Monitoring glyphosate residues in transgenic glyphosate-resistant soybean     

Arregui MC  Lenardón A  Sanchez D  Maitre MI  Scotta R  Enrique S 《Pest management science》2004,60(2):163-166

The availability of Roundup Ready (RR) varieties of soybean has increased the use of glyphosate for weed control in Argentina. Glyphosate [(N-phosphonomethyl)glycine] is employed for the eradication of previous crop vegetation and for weed control during the soybean growing cycle. Its action is effective, and low environmental impact has been reported so far. No residues have been observed in soil or water, either of glyphosate or its metabolite, AMPA (aminomethylphosphonic acid). The objective of this work was to monitor glyphosate and AMPA residues in soybean plants and grains in field crops in Santa Fe Province, Argentina. Five sites were monitored in 1997, 1998 and 1999. Individual soybean plants were sampled from emergence to harvest, dried and ground. Analysis consisted in residue extraction with organic solvents and buffers, agitation, centrifugation, clean-up and HPLC with UV detection. In soybean leaves and stems, glyphosate residues ranged from 1.9 to 4.4 mg kg(-1) and from 0.1 to 1.8 mg kg(-1) in grains. Higher concentrations were detected when glyphosate was sprayed several times during the crop cycle, and when treatments approached the flowering stage. AMPA residues were also detected in leaves and in grains, indicating metabolism of the herbicide.  相似文献   

Association between cellulitis (enlarged sternal bursa) and focal ulcerative dermatitis in Ontario turkeys at the time of processing     

St-Hilaire S  Arellano S  Ribble C 《Avian diseases》2003,47(3):531-536

We conducted a processing plant survey to determine the prevalence of cellulitis (enlarged sternal bursa) and focal ulcerative dermatitis (FUD) in Ontario turkeys during the summer and to establish whether the two conditions were associated. A total of 11,772 birds from 24 different farms were observed at three processing plants in Ontario between June and August 2001. Each bird was examined for the presence of cellulitis and FUD. The severity and location of lesions were also noted. The overall prevalence of severe cellulitis (requiring either extensive trimming or condemnation of the bird) was 8.8% (95% confidence interval [CI] = 6.7, 10.9) and the overall prevalence for FUD was 22.6% (19.3, 25.9). The Pearson correlation coefficient between the prevalences of the two lesions was 0.56 (P = 0.0043), suggesting farms with a high prevalence of FUD in their birds also had a high prevalence of cellulitis. More specifically, birds with FUD were, on average, 10.8 times more likely to have cellulitis than birds without FUD (Mantel-Haenszel summary odds ratio = 10.8; 95% CI = 9.5, 12.3). Our observations suggest FUD may predispose birds to cellulitis, in which case, preventing FUD may reduce the occurrence of cellulitis condemnations in turkeys.  相似文献   

Thermal decomposition and isomerization of cis-permethrin and beta-cypermethrin in the solid phase     

González Audino P  Licastro SA  Zerba E 《Pest management science》2002,58(2):183-189

The stability to heart of cis-permethrin and beta-cypermethrin in the solid phase was studied and the decomposition products identified. Samples heated at 210 degrees C in an oven in the dark showed that, in the absence of potassium chlorate (the salt present in smoke-generating formulations of these pyrethroids), cis-permethrin was not isomerized, although in the presence of that salt, decomposition was greater and thermal isomerization occurred. Other salts of the type KXO3 or NaXO3, with X being halogen or nitrogen, also led to a considerable thermal isomerization. Heating the insecticides in solution in the presence of potassium chlorate did not produce isomerization in any of the solvents assayed. Salt-catalysed thermal cis-trans isomerization was also found for other pyrethroids derived from permethrinic or deltamethrinic acid but not for those derived from chrysanthemic acid. The main thermal degradation processes of cis-permethrin and beta-cypermethrin decomposition when potassium chlorate was present were cyclopropane isomerization, ester cleavage and subsequent oxidation of the resulting products. Permethrinic acid, 3-phenoxybenzyle chloride, alcohol, aldehyde and acid were identified in both cases, as well as 3-phenoxybenzyl cyanide from beta-cypermethrin. A similar decomposition pattern occurred after combustion of pyrethroid fumigant formulations.  相似文献   

A Laboratory method for estimating survival of tobacco whitefly nymphs after insecticide treatment,based on honeydew excretion     

