[1] A chamber study was carried out to investigate the stable carbon isotopic composition (d 13 C) of secondary organic aerosol (SOA) formed from ozonolysis of b-pinene. b-Pinene (600 ppb) with a known d 13 C value (À30.1%) and 500 ppb ozone were injected into the chamber in the absence of light and the resulting SOA was collected on preheated quartz fiber filters. Furthermore, d 13 C values of the gas-phase b-pinene and one of its oxidation products, nopinone, were measured using a gas chromatograph coupled to an isotope ratio mass spectrometer (GC-IRMS). b-Pinene was progressively enriched with the heavy carbon isotope due to the kinetic isotope effect (KIE). The KIE of the reaction of b-pinene with ozone was measured to be 1.0026 ( O 3 e 2.6 ± 1.5%). The d 13 C value of total secondary organic aerosol was very similar to that of its precursor (average = À29.6 ± 0.2%) independent of experiment time. Nopinone, one of the major oxidation products of b-pinene, was found in both the gas and aerosol phases. The gas-phase nopinone was heavier than the initial b-pinene by 1.3% but lighter than the corresponding aerosol-phase nopinone. On average, the gas-phase nopinone was lighter by 2.3% than the corresponding aerosol-phase nopinone. The second product found in the SOA was detected as acetone, but it desorbed from the filter at a higher temperature than nopinone, which indicates that it is a pyrolysis product. The acetone showed a much lower d 13 C (À36.6%) compared to the initial b-pinene d 13 C.

The snow flea Ceratophysella sigillata, a winter-active species of springtail, produces unique polychlorinated octahydroisocoumarins to repel predators. The structure of the major compound, sigillin A, was elucidated through isolation, spectroscopic analysis, and X-ray crystallography. Sigillin A showed high repellent activity in a bioassay with predatory ants. A promising approach for the total synthesis of members of this new class of natural compounds was also developed.

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Two phenolic acids were identified in the collembolan Ceratophysella denticulata: 3-hydroxy-4,5 dimethoxy benzoic acid and 4-hydroxy-3,5-dimethoxybenzoic acid (syringic acid). These are localized on or in the integument of the springtail, in field-collected animals, in a ratio of 47:100 (v/v). Springtails kept under different temperature regimes showed differences in production and ratio of the benzoic acid derivatives. At 20 degrees C, C. denticulata produced only syringic acid, whereas at 10 degrees C both isomers in a ratio of 100:61 (v/v) were detected. Bioassays with C. denticulata as well as with the specialized collembolan predator Stenus comma (Staphylinidae) were carried out. Staphylinid beetles topically treated with the acids try to clean their mouthparts by rubbing them on the ground significantly more often than do control beetles. Both compounds individually and as a natural mixture have deterrent effects towards the predator S. comma.

Der winteraktive Springschwanz Ceratophysella sigillata produziert einzigartige polychlorierte Octahydroisocumarine um Fressfeinde abzuschrecken. Die Struktur der Hauptverbindung Sigillin Awurde durchI solierung,s pektroskopische Untersuchungen und Rçntgenstrukturanalyse aufgeklärt. Sigillin Az eigtei ne inem Biotest mit räuberischen Ameisen eine hohe abschreckende Wirkung. Ein vielversprechender Syntheseansatz für diese neue Klasse von Naturstoffen wurde entwickelt.