Einsatz von V. lecanii als biologisches Schädlingsbekämpfungsmittel gegen den Bohnenrostpilz U. appendiculatus var. appendiculatus im Feld und im Gewächshaus

The use of Verticillium lecanii as a biological control agent against the bean rust fungus Uromyces appendiculatus var. appendiculatus in the field and in the glasshouse The deuteromycete V. lecanii parasites uredo- and teliospores of the bean-rust-fungus U. appendiculatus var. appendiculatus. We investigated the conditions for the use of the hyperparasite as biological control agent in the field and in glasshouses. The growth rate of the hyperparasite was 0,3 cm per day at 25 °C. Under suitable conditions in the lab (25 °C, 100 % r. h.) it took about 20 days to invade 100 % of uredospores and 65 % of teliospores. We failed to prevent the spread of bean-rust-fungus spores in the field, but we succeeded in the glasshouse by 68 %, compared to the untreated controls, using the hyperparasite V. lecanii as biological control agent.     

Stromuli. Plastiden‐Brücken im Netzwerk der Zelle

Plastidic bridges in the plant cell network: Stromules Stromules are mobile protrusions emanating from plastids. They might form bridges between plastids and connect them also with other compartments of the plant cell. They could be involved in coordination of plastid activities and in signalling. Stromules have been first observed in the water fern Selaginella more than 100 years ago. Later improved light microscopy enabled the visualization of stromules in higher plant plastids. 15 years ago, since plants accumulating the green fluorescing proteins (GPF) in the stroma became available they have been newly detected and are now studied intensively. Formation of stromules differs among plant tissues, developmental stages and environmental situations. Actin and myosin are required for the formation of stromules.     

Duftstoffe im Erdreich. Flüchtige Metabolite als Infochemikalien

Volatile metabolites diffuse not only in the atmosphere to possess their actions aboveground, but also belowground living organisms benefit from volatiles in the soil since they can act as communication signals, defence and chemo‐attraction compounds, as well as mediators for cell‐to‐cell recognition. Various eucaryotes (e.g. plant (roots), invertebrates, fungi) and also procaryotes (e.g. rhizobacteria) are verifiable involved in these volatile mediated interactions.     

Siebengebirge – im Saum der Großlandschaften. Die Exkursion

The Siebengebirge Mountains, facing Bonn and situated between the Lower Rhine Bight and the well known Middle Rhine valley, cover an area of only some 4800 ha, but represent a fairly unusual complex with respect to landscape and nature. Already some famous exploring travellors of the 18th century such as Georg Forster, Johann Wolfgang von Goethe, and Alexander von Humboldt consistently emphasized the striking diversity and natural beauty of this area. No other part of Germany has hitherto been dealt with by a comparable array of special (geologically as well as biologically centered) investigations and compiling contributions. An excursion proposal recommends a closer inspection of that fascinating landscape.     

Nord‐ und Südpolarmeer im Klimawandel. Ein biologischer Vergleich

Impacts of climate change on polar seas The polar seas in the Arctic and Antarctic are characterized by extreme cold and the prevalence of sea ice, which provides a unique polar habitat but also strongly affects the pelagic and benthic biota beneath. Life conditions for the marine fauna and flora differ considerably between the Arctic and Southern Oceans, as a result of contrasts in geography, geological history, as well as seasonal dynamics in light regime, sea ice cover and, hence, biological production. Climate change is particularly obvious in the Arctic Ocean and off the Antarctic Peninsula where warming results in a rapid shrinkage of the summer sea ice cover. Such decline threatens the sea‐ice communities and their associated fauna and will also have far reaching effects for the plankton and benthos of the polar seas.