The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Michael T. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Identification of environmental factors limiting plant uptake of Metaldehyde seed treatments under field conditions.
Journal of agricultural and food chemistry, 2006Co-Authors: Louise Simms, Julian J.c. Dawson, Graeme I. Paton, Michael T. WilsonAbstract:Slugs are serious pests of oilseed rape (canola) and wheat with most damage occurring just after sowing and seedling emergence. As an alternative to the use of bait pellets, molluscicidal seed treatments have been shown to protect seeds and seedlings from slug damage in laboratory and semi-field experiments. However, protection offered to plants in field trials was diminished and short-lived in comparison with laboratory experiments. To determine why field efficacy was reduced, we grew seedlings under a range of environmental conditions, with appropriate controls, that simulated differences between laboratory and field experiments. We then measured the Metaldehyde content of plant seedlings using a previously unpublished methodology described herein, which, unlike previous methods, did not first depolymerize the Metaldehyde to acetaldehyde. We confirmed that naturally abundant plant-derived acetaldehyde could not interfere with our measurements of Metaldehyde, even if depolymerization took place within th...
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Seed dressings to control slug damage in oilseed rape.
Pest Management Science, 2002Co-Authors: Louise Simms, Christopher E. Mullins, Michael T. WilsonAbstract:Slugs are major pests of oilseed rape that are poorly controlled by conventional bait pellets. A series of laboratory experiments investigated the potential of seed-dressings to control slug damage in this crop. Four compounds: Metaldehyde, methiocarb, cinnamamide and 3,5-dimethoxycinnamic acid (DMCA) were tested at a range of doses for phytotoxicity and ability to reduce damage by Deroceras reticulatum (Muller). Metaldehyde and methiocarb were not phytotoxic at any doses, whereas all doses of cinnamamide and DMCA were. All compounds reduced slug damage, but Metaldehyde and methiocarb consistently performed better than cinnamamide and DMCA. Metaldehyde and methiocarb seed-dressings were compared with baited pellets containing the same active ingredients at recommended field doses. The seed-dressings protected plants from damage by D reticulatum and Arion subfuscus (Draparnaud) as well as, or better than, baited pellets. We therefore recommend that Metaldehyde and methiocarb should be field-tested as seed dressings to control slugs in oilseed rape.
Gary R. Fones - One of the best experts on this subject based on the ideXlab platform.
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Comparison of different monitoring methods for the measurement of Metaldehyde in surface waters.
Environmental monitoring and assessment, 2019Co-Authors: Glenn D. Castle, Anthony Gravell, Graham A Mills, Alister Leggatt, Jeff Stubbs, Richard C. Davis, Gary R. FonesAbstract:Metaldehyde is recognised as an emerging contaminant. It is a powerful molluscicide and is the active compound in many types of slug pellets used for the protection of crops. The application of pellets to land generally takes place between August and December when slugs thrive. Due to its high use and physico-chemical properties, Metaldehyde can be present in the aquatic environment at concentrations above the EU Drinking Water Directive limit of 100 ng L−1 for a single pesticide. Such high concentrations are problematic when these waters are used in the production of drinking water. Being able to effectively monitor this pollutant of concern is important. We compared four different monitoring techniques (spot and automated bottle sampling, on-line gas chromatography/mass spectrometry (GC/MS) and passive sampling) to estimate the concentration of Metaldehyde. Trials were undertaken in the Mimmshall Brook catchment (Hertfordshire, UK) and in a feed in a drinking water treatment plant for differing periods between 17th October and 31st December 2017. This period coincided with the agricultural application of Metaldehyde. Overall, there was a good agreement between the concentrations measured by the four techniques, each providing complementary information. The highest resolution data was obtained using the on-line GC/MS. During the study, there was a large exceedance (500 ng L−1) of Metaldehyde that entered the treatment plant; but this was not related to rainfall in the area. Each monitoring method had its own advantages and disadvantages for monitoring investigations, particularly in terms of cost and turn-a-round time of data.