Venezia Melamed-Madjar  U. Gerson  Susana Tal 《Phytoparasitica》1983,11(1):25-32

A quick and easy method for estimating the number of surviving nymphs of the tobacco whitefly (TWF),Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), after spray applications was developed in the laboratory. The method is based on the number of honeydew droplets ejected by TWF immatures during 30 minutes. Since the nymphs ofB. tabaci feed on the lower leaf surfaces, the honeydew excreted falls downward. In this study infested cotton leaves were placed with their lower side up, forcing the nymphs to eject the honeydew droplet upwards. Inverted plastic petri dish covers were placed over infested cotton leaves and after 30 minutes the droplets deposited on the inner side of each cover were counted and the average number of droplets per nymph was calculated. To estimate the number of live nymphs on an infested cotton leaf, the number of droplets ejected during 30 minutes was divided by the average number of droplets per nymph (factor of 1.23).  相似文献   

Polymerase chain reaction typing of genes of the locus of enterocyte effacement of ruminant attaching and effacing Escherichia coli          下载免费PDF全文

María Yuste  Jos A. Orden  Ricardo De La Fuente  Jos A. Ruiz-Santa-Quiteria  Dolores Cid  Susana Martínez-Pulgarín    Gustavo Domínguez-Bernal 《Canadian journal of veterinary research》2008,72(5):444-448

The variability of the tir, espA, and espD genes of the locus of enterocyte effacement (LEE) in 185 attaching and effacing Escherichia coli (AEEC) strains isolated from healthy and diarrheic cattle, sheep, and goats was investigated by polymerase chain reaction. Nineteen of the strains were enterohemorrhagic E. coli (EHEC); the other 166 were enteropathogenic E. coli (EPEC). The combinations of the tir and esp genes were associated with the variants of the eae gene but not with a strain’s belonging to the EPEC or EHEC group, animal species, or health status (healthy or diarrheic) of the animal. In addition, most of the strains showed the same combinations of LEE genes and serogroups as have been found in AEEC strains isolated from humans, which indicates that ruminants seem to be an EPEC reservoir for humans.  相似文献   

Evaluation of inciting causes, alternative targets, and risk factors associated with redirected aggression in cats     

Amat M  Manteca X  Brech SL  Ruiz de la Torre JL  Mariotti VM  Fatjó J 《Journal of the American Veterinary Medical Association》2008,233(4):586-589

OBJECTIVE: To identify inciting causes, alternative targets, and risk factors associated with redirected aggression in cats. DESIGN: Case-control study. ANIMALS: 19 cats with a history of redirected aggression and 64 cats with no such history. PROCEDURES: Medical records were reviewed to identify cats evaluated for problems with redirected aggression (case cats), in which the primary inciting stimulus and alternative target of aggression were clearly identifiable. Data obtained from the records and from follow-up interviews included details about the cats and incidents of redirected aggression. Owners of control cats were interviewed via telephone to obtain similar information on their cats. RESULTS: 22 incidents of redirected aggression were reported for the 19 case cats. In 95% of those incidents, loud noises or interactions with other cats were identified as the inciting stimuli. Case cats most commonly redirected their aggression toward the owner, followed by another cat living in the same household. Compared with control cats, case cats were more likely to have a sound phobia but were less likely to be outdoor cats. In addition, case cats were more likely to be from small households (相似文献   

Can jumping capacity of adult show jumping horses be predicted on the basis of submaximal free jumps at foal age? A longitudinal study     

Bobbert MF  Santamaría S  van Weeren PR  Back W  Barneveld A 《Veterinary journal (London, England : 1997)》2005,170(2):212-221

The purpose of this study was to quantify performance characteristics of good jumping horses, and to determine whether these were already detectable at foal age. Kinematic data were collected of horses performing free jumps over a 0.60 m high fence at six months of age and of these same horses jumping with a rider over a 1.15 m high fence at five years of age. At five years of age the horses were divided into three groups on the basis of a puissance competition: a group of seven best jumpers that made no errors and in the end cleared a 1.50 m high fence, a group of nine worst jumpers that were unable to clear a 1.40 m high fence, and an intermediate group of 13 horses. Longitudinal kinematic data was available for all seven best jumpers and for six of the nine worst jumpers. Average values of variables for the best jumpers were compared with those of the worst jumpers for the jumps over 1.15 m. In the group of best jumpers, the forelimbs were shorter at forelimb clearance due to increased elbow flexion, and the hind limbs were further retroflexed at hind limb clearance. The same superior technique in clearing fences with the limbs was also found in this group at six months of age. Nevertheless, for individual horses it turned out to be too far-fetched to predict adult jumping capacity on the basis of kinematic variables collected during submaximal jumps at foal age.  相似文献   

Metabolic and physiological characteristics of salt-tolerant strains of Bradyrhizobium spp.     

