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In September 2005, one male specimen of the wolf spider genus Alopecosa was discovered and photographed in heathland near Haltern, North Rhine-Westphalia, Germany. It was identified as A. barbipes (Sundevall, 1833), as it showed the species- and sex-specific tibial hair-brush absent in the sibling species A. accentuata. Three years later, two other specimens of A. barbipes were collected in the same area. These findings indicate that the species is more widespread than originally thought. Some details concerning the distribution of A. accentuata and A. barbipes and the problem of synonymy are discussed.
Wir untersuchten eine Kolonie der Brückenspinne Larinioides sclopetarius (Clerck, 1757) an einem Strassendamm im Innenhafen von Duisburg. Die Studie fand zwischen März und Oktober 2004 statt. Die mittlere Populationsdichte über alle Größenklassen betrug 26,2 Ind./qm, das absolute Maximum wurde im Juli festgestellt (71,3 Ind./qm). Die kleinsten Juvenilstadien fanden wir hauptsächlich von Juni bis Oktober, mit einer maximalen mittleren Dichte von 30,9 Ind./qm im Juli, so dass man auf den Sommer als Schlupftermin schließen kann. Große Männchen und Weibchen gab es bereits vereinzelt im Frühjahr, allerdings wurden die höchsten Abundanzen (mit mehr als 3 Ind./qm je Geschlecht) im Sommer und Herbst erreicht. Das durchschnittliche Geschlechtsverhältnis der adulten Spinnen lag über die gesamte Untersuchungszeit gesehen bei 1:1,2 (männl.:weibl.). Es werden einige Vergleiche mit anderen Araneiden, darunter solitäre und soziale Arten, gezogen.
Larinioides sclopetarius is one of very few Central European spiders known to be found in colonies in which the orb-webs are attached to each other. Individuals of different generations cooperate at least in web-building, i.e. they share the same framework or irregular “web carpet”. This behaviour is called parasocial and up to now it has been studied mainly in subtropical and tropical species. Parasocial (colonial) life can lead to total degeneration of the orb-webs and is the result of increased tolerance, which depends on local superabundance of prey. Initial surveys in Essen (Germany) showed that groups of 60 to 200 individuals do not seem to be exceptional. More detailed studies on the group-living of L. sclopetarius are needed.
We found the ichneumonid Polysphincta rufipes Gravenhorst, 1829 (tribus Polysphinctini) to be a koinobiont parasitoid of two species of araneid orb-weavers, Larinioides sclopetarius and Zygiella x-notata, in Central Europe. Some notes on the biology of P. rufipes are given, based on observations both in the field and in the laboratory. The wasps directly attack non-adult spiders sitting in the hubs of their webs. Parasitized spiders could be found from, at least, August to early December. The duration of the development of the wasp larvae, including the pupal stage, is about two months. It seems conceivable that at the end of the larval stage the larva somehow manipulates its host spider; i.e. the spider is forced to enter its retreat – a safe place where the larva can kill the host, complete its development and spin a cocoon for pupation (pupa libera).
A wide variety of enzymatic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Minimum Information about a Biosynthetic Gene cluster (MIBiG) data standard.
