Increasing Pesticide Concentration Research Articles

The effect of plant pesticide Tondxir against the stored product Moth, Ephestia cautella (Walker) (Lepidoptera: Pyralidae)

T Many plant extracts could be considered natural, effective methods for controlling insect pests instead of synthetic chemicals. The current examination was designed to assess the mortality percentages of the plant-based pesticide Tondxir on the date moth Ephestia cautella. A series of experiments were carried out in the laboratory to evaluate the pesticide Tondxir's effectiveness in controlling the second and fifth larval stages and the adults of t he date moth. The highest percentage of mortality rates for the second larval stage reached 100% after 5 days at a concentration of 3 ml/liter. However, the mortality rates of the fifth stage and the adult of E. cautella reached 42.14% and 17.50% after two weeks of treatment. A direct relationship was found between the increase in mortality rates with increasing pesticide concentration. The highest percentage of mortality was increased in the fifth larval stage of E. cautella, and they reached 42.14% at the third concentration, compared with the rest of the concentrations. The lowest mortality rate was for the concentration (1ml/liter), as the mortality rate reached (26.07) after 14 days of treatment.

Thermo-acoustic approach for pesticide-plasma protein binding in colloidal system: An impact of membrane mimic structures on molecular interactions in biological systems

Recently, use of agrochemicals, most importantly pesticides has experienced an enormous upsurge as a consequence of continuously increasing demand of enhanced crop production. Various toxins in the environment interact with bio-molecules and causes serious ailments in human beings. Different physicochemical, computational and spectroscopic methods have been used to study binding of toxins with bio-molecules. In present study, thermo-acoustic method was aimed to employ for studying binding of organophosphate pesticides with plasma protein in absence and presence of colloidal solutions of ionic surfactants. Role of different binding sites in protein molecules, nature of pesticide molecules and forces involved in pesticide-plasma protein binding were investigated. Volumetric and acoustic parameters such as apparent (Vϕ) and partial molar volume (Voϕ), expansibility factor (Eoϕ), Hepler’s constant, compressibility factor (Kϕ) and intermolecular free length (Lf) were calculated using density and sound velocity data at different temperatures (293.15–313.15)K. Positive values of Vϕ increased with increasing pesticide concentration in aqueous plasma protein solutions which were indicative of strong associative molecular interactions in solutions. Obtained results of this study about pesticides-protein binding will be helpful for medical and pharmaceutical researchers.

Commercial pesticides for urban applications induced population growth and sub-cellular alterations in Raphidocelis subcapitata (Chlorophyceae) at concerning environmental concentrations.

Information regarding the safety and environmental risks of pesticides intended for urban use remains limited. This study aimed to assess the effects of four common pesticides on the microalga Raphidocelis subcapitata: DIAZINON® 25% C. E., Roundup®, URBACIN® 20C. E., and VAPODEL® 20% C. E., which are commercial formulations of diazinon, glyphosate, dichlorvos, and cypermethrin, respectively. According to 96-h inhibition of population growth bioassays, the four pesticide toxicities exemplified the following order: DIAZINON® (diazinon) > Roundup® (glyphosate) > VAPODEL® (dichlorvos) > URBACIN® (cypermethrin). Increasing pesticide concentrations elicited alterations in the specific growth rates (µmax). The macromolecule contents and photosynthetic pigments increased in groups exposed to the highest concentrations of DIAZINON® 25%, Roundup®, and URBACIN® 20 compared to the control group, despite these treatments inducing lower population growth rates. VAPODEL® 20% induced higher growth rates and lower macromolecule content compared to the control. Since active ingredients were not quantified, certain comparisons may prove limiting, but it is important to assess the effects of the whole mixtures in the form that they enter the environment, especially for urban-intended applications or generic formulations with higher additive contents. Finally, this study demonstrated that commercial pesticide formulations designed for urban applications might pose a threat to freshwater microalgae due to their underestimated toxic potential, but further studies are required.