Faviana Barboza  Néstor S Correa  Susana B. Rosas 《Biology and Fertility of Soils》2000,32(5):368-373

 Biochemical and physiological characteristics of salt-tolerant (88 mM, 264 mM and 440 mM NaCl) strains of Bradyrhizobium were evaluated according to their capacity for using different carbon sources, growth rate, resistance to antibiotics, plasmid profile and exopolysaccharide production. Salt-tolerant strains significantly enhance their capacity to oxidize C sources (about 75–85 compounds) by increasing growth rate and exopolysaccharide production involved in adhesion, resulting in a greater adapting capacity to colonize unfavorable saline environments. However, salt stress could work as a curing agent and thus the gene stability would become critical for the biological nitrogen-fixation information present in plasmids, as is the case in Rhizobium. Received: 5 January 1998  相似文献   

Nutrient availability of composted and noncomposted residues in a Patagonian Xeric Mollisol     

F. Laos  Patricia Satti  Ingrid Walter  María Julia Mazzarino  Susana Moyano 《Biology and Fertility of Soils》2000,31(6):462-469

 The main objectives of this study were to determine: (1) the agronomic value of composted and noncomposted residues originated in the Andean-Patagonian region (APR), and (2) whether aerobic incubations provide a reliable index of nutrient availability to estimate application rates. A Xeric Mollisol of the transitional zone between the APR and the Patagonian steppe, amended with composted and noncomposted residues, was employed in laboratory incubations without plants and in a 5-month greenhouse trial with ryegrass. Noncomposted residues were biosolids and fish wastes (FW) collected under farming cages. Composts were obtained from fish offal and biosolids mixed with sawdust, woodshavings and yard trimmings. A commercial compost was also included. In laboratory incubations at similar rates of application (10 g kg^–1), net N mineralization (N_min) was about two-fold higher with the noncomposted (17–23%) than with the composted residues (0–12%) and P release was very high with the FW. Ryegrass yields were closely related to the total Kjeldahl N and mineralized N of the organic residues and weakly related to their P contents (total or extractable). Yields were increased even in the case of composts which exhibited very low values of N_min (and slight N immobilization) during laboratory incubation, suggesting that the presence of plants enhanced N_min at rates of 10–20 g kg^–1. Soil residual extractable P after ryegrass removal was high for fish-derived amendments and the commercial product, suggesting a potential risk of P pollution when these are applied according to N requirements. Aerobic incubations provided a relatively good index with which to assess adequate rates of application. Received: 17 July 1999  相似文献   

Spatial and temporal variability of physical properties of Aquands under different land uses in southern Chile          下载免费PDF全文

José Dörner  Dorota Dec  Oscar Thiers  Leandro Paulino  Felipe Zúñiga  Susana Valle  Oscar Martínez  Rainer Horn 《Soil Use and Management》2016,32(3):411-421

The aquands found in southern Chile are derived from volcanic ash and contain high levels of organic matter. Due to the presence of an impermeable stratum, they have shallow soil profiles, which induce waterlogging for several months each year. These fragile soils, locally known as ‘Ñadi’, cover an area of 475 000 hectares and have undergone intensive land use changes, which have affected the soil physical properties. These are still not well understood but are relevant for the design of efficient drainage systems. The aim of this research was to analyse the impact of the land use change in Ñadi soils on the spatial and temporal variability of their soil physical properties. For the land use change from secondary native forest (sNF) to naturalized grassland (NG), the effective soil depth was measured at defined points. Time‐ and space‐dependent changes of water‐table depth and penetration resistance were recorded. Volumetric water content and soil temperature were measured with sensors installed at three depths and the water retention curve and air permeability at these depths were also determined. The changes in land use over time have induced a reduction in soil depth. Soils under NG showed a smaller soil water storage capacity, air capacity and permeability compared with soils under sNF, as well as waterlogging during winter and greater mechanical strength and soil profile temperatures during summer. Therefore, the land use change affected the spatial and temporal variability of soil physical functions across the field.  相似文献