Identifizierung und Synthese von Semiochemikalien aus Arthropoden

GC-MS analysis of head space extracts from virgin and mated female Argiope bruennichi spiders showed the presence of a compound closely related to the primary metabolite citric acid. Analysis of the mass spectrum and synthesis proved it to be trimethyl methylcitrate which is released only by female virgin spiders that proved to be highly attractive for males in the field. Investigation of cuticular extracts from the spider Argyrodes elevatus by GC-MS revealed the presence of unusual esters not known from spiders before. The mass spectra were analyzed and structural proposals were made. The unknown esters proved to be methyl-branched long-chain compounds with an internal location of the ester functional group. Employing efficient enantioselective methods three isomers out of 32 possible stereoisomers have been synthesized. More enantioselective synthesis has to be performed to assign the stereochemistry for the natural compounds, and as well to study the stereochemistry-activity relationship. GC-MS analysis of the extracts from the beetle Pachnoda interrupta which is a serious pest on Sorghum bicolor in Ethiopia showed 21 female specific compounds that were exclusively found in the abdominal tip. Field testing with these compounds both singly and in a mixture, in search of behaviorally active pheromone components, revealed the attraction of males to one of the female specific compound namely phenylacetaldehyde, that caught significantly more beetles than any other trap. The biosynthesis of the sex pheromone (3Z,6Z,9Z)-1,3,6,9-nonadecatetraene in the geometrid moth Operophtera brumata was proposed to follow the sequence of chain elongation of alpha-linolenic acid, desaturation, and reductive decarboxylation. In order to resolve the biosynthetic pathway of this pheromone released, isotopic labeled polyunsaturated fatty acid and fatty acid methyl esters were synthesized.Eine Analyse von Headspace-Extrakten von unverpaarten und verpaarten weiblichen Spinnen der Art Argiope bruennichi mittels GC/MS zeigte eine unbekannte Verbindung, deren Struktur eng mit der der Citronensäure verwandt ist. Durch Auswertung des Massenspektrums und anschließende Verifizierung durch Totalsynthese wurde gefunden, dass es sich bei dieser Verbindung um Methylcitronensäuretrimethylester handelt, welcher nur von unverpaarten Spinnenweibchen freigesetzt und sich im Feldversuch als sehr attraktiv auf Männchen dieser Art erwies. Bei Untersuchungen von Extrakten der Cuticula von Spinnen der Art Argyrodes elevatus wurden ungewöhnliche Ester gefunden, die bislang nicht aus Spinnen bekannt waren. Durch Analyse der Massenspektren konnten Strukturvorschläge erarbeitet werden. Die unbekannten Ester erwiesen sich als methylverzweigte, langkettige Wachsester. Durch Einsatz effizienter stereoselektiver Methoden wurden bereits drei der 32 möglichen Stereoisomere synthetisiert; es sind allerdings weitere enantioselektive Synthesen nötig, um die absolute Konfiguration der Naturstoffe und den Zusammenhang zwischen Stereochemie und biologischer Aktivität aufzuklären. Eine Analyse von Extrakten sämtlicher Körperteilen des Käfers Pachnoda interrupta (einem Schädling an Sorghum bicolor) mittels GC/MS ergab in der Spitze des Abdomens des Weibchens 21 Verbindungen, die nur dort auftreten. Diese wurden in Feldversuchen sowohl einzeln als auch als Gemisch auf ihre pheromonelle Aktivität untersucht, wobei die Männchen besonders von Phenylacetaldehyd angezogen wurden. Für die Biosynthese des Sexuallockstoffs (3Z,6Z,9Z)-1,3,6,9-Nonadecatetraen der Motte Operophtera brumata wurde ein Mechanismus postuliert, der ausgehend von alpha-Linolensäure über Desaturierung und reduktive Decarboxylierung zum Pheromon führt. Um diese Hypothese zu überprüfen, wurden isotopenmarkierte polyungesättigte Fettsäuren und Fettsäureester synthetisiert, die als Intermediate der Biosynthese postuliert wurden

Biosynthesis and PBAN-regulated transport of pheromone polyenes in the Winter Moth, Operophtera brumata

The trienoic and tetraenoic polyenes, (3Z,6Z,9Z)-3,6,9-nonadecatriene, (3Z,6Z,9Z)-3,6,9-henicosatriene, and (3Z,6Z,9Z)-1,3,6,9-henicosatetraene were found in the abdominal cuticle and pheromone gland of the Winter Moth Operophtera brumata L. (Lepidoptera: Geometridae), in addition to the previously identified single component sex pheromone (3Z,6Z,9Z)-1,3,6,9-nonadecatetraene. The pheromone biosynthesis activating neuropeptide (PBAN) is involved in the regulation of polyene transport from abdominal cuticle to the pheromone gland. In vivo deuterium labeling experiments showed that (11Z,14Z,17Z)-11,14,17-icosatrienoic acid, the malonate elongation product of linolenic acid, (9Z,12Z,15Z)-9,12,15-octadecatrienoic acid, is used to produce (3Z,6Z,9Z)-3,6,9-nonadecatriene and (3Z,6Z,9Z)-1,3,6,9-nonadecatetraene

Pheromone-based mating and aggregation in the Sorghum chafer, Pachnoda interrupta

Adults of the sorghum chafer, Pachnoda interrupta Olivier (Coleoptera: Scarabaeidae: Cetoniinae), form aggregations during the mating period in July, but also in October. The beetles aggregate on food sources, e.g., Acacia spp. trees or sorghum with ripe seeds, to feed and mate. During the mating season, field trapping experiments with live beetles as bait demonstrated attraction of males to unmated females, but not to mated females or males, indicating the presence of a female-emitted sex pheromone. Unmated females combined with banana (food source) attracted significantly more males and females than did unmated females alone. Other combinations of beetles with banana were not more attractive than banana alone. Thus, aggregation behavior appears to be guided by a combination of pheromone and host volatiles. Females and males were extracted with hexane during the mating period, and the extracts were compared by using GC-MS. In a field trapping experiment, 19 compounds found only in females were tested, both singly and in a mixture. Traps baited with one of the female-associated compounds, phenylacetaldehyde, caught significantly more beetles than any other treatment. However, the sex ratio of beetles caught in these traps did not differ from that of control traps and it is possible that other components may be involved in the sex pheromone signal. Furthermore, traps baited with a mixture of all 19 compounds attracted significantly fewer beetles than did phenylacetaldehyde alone

Biosynthesis and PBAN-regulated transport of pheromone polyenes in the winter moth, Operophtera brumata.

The trienoic and tetraenoic polyenes, (3Z,6Z,9Z)-3,6,9-nonadecatriene, (3Z,6Z,9Z)-3,6,9-henicosatriene, and (3Z,6Z,9Z)-1,3,6,9-henicosatetraene were found in the abdominal cuticle and pheromone gland of the winter moth Operophtera brumata L. (Lepidoptera: Geometridae), in addition to the previously identified single component sex pheromone (3Z,6Z,9Z)-1,3,6,9-nonadecatetraene. The pheromone biosynthesis activating neuropeptide (PBAN) is involved in the regulation of polyene transport from abdominal cuticle to the pheromone gland. In vivo deuterium labeling experiments showed that (11Z,14Z,17Z)-11,14,17-icosatrienoic acid, the malonate elongation product of linolenic acid, (9Z,12Z,15Z)-9,12,15-octadecatrienoic acid, is used to produce (3Z,6Z,9Z)-3,6,9-nonadecatriene and (3Z,6Z,9Z)-1,3,6,9-nonadecatetraene