Expression of heat shock protein 70 (hsp70) in liver and kidney organ of silver rasbora (rasbora argyrotaenia) exposed by sublethal organophosphate pesticides

Heat Shock Protein 70 (HSP70) is a stress protein that can appear in all cell types. HSP70 test is useful as a biomarker (biological response marker) that can be used as a stress marker in fish. Liver and kidney tissue, including types of organs that play an important role in metabolic processes in fish, make it possible for these tissues to respond to the presence of HSP70. This research aims to determine the effect of sublethal exposure to organophosphate pesticides on the expression of HSP70 in the liver and kidneys organ of Silver Rasbora, and to determine the comparison of HSP70 expression between the liver and kidneys organ of Silver Rasbora that exposed to sublethal organophosphate pesticides. This research was conducted in November 2020 - February 2021 using a completely randomized design (RAK) method consisting of 5 treatments and 4 replications. Each treatment consisted of a concentration of 0.001 ppm, 0.005 ppm, 0.01 ppm, 0.05 ppm and control treatment of 0 ppm. Silver Rasbora were acclimatized and maintained for 7 days and subjected to pesticide exposure treatment for the last 96 hours. The main parameters in this research were the expression of HSP70 in the liver and kidneys of Silver Rasbora and the supporting parameters observed were survival rate, temperature, pH, ammonia, and dissolved oxygen (DO). The main parameters were analyzed using the one-factor ANOVA test and Duncan's advanced test. Meanwhile, to determine the average difference between liver and fish kidneys, the independent sample T test was used. Supporting parameters were analyzed descriptively using tables and graphs. The results showed that exposure to sublethal organophosphate pesticides affected the appearance of HSP70 expression in the liver and kidneys of Silver Rasbora. The HSP70 value in both organs increased with increasing pesticide concentration. The liver organ has an average HSP70 value higher than that of the kidneys organ.

Detection of Pesticide Residues Based on a Porous Silicon Optical Biosensor With a Quantum Dot Fluorescence Label

In this paper, a grayscale variation of fluorescence Image based on porous silicon (PSi) Bragg mirrors (Bm) was proposed to detect pesticides quickly and easily. In this way, CdSe/ZnS quantum dots (QDs) were used as fluorescence labelling to weaken the fluorescence intensity, and a digital imaging method was used for detection. The QDs were coupled with complementary strand aptamers and interacted with aptamers immobilized on the PSi‘inner wall; thus, the fluorescence of the QDs produced by the PSi Bm was further enhanced. Acetamiprid would bind specifically to its corresponding aptamer, the complementary strand aptamers of the coupled QD would be replaced, and the fluorescence intensity would weaken. The fluorescence image of the PSi Bm surface was acquired by imaging device, and the acetamiprid pesticide was detected by computing the average grey value variation of the image. Experimental results presented that the variation in the average grey value increased with increasing pesticide concentration and presented a linear relationship within a certain range. The detection limit of acetamiprid pesticide with this type of way was 2.8 nM, indicating that this method achieved a low-cost, rapid and simple detection of pesticide.

Which Is More Toxic? Evaluation of the Short-Term Toxic Effects of Chlorpyrifos and Cypermethrin on Selected Biomarkers in Common Carp (Cyprinus carpio, Linnaeus 1758).

The general aim of this study was to investigate the negative short-term effects of different concentrations of chlorpyrifos (CPF) and cypermethrin (CYP), based on the EU legislation (MAC-EQS) in common carp (Cyprinus carpio Linnaeus, 1758) under laboratory conditions and to compare their toxicity. The fish were exposed to the pesticides for 96 h and then different histological and biochemical biomarkers were investigated in the gills and liver, and bioaccumulation analyses were conducted. The chemical studies showed increased pesticide concentrations in the gills as the first site for pollutants compared to the liver at the 96th hour. In addition, the histological analyses showed severe alterations in the gills and liver after exposure to both tested pesticides. In the gills, we found mainly intense proliferative and, to a lesser extent, degenerative changes and alterations in the circulatory system, such as necrosis and vasodilation. In the liver, regressive and progressive lesions, as well as circulatory disturbances and inflammation, were observed. The regressive lesions showed a higher degree of expression compared to the other changes. Furthermore, we found altered enzymatic activities—catalase, glutathione reductase, and glutathione peroxidase—in the liver, compared to the control. Overall, both tested pesticides impacted the studied biomarkers in common carp, even at concentrations lower than those permitted by law. However, the results of the comparative analysis showed a relatively higher toxicity of CYP compared to CPF in the fish. Still, questions persist as to whether the observed changes are adaptive or entirely destructive. To avoid any danger or risk, these pesticides must be applied cautiously, especially near water bodies.