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measuring Metaldehyde in surface waters in the uk using two monitoring approaches
Environmental Science: Processes & Impacts, 2018Co-Authors: Glenn D. Castle, Anthony Gravell, Graham A Mills, Adil Bakir, Melanie Schumacher, Kate Snow, Gary R. FonesAbstract:Metaldehyde is a molluscicide and the active ingredient in formulated slug pellets used for the protection of crops. Due to its mobility in the environment it is frequently found in river catchments, often at concentrations exceeding the EU Drinking Water Directive limit of 100 ng L−1 for a single pesticide. This presents a major problem for water companies in the UK where such waters are abstracted for production of potable drinking water supplies. Therefore, it is important to understand the sources, transport and fate of this emerging pollutant of concern in the aquatic environment. We monitored Metaldehyde in two contrasting river catchments (River Dee (8 sites) and River Thames (6 sites)) over a twelve month period that coincided with the agricultural application period of the molluscicide. Spot samples of water were collected typically weekly or fortnightly. Chemcatcher® passive samplers were deployed consecutively every two weeks. At the River Dee, there was little variability in the concentrations of Metaldehyde (<10–110 ng L−1) measured in the spot samples of water. The Chemcatcher® gave similar time-weighted average concentrations which were higher following increased rain fall events. At the River Thames, concentrations of Metaldehyde varied more widely (<9–4200 ng L−1) with several samples exceeding 100 ng L−1. Generally these concentrations were reflected in the time-weighted average concentrations obtained using the Chemcatcher®. Both monitoring techniques gave complementary data for identifying input sources, and in the development of catchment management plans and environmental remediation strategies.
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Measuring Metaldehyde in surface waters in the UK using two monitoring approaches
Environmental Science: Processes & Impacts, 2018Co-Authors: Glenn D. Castle, Anthony Gravell, Graham A Mills, Adil Bakir, Melanie Schumacher, Kate Snow, Gary R. FonesAbstract:Metaldehyde is a molluscicide and the active ingredient in formulated slug pellets used for the protection of crops. Due to its mobility in the environment it is frequently found in river catchments, often at concentrations exceeding the EU Drinking Water Directive limit of 100 ng L−1 for a single pesticide. This presents a major problem for water companies in the UK where such waters are abstracted for production of potable drinking water supplies. Therefore, it is important to understand the sources, transport and fate of this emerging pollutant of concern in the aquatic environment. We monitored Metaldehyde in two contrasting river catchments (River Dee (8 sites) and River Thames (6 sites)) over a twelve month period that coincided with the agricultural application period of the molluscicide. Spot samples of water were collected typically weekly or fortnightly. Chemcatcher® passive samplers were deployed consecutively every two weeks. At the River Dee, there was little variability in the concentrations of Metaldehyde (
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Calibration and field evaluation of the Chemcatcher® passive sampler for monitoring Metaldehyde in surface water
Talanta, 2017Co-Authors: Glenn D. Castle, Anthony Gravell, Lewis Jones, Ian Townsend, Graham A Mills, Adil Bakir, Melanie Schumacher, Richard Greenwood, Stuart Knott, Gary R. FonesAbstract:Abstract Metaldehyde is a potent molluscicide. It is the active ingredient in most slug pellets used for crop protection. This polar compound is considered an emerging pollutant. Due to its environmental mobility, Metaldehyde is frequently detected at impacted riverine sites, often at concentrations above the EU Drinking Water Directive limit of 0.1 µg L−1 for an individual pesticide. This presents a problem when such waters are abstracted for use in the production of potable water supplies, as this chemical is difficult to remove using conventional treatment processes. Understanding the sources, transport and fate of this pollutant in river catchments is therefore important. We developed a new variant of the Chemcatcher® passive sampler for monitoring Metaldehyde comprising a Horizon Atlantic™ HLB-L disk as the receiving phase overlaid with a polyethersulphone membrane. The sampler uptake rate (Rs) was measured in semi-static laboratory (Rs = 15.7 mL day−1) and in-field (Rs = 17.8 mL day−1) calibration experiments. Uptake of Metaldehyde was linear over a two-week period, with no measurable lag phase. Field trials (five consecutive 14 day periods) using the Chemcatcher® were undertaken in eastern England at three riverine sites (4th September-12th November 2015) known to be impacted by the seasonal agricultural use of Metaldehyde. Spot samples of water were collected regularly during the deployments, with concentrations of Metaldehyde varying widely (~ 0.03–2.90 µg L−1) and often exceeding the regulatory limit. Time weighted average concentrations obtained using the Chemcatcher® increased over the duration of the trial corresponding to increasing stochastic inputs of Metaldehyde into the catchment. Monitoring data obtained from these devices gives complementary information to that obtained by the use of infrequent spot sampling procedures. This information can be used to develop risk assessments and catchment management plans and to assess the effectiveness of any mitigation and remediation strategies.
