Inorganic ions and the hatching of Heterodera spp

Of various inorganic ions tested for their ability to stimulate hatching of eggs of the cyst nematodes of cereals (Heterodera avenae Woll), carrot (H. carotae Jones), cabbage (H. cruciferae Franklin), soybean (H. glycines Ichinohe), pea (H. goettingiana Liebs.), potato (H. rostochiensis Woll.), beet (H. schachtii Schm.), tobacco (H. tabacum Lownsbery & Lownsbery) and clover (H. trifolii Goffart), some were active. Zn²⁺ hatched many eggs of seven species and some of H. goettingiana, but inhibited hatch of H. avenae to below that in water. Zinc salts are the first recorded very active hatching stimulants for H. glycines in vitro. Many other metal ions stimulated hatching of H. schachtii eggs to varying extents; these also hatched some but not all of the other species. Vanadate ions were particularly effective for H. rostochiensis, more so than Zn²⁺. No ion increased the hatch of H. avenae to above that in water. The most active ions were not those most abundant in soil. The behaviour of different ions with different species did not suggest any obvious affinities between species, but the differences between the hatching of H. tabacum and H. rostochiensis add weight to the view that, despite morphological similarities and overlapping host ranges, they are distinct species rather than pathotypes of a single species. Ions and other hatching agents may be absorbed by materials within the egg or larva and alter the structure and function of these materials. The lack of correlation between the hatching of H. schachtii by ions and the known stability sequences of various biological metal-binding systems suggests that there may be several sites of action that differ in their response.     

Modeling Wolverine Occurrence Using Aerial Surveys of Tracks in Snow

ABSTRACT We designed a novel approach to determining extent of distribution and area of occupancy for wolverines (Gulo gulo) by using aerial surveys of tracks in snow and hierarchical spatial modeling. In 2005 we used a small, fixed-wing aircraft with pilot and one observer to search 575 of 588 survey units for wolverine tracks in approximately 60,000 km² of boreal forest in northwestern Ontario, Canada. We used sinuous flight paths to scan open areas in the forest in the 100-km² survey units. We detected tracks in 138 (24%) of the 575 sampled units. There was strong evidence of occurrence (probability of occurrence >0.80) in 30% of the 588 survey units, weak evidence of occurrence (0.50–0.80) in 12%, weak evidence of absence (0.20–0.50) in 15%, and strong evidence of absence (< 0.20) in 43%. Wolverine range comprised 59% of the study area and area of occupancy was 33,400 km². With information on probability of occurrence and core areas of occupation for wolverines in our study area, resource managers and others can examine factors that influence wolverine distribution patterns and use this information to formulate best management practices that will maintain wolverines on the landscape in the face of increasing resource development. Comparing future survey results with those of our 2005 survey will provide an objective way to assess the efficacy of management practices.     

GLOBALIZATION, HUMAN RIGHTS, AND THE SOCIAL DETERMINANTS OF HEALTH

Globalization, a process characterized by the growing interdependence of the world's people, impacts health systems and the social determinants of health in ways that are detrimental to health equity. In a world in which there are few countervailing normative and policy approaches to the dominant neoliberal regime underpinning globalization, the human rights paradigm constitutes a widely shared foundation for challenging globalization's effects. The substantive rights enumerated in human rights instruments include the right to the highest attainable level of physical and mental health and others that are relevant to the determinants of health. The rights stipulated in these documents impose extensive legal obligations on states that have ratified these documents and confer health entitlements on their residents. Human rights norms have also inspired civil society efforts to improve access to essential medicines and medical services, particularly for HIV/AIDS. Nevertheless, many factors reduce the potential counterweight human rights might exert, including and specifically the nature of the human rights approach, weak political commitments to promoting and protecting health rights on the part of some states and their lack of institutional and economic resources to do so. Global economic markets and the relative power of global economic institutions are also shrinking national policy space. This article reviews the potential contributions and limitations of human rights to achieving greater equity in shaping the social determinants of health.     

Mechanistic basis of differences in water-use efficiency between a CAM and a C3 species of Peperomia (Piperaceae)

Under ecologically realistic environmental conditions, the water-use efficiency (WUE) of Peperomia scandens , a CAM plant, was higher than that of the C₃ congener P. obtusifolia . This difference has been attributed to differences in stomatal activity between C₃ and CAM plants, coupled with differences in the evaporative demand of the atmosphere during which the stomata are open. This explanation has apparently not, however, been experimentally tested. Thus, WUEs were compared in these species in two experiments in which the atmospheric evaporative demand was identical (or nearly so) during the period of stomatal opening (i.e. during the night for the CAM plant and during the day for the C₃ species). In both experiments, the WUE of the CAM species was higher than that of the C₃ species. These results suggest that factors other than differences in atmospheric environmental conditions must also be responsible for the observed differences in WUE. Because CO₂ uptake rates of the CAM species were substantially lower than those of the C₃ species, the lower WUE in the CAM species resulted primarily from lower transpiration rates. Lower rates of water loss in P. scandens , relative to rates in P. obtusifolia , were ascribed, in part, to lower stomatal densities. Thus, leaf morphological differences, in addition to differences in atmospheric evaporative demand, help to explain the high WUE typically measured in CAM plants.     

Testing the hypothesis of greater eurythermality in invasive than in native ladybird species: from physiological performance to life‐history strategies

1. Global warming and biological invasions are important threats to biodiversity. Nonetheless, there is little information on how these factors influence performance or life‐history traits of invasive and native species. 2. The effects of temperature on physiological and fitness traits of two invasive alien species (Harmonia axyridis and Hippodamia variegata) and one native species (Eriopis chilensis) of coccinellid were evaluated, testing a model of eurythermality. Eggs of all species were exposed to four temperature treatments (20, 24, 30 and 33 °C). In adult F₂ we measured fecundity, locomotor performance, development time (total and per life stage), survival, and preferred body temperature in a thermal gradient. 3. It was found that H. axyridis had comparatively better performance at low temperatures (i.e. 20 °C), while the performance of H. variegata and E. chilensis did not change with temperature or was better at higher temperatures (30 °C). The standardised Levins index showed that all species are eurythermic. E. chilensis had a high niche overlap with the invasive alien ladybird species, rejecting the hypothesis of greater eurythermality of invasive species than native species. 4. Although there were differences in the temperature preferences and in the response of some physiological and life‐history traits of ladybirds to temperature, both the native and invasive alien species are eurythermic, contrary to the prediction. The better performance of H. axyridis at lower temperatures may result in displacement of its current distribution, and thus not all invasive species will respond favourably to global warming.