Farmers’ Fruit Tree-growing Strategies in the Humid Forest Zone of Cameroon and Nigeria

Many studies have stressed the importance of trees to rural households. Few, however, have focused on actual numbers and densities of trees in different land-use systems. Based on community-level participatory research in six communities, semi-structured household interviews and full-farm fruit tree inventories, this study aims to understand farmers’ tree-planting strategies. Relationships between the diversity, number and density of fruit trees and farm size, land-use system, land tenure, distance from the homestead, proximity to the forest, market access and household characteristics are investigated. The key factors determining the differences in tree-growing strategies between communities appear to be market access, land use and access to forest resources. Within communities, differences between individual households were less easy to explain but tenure was important as was farm size. Smaller farms had higher fruit tree densities, a relationship that was particularly strong in communities with good market access. Overall there was a great deal of variability both within and between communities and many of the factors affecting tree-planting decisions were found to be highly inter-related. Despite this complexity, trees on farm play an important role in rural household's livelihoods. Therefore, expansion of tree cultivation should be recognized as a promising pathway to achieve increased income and food production by policy makers and extensionists alike. In addition to improved tree propagation and management techniques, farmers should be strengthened in the processing and marketing of agroforestry tree products and more emphasis should be placed on the development of tree enterprises. By doing so, farmers will be able to earn a more important and consistent income from fruit trees, contributing to the Millennium Development Goals.     

Invasion and persistence of Mycoplasma bovis in embryonic calf turbinate cells

Mycoplasma bovis is a wall-less bacterium causing bovine mycoplasmosis, a disease showing a broad range of clinical manifestations in cattle. It leads to enormous economic losses to the beef and dairy industries. Antibiotic treatments are not efficacious and currently no efficient vaccine is available. Moreover, mechanisms of pathogenicity of this bacterium are not clear, as few virulence attributes are known. Microscopic observations of necropsy material suggest the possibility of an intracellular stage of M. bovis. We used a combination of a gentamicin protection assay, a variety of chemical treatments to block mycoplasmas entry in eukaryotic cells, and fluorescence and transmission electron microscopy to investigate the intracellular life of M. bovis in calf turbinate cells. Our findings indicate that M. bovis invades and persists in primary embryonic calf turbinate cells. Moreover, M. bovis can multiply within these cells. The intracellular phase of M. bovis may represent a protective niche for this pathogen and contribute to its escape from the host’s immune defense as well as avoidance of antimicrobial agents.

Electronic supplementary material

The online version of this article (doi:10.1186/s13567-015-0194-z) contains supplementary material, which is available to authorized users.     

Einfluß des Belastungsgrades unterschiedlicher Böden an ausgewählten Pestizid wirkenden Chlorkohlenwasserstoffen auf deren Aufnahme durch Möhren im Gefäßversuch

Influence of contamination of selected, pesticid effective hydrocarbons on their uptake by carrots in a pot experiment Exemplary soils from low up to higher grades of contamination with selected pesticid effective hydrocarbons (CHC) were used in a pot experiment on the uptake of these xenobiotica by carrot plants. Carrots are able to take up pesticid effective chlorinated hydrocarbons which was expected because of their oil cells and the lipophilic character of the examined substances. There is a correspondingly higher plant uptake from soils with a higher load of pollutants as from soils with a lower grade of contamination. Despite the high concentrations of beta- and alpha-HCH in the plants from the site Muldenaue (mg/kg dm] the total uptake per pot was relatively small (below 2 mg/pot). The transferfactors soil/plant show in all plant parts no enrichment of organochlorpesticides (foliage 0.021 < carrot body 0.156 < fine roots 0.975).     

