Plant surface wax affects parasitoid’s response to host footprints

The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants (cer-za.126, cer-yp.949) and wild-type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild-type plants and on both cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones.     

Exit and voice: A test of hypotheses based on fight/flight responses to job stress

Hypotheses were developed based on a coping model that views political behaviour (voice) as a fight response and turnover (exit) as a flight response to job stress. Data were collected from a group of professional, public employees and turnover dates were obtained for the group 13 months after completion of questionnaires. Multiple regression analysis was employed to test hypotheses. Stressors of interest were person-environment fit (P-E fit), role conflict (RC), and role ambiguity (RA). Psychological strains (job dissatisfaction and lowered commitment) were hypothesized to mediate the stressor-coping behaviour relationship. Turnover (TO) behaviour was the ultimate organizationally relevant outcome of coping behaviours. Job satisfaction and commitment were significantly related to intentions to leave. Political action was directly related to P-E fit and this relationship was not mediated by satisfaction or commitment. The relationship between RA and politics was moderated by commitment. Less committed employees tended to exhibit political behaviour in response to RA. Both coping responses (intentions to leave and political action) predicted significant portions of retention/turnover variance.     

Configuration of a functional department: A study of contextual and structural variables

This study investigates whether departments performing the same functions in different firms incur similar changes in structural configuration in response to industry-wide stimuli. Based on the proposition that the context of functional departments is similar across firms, changes in differentiation, integration, and perspective are hypothesized. Managers' perceptions of the validity of a series of statements to conditions five to 10 years ago and to present conditions are contrasted and show statistically significant shifts in these structural configurations. This change is confirmed by the analysis of responses of other managers in different departments within the same firms. Correlation analysis shows significant agreement among alternative measures of the same aspects of structure, and significant comovement among different structural dimensions. The later result supports the quantum theory of organizations.     

An energy systems view of sustainability: emergy evaluation of the San Luis Basin, Colorado

Energy Systems Theory (EST) provides a framework for understanding and interpreting sustainability. EST implies that "what is sustainable" for a system at any given level of organization is determined by the cycles of change originating in the next larger system and within the system of concern. The pulsing paradigm explains the ubiquitous cycles of change that apparently govern ecosystems, rather than succession to a steady state that is then sustainable. Therefore, to make robust decisions among environmental policies and alternatives, decision-makers need to know where their system resides in the cycles of change that govern it. This theory was examined by performing an emergy evaluation of the sustainability of a regional system, the San Luis Basin (SLB), CO. By 1980, the SLB contained a climax stage agricultural system with well-developed crop and livestock production along with food and animal waste processing. The SLB is also a hinterland in that it exports raw materials and primary products (exploitation stage) to more developed areas. Emergy indices calculated for the SLB from 1995 to 2005 revealed changes in the relative sustainability of the system over this time. The sustainability of the region as indicated by the renewable emergy used as a percent of total use declined 4%, whereas, the renewable carrying capacity declined 6% over this time. The Emergy Sustainability Index (ESI) showed the largest decline (27%) in the sustainability of the region. The total emergy used by the SLB, a measure of system well-being, was fairly stable (CV?=?0.05). In 1997, using renewable emergy alone, the SLB could support 50.7% of its population at the current standard of living, while under similar conditions the U.S. could support only 4.8% of its population. In contrast to other indices of sustainability, a new index, the Emergy Sustainable Use Index (ESUI), which considers the benefits gained by the larger system compared to the potential for local environmental damage, increased 34% over the period.     

A factor analytic study of attitudinal structure and its impact on rural landowners' access policies

Previous research has shown that rural landowners' hunter access policies are determined in large part by their attitudes towards hunters, legal liability, conservation, and economic incentives. The results of this study support this research and indicate that East Texas, USA, landowners' decisions to allow or restrict access are based, in part, on attitudes toward hunter behavior, hunting as a social activity, leasing as a management practice, and a perceived obligation toward wildlife stewardship. Attitude-based profiles of landowners who adopted one of four access policies are compared.     

Characterization of iron- and manganese-cemented redoximorphic aggregates in wetland soils contaminated with mine wastes

In wetlands, translocation of Fe and Mn from reducing to oxidizing zones creates localized enrichments and depletions of oxide minerals. In zones of enrichment, oxides cement matrix particles together into aggregates. In this paper, we describe the various Fe- and Mn-cemented features present in the 1 to 2-mm size fraction of mine-waste contaminated wetland soils of the Coeur d'Alene (CDA) River Basin in northern Idaho. These aggregates are categorized based on color and morphology. Total Fe and Mn concentrations are also reported. Distribution of the aggregates in soil profiles along an elevation transect with varying water table heights was investigated. Six distinct categories of aggregates were characterized in the 1 to 2-mm size fraction. The two most predominant categories were aggregates cemented by only Fe oxides and aggregates cemented by a mixture of Fe and Mn oxides. Iron-depleted aggregates, Fe and Mn-cemented sand aggregates, and root channel linings were also identified. The remaining aggregates were categorized into a catch-all category that consisted of primarily charcoal particles. The highest Fe content was in the root channel linings, and the highest Mn content was in the Fe/Mn cemented particles. Iron-cemented aggregates were most common in surface horizons at all sites, and root channels were most common in the 30 to 45-cm core at the lowland point, reflecting the presence of deep rooting vegetation at this site. Spatial distributions of other aggregates at the site were not significant.     

