A monitoring study to assess the acute mortality effects of indoxacarb on honey bees (Apis mellifera L.) in flowering apple orchards

To evaluate the effect of the indoxacarb 300 g kg(-1) WG, Steward 30WDG, on the honey bee (Apis mellifera L.) in apple orchards, a monitoring study was conducted in Dutch apple orchards in April/May 2004. Before apple flowering began, two honey bee colonies were placed in each orchard to investigate honey bee mortality. Each hive was provided with a Münster dead bee trap to collect dead honey bees. The numbers of dead bees found in these Münster dead traps were counted every 3-4 days for about 2 weeks before and after the period of the insecticide treatment. In nine flowering orchards no indoxacarb was applied during the flowering period, which served as control sites. In 30 flowering orchards indoxacarb was sprayed by the fruit growers according to local practice at 170-260 g formulated product ha(-1) (51-78 g AI ha(-1)). In the control orchards the average mortality was 8 honey bees colony(-1) day(-1). The average daily honey bee mortality before and after indoxacarb application was 8 and 10 honey bees colony(-1) day(-1) respectively. At one test site, indoxacarb was mixed with other plant protection products plus plant nutrients, and in this orchard a slight but biologically non-significant increase in acute honey bee mortality was recorded. It was concluded that the application of indoxacarb caused no effects on honey bee mortality, and that the number of dead honey bees counted in the Münster traps in the orchard treated with indoxacarb was comparable with those determined in control orchards.     

Fifty years after deep-ploughing: Effects on yield,roots, nutrient stocks and soil structure

Deep-ploughing far beyond the common depth of 30 cm was used more than 50 years ago in Northern Germany with the aim to break root-restricting layers and thereby improve access to subsoil water and nutrient resources. We hypothesized that effects of this earlier intervention on soil properties and yields prevailed after 50 years. Hence, we sampled two sandy soils and one silty soil (Cambisols and a Luvisol) of which half of the field had been deep-ploughed 50 years ago (soils then re-classified as Treposols). The adjacent other half was not deep-ploughed and thus served as the control. At all the three sites, both deep-ploughed and control parts were then conventionally managed over the last 50 years. We assessed yields during the dry year 2019 and additionally in 2020, and rooting intensity at the year of sampling (2019), as well as changes in soil structure, carbon and nutrient stocks in that year. We found that deep-ploughing improved yields in the dry spell of 2019 at the sandy sites, which was supported by a more general pattern of higher NDVI indices in deep-ploughed parts for the period from 2016 to 2021 across varying weather conditions. Subsoil stocks of soil organic carbon and total plant-available phosphorus were enhanced by 21%–199% in the different sites. Root biomass in the subsoil was reduced due to deep-ploughing at the silty site and was increased or unaffected at the sandy sites. Overall, the effects of deep-ploughing were site-specific, with reduced bulk density in the buried topsoil stripes in the subsoil of the sandy sites, but with elevated subsoil density in the silty site. Hence, even 50 years after deep-ploughing, changes in soil properties are still detectable, although effect size differed among sites.     

The epidemiology of Staphylococcus aureus infections from subclinical mastitis in dairy cows during a control programme

The objective was to investigate the spread of S. aureus in seven dairy herds. Milk samples were taken to determine mastitis pathogens and somatic cell count. An approved hygiene programme was established to control the spread of S. aureus from quarter to quarter. S. aureus isolates were differentiated by geno- and phenotyping to trace their spread within a herd.In two herds S. aureus showed a high prevalence, but were eliminated from the herds by the control programme. In these herds and a third herd typing results identified a particular type that was found much more frequently than all other types. The frequent types were repeatedly detectable during the study. In three other herds with a lower S. aureus prevalence and also in one herd with a long history of S. aureus and high prevalence subclinical mastitis was caused by several distinguishable S. aureus types. These types occurred simultaneously in the particular herd and showed little or no tendency to spread from quarter to quarter. They seemed to circumvent the control procedures resulting in a relatively high rate of new infected animals and therefore were hardly eliminated. The typing results and the clinical observations indicated that strains differed in their tendency to spread and their ability to infect udder quarters. In three herds typing methods identified a predominant type with the common epidemiological features of a contagious mastitis pathogen, while in the other herds the S. aureus type patterns were similar to that of environmental pathogens.     