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Review of the molluscicide Metaldehyde in the environment
Environmental Science: Water Research & Technology, 2017Co-Authors: Glenn D. Castle, Anthony Gravell, Lewis Jones, Ian Townsend, D. G. Cameron, Graham A Mills, Gary R. FonesAbstract:Metaldehyde is the active ingredient in most slug pellets used to protect crops. This molluscicide is considered an emerging pollutant and is frequently detected in surface water bodies above the EU statutory drinking water limit of 0.1 μg L−1 for a pesticide. This presents a challenge for providers of drinking water. Understanding the sources, transport and environmental fate of this compound is therefore important. This critical review discusses these aspects including monitoring and analytical techniques used for the detection of Metaldehyde in environmental matrices. Novel techniques used for the removal of Metaldehyde from drinking water are presented together with potential catchment management strategies and initiatives useful for the mitigation of this molluscicide in the environment.
Louise Simms - One of the best experts on this subject based on the ideXlab platform.
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Identification of environmental factors limiting plant uptake of Metaldehyde seed treatments under field conditions.
Journal of agricultural and food chemistry, 2006Co-Authors: Louise Simms, Julian J.c. Dawson, Graeme I. Paton, Michael T. WilsonAbstract:Slugs are serious pests of oilseed rape (canola) and wheat with most damage occurring just after sowing and seedling emergence. As an alternative to the use of bait pellets, molluscicidal seed treatments have been shown to protect seeds and seedlings from slug damage in laboratory and semi-field experiments. However, protection offered to plants in field trials was diminished and short-lived in comparison with laboratory experiments. To determine why field efficacy was reduced, we grew seedlings under a range of environmental conditions, with appropriate controls, that simulated differences between laboratory and field experiments. We then measured the Metaldehyde content of plant seedlings using a previously unpublished methodology described herein, which, unlike previous methods, did not first depolymerize the Metaldehyde to acetaldehyde. We confirmed that naturally abundant plant-derived acetaldehyde could not interfere with our measurements of Metaldehyde, even if depolymerization took place within th...
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Mini-plot field experiments using seed dressings to control slug damage to oilseed rape
Crop Protection, 2006Co-Authors: Louise Simms, David Mckellar Glen, M. J. WilsonAbstract:Abstract Previous studies have shown that seed dressing with methiocarb or Metaldehyde can protect newly emerged oilseed rape seedlings from slug damage. Here, we document two mini-plot field experiments testing these seed dressings. Both Metaldehyde and methiocarb significantly reduced slug damage compared with untreated control seeds, but both seed dressings performed less well to the Metaldehyde bait pellets. Protection offered by Metaldehyde seed dressing was short-lived, whereas methiocarb seed dressings gave protection throughout the 4 weeks duration of both experiments.
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Seed dressings to control slug damage in oilseed rape.
Pest Management Science, 2002Co-Authors: Louise Simms, Christopher E. Mullins, Michael T. WilsonAbstract:Slugs are major pests of oilseed rape that are poorly controlled by conventional bait pellets. A series of laboratory experiments investigated the potential of seed-dressings to control slug damage in this crop. Four compounds: Metaldehyde, methiocarb, cinnamamide and 3,5-dimethoxycinnamic acid (DMCA) were tested at a range of doses for phytotoxicity and ability to reduce damage by Deroceras reticulatum (Muller). Metaldehyde and methiocarb were not phytotoxic at any doses, whereas all doses of cinnamamide and DMCA were. All compounds reduced slug damage, but Metaldehyde and methiocarb consistently performed better than cinnamamide and DMCA. Metaldehyde and methiocarb seed-dressings were compared with baited pellets containing the same active ingredients at recommended field doses. The seed-dressings protected plants from damage by D reticulatum and Arion subfuscus (Draparnaud) as well as, or better than, baited pellets. We therefore recommend that Metaldehyde and methiocarb should be field-tested as seed dressings to control slugs in oilseed rape.
Shady Selim - One of the best experts on this subject based on the ideXlab platform.
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Contact toxicity and biochemical impact of Metaldehyde against the white garden snail Theba pisana (Müller, 1774).
Pest management science, 2021Co-Authors: Yasser Abobakr, Amira F Gad, Hamza S Abou-elnasr, Gaber M Abdelgalil, Hamdy I Hussein, Shady SelimAbstract:Terrestrial snails are one of the most damaging threats to sustainable agriculture. Chemical control using molluscicides is the main approach used to combat these agricultural pests. Metaldehyde is the active ingredient in most snail control products in use. However, its toxicity indices and mode of action have scarcely been investigated. For the first time, we characterized the Metaldehyde contact toxicity indices against the white garden snail Theba pisana. The biochemical impact of Metaldehyde on acetylcholinesterase (AChE), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), alkaline phosphatase (ALP) and glutathione S-transferase (GST) activities and the lipid peroxidation (LPO) level was investigated. The median lethal dose (LD50 ) values at 24, 48 and 72 h of treatment were 11.33, 8.53, and 6.87 μg g-1 body weight (BW), respectively; while, the median lethal time (LT50 ) values were 88.16, 55.85, and 25.67 h when doses of 6, 8, and 12 μg g-1 BW were applied, respectively. In the snails treated with 2.83 and 5.67 μg g-1 BW (¼ and ½ LD50 at 24 h of treatment) and 2.13 and 4.27 μg g-1 BW (¼ and ½ LD50 at 48 h of treatment), higher AChE, GST, AST, ALT, and ALP activities as well as higher levels of LPO were observed compared with that of untreated snails. Metaldehyde displayed dose- and time-dependent contact toxicity. The biochemical results suggest that Metaldehyde may have neurotoxic and cytotoxic actions in terrestrial snails. Application of Metaldehyde in ways that could control pest snails and slugs and reduce its negative impact on the environment are discussed. © 2021 Society of Chemical Industry.
