Dispersal and tributary immigration by juvenile coho salmon contribute to spatial expansion during colonisation     

Joseph H. Anderson  George R. Pess  Peter M. Kiffney  Todd R. Bennett  Paul L. Faulds  William I. Atlas  Thomas P. Quinn 《Ecology of Freshwater Fish》2013,22(1):30-42

Anadromous fishes are frequently restricted by artificial barriers to movement such as dams and culverts, so measuring dispersal helps identify sites where improved connectivity could promote range expansion and population viability. We used a combination of DNA‐based parentage analysis and mark–recapture techniques to evaluate dispersal by juvenile coho salmon (Oncorhynchus kisutch) in a population in the initial stages of colonisation following installation of fish passage structures at a previously impassable dam on the Cedar River, WA, USA. The spatial distribution of individuals within maternal families revealed that dispersal was common. Among the offspring of radio‐tagged mothers, 28% were collected outside the spawning reach and dispersed up to 6.3 km (median = 1.5 km). Most juveniles captured in a tributary (Rock Creek, where few adults spawned) had immigrated from the Cedar River and represented many different families. Juvenile dispersal therefore provided a secondary phase of spatial expansion following initial colonisation by adults. Consistent with the condition‐dependent dispersal hypothesis, juveniles that dispersed farther upstream in the tributary were larger than fish collected near the tributary mouth. Overall, the results demonstrated widespread dispersal in a system with low coho salmon densities, and this might increase the rate of population growth if it reduces the effects of local density dependence. By implication, juveniles can take advantage of rearing habitats reconnected through barrier removal, even when such areas are located several kilometres from adult breeding grounds.  相似文献   

Major Extractable Organic Compounds in the Biologically Degradable Fraction of Fresh,Composted and Anaerobically Digested Household Waste     

Marie-Louise Nilsson  Henrik Kylin  Peter Sundin 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(2):57-65

The recirculation of plant nutrients from urban areas to agriculture and horticulture and a need to reduce waste disposal by landfilling and incineration are the main reasons for recycling the biologically degradable fraction of household waste. However, before using the recycled material in agricultural and horticultural production it is necessary to make sure that the material does not contain any unwanted contaminants. In general, there is a lack of knowledge about organic contaminants in the degradable fraction of household waste and its compost and anaerobic digestion products. As a first step in a study of organic contaminants in household waste, and as part of the characterization of the degradation processes during composting and anaerobic digestion, the major extractable organic compounds were identified in the biologically degradable fraction of fresh, composted and anaerobically digested household waste. The organic compounds were isolated by supercritical fluid extraction using carbon dioxide as extraction medium. Gas chromatography-mass spectrometry was used for qualitative analyses. Natural products, such as fatty acids, fatty acid esters, n-alkanes, aliphatic alcohols, monoterpenes and triterpenes constituted the major organic components in the waste samples. In addition bis-(2-ethylhexyl) phthalate, frequently used as a plasticizer in polymers, was found in the extracts. In the chromatograms of the extracts of the fresh and composted household waste, fatty acids and fatty acid esters dominated with respect to peak heights and the number of peaks identified. In the anaerobically digested household waste n-alkanes were the dominating compound class. The pattern of the n-alkanes, also found in the fresh waste, possibly indicates a petrogenic origin of these compounds, perhaps caused by contamination during the collection of the household waste.  相似文献   

Preface     

Peter Shewry 《Journal of Cereal Science》2013

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Effect of glyphosate on the tripartite symbiosis formed by Glomus intraradices,Bradyrhizobium japonicum,and genetically modified soybean     

Jeff R. Powell  Rachel G. Campbell  Kari E. Dunfield  Robert H. Gulden  Miranda M. Hart  David J. Levy-Booth  John N. Klironomos  K. Peter Pauls  Clarence J. Swanton  Jack T. Trevors  Pedro M. Antunes 《Applied soil ecology》2009,41(1):128-136

Most soybeans grown in North America are genetically modified (GM) to tolerate applications of the broad-spectrum herbicide glyphosate; as a result, glyphosate is now extensively used in soybean cropping systems. Soybean roots form both arbuscular mycorrhizal (AM) and rhizobial symbioses. In addition to individually improving host plant fitness, these symbioses also interact to influence the functioning of each symbiosis, thereby establishing a tripartite symbiosis. The objectives of this study were to (1) estimate the effects of glyphosate on the establishment and functioning of AM and rhizobial symbioses with GM soybean, and (2) to estimate the interdependence of the symbioses in determining the response of each symbiosis to glyphosate. These objectives were addressed in two experiments; the first investigated the importance of the timing of glyphosate application in determining the responses of the symbionts and the second varied the rate of glyphosate application. Glyphosate applied at recommended field rates had no effect on Glomus intraradices or Bradyrhizobium japonicum colonization of soybean roots, or on soybean foliar tissue [P]. N₂-fixation was greater for glyphosate-treated soybean plants than for untreated-plants in both experiments, but only when glyphosate was applied at the first trifoliate soybean growth stage. These data deviate from previous studies estimating the effect of glyphosate on the rhizobial symbiosis, some of which observed negative effects on rhizobial colonization and/or N₂-fixation. We did observe evidence of the response of one symbiont (stimulation of N₂-fixation following glyphosate) being dependent on co-inoculation with the other; however, this interactive response appeared to be contextually dependent as it was not consistent between experiments. Future research needs to consider the role of environmental factors and other biota when evaluating rhizobial responses to herbicide applications.  相似文献   

