyl esters in Dufour's gland secretions ofNomia bees (Hymenoptera: Halictidae).

The volatile components of Dufour's gland extracts were analyzed in four species of NearcticNomia bees;Nomia (Dieunomia)heteropoda, N. (Tetrazonata)tetrazonata, N. (Epinomia)nevadensis, andN. (Epinomia)triangulifera. A homologous series of five saturated macrocyclic lactones ranging from C18 to C26 was identified. A series of esters (branched C5-alkenols and fatty acids) was also identified in all species investigated. Two of these esters are new natural products reported for bees. A discussion of the significance of the Dufour's gland secretion for halictid systematics and its function in the Halictidae is also presented.