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contact toxicity and biochemical impact of Metaldehyde against the white garden snail theba pisana muller 1774
Pest Management Science, 2021Co-Authors: Yasser Abobakr, Amira F Gad, Gaber M Abdelgalil, Hamdy I Hussein, Hamza Samir Abouelnasr, Shady SelimAbstract:BACKGROUND Terrestrial snails are one of the most damaging threats to sustainable agriculture. Chemical control using molluscicides is the main approach used to combat these agricultural pests. Metaldehyde is the active ingredient in most snail control products in use. However, its toxicity indices and mode of action have scarcely been investigated. For the first time, we characterized the Metaldehyde contact toxicity indices against the white garden snail Theba pisana. The biochemical impact of Metaldehyde on acetylcholinesterase (AChE), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), alkaline phosphatase (ALP) and glutathione S-transferase (GST) activities and the lipid peroxidation (LPO) level was investigated. RESULTS The median lethal dose (LD50 ) values at 24, 48 and 72 h of treatment were 11.33, 8.53, and 6.87 μg g-1 body weight (BW), respectively; while, the median lethal time (LT50 ) values were 88.16, 55.85, and 25.67 h when doses of 6, 8, and 12 μg g-1 BW were applied, respectively. In the snails treated with 2.83 and 5.67 μg g-1 BW (¼ and ½ LD50 at 24 h of treatment) and 2.13 and 4.27 μg g-1 BW (¼ and ½ LD50 at 48 h of treatment), higher AChE, GST, AST, ALT, and ALP activities as well as higher levels of LPO were observed compared with that of untreated snails. CONCLUSION Metaldehyde displayed dose- and time-dependent contact toxicity. The biochemical results suggest that Metaldehyde may have neurotoxic and cytotoxic actions in terrestrial snails. Application of Metaldehyde in ways that could control pest snails and slugs and reduce its negative impact on the environment are discussed.
Melanie Schumacher - One of the best experts on this subject based on the ideXlab platform.
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measuring Metaldehyde in surface waters in the uk using two monitoring approaches
Environmental Science: Processes & Impacts, 2018Co-Authors: Glenn D. Castle, Anthony Gravell, Graham A Mills, Adil Bakir, Melanie Schumacher, Kate Snow, Gary R. FonesAbstract:Metaldehyde is a molluscicide and the active ingredient in formulated slug pellets used for the protection of crops. Due to its mobility in the environment it is frequently found in river catchments, often at concentrations exceeding the EU Drinking Water Directive limit of 100 ng L−1 for a single pesticide. This presents a major problem for water companies in the UK where such waters are abstracted for production of potable drinking water supplies. Therefore, it is important to understand the sources, transport and fate of this emerging pollutant of concern in the aquatic environment. We monitored Metaldehyde in two contrasting river catchments (River Dee (8 sites) and River Thames (6 sites)) over a twelve month period that coincided with the agricultural application period of the molluscicide. Spot samples of water were collected typically weekly or fortnightly. Chemcatcher® passive samplers were deployed consecutively every two weeks. At the River Dee, there was little variability in the concentrations of Metaldehyde (<10–110 ng L−1) measured in the spot samples of water. The Chemcatcher® gave similar time-weighted average concentrations which were higher following increased rain fall events. At the River Thames, concentrations of Metaldehyde varied more widely (<9–4200 ng L−1) with several samples exceeding 100 ng L−1. Generally these concentrations were reflected in the time-weighted average concentrations obtained using the Chemcatcher®. Both monitoring techniques gave complementary data for identifying input sources, and in the development of catchment management plans and environmental remediation strategies.
