Showing papers on "Bark published in 1976"

The aggregation pheromones of bark beetles: Progress and problems

Abstract: Bark beetles (Coleoptera: Scolytidae) are insect pests inhabiting the subcortical tissues of trees. They account for much of the timber losses in coniferous forests throughout the Northern Hemisphere. Destructive outbreaks have been recorded in the past and present alike as soon as windstorms, drought, flood, root competition, or defoliation impair tree health and provide suitable host material for exploding beetle populations. Attacking en masse, aggressive populations overcome their host trees regardless of health or vigor. What appears to be attack by brute force, however, is actually the outcome of an intriguing system of chemical communication which in many respects resembles that of social insects more closely than the sex pheromones of lepidoptera. The elements of scolytid communication are host-produced volatiles as well as insect-produced pheromones; the response is not truly sex-specific, with both male and female beetles aggregating [1]. This ensures the utilization of temporary habitats [2] such as broken limbs or lightning-struck trees, providing an obvious mechanism for survival of endemic populations. But the same mechanism may mark resistant trees for simultaneous mass attack when and where epidemic populations prevail. Consequently, the term \"population aggregating pheromones\" or briefly \"aggregation pheromones\" (Populationslockstoffe) was introduced to emphasize the pheromonal function in host colonization. This is not to overlook the fact that aggregation of both sexes leads to the encounter of a mate. Nevertheless, the target marked by bark-beetle pheromones is the host, in contrast to the sex pheromones, where it is the mate. The fact that bark beetles are attracted to, and aggregate on, suitable host material has been commonly known for centuries and was used empirically in Europe to combat the pest with \"trap trees\". Gmelin [3] described such procedures in his remarkable essay \"Abhandlung fiber die Wurmtrocknis\" as early as 1787. However, Anderson [4] was first to prove the existence of attractants experimentally in 1948 and another decade passed before research investigated this phenomenon systematically [5]. The experimental proof that beetle-produced volatiles are involved in bark-beetle attraction was followed by the first successful identification of three terpene alcohols [6] in 1966. Since then, considerable progress has been made in the identification of aggregation pheromones and related structures, as well as in the biosynthesis of such compounds and the insect's response behavior. Aggregation pheromones are thought to occur throughout the family of Scolytidae with a few possible exceptions [7]; but there are many bark-beetle species which respond most readily to resinous materials exuding from damaged or infested timber as, for example, Blastophagus piniperda [8]. In general, the beetles emerge from a brood tree or overwintering site and disperse in search of new breeding places. Random dispersal and close-range host recognition, which may include olfactory response to host odors (primary attraction), are considered instrumental. Invariably, the beetle initiating gallery construction selects the host. In monogamous bark-beetle species, this is the female; among polygamous beetles, the male. As they enter the bark, pheromones are released usually by defecation, and/or host volatiles are activated. Colonization starts in response to this strong and specific secondary attraction, which increases as more beetles enter the same host and generate more of the attractive principle (Fig. 1). During this stage of attack, the focus of attraction may extend from a part of a tree to the whole, and from several trees into an attractive area in which beetles aggregate for mutual attack of additional hosts. Many Dendroctonus and some Ips spp. are capable of marking new host trees in spite of copious resin flow which prevents the beetles from feeding. Such \"contact pheromones\" are appar-

The Bark-Eating Habits in Primates, with Special Reference to Their Status in the Diet of Wild Chimpanzees

Abstract: Chimpanzees of the Mahali Mountains, Tanzania, were recorded to chew barks of 21 species of trees and wood vines. They mainly utilize the barks of savanna-living deciduous trees during the mid-rainy season of the year when few fruits are available. The degree of their dependence on bark for food varies drastically year by year. The bark seems to occupy an important role as emergency food in a lean year in the survival of chimpanzees, as well as in that of some other higher primates.

Microbial degradation of condensed tannins

Abstract: A strain of Penicillium adametzi Zaleski was isolated from enrichment cultures with condensed tannins as the carbon source. Low-molecular-weight condensed tannins, extracted and purified from Pinus radiata bark, were used as substrates for quantitative growth measurements on this fungus in defined culture conditions.