Inactivation of fenitrothion on stored maize at different moisture contents     

Peter R. Samson  Russell J. Parker  Julie A. Keating 《Pest management science》1988,22(1):83-92

Biological activity of fenitrothion on stored maize at various moisture contents and at different times after application was measured by biological assay using adults of Tribolium castaneum (Herbst). Inactivation of actual residues over time was then determined after making the necessary allowance for chemical breakdown. At a given moisture content, the inactivation process was substantially completed during the first 6 weeks after application and loss of effectiveness from 6 weeks onwards resulted mainly from chemical breakdown. At a given time after application, residues were less active at higher moisture content (m.c). Differences in activity between moisture contents were apparent within a few hours of application and continued to increase for up to 3 days, with relatively little change thereafter during storage of 24 weeks. Thus after 24 weeks, residues on maize of 18% m.c. had an activity about 20% that of similarly-aged residues at 10% m.c. and 4% that of freshly-applied residues at 10% m.c. These results were in general accord with changes in the proportion of the residue which was collected from the kernels by a surface wash with methanol, this readily-extractable residue presumably representing the insecticide that may be picked up by insects.  相似文献   

Imidazolinone herbicides: Synthesis and novel chemistry     

Peter Wepplo 《Pest management science》1990,29(3):293-315

The imidazolinone herbicides were prepared from reaction of an α- methylvaline fragment with an o-dicarboxylic acid. Early syntheses were completed through an imide amide intermediate, such as I or XV , followed by further cyclization to 2,5-diones III or XXI . Reaction of these diones with nucleophiles led to imidazolinones IV and V . The significant and interesting activity of these compounds led to new and versatile methods of synthesis, including resolution of the α-methylvaline fragments, development of a metallation-carboxylation route, a one-step picoline to imidazolinone route, and several pyridine and fused-ring pyridine syntheses.  相似文献   

Industrieberichte     

Peter Fritsch  Werner Knaus  Gerhard Merkl  Erwin Preininger  Joachim Rautenberg  et al. 《Anzeiger für Sch?dlingskunde》1991,64(2):40

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Permethrin treatments in canadian forests. Part 1: Impact on stream fish     

Peter D. Kingsbury  David P. Kreutzweiser 《Pest management science》1987,19(1):35-48

The effects of permethrin on native and caged fish when aerially applied directly to forest streams at dosages between 8.8 and 70 g ha^?1 were studied between 1976 and 1981. None of the applications caused mortality of caged or native fish in streams. Trout and salmon diets were altered by the treatments due to effects on fish food organisms. The duration of the effects varied from several months to over a year with increasing dosage. Reductions in salmonid growth rates and reductions in fish densities in treated areas, presumably due to emigration, were documented following severe impacts on aquatic invertebrates in salmon nursery streams. Growth rates and population densities both recovered within four months after treatment.  相似文献   

Permethrin treatments in canadian forests. Part 2: Impact on stream invertebrates     

David P. Kreutzweiser  Peter D. Kingsbury 《Pest management science》1987,19(1):49-60

A series of experiments was conducted between 1977 and 1981 to evaluate the effects of aerially applied permethrin on forest stream invertebrates. All permethrin applications to forest streams resulted in large drift increases, and most produced measurable reductions in benthos density. Recovery of benthic fauna following the various permethrin applications was apparent from 1 to 18 months post-spray. In double-application experiments, the second treatments reduced benthos density to a point at which recovery of numbers was slower than after the impact resulting from a single application of the same dosage.  相似文献   

Modelling the microbial breakdown of pesticides in soil using a parameter estimation technique     

Jos P. M. Vink  Peter Nrtersheuser  Otto Richter  Bernd Diekkrüger  Klaas P. Groen 《Pest management science》1994,40(4):285-292

Results of field measurements and laboratory experiments were used to simulate the behaviour of 1,3-dichloropropene (1,3-D) in a loamy sand soil. Microbial activity was described using pre-set conditions to compute transformation rates as dependent on compound concentrations and temperature. These kinetics could only be analysed using non-linear transformation rates. To link the development of microbial populations and the consumption of the compound over time, an iterative technique was used to estimate the necessary parameters.  相似文献