Active enzymes in wood chips and their action on lignin during outside storage

Summary Wood storage has a great influence on the efficiency of a pulpmill. Great problems arise when using outside chip storage, especially in processing hardwoods, in that hardwood chips discolorate after a few days, which is not the case with spruce chips. The causes of such a different behavior of beech and spruce were investigated. It could be shown that a sufficient amount of active peroxidase, malate dehydrogenase and oxygen are prerequisites for the formation of phenoxy radicals within the beech lignin. This causes formation of new chromophores that discolorize the wood. Sufficient amounts of such enzymes are present in beech wood after harvesting.     

Einige Eigenschaften des weiblichen Sexualpheromons des KartoffelkäfersLeptinotarsa decemlineata Say. (Col. Chrysomelidae)

The female sex pheromone ofL. decemlineata is an aphrodisiacum, switching on mating behaviour in contacting males. A biotest is described to estimate quantitatively the exciting power of a subject (female, isolated elytrae, glass dummy coated with extract) to males. The pheromone is present only in fertile females, also in freshly killed ones. It can be extracted by organic solvents. A dummy imitating a beetle's abdomen and contaminated with the residue of a female s wash solution is exciting to males too. Suitable solvents are ethylalcohol, acetonet, hexane. By this, the pheromone of 0,1 female is detectable. The residue can be taken up again with the same or an other solvent. The solution can be stored at ?18°C without significant losses, but at temperatures>+5°C their efficacy diminishes during 2 weeks. The exciting efficacy of the dry residue desreases to about 50% during nearly 4 weeks (at+22°C) or 9 weeks (at+5°C). The pheromone resists heating to about+160°C and is destroyed at higher temperatures.     

Bioactivity of some formulations of neem seed extracts against the whiteflyBemisia tabaci (Genn.)

The bioactivity of different formulations of neem seed extracts against the whiteflyBemisia tabaci (Genn.) was assayed in semifield trials during 1992. Tomato plants variety UC-97 were cultivated in pots and left to natural infestation with whitefly in an open field and sprayed with various concentrations of each extract. The high concentrations of all the extracts tested exhibited obvious activity. Also, the different treatments reduced the population density of the adult whiteflies compared with the control. The percentage reduction in the population reached its maximum level one hour after treatment with any tested extract.With one table     

Antagonismusin vitro vonBacillus spp. gegenüberRhizoctonia solani undPythium spp.

Zusammenfassung Es konnten 132Bacillus-Stämme isoliert und gegenüber7 Rhizoctonia-solani- und 6Pythium-Stämmen auf Antagonismusin vitro untersucht werden. Die gefundenen Antagonisten hemmten die Pilzisolate unterschiedlich stark, so daß Gemische von Antagonisten für die Praxis zu empfehlen sind.

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Antagonismin vitro ofBacillus spp. againstRhizoctonia solani andPythium spp.

There were 132Bacillus-strains isolated and tested for antagonism against 7 strains ofRhizoctonia solani and 6 strains ofPythium spp. The isolated antagonists didn't show a uniform effect against the tested strains ofRhizoctonia solani andPythium spp. For an application in practice it will be better to use a mixture of antagonists.

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Mit 4 Abbildungen und einer Tabelle     

Zur Wirkung von Milchsäure auf den Varroa-Befall der Biene

40% lactic acid was sprayed 3 times into each of two bee colonies. The rate of infestation was determined, before beginning the experiment and after each of the applications. The treatments showed a mean percentage reduction in the brood infestation byVarroa of 76,7% in the first colony and 85,2% in the second. These data indicate that it is possible to control the Varroasis by means of lactic acid successfully and without side effects.     

Zum saisonalen Auftreten der Baumwolleule,Spodoptera littoralis (Boisd.) (Lep., Noctuidae) und ihrer Kernpolyedrose (NPV) in verschiedenen Distrikten Ägyptens

Infection rates of the nuclear polyhedrosis virus (NPV) in the cotton leafworm,Spodoptera littoralis larvae were assessed from 1985 through 1986 in clover fields at El-Behiera, El-Fayoum and El-Gharbia governorates. Infection rates of the pathogen were highest near the end of spring when the cotton leafworm larval populations were increasing. For the different governorates, the percentages of virus infection were almost higher in 1985-season than in 1986. El-Fayoum-larval population was the most infected by NPV followed by El-Gharbia and El-Behiera-populations, respectively. There was a positive correlation between infection rates of NPV on one hand, and density of larva and ambient temperature on the other.     

Physikalische Felder und Insekten. Ein Übersichtsreferat

First-zones of earth radiations are shown as preferred places of aggregations of insects, especially forest insects. After a survey given about factors, probably evoking dowsing, many examples are given for influences of electric-magnetic powers and such of gravity phenomens to behaviour and vital functions of insects, particularly mentioning the results of research ofG. Becker andF. Schneider. Considering facts in literature together with own experiences in this field of investigation the opinion is expressed, that both ultraoptic factors-both of efficiency on insects: a) the electric-magnetic powers-different from their environment and b) the metal effect as a gravity phenomen are necessary for the appearance of the dowsing phenomen. The metal effect is capable to stimulate the movement of the rod, but needs for its releasing from coverings the presence of altered electric-magnetic fields. The metal effect may likely be compared to resonance oscillations of gravity waves arising on Aluminium plates, as it is supposed bySchneider.     

Polymer distribution in the cell wall of a wood-polyethylenimine composite

Summary A light microscopic (LM) visual technique to determine the polyethylenimine (PEI) distribution in a wood-PEI composite was studied by the adsorption of acid red or the circulation of Cu(II) ion with PEI in the composite. The amount of the adsorbed dye or Cu(II) on the composite increased linearly with an increase in the PEI content of the wood-PEI. The dyed composites were observed with LM under monochromatic light, corresponding to their absorption maxima at 560 nm for acid red and at 640 nm for copper chelate. The microscopic image was photographically recorded and the negative was subjected to densitometric analysis. At a polymer content lower than 4% in the composite, about 70% of total polymer was located in the middle lamella region, leaving only 30% in the secondary wall. With increasing PEI content of the composite, the concentration in the secondary wall increased, and about 80% of the polymer was located in the secondary wall at a PEI content of 27%. There were no noticeable differences between the amount of polymer detected by dyeing with acid red and by chelating with Cu(II). From the results of the line analysis of the intensity of the characteristic X-ray of uranium, the distribution of the PEI in the cell wall agreed closely with that determined by the LM method. It was concluded that the LM visual technique to determine the PEI location in the wood-PEI composite by dyeing with acid red or by chelating with Cu(II) is a simple and reliable method.