Implications of soil substrate and land use for properties of fen soils in North-East Germany Part I: Basic soil conditions,chemical and biological properties of topsoils

Abstract

The objective of the paper was to analyse the implications of the origin of peat (muck) soil substrate, the current type of land use and the state of anthropogenic soil development for the topsoil properties of fens. Chemical and biological properties of peat soils of the Rhin-Havelluch lowland and the Uckermark rural landscape were analyzed. The unit water content according to Ohde and the ash content were utilized to characterize the anthropogenic development status of peat topsoils. Several chemical properties were significantly influenced by soil substrate, in particular by the proportion and kind of the mineral component. The substrate was associated with the hydrological type of mire and the soil development state. TOC/N ratio and microbial activity were increased in cases of high lime spring mires and moorshified low ash peat. The proportion of easily soluble organic carbon increased, whereas the sulphur content decreased with the soil development state. The nitrogen content and the proportions of oxalate soluble iron and aluminium reached maxima in the moorshified state. The type of land use (grassland, forest) significantly influenced the topsoil pH and the proportion of oxalate soluble phosphorus. Soils under forest were clearly determined by topsoil acidification.     

Assembling a core collection from the flax world collection maintained by Plant Gene Resources of Canada

Between 1998 and 2008, numerous projects were conducted by the Canadian national genebank, Plant Gene Resources of Canada, for the regeneration, characterization and evaluation of the whole flax (Linum usitatissimum L.) germplasm collection. The whole collection comprised 3378 accessions and, according to the passport data, several of these were probably genetically very similar or even identical. Therefore, a subset of 381 accessions was selected that represented the diversity found in the whole collection. Sampling accessions from the whole collection was made using characterization and evaluation data and followed six different methods: (1) For seven qualitative characters, each unique combination of character expression was represented by three accessions; (2) for quantitative characters, a fixed number of accessions representing the lowest and highest observed values was included; (3) for stem fibre content, disease ratings, seed vigour and drought tolerance, a fixed number of accessions with desirable performance was included; (4) a subset of the 57 most distinct accessions based on RAPD markers was included; (5) a subset of 40 pure lines that were created based on extreme low and high values for 1000 seed weight, seed oil content and fatty acid profiles was included; (6) a subset of fibre flax cultivars of known relevance in European flax breeding and another subset of flax cultivars of known relevance for North American linseed breeding were included. The goal was to maximize the diversity available in a limited number of flax accessions by preserving the range of variation present in the whole collection, while improving evenness. The core collection was assembled in response to requests by flax breeders. This paper compares distribution parameters in the whole and core collections.     

Storm damage of Douglas-fir unexpectedly high compared to Norway spruce

Context

Since storm damage has a large impact on forest management in Central Europe, we investigated the main storm risk factors for two important conifer species, Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco) and Norway spruce (Picea abies [L.] Karst.).

Aims

We compared general storm damage levels of Douglas-fir and Norway spruce, the latter being known to have high storm risk among European tree species.

Methods

Generalized linear mixed models and boosted regression trees were applied to recorded storm damage of individual trees from long-term experimental plots in southwest Germany. This included two major winter storm events in 1990 and 1999. Over 40 candidate predictors were tested for their explanatory power for storm damage and summarized into predictor categories for further interpretation.

Results

The two most important categories associated with storm damage were timber removals and topographic or site information, explaining between 18 and 54 % of storm damage risk, respectively. Remarkably, general damage levels were not different between Douglas-fir and Norway spruce.

