Systematic relationship of halictinae bees based on the pattern of macrocyclic lactones in the Dufour gland secretion

Abstract

The volatile Dufour gland secretion from 16 species within the subfamily Halictinae has been studied by gas chromatography and mass spectrometry. Isolation and identification was performed on single individuals. From 1 to 15 individuals of each species were collected and chemically analyzed over a period of 1 to 5 yr. The secretions of each species were found to be built up by characteristic combinations of saturated and mono-unsaturated macrocyclic C 16-, C 18-, C 20-, C 22- and C 24-lactones, together with some straight chain hydrocarbons. Individuals of each species did not vary appreciably in the set-up of their secretions. Of the species studied five represent the genus Halictus and 11 represent the genus Lasioglossum. H. eurygnathus and H. rubicundus, which belong to the subgenus Halictus, have 24-tetracosanolide and 22-docosanolide as the main volatile constituents, whereas L. albipes and L. calceatus, which belong to the subgenus Evylaeus, have 16-hexadecanolide as the dominating volatile component. Based on the pattern of compounds in the secretions of the species, the systematical relationships between these species are discussed.