Volatile compounds released by disturbed and undisturbed adults of Anchomenus dorsalis (Coleoptera, Carabidae, Platynini) and structure of the pygidial gland.

Volatile compounds produced by adults of Anchomenus dorsalis under undisturbed and disturbed conditionswere investigated with an all-glass aeration apparatus. GC-MS analysis of the crude extracts fromundisturbed and disturbed adults highlighted four major volatile compounds, undecane, heneicosane,Z-9 tricosene and tricosane, of which signifi cantly more undecane was released by disturbed adults comparedto undisturbed beetles. Th e pygidial glands of adults of A. dorsalis were investigated using light andTransmission Electron Microscopy (TEM). Each gland showed dense aggregates of secretory cells organizedinto visually distinct lobes; a long collecting canal that drains the secretion towards the reservoir, abean-shaped double lobed muscular reservoir in which secretion is stored and a short duct (eff erent duct)through which the secretion is discharged. Th e function of the pygidial glands and the possible role playedby undecane as a defensive allomone and/or chemical signalling molecule are discussed.