Determination of 2H/1H and 13C/12C isotope ratios of (E)-methyl cinnamate from different sources using isotope ratio mass spectrometry

For the authenticity assessment of (E)-methyl cinnamate from different origins, combustion/pyrolysis-isotope ratio mass spectrometry (C/P-IRMS) was used by an elemental analyzer (EA) and on-line capillary gas chromatography coupling (HRGC-C/P-IRMS). For that reason, (E)-methyl cinnamate self-prepared from synthetic, natural, and semisynthetic educts was analyzed in comparison to the commercial synthetic and natural ester. In addition, (E)-methyl cinnamate from basil extract and a number of commercial natural aromas was investigated. The data of self-synthesized synthetic (E)-methyl cinnamate, i.e., delta(13)C(V)(-)(PDB) = -33.8 per thousand and delta(2)H(V)(-)(SMOW) = +349 per thousand, corresponded with that found for the commercial synthetic samples (-29.5 to -31.4 per thousand and +328 to +360 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively). The ester produced from natural educts by acid as well as Candida antarctica catalysis revealed delta(13)C(V)(-)(PDB) = -25.6 and -30.1 per thousand as well as delta(2)H(V)(-)(SMOW) = -162 and -169 per thousand, respectively. Acid-catalyzed semisynthetic products differed in their delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) values depending on the origin of their educts. For the ester from synthetic methanol and natural cinnamic acid, -27.3 and -126 per thousand were determined for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively, whereas for the ester produced from natural methanol and synthetic acid delta(13)C(V)(-)(PDB) = -30.6 per thousand and delta(2)H(V)(-)(SMOW) = +287 per thousand were found. Basil extract showed -28.9 and -133 per thousand for delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW), respectively. Commercial aromas declared to be natural revealed delta(13)C(V)(-)(PDB) and delta(2)H(V)(-)(SMOW) data ranging from -25.7 to -28.5 per thousand as well as -85 to -191 per thousand, respectively, indicating, in part, incorrect declaration.     

Arbuscular mycorrhizal fungi and their response to pesticides

Arbuscular mycorrhizal fungi (AMF) form symbioses with the majority of plant species and can provide multiple benefits to the host plant. In agro‐ecosystems, the abundance and community structure of AMF are affected by agricultural management practices. This review describes and discusses current knowledge on the effects of inorganic and organic chemical pesticides on AMF in the conflicting area between agricultural use and environmental concerns. Variable effects have been reported following chemical pesticide use, ranging from neutral to positive and negative. Moreover, a species‐specific reaction has been documented. The reported effects of pesticides on arbuscular mycorrhizal symbiosis are very diverse, and even when the same substance is investigated, the results are often contradictory. These effects depend on many parameters, such as the active substance, the mode of action, the mode of application and the dosage. In the field, determinants such as the physico‐chemical behavior of the active substances, the soil type and other soil microorganisms contribute to the fate of pesticides and thus the amount of active substances to which AMF are exposed. This review highlights that the fate of AMF following pesticide use needs to be addressed in a broader agro‐ecosystem context. © 2018 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Plates of the dinosaur stegosaurus: forced convection heat loss fins?

It is suggested that the plates along the arched back and tail of Stegosaurus served an important thermoregulatory function as forced convection "fins." Wind tunnel experiments on finned models, internal heat conduction calculations, and direct observations of the morphology and internal structure of stegosaur plates support this hypothesis, demonstrating the comparative effectiveness of the plates as heat dissipaters, controllable through input blood flow rate, temperature, and body orientation (with respect to wind).     

Typing of heat-stable soluble Haemophilus parasuis antigen by means of agargel precipitation and the dot-blot procedure.

According to Morozumi's and Nicolet's (1986) investigations, a serological classification procedure for H. parasuis and to a certain extent, for H. parasuis-like strains was proposed on the basis of heat-stable cell antigens in the immunodiffusion test. It was possible to classify 72.8% of the investigated strains serologically using this procedure. 7 of 12 serotypes were described for the first time. 60.1% of the classified strains belonged to the already known serotypes SV 1 to SV 5, whereas the new serotypes SV Jena 6 to SV Jena 12 amounted to only 12.7% of the field isolates. The serotypes SV Jena 7 to 9 are represented by H. parasuis-like strains. Unencapsulated strains and isolates of serotype SV 5 dominate in animals with Glasser's disease. The serotypes SV 1, SV 5, Jena 6 and SV Jena 10 proved to be highly virulent in SPF pigs, SV 2 and SV 4 were of medium virulence. The other serotypes were non-virulent. The high specificity in AGPT was not reproducible in the more sensitive dot-blot procedure. This must be taken into account, if the dot-blot is to be used for the classification of serotypes of H. parasuis. The results point to a participation of nonimmunogenic polysaccharides in the detection reaction.