REAL-TIME SNOW SIMULATION MODEL FOR THE MONONGAHELA RIVER BASIN1

ABSTRACT: The Pittsburgh District, U.S. Army Corps of Engineers, is responsible for operating two multipurpose reservoirs in the 7384 square mile (19198 square kilometer) Monongahela Basin. A third reservoir, presently under construction, will soon be operating. The real-time forecasting of runoff for operational purposes requires simulation of snow accumulation and snowmelt throughout the Basin during the winter season. This article describes capabilities of SNOSIM, a model being developed for performing such simulation. The application of this model as part of a comprehensive system of water control software, and some initial simulation results are presented.     

Principles and issues in radiological ecological risk assessment

This paper provides a bridge between the fields of ecological risk assessment (ERA) and radioecology by presenting key biota dose assessment issues identified in the US Department of Energy's Graded Approach for Evaluating Radiation Doses to Aquatic and Terrestrial Biota in a manner consistent with the US Environmental Protection Agency's framework for ERA. Current radiological ERA methods and data are intended for use in protecting natural populations of biota, rather than individual members of a population. Potentially susceptible receptors include vertebrates and terrestrial plants. One must ensure that all media, radionuclides (including short-lived radioactive decay products), types of radiations (i.e., alpha particles, electrons, and photons), and pathways (i.e., internal and external contamination) are combined in each exposure scenario. The relative biological effectiveness of alpha particles with respect to deterministic effects must also be considered. Expected safe levels of exposure are available for the protection of natural populations of aquatic biota (10 mGy d(-1)) and terrestrial plants (10 mGy d(-1)) and animals (1 mGy d(-1)) and are appropriate for use in all radiological ERA tiers, provided that appropriate exposure assumptions are used. Caution must be exercised (and a thorough justification provided) if more restrictive limits are selected, to ensure that the supporting data are of high quality, reproducible, and clearly relevant to the protection of natural populations.     

Vacuum promotes metabolic shifts and increases biogenic hydrogen production in dark fermentation systems

The successful operation of any type of hydrogen-producing bioreactor depends on the performance of the microorganisms present in the system. Both substrate and partial gas pressures are crucial factors affecting dark fermentation metabolic pathways. The main objective of this study was to evaluate the impact of both factors on hydrogen production using anaerobic granular sludge as inoculum and, secondly, to study the metabolic shifts of an anaerobic community subjected to low partial gas pressures. With this goal in mind, seven different wastewater (four synthetic media, two industrial wastewater, and one domestic effluent) and the effect of applying vacuum on the systems were analyzed. The application of vacuum promoted an increase in the diversity of hydrogenproducing bacteria, such as Clostridium, and promoted the dominance of acetoclastic- over hydrogenotrophic methanogens. The application of different media promoted a wide variety of metabolic pathways. Nevertheless, reduction of the hydrogen partial pressure by application of vacuum lead to further oxidation of reaction intermediates irrespective of the medium used, which resulted in higher hydrogen and methane production, and improved the COD removal. Interestingly, vacuum greatly promoted biogenic hydrogen production from a real wastewater, which opens possibilities for future application of dark fermentation systems to enhance biohydrogen yields.     

氯乙酰苯胺除草剂及其降解产物在肯尼亚Nzoia流域的演变

采用气相色谱法对肯尼亚沿Nzoia河9个地点的水样和沉积物样中草不绿(也称杂草锁)(α'-氯-N-(2,6-二乙基苯基)-N-(甲氧基甲基)乙酰胺)、甲氧毒草安(α-氯6'-乙基-N-(2甲氧基-1-甲基乙基)乙酰邻甲苯胺)及它们各自环境稳定的苯胺类降解物2,6-二乙基苯胺、2-乙基-6-甲基苯胺进行分析.降解物在90%以上的沉积物样和水样中检出,而母体化合物只在不到14%的水样中检出.沉积物中的杀虫剂和它们的降解物比在水中浓度高很多(1.4～10 800倍),显示出化合物在沉积物中的积累.在研究时间内沉积物中降解物的普遍存在意味着这些化合物的持续性.可以假定在热带气候为主的条件下,促使杀虫剂快速分解为环境稳定的降解物,从而在研究区域内使后者成为比其母体更重要的污染物.