Threshold and weighted-distance methods: a combined multiscale approach improves explanatory power of forest carabid beetle abundance in agricultural landscape

Landscape Ecology - To analyze the scales at which landscape structure influences ecological processes, two approaches with different underlying ecological assumptions exist; the usual threshold...     

世界农产品贸易现状及其相关问题

[编者按]世界贸易组织(WTO)将于2008年7月底在瑞士日内瓦重新启动新一轮多边贸易谈判,欧盟、美国月23日将与代表发展中国家的20国集团会谈.本次谈判的主要内容依然是争议最大的农业问题.     

A parametric and microstructural study of the formation of gluten network in mixed flour–water batter

The mechanism of gluten network development is still unclear and remains difficult to study since gluten network formation in bread dough is a rather quick process. In order to better characterize this dynamic event, we slowed down its kinetics by increasing the dough water content. During mixing, performed with a planetary mixer at variable mixing speeds and flour/water ratios, the torque was recorded. Common flours from wheat cultivars Orvantis, Caphorn and Isengrain, similar in composition and Farinograph parameters, were studied.     

Colour and decay resistance and its relationships in Eperua grandiflora

? Eperua grandiflora, which is widely distributed in the French Guiana forest region, shows high variability in decay resistance. Further information concerning this wood quality parameter is necessary, but standard testing methods are complex and time-consuming. We assessed the use of colorimetry to determine durability in heartwood samples from a range of trees.

? Eperua grandiflora colour parameters were measured using a CIELAB system, revealing that the tree effect was greater than the radial position and height effects.

? The wood samples were exposed to Coriolus versicolor and Antrodia sp. according to two European standards (En 350-1 and XP CEN TS 15083-1). Eperua grandiflora is more susceptible to brown rot. These two standards did not give the same durability classes. The high variation in natural durability was due to the tree effect.

? These two properties were found to be correlated and the assessment also distinguished the extreme durability classes but they are not sufficient to classify the class of durability of this species.

     

Crop border and mineral oil sprays used in combination as physical control methods of the aphid‐transmitted potato virus Y in potato

BACKGROUND: The objectives of this work were to determine if the control of potato virus Y (PVY, genus Potyvirus, family Potyviridae) in seed potato could be improved by combining border crops and mineral oil sprays, and if the border crop acts as a barrier or a virus sink. RESULTS: Field tests over 3 years confirmed that mineral oils alone are an effective barrier to PVY, and showed that borders alone act as a PVY sink. Combining the familiar mineral oil and the more recent crop border methods was almost twice as effective in reducing PVY incidence as either one used alone. The combination provided consistently high PVY control compared with the variable and often lower level of control by either method alone. The contribution of the oil to PVY reduction was similar whether it was applied to the border, the center seed plot, or both. Oil application to the border alone should not affect efficacy and would help keep control costs down. CONCLUSION: Combining border and oil provided the best reduction in PVY incidence 3 years out of 3, providing producers with a tool to reduce year‐to‐year variation in the effectiveness of crop borders or oil sprays used separately. © Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri‐Food Canada. Published by John Wiley and Sons, Ltd.     

Metabolism of fungicidal cyanooximes, cymoxanil and analogues in various strains of Botrytis cinerea

BACKGROUND: The metabolism of cymoxanil [1‐(2‐cyano‐2‐methoxyiminoacetyl)‐3‐ethylurea] and fungicidal cyanooxime analogues was monitored on three phenotypes of Botrytis cinerea Pers. ex Fr. differing in their sensitivity towards cymoxanil. For this purpose, labelled [2‐¹⁴C]cymoxanil was added either to the culture medium of these strains or to its cell‐free extract. RESULTS: In the culture medium of the most sensitive strain, four main metabolites were detected. Three were isolated and identified. Cymoxanil was quickly metabolised by at least three concurrent enzymatic pathways: (i) cyclisation leading, after hydrolysis, to ethylparabanic acid, (ii) reduction giving demethoxylated cymoxanil, (iii) hydrolysis followed by reduction and then acetylation leading to N‐acetylcyanoglycine. In the cell‐free extract of the same strain, only the first and the second of these enzymatic reactions occurred. By comparing the metabolic profile of the most sensitive strain with that of the less sensitive ones, it was shown that the decrease in sensitivity to cymoxanil correlates with a reduced acetylcyanoglycine formation. Among all metabolites, only N‐acetylcyanoglycine is active against the most sensitive strain. Moreover, in a culture of this strain, two other fungicidal cyanooximes were also metabolised into this metabolite. CONCLUSION: The formation of N‐acetylcyanoglycine may play an important role in the fungitoxicity of cymoxanil and cyanooxime derivatives. Copyright © 2008 Society of Chemical Industry     

