The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Alper Can - One of the best experts on this subject based on the ideXlab platform.
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quantitative structure toxicity relationship qstr studies on the Organophosphate Insecticides
Toxicology Letters, 2014Co-Authors: Alper CanAbstract:Abstract Organophosphate Insecticides are the most commonly used pesticides in the world. In this study, quantitative structure–toxicity relationship (QSTR) models were derived for estimating the acute oral toxicity of Organophosphate Insecticides to male rats. The 20 chemicals of the training set and the seven compounds of the external testing set were described by means of using descriptors. Descriptors for lipophilicity, polarity and molecular geometry, as well as quantum chemical descriptors for energy were calculated. Model development to predict toxicity of Organophosphate Insecticides in different matrices was carried out using multiple linear regression. The model was validated internally and externally. In the present study, QSTR model was used for the first time to understand the inherent relationships between the Organophosphate insecticide molecules and their toxicity behavior. Such studies provide mechanistic insight about structure–toxicity relationship and help in the design of less toxic Insecticides.
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Quantitative structure–toxicity relationship (QSTR) studies on the Organophosphate Insecticides
Toxicology letters, 2014Co-Authors: Alper CanAbstract:Abstract Organophosphate Insecticides are the most commonly used pesticides in the world. In this study, quantitative structure–toxicity relationship (QSTR) models were derived for estimating the acute oral toxicity of Organophosphate Insecticides to male rats. The 20 chemicals of the training set and the seven compounds of the external testing set were described by means of using descriptors. Descriptors for lipophilicity, polarity and molecular geometry, as well as quantum chemical descriptors for energy were calculated. Model development to predict toxicity of Organophosphate Insecticides in different matrices was carried out using multiple linear regression. The model was validated internally and externally. In the present study, QSTR model was used for the first time to understand the inherent relationships between the Organophosphate insecticide molecules and their toxicity behavior. Such studies provide mechanistic insight about structure–toxicity relationship and help in the design of less toxic Insecticides.
Patricia Chueca - One of the best experts on this subject based on the ideXlab platform.
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Factors influencing the efficacy of two Organophosphate Insecticides in controlling California red scale, Aonidiella aurantii (Maskell). A basis for reducing spray application volume in Mediterranean conditions
Pest Management Science, 2014Co-Authors: Cruz Garcera, Eduardo Moltó, Patricia ChuecaAbstract:BackgroundBecause society is seeking ways to lessen the environmental impact of agricultural activity, dose adjustment has become a key issue in current plant protection treatments with high spray application volumes, such as on citrus plants. This work investigates, in field conditions, the factors affecting the efficacy of Organophosphate Insecticides against California red scale (CRS), Aonidiella aurantii (Maskell), when the delivery rate is decreased. Insecticide rate changes were induced by modifying the spray application volumes of two commercial Organophosphate pesticides based on chlorpyrifos and chlorpyrifos-methyl. ResultsResults showed that, with increase in the spray volume, the coverage and the uniformity of deposition on the canopy increased, but final infestation depended neither on the spray application volume nor on the coverage. Furthermore, final infestation significantly depended on the pest pressure in the plot and the spray volume applied per unit volume of canopy (L m(-3) canopy). Moreover, it was found that the final infestation was influenced by the efficiency of deposition in the applications that were carried out against the second-generation of CRS. ConclusionBecause the spray application volume did not affect the final infestation, this research introduces the possibility that reducing the doses of current citrus Organophosphate treatments may still allow effective plant protection in Mediterranean conditions. (c) 2013 Society of Chemical Industry
Heinz Singer - One of the best experts on this subject based on the ideXlab platform.
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Picogram per liter quantification of pyrethroid and Organophosphate Insecticides in surface waters: a result of large enrichment with liquid–liquid extraction and gas chromatography coupled to mass spectrometry using atmospheric pressure chemical ion
Analytical and Bioanalytical Chemistry, 2019Co-Authors: Andrea Rösch, Birgit Beck, Juliane Hollender, Heinz SingerAbstract:Insecticides such as pyrethroids and Organophosphates are extensively used globally. Once released into surface water bodies, they can pose a major threat to aquatic ecosystems already at trace concentrations. Therefore, selected pyrethroids and Organophosphates are listed as priority substances within the European Water Framework Directive with chronic quality criteria in the picogram per liter range. Previously applied analytical methods were unable to detect pyrethroids and Organophosphates at ecotoxicological relevant concentrations, thereby hindering the assessment of surface water quality. In this work, we developed an ultra-sensitive method for the analysis of 12 pyrethroid and two Organophosphate Insecticides in surface waters. This method is based on the liquid–liquid extraction of surface water samples with n -hexane to achieve large enrichment factors (4000×) and subsequent chemical analysis by gas chromatography coupled to tandem mass spectrometry using atmospheric pressure chemical ionization, a soft ionization technique. Quality control parameters including the method limits of quantification (12.5–125 pg L^−1), intra-day precision (1–22%), intra-day accuracy (84–133%), and absolute recoveries covering liquid–liquid extraction (67–114%) showed that the method is sensitive and robust and therefore suitable for the analysis of pyrethroids and Organophosphates in surface waters. The developed method was applied to Swiss surface water samples and detected pyrethroids and Organophosphates below the ecotoxicological relevant concentrations, exemplifying the suitability of the proposed method for aquatic monitoring. Graphical abstract
