Chemical ecology of the defensive secretions of a ground beetle

The ground beetle Chlaenius cordicollis produces a pungent spray when agitated. Headspace solid phase micro-extraction and gas chromatography mass spectrometry were used to sample and analyze the defensive secretion. Samples were collected in Manitoba and Pennsylvania and their patterns of variation compared. By taking samples in both the beetles\u27 natural environment and in controlled laboratory settings, the effects of beetle life cycle stage, sex, food source and geographical origin on spray composition were explored. Temporal variation was found to be the most significant source of variation between the populations. Sexual dimorphism was documented in Manitoba and this difference provides a chemical basis for observed behavioral responses to defensive secretions. Future studies may include larval defensive secretions and Pennsylvanian variation in order to characterize patterns of variation across C. cordicollis\u27 life cycle