The analysis of bud exudate of Populus x euramericana , and of propolis, by gas chromatography–mass spectrometry

Propolis and bud exudate of Populus x euramericana have been analysed by high-resolution gas chromatography–mass spectrometry; 104 compounds have been identified, including 26 not previously identified in propolis or bud exudate. The compounds identified in propolis are derived from three sources: plant exudate collected by bees, wax secreted by bees, and materials such as sugars, which are probably introduced accidentally either during propolis manufacture or during subsequent passage of bees over the propolis. Previous observations that bees use bud exudate from Populus as a primary source for propolis manufacture are confirmed.