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picogram per liter quantification of pyrethroid and Organophosphate Insecticides in surface waters a result of large enrichment with liquid liquid extraction and gas chromatography coupled to mass spectrometry using atmospheric pressure chemical ioni
Analytical and Bioanalytical Chemistry, 2019Co-Authors: Andrea Rösch, Birgit Beck, Juliane Hollender, Heinz SingerAbstract:Insecticides such as pyrethroids and Organophosphates are extensively used globally. Once released into surface water bodies, they can pose a major threat to aquatic ecosystems already at trace concentrations. Therefore, selected pyrethroids and Organophosphates are listed as priority substances within the European Water Framework Directive with chronic quality criteria in the picogram per liter range. Previously applied analytical methods were unable to detect pyrethroids and Organophosphates at ecotoxicological relevant concentrations, thereby hindering the assessment of surface water quality. In this work, we developed an ultra-sensitive method for the analysis of 12 pyrethroid and two Organophosphate Insecticides in surface waters. This method is based on the liquid-liquid extraction of surface water samples with n-hexane to achieve large enrichment factors (4000×) and subsequent chemical analysis by gas chromatography coupled to tandem mass spectrometry using atmospheric pressure chemical ionization, a soft ionization technique. Quality control parameters including the method limits of quantification (12.5-125 pg L-1), intra-day precision (1-22%), intra-day accuracy (84-133%), and absolute recoveries covering liquid-liquid extraction (67-114%) showed that the method is sensitive and robust and therefore suitable for the analysis of pyrethroids and Organophosphates in surface waters. The developed method was applied to Swiss surface water samples and detected pyrethroids and Organophosphates below the ecotoxicological relevant concentrations, exemplifying the suitability of the proposed method for aquatic monitoring. Graphical abstract.
Yongqi Shao - One of the best experts on this subject based on the ideXlab platform.
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gut bacteria of the silkworm bombyx mori facilitate host resistance against the toxic effects of Organophosphate Insecticides
Environment International, 2020Co-Authors: Bosheng Chen, Nan Zhang, Sen Xie, Xiancui Zhang, Abrar Muhammad, Chao Sun, Yongqi ShaoAbstract:Organophosphate Insecticides that are heavily used in agriculture for pest control have caused growing environmental problems and public health concerns worldwide. Ironically, insecticide resistance develops quickly in major lepidopteran pests, partially via their microbial symbionts. To investigate the possible mechanisms by which the microbiota confers insecticide resistance to Lepidoptera, the model organism silkworm Bombyx mori (Lepidoptera: Bombycidae) was fed different antibiotics to induce gut dysbiosis (microbiota imbalance). Larvae treated with polymyxin showed a significantly lower survival rate when exposed to chlorpyrifos. Through high-throughput sequencing, we found that the abundances of Stenotrophomonas and Enterococcus spp. changed substantially after treatment. To assess the roles played by these two groups of bacteria in chlorpyrifos resistance, a germ-free (GF) silkworm rearing protocol was established to avoid the influence of natural microbiota and antibiotics. Monoassociation of GF silkworms with Stenotrophomonas enhanced host resistance to chlorpyrifos, but not in Enterococcus-fed larvae, consistent with larval detoxification activity. GC-μECD detection of chlorpyrifos residues in feces indicated that neither Stenotrophomonas nor Enterococcus degraded chlorpyrifos directly in the gut. However, gut metabolomics analysis revealed a highly species-specific pattern, with higher levels of essential amino acid produced in the gut of silkworm larvae monoassociated with Stenotrophomonas. This critical nutrient provisioning significantly increased host fitness and thereby allowed larvae to circumvent the deleterious effects of these toxic chemicals more efficiently. Altogether, our study not only suggests a new mechanism for insecticide resistance in notorious lepidopteran pests but also provides a useful template for investigating the interplay between host and gut bacteria in complex environmental systems.
Alan G. Clark - One of the best experts on this subject based on the ideXlab platform.
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The Role of E3 Esterase, GlutathioneS-Transferases and Other Nonoxidative Mechanisms in Resistance to Diazinon and Other Organophosphate Insecticides inLucilia cuprina
Pesticide Biochemistry and Physiology, 1996Co-Authors: J.a. Wilson, Alan G. ClarkAbstract:Abstract Seven possible nonoxidative mechanisms which might contribute to resistance to Organophosphate Insecticides have been examined in larvae and adults from field isolates of the sheep blow fly, Lucilia cuprina, selected for resistance to diazinon. The basal resistance mechanism appears to be an altered esterase (the E3 esterase). In addition, in adults, there is a strong correlation between resistance to diazinon and the glutathione S -transferase activity with 3,4-dichloronitrobenzene as substrate. This correlation is marginal in the larvae of this species. There was also a marginal negative correlation between the resistance to diazinon and the rate of inactivation of acetylcholine esterase by tetrachlorvinphos. No significant degree of correlation was found between resistance to diazinon and total esterase, with either α- or β-naphthyl actetate as substrate, total acetylcholine esterase activity, or glutathione S -transferase using 1-chloro-2,4-dinitrobenzene as substrate. Significant correlations were found between resistance to diazinon and that to other Organophosphate Insecticides including chlorpyrifos, propetamphos, and dichlofenthion. In light of these correlations, it is concluded that the same basic mechanisms of resistance are operating with respect to all of these Insecticides. Since the field isolates were sampled over a wide geographical range and over several years, it appears that the mechanisms of resistance are stable and widely distributed.