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- Evolution (4)
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- 4 Material und Umwelt (13)
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- 4.6 Molekulare und angewandte Entomologie (2)
- 5 Werkstofftechnik (1)
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- 6 Materialchemie (1)
- 6.1 Oberflächen- und Dünnschichtanalyse (1)
- 8 Zerstörungsfreie Prüfung (1)
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In collaboration with the United States Department of Agriculture and a number of major milling companies, the "Insect-Detect" immunoassay for analyzing insect contamination in grains has been compared with three more traditional methods, X-ray analysis, cracking and flotation, and the insect fragment test (IFT). Testing was carried out in blind fashion using clean wheat samples that were spiked with differing numbers of grain kernels infested with late instar larvae of the granary weevil (Sitophilus granarius (L.)). Three different laboratories analyzed the samples for each of the four methods. The collaborative trials showed that the insect immunoassay clearly provided the most accurate measurement of actual insect infestation, followed by X-ray analysis. While both cracking and flotation and IFT procedures provided a general measure of contamination, they showed much greater variability.
Seit mehreren Jahrzehnten ist der Einsatz von Lockstoffen gegen Insekten zur Schadensabwehr an Lagergütern und Materialien etabliert. Die Hauptkomponenten der Pheromone aller wirtschaftlich relevanten vorrats- und materialschädlichen Insekten sind bekannt. Zur Früherkennung und zur Populationsdichteüberwachung von Schädlingen nehmen Pheromonfallen eine zentrale Position im Konzept der ökonomischen Schadensschwelle und damit im integrierten Vorrats- und Materialschutz ein. Dies gilt vor allem für Sexuallockstoff-Fallen gegen paarungsbereite Männchen von vorratsschädlichen Motten aus den Gruppen der Zünsler (Pyralidae) mit Dörrobst-, Mehl- und Speichermotte und gegen Kleinschmetterlinge(Tineiden) mit Kleider- und Pelzmotte sowie gegeneinige Nagekäfer mit Brot-, Tabak- und Gemeiner Nagekäfer. Durch das sogenannte "Monitoring" können Bekämpfungsstrategien zunächst zeitlich und räumlich optimiert und anschließend auf Erfolg bewertet werden. Neben Sexualpheromonen sind bei einigen Käfern wie beispielsweise den Korn- und Reismehlkäfern auch Aggregationspheromone, die attraktiv auf beide Geschlechter wirken, verbreitet. Ihr Einsatz zur Bekämpfung, d.h. zum Massenfang von Individuen, wie dies im forstwirtschaftlichen Bereich gegen Borkenkäfer nutzbringend durchgeführt wird, hat sich aufgrund mangelnden Erfolgs im Nachernteschutz jedoch nicht etabliert.
Neben einem wirtschaftlich orientierten Einsatz von Pheromonfallen kann deren Anwendung auch wertvolle allgemein biologische Informationen über Schadinsekten liefern. Wird das "Monitoring" z.B. im Freiland abseits von Lagerstätten für faunistische Erhebungen durchgeführt, können natürliche Vorkommen von Schädlingsarten ermittelt werden. Dies erlaubt Rückschlüsse auf ihre ursprünglichen Lebensräume und auf mögliche adaptative Szenarien beim Übergang zu einer synanthropen und damit für den Menschen schädlichen Lebensweise. Zusätzlich werden auf diese Weise natürliche Habitate, die als Reservoire für Schadpopulationen fungieren könnten, aufgespürt und, wenn notwendig, in ein Bekämpfungsprogramm integriert.
It is generally accepted that the natural habitats of most pest insects can be found outside the synanthropic environment in layers of leaf litter, under bark, as well as in rodent or bird nests. Indeed, most of the common pests have been reported as being facultative nidicolous. Therefore infestation of commodities by pest insects out of these reservoirs is one considerable possibility. However, the likelihood of a pest´s occurrence and survival out-doors largely depends on its ecological potential and competitiveness against other species of the same ecological guild. Some pest species are rarely found in wild habitats, especially in those regions where they are not native and where they have been introduced by man. The fabric pest Tineola bisselliella serves as a good example. Most likely originating in Central or Southern Africa this insect was introduced into Europe probably not earlier than the late 18th century. Being more tolerant to dry environments than other fabric pests its economical importance increased during the 20th century when in-door climates changed because of central heating systems. Its occurrence in out-door natural habitats must be regarded as accidental. Reported founds of webbing clothes moth larvae in bird nests e.g. have been largely overstated in the literature. T. bisselliella should be regarded as an eusynanthropic species
Adapted and effective pest management strategies for the protection of irreplaceable culture heritage as well as for the prevention of damages in households and warehouses are based on reliable information about the presence and distribution of the pest organisms. Monitoring the webbing clothes moth Tineola bisselliella at thirteen outdoor stations in the broader area of Berlin give a first idea of their occurrence in an urban area and the hinterlands. The results demonstrate a seasonal abundance in the city and a missing of this species in the countryside. Data suggest a synanthropic occurrence of the webbing clothes moth rather than an invasion from natural reservoires. Possible molecular examinations on the species and subspecies level are presented to analyze the gene flow between populations and give an impression of species mobility as well as pathways of infestation.