Uptake of minerals, particularly metals, by epiphytic Hypnum cupressiforme

Abstract: Samples of bulk precipitation, epiphytic moss (Hypnum cupressiforme Hedw.) and phorophyte bark were analysed for contents of Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Pb, S, V and Zn. These analyses were the basis for a compartment study of the mineral cycling in an epiphytic ecosystem. The conductivity, pH, buffer capacity and concentrations of Ca, K, Mg and Na of Fraxinus excelsior L. and Fagus silvatica L. bark were determined in the traditional way on bark powder suspensions and also in solutions in equilibrium with discs of bark surface. The relation between bark properties and input-output of chemical elements to the epiphytic bryophytes was discussed. The differences in the epiphytic vegetation on Fraxinus and Fagus were assumed not to have been determined by the observed differences between Fraxinus and Fagus in properties of the bark powder suspensions, as these were not reflected in the solutions in equilibrium with the bark surface. Comparisons with other Scandinavian investigations on heavy metal contents in epigeic moss were made, and it was concluded that the metal contents of epiphytic moss originate mainly from the atmosphere.

Aqueous Leachate from Western Red Cedar: Effects on Some Aquatic Organisms

Abstract: Water-soluble extractives from western red cedar heartwood, bark, and foliage were investigated for their toxicity to aquatic organisms. The heartwood lignans and bark extractives were found to be ...

Corticolous Myxomycetes V: Observations on the Genus Echinostelium

Abstract: SUMMARYSystematic screening of bark samples from living trees and vines placed in moist chambers has resulted in the discovery of two new species of corticolous Myxomycetes, Echinostelium arboreum ...

Ultrastructural aspects of beech bark degradation by fungi

Abstract: The degradation of beech bark by three wood-decaying fungi has been analyzed at the ultra-structural level and the micromorphological changes occurring in the walls of the diverse cell types compared with the decay pattern in wood cells.

Acute Toxicities of Spruce and Hemlock Bark Extracts to some Estuarine Organisms in Southeastern Alaska

Abstract: Sitka spruce bark extracts were found to be toxic to adult and larval pink shrimp (Pandalus borealis) and larval Dungeness crab (Cancer magister). Sitka spruce and western hemlock bark extracts wer...

Manufacture of polyurethanes from bark

Abstract: Polyurethane compositions formed by the reaction of polyisocyanate with bark and/or bark components such as tannins, as the source of polyol. Mixtures of bark material with conventional polyols, with the bark material comprising at least 30% by weight, may also be used. Polyurethane foams prepared by this process possess a high degree of thermal stability and are fire-retardant.

Metabolism of ethephon (2-chloroethylphosphonic acid) and related compounds in Hevea brasiliensis.

Abstract: Ethephon (I) is used commercially to prolong the flow of latex from the rubber tree after tapping (Yield stimulation). The compound is applied to the bark in the region of the tapping cut and the effect on latex flow is due to the ethylene released by chemical decomposition, since gaseous ethylene itself is also a very effective stimulant. When14C-I is applied to the bark of a youngHevea seedling, it is absorbed into the plant by processes which appear to be largely non-metabolic. Ethylene formation commences immediately at the site of application, and the gas is quickly translocated throughout the plant. Translocation of I to all parts of the plant also occurs and the accumulation of14C in the bark above the zone of application is greater than that below. Chromatographic analysis has shown that compounds other than I remain in the plant tissue.

On the Structural Changes in Wood and Bark of a Salt-damaged Horsechestnut Tree

Abstract: Schlüsselwörter (Sachgebiete) Auftausalz Straßenbäume Roßkastanie Holz Rinde On the Structural Changes in Wood and Bark of a Salt-damaged Horsechestnut Tree Summary The qualitative and quantitative changes in the structure of wood and bark of a salt-damaged horsechestnut tree were investigated. Following application of salt the vessels become smaller and more circular; they are frequently distributed in radial groups and their proportion increases. Axial parenchyma is more numerous. On the other hand, the proportion and length of wood fibres show a reduction. The phloem fibres are already differentiated in the youngest growth zone; their number per unit area is higher. A further notable feature is the occurrence of numerous calcium oxalate crystals in idioblasts in the phloem zone near the cambium. These changes in wood and bark are discussed in relation to their possible causes.

Synthesis of optically pure (+)-trans-verbenol and its antipode, the pheromone of Dendroctonus bark beetles.

Abstract: Pure (+)-trans-Verbenol (2b) and its antipode (2b′) were synthesized for the first time and their optical purities were checked by NMR as their MTPA esters (2e and 2e′, respectively).

Note on the nitrification inhibitors in the seeds, bark and leaves of Pongamia glabra Vent

Abstract: The manurial value of P. glabra seed-cake in India has been attributed to nitrification inhibitors. In laboratory experiments with soil samples, both seed and bark extracts inhibited the oxidation of NH4-N (NH4-N concn. approx. twice that of controls at 45 days), the effect being slightly greater with the seed extract. Dried leaves had no such effect. It is concluded that components of the alcoholic seed extract may be used to increase the efficiency of ammoniacal fertilizers