Chemistry of the Dufour's gland secretions of North American andrenid bees (Hymenoptera: Andrenidae).

The volatile components of the Dufour's gland secretions were examined in 22 Nearctic species of andrenid bees representing 10 subgenera. Farnesyl hexanoate was the dominant component in the secretion of 17 species. In others, various terpenoid esters such as geranyl octanoate, farnesyl octanoate and geranylgeranyl octanoate were the major components. Approximately 30 compounds have been identified in the secretions; many are newly identified in andrenid bees. Three different groups of secretions are discerned with "exceptions." A discussion of the possible function of the Dufour's gland secretion in the biology of, and its use in, the systematics of these bees is presented.