Conclusion

Under current forest management approaches, Douglas-fir may be considered a species with high storm risk in Central Europe, comparable to that of Norway spruce.     

Application of the CSM-CERES-Rice model for evaluation of plant density and irrigation management of transplanted rice for an irrigated semiarid environment

The objectives of this study were to evaluate the performance of the Cropping System Model (CSM)-CERES (Crop-Environment Resource Synthesis)-Rice for simulating growth and yield of rice under irrigated conditions for a semiarid environment in Pakistan and to determine the impact of plant density and irrigation regime on grain yield and economic returns. The crop simulation model was evaluated with experimental data collected in 2000 and 2001 in Faisalabad, Punjab, Pakistan. The experiment utilized a randomized complete block design with three replications and included three plant densities (one seedling hill^?1, PD₁; two seedlings hill^?1, PD₂; and three seedlings hill^?1, PD₃) and five irrigation regimes (625 mm, I₁; 775 mm, I₂; 925 mm, I₃; 1075 mm, I₄; and 1225 mm, I₅). To determine the most appropriate combination of plant densities and irrigation regimes, four plant densities from one seedling hill^?1 to four seedlings hill^?1 and 17 irrigation regimes ranging from 0 to 1600 mm, for a total of 68 different scenarios, were simulated for 35 years of historical daily weather data. The evaluation of CSM-CERES-Rice showed that the model was able to accurately simulate growth and yield of rice for irrigated semiarid conditions, with an average error of 11% between simulated and observed grain yield. The results of the biophysical analysis showed that the combination of the two seedlings hill^?1 plant density and the 1,300 mm irrigation regime produced the highest yield compared to all other scenarios. Furthermore, the economic analysis through the Mean-Gini Dominance (MGD) also showed the superiority of this treatment compared to the other treatment combinations. The mean monetary return ranged from ?47 to 1,265 $ ha^?1 among all 68 scenarios. However, to be able to furnish the demand of rice grain for local consumption and to increase export, there is a need to expand this technology among the rice growers of other rice producing areas in Pakistan through extension workers.     

Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage

Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.     

Causes for the small scale variability of nitrate concentration in seepage water of an N saturated mature spruce stand

Context

In N-saturated forests nitrate concentrations in seepage water ( $ {\text{N}}{{\text{O}}_3}{^{ - }_{\text{seepage}}} $ ) regularly show high spatial variability even within homogeneous stands. Up to now the reasons of this variability are not fully understood.

Aims

The main objective was to identify the crucial parameters that control spatial variability of $ {\text{N}}{{\text{O}}_3}{^{ - }_{\text{seepage}}} $ at the H?glwald site.

Methods

We investigated a multitude of parameters (e.g. N turnover, root biomass, soil chemistry, soil physics, stand parameters) and related them to $ {\text{N}}{{\text{O}}_3}{^{ - }_{\text{seepage}}} $ , measured in 40?cm depth with suction cups.

Results

A small number of biological parameters (net N mineralization, root distribution, and stand density) explained up to 93?% of the variability of $ {\text{N}}{{\text{O}}_3}{^{ - }_{\text{seepage}}} $ in linear regression models. Net N-mineralization rates in the humus layer and fine root biomass in the upper mineral soil influenced $ {\text{N}}{{\text{O}}_3}{^{ - }_{\text{seepage}}} $ positively. Fine root biomass in deeper soil layers (30?C40?cm depth) and stand density had a negative influence.

Conclusion

The rate of net N mineralization in the organic layer is decisive for the nitrate production in the soil. Roots in the upper mineral soil increase $ {\text{N}}{{\text{O}}_3}{^{ - }_{\text{seepage}}} $ by intensive water uptake but excluding nitrate at the same time. The variation of these two parameters is responsible for most of the small-scale variability of $ {\text{N}}{{\text{O}}_3}{^{ - }_{\text{seepage}}} $ .