Gypsum Precipitation – A Medium to Control Sulphate Pollution of Freshwater Sediment Leachates

To treat sulphate pollution resulting from freshwater sediments,an experimental study was done. This experimental study was carried out to determine the effects of pH values and calcium supplements (as CaCl₂) on the formation of gypsum in a representative wetland sediment that was aerated. It was foundthat the differences between dissolved sulphate in untreatedcontrol and the other treatments with CaCl₂ amendments canbe attributed to the precipitation of gypsum. At the same time, the system was highly affected by Ca adsorption/desorption thatwas controlled by pH values. ECOSAT equilibrium simulations showed that CaCl₂ additions (0.2–0.3 mol L^-1) to aerated freshwater sediment resulted in removal of 78–98% ofsulphate (from its total content) from the solution. It wascaused by favourable conditions for gypsum formation i.e. acidicpH values were not increased due to the neutral character of CaCl₂. On the contrary to CaCl₂ amendments, CaCO₃supplements (in the same Ca doses as applied in CaCl₂) caused the removal of only 5–25% of sulphate. The significantincrease of pH values after the application of CaCO₃ limitedgypsum formation due to high saturation of the system with CO₃ ^-2 and HCO₃ ^-. It resulted in the prevalence of CaCO₃ formation in this system. However, theaddition of Cl^- can facilitate the mobilisation of cationicmetals like Cd and Pb in the form of Cl^--complexes. Therefore, CaCl₂ treatment should be used in the sites thatdo not contain elevated amounts of these metals.     

Studies on phenology and harmfulness of Aceria carvi Nal. (Acari: Eriophyidae) on caraway, Carum carvi L., in the Czech Republic

Caraway (Carum carvi L.) belongs to the traditional crops which have been grown in Bohemia since the end of the 19th century. Depressaria daucella (Denis and Schiffermüller) and Aceria carvi Nal. are two main pests of caraway in the Czech Republic. The latter becomes a serious problem in major caraway-growing areas. So far, no effective method for its control is known. The aim of this paper is to describe the phenology of symptoms of A. carvi infestation and damage caused by this pest. Our observation revealed that although A. carvi overwinters hidden within leaves of young caraway plants, the first symptoms are usually not visible before the start of flowering. Though the initial density of the pest is low, the mite population multiplies during the season when the pest attacks plant tissues and causes development of galls on leaves and flowers. Comparison of healthy plants and plants infested by A. carvi showed that infested plants had significantly more umbels but produced far fewer seeds, and the yield of caraway was thus substantially decreased. Recommendations for crop management methods to suppress the pest are given.Electronic Supplementary Material Supplementary material is available for this article at     

Production potential,biodiversity and soil properties of forest reclamations: Opportunities or risk of introduced coniferous tree species under climate change?

European Journal of Forest Research - In the time of ongoing climate change and the increasing area of post-mining landscape, the successful afforestation of reclamation sites by suitable adaptive...     

Effects of metabolic inhibitors on activity of Cry1Ab toxin to inhibit growth of Ephestia kuehniella larvae

BACKGROUND: Although the toxins of Bacillus thuringiensis Berliner (Bt) are frequently used to control lepidopteran pests, the tolerance or resistance of some lepidopteran moth strains may limit Bt applications. In this study, insecticidal cocktails consisting of sublethal doses of Cry1Ab toxin and additive compounds were tested for their suppressive effect on larval relative growth rate (RGR) in Ephestia kuehniella Zeller under laboratory conditions.RESULTS: In the first step, the suppressive effect of diflubenzuron, soybean trypsin inhibitor (STI) and chitinase on RGR was confirmed. In the second step, these compounds were incorporated into a mixture of crushed kernels of Bt maize hybrid MON 810-YieldGard((R)) and its isoline with concentrations of Cry1Ab toxin ranging from 0.011 to 0.091 microg g(-1) diet. An additive effect on the suppression of larval RGR in E. kuehniella was found in a combination of diflubenzuron, STI and STI + chitinase as secondary compounds in insecticidal cocktails. Chitinase showed no additive effect on RGR.CONCLUSION: The highest suppression level was found in cocktails with STI + chitinase as a secondary compound. It is hypothesized that the protease inhibitor (STI) protects both chitinase and Cry1Ab proteins from endogenous proteases in the larval midgut and prolongs their insecticidal activities. The possible application of insecticidal cocktails in the control of E. kuehniella is discussed. Copyright (c) 2008 Society of Chemical Industry.     

