1Dipartimento di Biologia Animale e Genetica, Università di Firenze, Via Romana 17, Firenze, 50125, Italy.
2Centro Interdipartimentale di Spettrometria di Massa, Università di Firenze, Viale G. Pieraccini 6, 50139, Firenze, Italy.
3Department of Chemistry, University of Keele, Staffordshire, ST5 5BG, England.
4Department of Ecology and Genetics, University of Aarhus, 8000 Aarhus C, Denmark.
Chemical communication is widely used by insects, relying on substances produced in numerous exocrine glands, and often released by correspondingly well defined structures of the cuticle. Classical methods of analysing insect exocrine secretions involve extraction by solvents. Extracts are then usually injected into a gas chromatograph/mass spectrometer system for analysis. This method, though, can be time consuming, and results may vary depending on factors such as time of extraction and type of solvent used. Extraction of unwanted contaminants originating from body sources other than the gland may also occur. A further disadvantage is the fact that specimens have to be killed preventing the assessment of temporal dynamics in insect exocrine secretions. We present and discuss several new methods, including solid-phase microextraction (SPME), of extraction of glandular contents in social wasps. Using these techniques we demonstrate that the results are comparable with those obtained with the more classical methods that use solvents, eliminating, in many cases, the shortcomings of these methods in insect pheromone analysis. We have further combined these extraction techniques with improved analysis methods. These include positive chemical ionization (CI) mass spectrometry with acetonotrile that allows for the identification of saturated and unsaturated hydrocarbons, alcohols and aldehydes. As a result of the simplicity of these methods they will prove to be valuable in research on the chemical ecology of social wasps, and on insect communication in general.