Labial gland chemistry of three species of bumblebees (Hymenoptera: Apidae) from North America.

The volatile secretion emanating from the cephalic part of the paired labial gland in male bumblebees of three North American species, viz. Bombus sonorus Say, Bombus huntii Greene and Psithyrus insularis (F. Smith) has been analysed by GC-MS and GC-FTIR. The secretion, which is deposited as a marking secretion on various objects along a repetitive flight path, is composed of isoprenoids, (acyclic sesqui- and diterpenes) and straight-chain fatty acid derivatives (alcohols containing 14, 16 and 18 carbon atoms, and odd numbered hydrocarbons ranging from 23 to 27 carbons). The secretions are species-specific with just a few major components. In B. sonorus (Z)-11-octadecen-1-ol is the main compound accompanied by geranylgeraniol and tetradecan-1-ol; in B. huntii the dominating compound is trans-2,3-dihydrofarnesol and it also contains (Z)-11-octadecen-1-ol and hexadecan-1-ol; P. insularis is characterized by geranylcitronellol, together with the (Z)-11-octadecen-1-ol and hexadecan-1-ol. These results agree with analyses of 36 species and two forms of Scandinavian bumblebees analysed previously.