Host plant preference of aphids, thrips and spider mites on GNA-expressing and control potatoes

The effect of snowdrop lectin (Galanthus nivalis agglutinin: GNA) expression on host-plant preference was examined with a two-choice disc test. Discrimination between a transgenic potato [Solanum tuberosum (Solanaceae)] capable of synthesizing GNA, and an isogenic cultivar, was studied under laboratory conditions using the glasshouse potato aphidAulacorthum solani (Hemiptera: Aphididae), the onion thripThrips tabaci (Thysanoptera: Thripidae), and the two-spotted spider miteTetranychus urticae (Acari: Tetranychidae). Adults of these species were placed individually on leaf discs (one half transgenic and one half control) and observed 1, 24, 48, 72 and 96 h after release, at which times also the distributions ofA. solani nymphs andT. urticae eggs on the discs were recorded. Aphids were found more frequently on control leaves at all observation periods, with the highest bias observed at 72 h (only 35.9% of all aphids were found on the GNA halves). Similarly, more aphid nymphs (57.6% of the total) were found on isogenic half-discs. The percentage of thrips found on GNA halves ranged from 36.8% to 48.4%, with significant control-potato bias at the first three observations. Contrary to this, the proportion ofT. urticae females found on GNA halves was significantly lower than the expected proportion (0.5) at 72 and 96 h, with a minimum of 34.0% on GNA. The distribution of spider mite eggs reflected the observed biased distribution of females (only 34.1% of all eggs were laid on GNA half-discs). These results indicate that potatoes expressing GNA for resistance against aphids are less preferred than an isogenic cultivar by all three tested species under a choice test condition using excised leaves.     

The structure of microbial communities in redoximorphic microsites of Gleysol

Microbial communities were studied in redoximorphic microsites of highly heterogeneous Gleysol at a mm scale using 16S and 18S amplicon sequencing to demonstrate if the composition of soil microbes reflects the differences in ferric and ferrous micro-sites. In both explored gley horizons with redoximorphic features (Bg2 and Cg), ferric mottles were significantly enriched with total P and Fe and depleted of O, Si, Al, K and Ca compared with the adjacent ferrous groundmass (SEM–EDS). Ferric mottles were determined as Fe oxide coatings and hypocoatings. In Bg2, both prokaryotic and micro-eukaryotic communities differed significantly between mottles and groundmass in composition of operational taxonomic units (OTUs) and in proportions of phyla, reflecting heterogeneities in the soil properties there. Mottles in Bg2 were characterized by increased proportion of Proteobacteria, decreased proportion of Acidobacteriota among prokaryotes and by dominance of a single proteobacterial OTU from Anaplasmataceae compared to all other samples. The composition of micro-eukaryotes showed an opposite trend, as micro-eukaryotes of Bg2 groundmass were unique among the other horizons, while micro-eukaryotes of Bg2 mottles had similar composition to neighbouring horizons. Microbial communities of adjacent samples were not more similar to each other than communities of randomly selected ones in Bg2 horizon. That suggests that at mm scale, the sample distance does not represent the driving factor of microbial community composition and that the adjacent samples differ rather due to physicochemical factors. The spatial organization of microbial communities revealed in Bg2 has not reappeared in similarly organized Cg horizon, probably due to other overriding factors. The differences revealed between Bg2 and Cg horizons, including granulometric composition, content of crystalline Fe, exchangeable Al, and organic carbon, as well as exposition to groundwater, were discussed as possible reasons of the distinct organization in Cg. The similarity of pro−/eukaryotic communities of adjacent and non-adjacent couples suggests no distance decay pattern at a mm scale. The agreement between patchiness in soil properties and microbial communities was revealed for the first time and confirms the importance of microscale patterns in soil.