Termite gut flagellates are colonized by host-specific lineages of ectosymbiotic and endosymbiotic bacteria. Previous studies have shown that flagellates of the genus Trichonympha may harbour more than one type of symbiont. Using a comprehensive approach that combined cloning of SSU rRNA genes with fluorescence in situ hybridization and electron microscopy, we investigated the phylogeny and subcellular locations of the symbionts in a variety of Trichonympha species from different termites. The flagellates in Trichonympha Cluster I were the only species associated with 'Endomicrobia', which were located in the posterior part of the cell, confirming previous results. Trichonympha species of Cluster II from the termite genus Incisitermes (family Kalotermitidae) lacked 'Endomicrobia' and were associated with endosymbiotic Actinobacteria, which is highly unusual. The endosymbionts, for which we suggest the name 'Candidatus Ancillula trichonymphae', represent a novel, deep-branching lineage in the Micrococcineae that consists exclusively of clones from termite guts. They preferentially colonized the anterior part of the flagellate host and were highly abundant in all species of Trichonympha Cluster II except Trichonympha globulosa. Here, they were outnumbered by a Desulfovibrio species associated with the cytoplasmic lamellae at the anterior cell pole. Such symbionts are present in both Trichonympha clusters, but not in all species. Unlike the intracellular location reported for the Desulfovibrio symbionts of Trichonympha agilis (Cluster I), the Desulfovibrio symbionts of T. globulosa (Cluster II) were situated in deep invaginations of the plasma membrane that were clearly connected to the exterior of the host cell.
The content of chromium in different oxidation states in chromium-treated wood was studied with XANES (X-ray absorption near-edge structure) measurements at the Cr K absorption edge. It could be shown that wood samples treated with Cr(VI) (pine and beech) did still contain a measurable content of Cr(VI) after four weeks conditioning. If such wood samples were heat exposed for 2 h with 135 °C prior conditioning, Cr(VI) was no longer detected by XANES, indicating a complete reduction to chromium (III).
The application of pheromone-baited traps to control pest insects in stored food or materials has become well established over the past decades. The main pheromone components of all major stored-product and material pests have been identified. Pest monitoring with pheromone traps is a key factor in integrated pest management to estimate population density build-ups and they may be used to define economic threshold levels. Male-attracting sex pheromones, e.g. for stored-product pyralids, the clothes moths, and some anobiid beetles, are especially effective in this aspect.
Monitoring pest population can facilitate optimal spatial and temporal control strategies, including efficacy evaluation of the implemented control measures. In addition to the sex pheromones, some beetles, such as grain and flour beetles, utilize aggregation pheromones, which attract both sexes.Implementation of these pheromones for mass trapping,which works well for the control of bark beetles in the forest environment, has been less successful for stored-product protection for various reasons and is thus not an established means of control.
When the monitoring tools are used in landscape areas, scrublands, forests, and away from anthropogenic influencedenvironments, natural reservoirs of a pest species and sources of new infestations can be identified. In addition to an economically driven adoption of pheromone traps, they may also provide information of a pest's general biology. Because stored-product and material pests must be considered neozoons in most parts of the world, their occurrence in natural habitats indicates a species' autecological capability to successfully compete with native species and to become faunistically established in non-synanthropic environments outside their zoogeographic origin. This review focuses on the use of pheromone traps for monitoring in outdoor situations.
Subterranean termites moving in the peripheral tubular network of their foraging area need to distinguish the trail direction. In a natural gallery or tunnel network of Reticulitermes flavipes the branches at bifurcations generally have an acute angle between them. the resulting obtuse angle from the main trail leading into a branch is preferred by commuting termites. In experiments with artificial gallery forks, termites returning from a food source only neglected the trail junction leading to the nest and preferred the trail to a second food source if the angle to the nest was acute. A right angle to the nest was preferred over a straight way leading to a second food source. This preference to the nest increased when the three branches at trifurcations were arranged equi-angular. This preferred orientation could be attributed to attracting odours from close-by gallery material. Additionally, R. flavipes moved more slowly towards a food source consisting of pine wood than on the way back to the nest, as was shown in artificial one-way galleries. However, the significance of this speed difference remains uncertain because the speed of a homing termite in an artificially reversed trail does not slow down to the speed of a food foraging termite.
Chemical modification of wood applying benzotriazolyl-activated carboxylic acids has proven to be a versatile method for the durable functionalization of its lignocellulosic biopolymers. Through this process, the material properties of Wood can be influenced and specifically optimized. To check the scope and limitations of this modification method, various benzamide derivatives with electron-withdrawing (EWG) or electron-donating (EDG) functional groups in different positions of the aromatic ring were synthesized and applied for covalent modification of Scots pine (Pinus sylvestris L.) sapwood in this study. The bonded amounts of substances (up to 2.20 mmol) were compared with the reactivity constants of the Hammett equation, revealing a significant correlation between the modification efficiency and the theoretical reactivity constants of the corresponding aromatic substitution pattern. The successful covalent attachment of the respective substituted benzamides was proven by attenuated total reflection infrared (ATR-IR) spectroscopy, while the stability of the newly formed ester bond was proven in a standardized leaching test.