III. Buchbesprechungen

Ohne Zusammenfassung     

Haematopinus aperis Ferris,eine für Deutschland neue Läuseart

Ohne Zusammenfassung Mit 4 Abbildungen     

Comparison of autogenous cancellous bone grafts obtained from the sternum and proximal portion of the tibia of llamas.

OBJECTIVE: To describe the anatomy of the sternum in llamas, define the surgical approach to the sternum for collection of cancellous bone graft tissue, and compare the histologic appearance of graft tissue obtained from the sternum with that obtained from the proximal portion of the tibia. DESIGN: Prospective study. ANIMALS: 12 llamas, 3 to 19 years old, that had been submitted for necropsy. PROCEDURE: Radiographs were taken of the sternum and left tibia of the llamas. Measurements of the sternum were determined from the radiographs and adjusted for magnification. Sternebrae volumes were estimated from these measurements. Anatomic dissections to the center of the fourth sternebra and the proximal portion of the tibia were made, and a surgical approach to the sternum was developed. Cancellous graft tissue was obtained from each site and submitted for histologic evaluation. RESULTS: Sternebrae 3, 4, and 5 were significantly larger in volume than the other sternebrae. The ventral aspect of the fourth sternebra was readily accessed for removal of graft tissue by making a 6-cm-long ventral midline incision centered 17 cm craniad to the xipnoid. Mean soft tissue thickness overlying the ventral aspect of the fourth sternebra was 3.1 cm. More tissue was obtained from the sternal (mean, 9.11 g) than from the tibial (mean, 5.16 g) sites. Sternal graft tissue consisted of trabecular bone spicules with predominantly hematopoietic marrow, whereas tibial tissue consisted of trabecular bone spicules with only fatty marrow. CONCLUSIONS AND CLINICAL RELEVANCE: The fourth sternebra in llamas is readily accessible for obtaining autogenous cancellous bone graft tissue that consists of predominantly hematopoietic marrow.     

Beziehungen zwischen Befallsdichte und Schaden im System Gewächshausgurke/Weiße Fliege

Zusammenfassung Befall mit Weißer Fliege führte zu einer deutlichen Abnahme der Blattfläche und zu Ertragsdepressionen, die in ihrem Ausmaß von der Ausgangspopulationsdichte des Schaderregers (2, 10 bzw. 25 Weibchen pro Pflanze) abhing. Jüngere Gurkenpflanzen reagierten in ihrem Blattflächenwachstum und im Fruchtertrag wesentlich stärker auf den Befall als Pflanzen in einem fortgeschrittenerem Entwicklungsstadium. Die durchT. vaporariorum hervorgerufenen Blattflächenreduktionen korrelierten positiv mit den Ertragsverlusten, ebenso bestand zwischen der Populationsdichte des Schaderregers und der Ertragseinbuße eine enge Beziehung. Die Ertragsverluste beruhten auf einer geringeren Anzahl erntefähiger Früchte und verstärktem Abstoßen junger Früchte und Blüten. Der von den Tieren abgegebene Honigtau wurde von Schwärzepilzen besiedelt, die Stärke ihres Auftretens hing von der Befallssstärke und Befallsdauer der Pflanzen mit der Weißen Fliege ab.

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Relation between population density and damage in the system cucumber/whitefly

Infestation of cucumber-plants with greenhouse whitefly,T. vaporariorum, had an adverse effect on leaf area and cucumber yield. The extent of reduction was dependent from initial density of whiteflies (2, 10 and/or 25 females per plant) just as much as from age of the plants at start of the experiments. Yield loss was strictly correlated with leaf area reduction, as well as with density of whitefly populations. Yield loss based on a decreased number of fruits worth for harvest and on increased drop of flowers and young fruits. Honeydew excreted by whiteflies was settled with sooty mould which extent was dependent from intensity and duration of whitefly infestation. This resulted also in leaf area reduction.