ĐÁNH GIÁ ĐỘC TÍNH CẤP TÍNH VÀ XÁC ĐỊNH GIÁ TRỊ LC50 CỦA o,p`- DDT ĐỐI VỚI PHÔI CÁ MEDAKA ORYZIAS LATIPES

The one-day-old O. latipes embryos is harvested and exposed to different concentrations of o, p`-DDT 0.04; 0.08; 0.12; 0.16; 0.2; 0.24; 0.28 and 0 µg/l (the control sample is not supplemented with o, p`-DDT) for 24, 48, 72 and 96 hours. After 24, 48, 72 and 96 hours, the results showed that LC50 value is gradually decreased, respectively 0.1013; 0.0772; 0.0486 and 0.0359 µg/l. The difference between LC50 values depends on the exposure concentration and exposure time. The results showed that the mortality rates of Medaka O. latipes increased with increasing pesticide concentrations as well as increasing exposure time. The experiment for observation of morphology and structure also found malformations in the spine and eyes of fish embryos. This chemical has strongly affected embryonic heart rate and embryonic morphology during growth and development.

Lethal and sublethal effects of acetamiprid on Eisenia andrei: Behavior, reproduction, cytotoxicity and oxidative stress

The neonicotinoid acetamiprid has been suggested as a worldwide substitute for organophosphates, due to its lower toxicity. The present study assessed several acetamiprid effects on Eisenia andrei earthworms in acute contact (ranging from 1.6 × 10−5 to 0.16 μg cm−2 acetamiprid), behavioral (0.1, 0.5, 1 mg kg−1) and chronic (0.001, 0.01, 0.05 and 0.1 mg kg−1 acetamiprid) assays carried out in natural soil. Reproduction, cytotoxicity (coelomocyte density and viability), immune cell typing (eleocytes and amoebocytes) and antioxidant defense system (glutathione (GSH), catalase (CAT) and glutathione S-transferase (GST)) responses were determined. The LC50 in the acute contact test was calculated as 1.86 × 10−2 μg cm−2. Acetamiprid concentrations of 0.5 and 1 mg kg−1 led to earthworm avoidance responses (NR = 61.09 ± 10.01%) and habitat loss (NR = 78.02 ± 12.03%), respectively. Reproduction was also affected, with a decreased number of cocoons and hatchlings per cocoon observed at 0.05 and 0.1 mg kg−1. Amoebocytes were the predominant immune system cells during the 15th and 30th assay days, while eleocytes were the main cells observed at the 45th day. CAT activities on the 30th and 45th day of exposure were increased at the lowest acetamiprid concentrations (0.001 and 0.01 mg kg−1) and decreased with increasing pesticide concentration (0.05 and 0.1 mg kg−1). Maximum GST activities and GSH levels were noted at 0.01 mg kg−1 acetamiprid. However, increasing concentrations led to GST inhibition, while GSH levels were maintained. A long-term acetamiprid exposure affected earthworm reproduction, behavior and immune and antioxidant systems, which could affect the ecological soil balance and, consequently, the entire food chain.

From laboratory to the field: Validating molecular markers of effect in Folsomia candida exposed to a fungicide-based formulation

Under controlled laboratory conditions, toxicity data tend to be less variable than in more realistic in-field studies and responses may thus differ from those in the natural environment, creating uncertainty. The validation of data under environmental conditions is therefore a major asset in environmental risk assessment of chemicals. The present study aimed to validate the mode of action of a commercial fungicide formulation in the soil invertebrate F. candida, under more realistic exposure scenarios (in-field bioassay), by targeting specific molecular biomarkers retrieved from laboratory experiments. Organisms were exposed in soil cores under minimally controlled field conditions for 4 days to a chlorothalonil fungicide dosage causing 75% reduction of reproduction in a previous laboratory experiment (127 mg a.i. kg−1) and half this concentration (60 mg a.i. kg−1). After exposure, organisms were retrieved and RNA was extracted from each pool of organisms. According to previous laboratorial omics results with the same formulation, ten genes were selected for gene expression analysis by qRT-PCR, corresponding to key genes of affected biological pathways including glutathione metabolism, oxidation-reduction, body morphogenesis, and reproduction. Six of these genes presented a dose-response trend with higher up- or down-regulation with increasing pesticide concentrations. Highly significant correlations between their expression patterns in laboratory and in-field experiments were observed. This work shows that effects of toxicants can be clearly demonstrated in more realistic conditions using validated biomarkers. Our work outlines a set of genes that can be used to assess the early effects of pesticides in a realistic agricultural scenario.