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Measuring Metaldehyde in surface waters in the UK using two monitoring approaches
Environmental Science: Processes & Impacts, 2018Co-Authors: Glenn D. Castle, Anthony Gravell, Graham A Mills, Adil Bakir, Melanie Schumacher, Kate Snow, Gary R. FonesAbstract:Metaldehyde is a molluscicide and the active ingredient in formulated slug pellets used for the protection of crops. Due to its mobility in the environment it is frequently found in river catchments, often at concentrations exceeding the EU Drinking Water Directive limit of 100 ng L−1 for a single pesticide. This presents a major problem for water companies in the UK where such waters are abstracted for production of potable drinking water supplies. Therefore, it is important to understand the sources, transport and fate of this emerging pollutant of concern in the aquatic environment. We monitored Metaldehyde in two contrasting river catchments (River Dee (8 sites) and River Thames (6 sites)) over a twelve month period that coincided with the agricultural application period of the molluscicide. Spot samples of water were collected typically weekly or fortnightly. Chemcatcher® passive samplers were deployed consecutively every two weeks. At the River Dee, there was little variability in the concentrations of Metaldehyde (
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Calibration and field evaluation of the Chemcatcher® passive sampler for monitoring Metaldehyde in surface water
Talanta, 2017Co-Authors: Glenn D. Castle, Anthony Gravell, Lewis Jones, Ian Townsend, Graham A Mills, Adil Bakir, Melanie Schumacher, Richard Greenwood, Stuart Knott, Gary R. FonesAbstract:Abstract Metaldehyde is a potent molluscicide. It is the active ingredient in most slug pellets used for crop protection. This polar compound is considered an emerging pollutant. Due to its environmental mobility, Metaldehyde is frequently detected at impacted riverine sites, often at concentrations above the EU Drinking Water Directive limit of 0.1 µg L−1 for an individual pesticide. This presents a problem when such waters are abstracted for use in the production of potable water supplies, as this chemical is difficult to remove using conventional treatment processes. Understanding the sources, transport and fate of this pollutant in river catchments is therefore important. We developed a new variant of the Chemcatcher® passive sampler for monitoring Metaldehyde comprising a Horizon Atlantic™ HLB-L disk as the receiving phase overlaid with a polyethersulphone membrane. The sampler uptake rate (Rs) was measured in semi-static laboratory (Rs = 15.7 mL day−1) and in-field (Rs = 17.8 mL day−1) calibration experiments. Uptake of Metaldehyde was linear over a two-week period, with no measurable lag phase. Field trials (five consecutive 14 day periods) using the Chemcatcher® were undertaken in eastern England at three riverine sites (4th September-12th November 2015) known to be impacted by the seasonal agricultural use of Metaldehyde. Spot samples of water were collected regularly during the deployments, with concentrations of Metaldehyde varying widely (~ 0.03–2.90 µg L−1) and often exceeding the regulatory limit. Time weighted average concentrations obtained using the Chemcatcher® increased over the duration of the trial corresponding to increasing stochastic inputs of Metaldehyde into the catchment. Monitoring data obtained from these devices gives complementary information to that obtained by the use of infrequent spot sampling procedures. This information can be used to develop risk assessments and catchment management plans and to assess the effectiveness of any mitigation and remediation strategies.
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An improved method for measuring Metaldehyde in surface water using liquid chromatography tandem mass spectrometry
MethodsX, 2016Co-Authors: Melanie Schumacher, Glenn D. Castle, Anthony Gravell, Graham A Mills, Gary R. FonesAbstract:The molluscicide Metaldehyde (2,4,6,8-tetramethyl-1,3,5,7-tetraoxocanemetacetaldehyde) is an emerging pollutant. It is frequently detected in surface waters, often above the European Community Drinking Water Directive limit of 0.1 μg/L for a single pesticide. Gas chromatography mass spectrometry (GC-MS) can be used to determine Metaldehyde in environmental waters, but this method requires time consuming extraction techniques prior to instrumental analysis. Use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) can overcome this problem. We describe a novel LC-MS/MS method, using a methylamine mobile phase additive, coupled with on-line sample enrichment that allows for the rapid and sensitive measurement of Metaldehyde in surface water. Only the methylamine adduct of Metaldehyde was formed with other unwanted alkali metal adducts and dimers being suppressed. As considerably less collision energy is required to fragment the methylamine adduct, a five-fold improvement in method sensitivity, compared to a previous method using an ammonium acetate buffer mobile phase was achieved. This new approach offers: •A validated method that meets regulatory requirements for the determination of Metaldehyde in surface water.•Improved reliability of quantification over existing LC-MS/MS methods by using stable precursor ions for multiple reaction monitoring.•Low limits of quantification for tap water (4 ng/L) and river water (20 ng/L) using only 800 μL of sample; recoveries > 97%.