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Mit 5 Abbildungen und 3 Tabellen     

Der Einfluß von Außenfaktoren auf das Wanderverhalten der Deutschen Schabe,Blattella germanica (L.) (Blattodea,Blattellidae), in einer Mülldeponie

Mass propagation of the German cockroach in refuse tips may result in an increased emigration of this species into the surrounding area of the tip and thus in a heavy infestation of nearby buildings. Therefore, knowledges about the migration behavior are important when refuse tips are managed or projected. The influence of several environmental factors (as sun, day time, wind, temperature, season, light intensity) on the running behavior of the German cockroach was investigated under outdoor conditions. The most important results are as follows:

1. The reaction of young larvae (especially of L₁ and L₂) on the investigated factors differs considerably from that of older larvae and adults. As the young larvae do not emigrate, their behavior can be neglected in respect to the questions discussed here.
2. During sunshine, the position of the sun is primarily responsible for the direction of the migration. The highest percentage of the cockroaches walks directly towards the sun or a few grade right and left from the sun. When the sun is covered by clouds, the variation in the running direction is very high and many cockroaches migrate even into the direction opposite to the sun.
3. From morning to evening, the main migration direction is shifting from east to west, following the position of the sun.
4. Wind direction (at speeds of less than 5 m/sec.) and temperature (within the activity range of the cockroaches from approximately 18 to more than 30°C) have no recognizable influence upon the migration direction.
5. The clearest reaction of the running cockroaches towards the position of the sun was noticed during the main migration-time in the year (June and July).
6. The results of these investigations confirm former findings made in the field during a mass emigration of the German cockroach from a refuse tip.

     

Arsenbefund in amerikanischen Äpfeln

Ohne Zusammenfassung     

Gesunde Pflanzen unter zukünftigem Klima

Predicted changes in average values of global climate variables (increased temperatures, altered precipitation patterns, increased concentrations of atmospheric CO₂) and changes in the frequency, duration, and degree of extremes (frost, heat, drought, hail, storms, floods, etc.) will affect agricultural crops, agroecosystems, and agricultural productivity. Although forecasts of regional climate changes are still imprecise, mean temperature increases in Europe are expected to be greater in the north (2.5–4.5°C) than in the south (1.5–4.5°C). Regional forecasts for precipitation changes are also very far from precise; however, problems with drought are expected to increase, especially in Mediterranean countries. Overall, shortage of water will be the predominant factor affecting plant growth. As higher temperatures are known to enhance plant development and especially the grain-filling duration of cereals, grain yield losses are possible in a warmer climate. On the other hand, elevated atmospheric CO₂ concentrations are known to stimulate photosynthesis and enhance growth and yield (“CO₂ fertilization”); concomitantly, leaf transpiration is reduced, resulting in improved water use efficiency. Total biomass and yield were enhanced by 20–30% in experiments with elevated CO₂ exposure (550–700 ppm) under more or less ideal growth conditions. Elucidating the interactions between positive and negative effects of climate change is of crucial importance for any prediction of future crop yields. The present paper is a brief summary mainly of the potential effects of elevated temperatures and atmospheric CO₂ on crop growth, quality, and yield. Also, adaptation measures, possible interactive effects of different climate variables, and interactions of climate change components with other growth variables (pathogens, air pollutants) are briefly described.     

Die Breitadrigkeit des Salats — ein Komplex aus zwei Viren

Since many years lettuce big-vein disease (LBVD) occurring in lettuce (Lactuca sativa) and endivia (Cichorium endivia) is a well known disease. It is widely spread all over the world and can cause important economical losses. For more than 20 years the lettuce big-vein virus (LBVV) was thought to be the causal agent. New results indicate that another virus, named “Mirafiori lettuce big-vein ophiovirus” (MLBVV), is responsible for the typical symptoms. Mostly both viruses are detected together in diseased plants. But also the presence of only one virus can be observed as shown in a sample which was sent to the Bavarian State Research Center for Agriculture (LfL), Freising, in the spring of 2005. In further investigations at the German Federal Authority and Federal Research Centre (BBA), Braunschweig, only the MLBVV was found. Like any other virus disease LBVD cannot be controlled directly. Therefore prevention is of utmost importance. If LBVD is already present integrated disease management strategies combining cultural and phytosanitary measures as well as growing tolerant lettuce cultivars are the only way to minimize economical damage.