Seidenspinnerkokons aus den Jahren 1870 und 1940

Ohne Zusammenfassung     

Bedeutung von Regenwurmröhren für die Verlagerung des Herbizids Diuron in Böden von Obstanlagen

Herbicide translocation was investigated in a Haplic Luvisol from loess (clayey silt; Klein-Altendorf near Bonn, Germany) and a Eutric Cambisol (sandy loam; fluvial sediments on the lower Rhine terrace north of Bonn) using the herbicide diuron as an example. diuron was applied once a year in May at the recommended dose of 2.4 kg/ha. It rapidly degraded in the topsoil: the “time for 50% disappearance” (DT₅₀) was 14–30 days. A population of adapted soil micro-organisms, which is repeatedly exposed to applications of the same compound every year, is thought to be responsible for this fast degradation. Remaining Diuron residues were largely degraded in the loess soil during the subsequent summer and became less mobile due to increasing binding strength. As a result, residue levels and leaching in the loess soil during the winter were negligible, with diuron traces of less than 10 µg/kg below the topsoil 11 months after application. Comparison of the translocation in a sandy loam soil showed—as expected—that diuron was leached to the subsoil to a higher extent than in clayey silt (loess). However, in the loess soil, diuron leached to the subsoil via macropores after 20 mm of natural precipitation within 1 week after herbicide application due to macropore flow. Colour tracer and analysis of the linings of earthworm burrows identified these macropores as preferred pathways of herbicide leaching. Macropore flow occurred in wet soil and moist soil with a sealed surface or crust but not in dry soil. Superficial mechanical soil cultivation before the herbicide application is discussed as one possibility to interrupt macropore entries and reduce herbicide leaching after its application in the spring.     

The potential for the Rapid Screening of Potato Cultivars (Solanum tuberosum) for Resistance to Powdery Scab (Spongospora subterranea) using a Laboratory Bioassay

Powdery scab of potato, once established in a field, is difficult to control because of the longevity of the resting spores (cystosori) of the causal organism, Spongospora subterranea f.sp. subterranea. Host resistance is likely to be the most efficient in a long-term control strategy for preventing build-up of field inoculum and spread of the disease. Resistance screening of potato cultivars is mostly done in laborious field trials where disease development is likely to be unpredictable. A bioassay with potato tissue cultured plantlets and cystosori as inoculum is described and was tested for its potential to screen potato cultivars at an early stage for their relative susceptibility to powdery scab by comparing the lab results with field data. With cystosori inoculum of Swiss origin, the laboratory test showed clear differences between the potato cultivars in the severity of zoosporangial root infection which correlated better with ranked tuber infection data, compared to root galling. There are apparent differences in the relative trends in susceptibility between roots and tubers of five selected cultivars when using naturally infested soil instead of prepared cystosori as inoculum in the lab bioassay. Furthermore, differences in the severity of zoosporangial root infection of two selected cultivars were found when cystosori from different countries where used as inoculum. A possible host genotype × pathogen interaction is discussed. The bioassay has the potential to screen and select for resistant material at an early breeding stage thus making field trials not unnecessary but more economical. It will allow the use of a standard set of pathogen collections and facilitate testing for inoculum virulence in infested soils.     

Genetic diversity and historic introgression in German Angler and Red Dual Purpose cattle and possibilities to reverse introgression

Recovering native uniqueness has major importance for breeds with historic introgression. The aim of the study was to estimate population genetic parameters for two local red cattle breeds from Northern Germany and to study possibilities to reverse introgression. Genealogical information consisted of 90,783 individuals for German Angler and 187,255 individuals for Red Dual-Purpose cattle breed, with additional information on sex, born, breed, status, and conventional breeding values. It is concluded that the native genetic contribution could be included as an additional trait in the total merit index in order to recover a part of the native genetic background. Native contributions should be estimated in the long term from marker data in order to account for Mendelian sampling. The maintenance of a sufficient genetic diversity of native alleles can be achieved by an advanced OCS with appropriate constraints.     

CD117‐ and vimentin‐positive telocytes in the bovine teat sphincter

Mastitis is a common economically relevant problem in dairy farming. As the major entry for pathogens is the papillary duct, one of the first defence mechanisms is the teat sphincter. This sphincter shows a rhythmic contractility of yet unknown origin. Searching for possible modulatory pacemaker cells, teat sphincters of eight cows were stained immunohistochemically with antibodies against CD117 and vimentin and evaluated microscopically for the presence of telocytes. CD117‐ and vimentin‐positive telocytes with telopodes were found in close contact with smooth muscle cells. Our findings present a first evidence of telocytes in the teat of bovines.     

Single step genomic evaluation for female fertility in Nordic Red dairy cattle

Joint Nordic (Denmark, Finland, Sweden) genetic evaluation of female fertility is currently based on the multiple trait multilactation animal model (BLUP). Here, single step genomic model (ssGBLUP) was applied for the Nordic Red dairy cattle fertility evaluation. The 11 traits comprised of nonreturn rate and days from first to last insemination in heifers and first three parities, and days from calving to first insemination in the first three parities. Traits had low heritabilities (0.015–0.04), but moderately high genetic correlations between the parities (0.60–0.88). Phenotypic data included 4,226,715 animals with records and pedigree 5,445,392 animals. Unknown parents were assigned into 332 phantom parent groups (PPG). In mixed model equations animals were associated with PPG effects through the pedigree or both the pedigree and genomic information. Genotype information of 46,914 SNPs was available for 33,969 animals in the pedigree. When PPG used pedigree information only, BLUP converged after 2,420 iterations whereas the ssGBLUP evaluation needed over ten thousand iterations. When the PPG effects were solved accounting both the pedigree and the genomic information, the ssGBLUP model converged after 2,406 iterations. Also, with the latter model breeding values by ssGBLUP and BLUP became more consistent and genetic trends followed each other well. Models were validated using forward prediction of the young bulls. Reliabilities and variance inflation of predicted genomic breeding values (values for parent averages in brackets) for the 11 traits ranged 0.22–0.31 (0.10–0.27) and 0.81–0.95 (0.83–1.06), respectively. The ssGBLUP model gave always higher validation reliabilities than BLUP, but largest increases were for the cow fertility traits.