Toxic and repellent effects of cypermethrin on the honeybee: Laboratory,glasshouse and field experiments

Cypermethrin is highly toxic to the honeybee Apis mellifera ligustica. The action of the chemical is rapid (within 2 days) and it has no long-term effects. The sensitivity of the bees increases with decrease in breeding temperature and with increasing age of the insect. The commercial formulation ‘QCymbush’ is repellent to bees: the effect appears to be due to the formulation ingredients because cypermethrin itself is not repellent. A floral odour lost its natural attractiveness in the presence of ‘Cymbush’. The repellency appears to persist for some 2 days after treatment, during which time the bees learnt to avoid the crop. No residues of cypermethrin were found in the hive products (pollen, wax or honey), nor in the oilseed rape at harvest.     

Seroprevalence of bovine brucellosis and associated risk factors in Nakasongola district,Uganda

A cross-sectional study was carried out between November 2015 and January 2016 to determine the seroprevalence of Brucella antibodies in cattle raised under communal, fenced farms and tethering systems and the associated factors. Seven hundred twenty-eight bovine sera were collected and tested with rose Bengal test as a screening test and the indirect enzyme-linked immunosorbent assay as a confirmatory test. Animal- and herd-level data were collected and binary logistic regression was used to assess the potential risk factors. True animal- and herd-level prevalence was highest in the fenced farms (4.5% (95%CI, 2.3–6.9) and 19.5% (95%CI, 8.2–32.7) respectively). The risks for natural brucellosis infection were sharing water with wild animals (OR = 0.21, 95%CI, 0.104–0.83), herd size (medium: OR = 0.089, 95%CI 0.017–0.449; large: OR = 0.024, 95%CI 0.003–0.203), fenced farms (OR = 3.7, 95% CI, 1.7–7.9), sex (OR = 0.03, 95%CI, 0.01–0.079), and lactation (OR = 0.013, 95%CI, 0.004–0.049). Changes in rangeland tenure and the shift towards intensive cattle production have influenced brucellosis epidemiology. Future studies should aim at identifying the infecting Brucellae and examining the role of wildlife in brucellosis epidemiology.

     

Effect of some granular insecticides currently used for the treatment of maize crops (Zea mays) on the survival of inoculated Azospirillum lipoferum

Four insecticides, carbofuran, chlormephos, terbufos and benfuracarb, currently used on maize (Zea mays) at sowing, were tested for their compatibility with Azospirillum lipoferum strain CRT₁ used as an inoculant to improve maize growth and yield. The growth or survival of A lipoferum was studied in the presence of the insecticides: (1) in liquid and solid cultures of the bacteria, (2) when a commercial inoculant (Azogreen‐m?, Liphatech, Meyzieu, France) was inoculated directly on insecticide granules, (3) when inoculated Azogreen‐m granules were mixed with insecticide granules and (4) when inoculated Azogreen‐m granules were delivered separately to the seed bed. Of the four insecticides tested, only terbufos had a slight effect on growth of A lipoferum in solid cultures. All the insecticides decreased the survival of A lipoferum when the bacteria were inoculated directly on to the granules, or when inoculated Azogreen‐m granules were mixed with an insecticide. We hypothesize that the discrepancies between bacterial culture tests and survival studies might be explained by the conditions of desiccation encountered during inoculation of the granules. Desiccation stress could increase the toxic effect of the insecticides. We therefore suggest including desiccation stress in the biotest used to assess inoculant‐pesticide compatibility. © 2001 Society of Chemical Industry