Flocculation characteristics of a biodegradable polymer based on dextran

Abstract The flocculation efficiency of a cationic polysaccharide with 1-(2-hydroxypropyl)-3-methyl imidazolium chloride groups attached to dextran (D40-MeIm36) was evaluated on synthetic wastewaters containing either inorganic particles (Zirconium silicate (kreutzonit), Kfeldspar, TiO2) or organic ones (pesticides (Decis) and (Dithane M45)). The effect of polymer dose, medium pH, its composition and contaminant concentration on the separation efficacy was followed by UV–Vis spectroscopy measurements. The interactions between D40-MeIm36 and inorganic particles led to maximum removal efficiency (of around 95%), irrespective of the medium pH and composition. The negative values of the zeta potential, at the optimum polymer doses, point to charge patch as mechanism for the particles flocculation. A good efficiency of D40-MeIm36 in separation of pesticides has been noticed; the maximum removal percent slightly increased with increasing pesticide concentration, namely, from 85% at c (v/v) = 0.01% to 92% – 94% for c (v/v) = 0.02% and 0.04% for Decis and from around 85% at c = 0.1 g L−1 to 89% at c = 0.2 g L−1 for Dithane M45. A minimum residual pesticide absorbance of about 10% has been recorded for both pesticides, at the established medium pH. Zeta potential and particle aggregates size data plead for the charge neutralization as the dominant mechanism for the flocculation of pesticide particles.

Relative Contributions of Agricultural Drift, Para-Occupational, and Residential Use Exposure Pathways to House Dust Pesticide Concentrations: Meta-Regression of Published Data.

Background:Increased pesticide concentrations in house dust in agricultural areas have been attributed to several exposure pathways, including agricultural drift, para-occupational, and residential use.Objective:To guide future exposure assessment efforts, we quantified relative contributions of these pathways using meta-regression models of published data on dust pesticide concentrations.Methods:From studies in North American agricultural areas published from 1995 to 2015, we abstracted dust pesticide concentrations reported as summary statistics [e.g., geometric means (GM)]. We analyzed these data using mixed-effects meta-regression models that weighted each summary statistic by its inverse variance. Dependent variables were either the log-transformed GM (drift) or the log-transformed ratio of GMs from two groups (para-occupational, residential use).Results:For the drift pathway, predicted GMs decreased sharply and nonlinearly, with GMs 64% lower in homes 250 m versus 23 m from fields (interquartile range of published data) based on 52 statistics from seven studies. For the para-occupational pathway, GMs were 2.3 times higher [95% confidence interval (CI): 1.5, 3.3; 15 statistics, five studies] in homes of farmers who applied pesticides more recently or frequently versus less recently or frequently. For the residential use pathway, GMs were 1.3 (95% CI: 1.1, 1.4) and 1.5 (95% CI: 1.2, 1.9) times higher in treated versus untreated homes, when the probability that a pesticide was used for the pest treatment was 1–19% and ≥ 20%, respectively (88 statistics, five studies).Conclusion:Our quantification of the relative contributions of pesticide exposure pathways in agricultural populations could improve exposure assessments in epidemiologic studies. The meta-regression models can be updated when additional data become available.Citation:Deziel NC, Beane Freeman LE, Graubard BI, Jones RR, Hoppin JA, Thomas K, Hines CJ, Blair A, Sandler DP, Chen H, Lubin JH, Andreotti G, Alavanja MC, Friesen MC. 2017. Relative contributions of agricultural drift, para-occupational, and residential use exposure pathways to house dust pesticide concentrations: meta-regression of published data. Environ Health Perspect 125:296–305; http://dx.doi.org/10.1289/EHP426

