THE CHEMISTRY OF THE ABDOMINAL GLAND SECRETION OF 6 SPECIES OF THE ROVE BEETLE GENUS BLEDIUS

The chemistry of the abdominal defensive secretions of six species of the rove beetle genus Bledius was examined. In all species the secreti on contains the solid toxin p-toluquinone and its precursor p-toluhydr oquinone dissolved in different solvents. In B. furcatus, B. tricornis and B. dissimilis these solvents are mainly alkenes and lactones, esp ecially 1-undecene and gamma-dodecalactone. In addition to alkenes and lactones the secretion contains decanoic acid and 3-methyl-2-butenoic acid in B. opacus and B. subterraneus. In B. arenarius the quinones a re dissolved in octanoic acid and octyloctanoate, exclusively. In B. a renarius and B. opacus the secretion's content of p-toluquinone is red uced in comparison with the other species. Application experiments wit h the natural predators revealed that in B. arenarius this quinone red uction does not involve a reduction of irritation efficiency. This is probably due to the irriation properties of the B. arenarius solvent o ctanoic acid. The results are discussed with respect to the evolution of the different secretion types within the genus Bledius and within t he subfamily Oxytelinae.