Predicting quantitative host plant resistance against phoma black stem in sunflower

Phoma black stem is an important disease in sunflower, against which no specific management method is currently deployed in France. Relevant phenotyping methods for quantitative resistance are critical for integration of this trait into breeding programmes. Components of resistance associated with physiological resistance, and morphological traits associated with disease escape were measured on 21 sunflower genotypes under growth chamber (on seedlings), greenhouse (on adult plants), and field conditions, together with disease intensity in the field. Potential predictors were first selected for sensitivity and robustness from mixed model anova s. Analyses involving ranking tests and logistic regressions were then performed to identify predictors for field resistance. The identification of predictors for resistance involved analyses conducted in two broad steps: process‐oriented experiments, and epidemic‐oriented experiments. This stepwise approach departs from many studies aimed at identifying predictors for field resistance, which rely mainly on the computation of correlation coefficients between predictors and measured field disease variables. Predictors for quantitative resistance were identified: (i) lesion length and lesion expansion on stems of plants before flowering stage, and (ii) lesion length on first leaf petioles of seedlings. A high number of leaves and tall plants were associated with disease escape. Control genotypes for susceptibility and quantitative resistance were identified, and implications for breeding and improvements were derived from this work.     

Parameters influencing service dogs' quality of response to commands: Retrospective study of 71 dogs

A retrospective study was carried out on 71 dogs to determine the parameters influencing the quality of service provided by service dogs and to modify the dog training and selection. The questionnaires were mailed 3 years after placing the dogs with disabled people. Two co-joined medical and veterinary studies were carried out. The questionnaires covered the quality of life and service evaluation of the dogs and owners. The response rate was 76%. Two classes of dogs were set up according to the capacity of carrying out the commands and then crossed with dog and owner characteristics to determine any correlation. No dog characteristics correlated with the quality of response to commands. The human population was very heterogeneous and the mobility of some owners was very restricted. However, the quality of service only correlated with the vocal capacity of the owners and did not correlate with the physical capacity of the owner. The study emphasizes the importance of nonverbal communication and voice strength when communicating with dogs, and stresses the importance of the applicant selection process to ensure the success of the program.     

Simulating multiple pest damage in varying winter wheat production situations

The production situation–injury profile paradigm can be used as a framework to assess the harmfulness of multiple-pest complexes in a changing agriculture. A mechanistic simulation model for wheat, WHEATPEST, was developed to incorporate drivers of (i) variable production situations and (ii) their related injury profiles. The model simulates the harmful effects of pathogens, pests, and weeds in a simple, open, generic manner. Simulation drivers were derived from published reports, in particular through a meta-analysis of highly detailed farmers’ field surveys in the United Kingdom and the Netherlands. Preliminary analysis of the model's performances indicates that WHEATPEST conforms with available published reports in a range of production situations and injury profiles. While improvement on some components of the model are discussed, this work points at the need for the collection of cross-disciplinary, reasonably accurate, and standardised data at a system's level, and at the usefulness of modelling tools for basic research and policy.     

Phagocytosis and Related Phenomena in Polymorphonuclear Leukocytes from Cow's Milk

There were fewer efficient phagocytes among leukocytes collected from artificially irritated mammary glands than among the leukocytes from blood of the same animals. The milk polymorphonuclear (PMN) leukocytes adhered poorly to a column of siliconised glass beads when compared with the blood cells. However, investigations of the O₂ uptake and CO₂ production of the milk PMN leukocytes revealed that these cells appeared to utilize metabolic pathways similar to those used by human and guinea pig PMN leukocytes during phagocytosis. These pathways are associated with degranulation and the production of H₂O₂ following particle ingestion. It is therefore suggested that the milk PMN leukocytes appear not to have lost the ability to produce this bactericidal substance.     

Exploring Patterns of Exotic Earthworm Distribution in a Temperate Hardwood Forest in South-Central New York, USA

Exotic earthworms invading forests in Canada and northeastern United States that were naturally devoid of large detritivores cause major changes in ecosystem function. To assess their long-term impacts, studies are needed to elucidate the factors that control the patterns of earthworm invasion at the landscape level. We analyzed the distribution patterns of exotic earthworms in a northern hardwood forest in south-central New York (USA), as explained by landscape variables thought to be important in determining earthworm distribution. Forest type, slope angle, elevation, and the distance to agricultural clearings and wet refugia were significant predictors of earthworm presence, whereas local wetness index and the distance to streams and roads were not. Forest type and distance to agricultural clearings were the two most significant predictors. Our data suggest that areas close to agricultural clearings, dominated by mixed hardwoods, and located towards valley bottoms or on gentle slopes are very likely to support communities of exotic earthworms. Steeper slopes, areas dominated by American beech or eastern hemlock, and locations in the core of extensive forest landscapes have lower probabilities of invasion by exotic earthworms. When applied to a nearby area, our statistical model correctly predicted earthworm presence for 67% of 377 sampling points. Most of the mistakes were incorrect predictions of earthworm absence, suggesting that our statistical model slightly underestimated earthworm presence, possibly because of the pervasive influence of active agricultural fields adjacent to the test site.     

Correction to: Coupling landscape graph modeling and biological data: a review

Landscape Ecology - In the original publication of the article, the sixth author name has been misspelt. The correct name is given in this Correction. The original article has been corrected.     

Environmental and site factors controlling the vertical distribution and radiocarbon ages of organic carbon in a sandy soil

Soil organic carbon (SOC) content and radiocarbon concentration were measured in three particle-size fractions and charcoal fragments at four depths to bedrock in a sandy soil from SE Australia. SOC content declined with depth for all fractions. The enrichment factors of SOC showed that the finest particles are most important for SOC storage throughout the soil profile, and their importance for SOC storage increased with depth. In the topsoil, all particle-size fractions contained modern SOC. In contrast, charcoal from this depth gave radiocarbon ages of 85–165 years Before Present (BP). This difference was more pronounced at 30–60 cm, where the charcoal was dated at 2,540 years BP, over 12 times as old as the youngest fraction at that depth. These results confirm charcoal as a highly stable form of SOC. The radiocarbon data in the topsoil and near bedrock indicate that neither microaggregation nor mineral association is important for SOC stability in this soil. At intermediate sampling depths, the mid-sized fraction was the oldest. We believe that this is the result of charcoal accumulation in this fraction, inducing a shift in radiocarbon age. However, near bedrock (100–120 cm), radiocarbon concentration did not differ significantly between fractions, despite greater SOC retention in smaller fractions. In addition, radiocarbon ages at 100–120 cm indicate that charcoal is not present at this depth. We propose that environmental and soil conditions (substrate limitation, water and oxygen availability, and temperature) are responsible for the stabilization of SOC at this depth, where SOC concentrations were very low (0.1–0.3 %). Our results demonstrate that, although fine particles retain more SOC than coarse ones, they do not stabilize SOC in this sandy soil. Instead, environmental (bushfires and climate) and site factors (soil texture and soil mineralogy) control the distribution and stability of SOC throughout the soil profile.