Ionic dextran derivatives for removal of Fastac 10 EC from its aqueous emulsions

Separation studies of Fastac 10 EC from model emulsions by cationic polysaccharides were followed by UV–vis spectroscopy and zeta potential measurements. Floc size measurements at the optimum polycation dose were also carried out using laser diffraction technology. The investigated polyelectrolytes contained various amounts of quaternary ammonium salt groups, N-ethyl(octyl)-N,N-dimethyl-2-hydroxypropyl ammonium chloride, attached to a dextran backbone. The effects of polycation dose, its charge density, emulsion pH and pesticide concentration on the flocculation performance were studied. The pesticide removal results (UV–vis spectroscopy) show that the optimum polycation dose decreased with increasing polymer charge density and the emulsion pH and increased with increasing pesticide concentration. The zeta potential values close to zero at the optimum polymer dose point to contribution, mainly, from charge neutralization mechanism for the flocculation process. The flocs size increase with increasing pesticide concentration was also observed.

Effect of acute exposure of acephate on hemocyte abundance in a non-target victim Drosophila melanogaster

Organophosphate insecticide acephate was tested to investigate effects on hemocyte abundance in a non-target dipteran insect Drosophila melanogaster. For this purpose, third-instar larvae were fed on four graded concentrations (2, 4, 6, or 8 μg/ml) acephate for a period of 12 and 24 hr (acute treatment). Control groups were simultaneously maintained for comparison. Relative proportions of plasmatocytes in hemolymph smear were found to fall with increasing concentrations of the test chemical. Similar decreasing trend in population of lamellocytes was also noted after 12 and 24 hr chemical exposure. In contrast to plasmatocytes and lamellocytes, crystal cell number was found to rise with increasing pesticide concentration. Several factors like oxidative stress, apoptosis induction, and mitotic failure might be the cause of reduced plasmatocyte and lamellocyte count. The elevated number of crystal cells in hemolymph smears is directly indicative of high melanin synthesis that assists larvae to combat chemical stress, since melanin is well known for its potential to minimize physical, chemical, and pathogenic stress.

Part II: temporal and spatial distribution of multiclass pesticide residues in lake sediments of northern Greece: application of an optimized MAE-LC-MS/MS pretreatment and analytical method

The development and application of an analytical methodology for the pretreatment and determination of 253 multiclass pesticides, in lake sediment samples, using liquid chromatography coupled with mass spectrometry (LC-MS/MS) are described in this work. Sediments of lakes Volvi, Doirani, and Kerkini, located in northern Greece, were collected in two-time periods (fall/winter 2010 and spring/summer 2011) and analyzed, applying the developed analytical methodology. Microwave-assisted extraction (MAE) was applied to extract the pesticide residues from lake sediment samples. Analytical results were stored, categorized, and visualized using geographical information systems, in order to assess and observe spatial and temporal variations of the pollution. Main pesticides that were detected included the following: amitrole, tebuconazole, phoxim, diniconazole, sethoxydim, temephos, tetrachlorvinphos, pendimethalin, boscalid, disulfoton sulfone, lenacil, propiconazole, cycloxydim, pyridaben, and terbuthylazine. Amitrole, diniconazole, and tebuconazole were found to be common in all three lakes. Lakes Kerkini and Doirani exhibited increased concentrations during the first sampling period (winter 2010) with predominant pesticide classes, triazines/triazoles and organophosphates. Pollution is mainly located near the populated villages of the lakes and the nearby cultivations. During the second sampling period, pesticide concentrations appear lower and located in sediments near the center of the lake. Lake Volvi exhibits increased pesticide concentrations during the second sampling period, temporal and spatial variations and different pesticide profile pattern. Increased pollution occurs near the center of the lake during the first sampling period, mainly comprised by triazines/triazoles and organophosphates. During the second sampling period, the majority of the sediment samples demonstrated a different pesticide profile dominated by unclassified pesticides and triazines/triazoles. Mineralogical analysis of the samples demonstrates that sediments are mainly composed of clay, mud, and sand particles, and they present spatial variations. Near the center of the lakes, sediments appear to be more fine-grained with higher clay content and are more likely to adsorb pesticides.

Survey of Aspergillus section Flavi presence in agricultural soils and effect of glyphosate on nontoxigenic A. flavus growth on soil-based medium

To evaluate the cultivable mycobiota from agricultural soils exposed to pesticides, the aflatoxigenic capacity of Aspergillus section Flavi strains and the effect of glyphosate on lag phase and growth rates of native nontoxigenic Aspergillus flavus under different water potential (MPa) conditions on soil-based medium. Culturable mycobiota analysis from different agricultural soils was performed by the surface spread method. The effect of glyphosate (0-20 mmol l(-1)) on the growth of A. flavus strains was evaluated on a soil extract solid medium. Mycobiota analysis of crop soils showed the presence of twenty-one genera of filamentous fungi. Aspergillus flavus and Aspergillus niger aggregate strains were isolated from the three soil types. Ninety-two per cent of A. flavus strains were toxigenic. In vitro assay results showed that at -0·70 MPa, a significant increase in growth rate in all strains was recorded at 5 and 20 mmol l(-1) of glyphosate. At -2·78 MPa, this parameter remained constant at all glyphosate concentrations, except in GM4 strain where an increase in growth rate was recorded with increasing pesticide concentrations. At -7·06 MPa, a significant increase in growth rate has also been observed in GM 3 strain with 5 mmol l(-1) and in GM 4 strain with 10 and 20 mmol l(-1). This study showed that the imperfecti fungi Aspergillus spp., Penicillium spp., Trichoderma spp., Cladosporium spp. and Paecilomyces spp. are isolated as prevalent groups in agricultural soil exposed to pesticides, and the capacity of nontoxigenic A. flavus strains to tolerate different glyphosate concentrations under different water potential (MPa) conditions. This manuscript makes a contribution to the knowledge of cultivable fungal populations from agricultural soils exposed to pesticides and the glyphosate tolerance of A. flavus strains.

低剂量杀虫剂对星豹蛛捕食效应的影响及其机理初探

PDF HTML阅读 XML下载 导出引用 引用提醒 低剂量杀虫剂对星豹蛛捕食效应的影响及其机理 DOI: 10.5846/stxb201307241940 作者: 作者单位: 山西农业大学农学院,山西农业大学研究生学院,山西农业大学农学院,山西农业大学资源环境学院,山西农业大学农学院 作者简介: 通讯作者: 中图分类号: X503.1 基金项目: 中国博士后基金（112125）；山西省科技攻关项目（20130311011-5，20120311013-4）；山西省留学基金项目（2013-重点6） The effect of low-dose of pesticide on predation of spider and its preliminary mechanisms Author: Affiliation: College of Agronomy,Shanxi Agricultural University,,College of Agronomy,Shanxi Agricultural University,College of Resources and Environment,Shanxi Agricultural University,College of Agronomy,Shanxi Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:探讨低剂量杀虫剂对蜘蛛捕食效应的影响及其生化机理。采用药膜法，测定了低剂量吡虫啉作用下，星豹蛛和甘蓝蚜敏感性、捕食效应以及成蛛体内乙酰胆碱酯酶（AChE）、谷胱甘肽S-转移酶（GSTs）、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和中肠蛋白消化酶的活力变化。低剂量农药作用下，星豹蛛对甘蓝蚜的功能反应类型为HollingⅡ型，与对照组相比，随着猎物密度的增大星豹蛛的捕食量增加，寻找效应降低，对猎物的处理时间Th缩短，从而增强了对猎物的捕食作用；低剂量农药处理后，星豹蛛体内AChE和GSTs活性均显著低于对照组（P < 0.05），说明酶活性受到抑制，且抑制作用随吡虫啉浓度的增大而加强，随作用时间的延长而减弱；SOD，CAT和中肠蛋白消化酶活性显著增强，与对照组相比存在显著或极显著差异（P < 0.05），且随吡虫啉浓度增大和作用时间的延长而逐渐降低，最后接近对照组。低剂量杀虫剂作用下，蜘蛛体内AChE活性受到抑制，AChE敏感性降低，对神经递质乙酰胆碱的分解作用下降，使蜘蛛的兴奋性增加；GSTs、SOD、CAT等代谢酶活性发生变化，使蜘蛛的新陈代谢加速，从而刺激捕食；中肠蛋白消化酶的活性增强，提高了对猎物的消化吸收功能。总之，在低剂量杀虫剂作用下，星豹蛛通过外在的捕食行为和体内一系列酶系生理生化反应的综合作用促进蜘蛛对害虫的控制作用。 Abstract:Spiders are among the most abundant predators of insects and other invertebrates in agro- and forest ecosystems, playing an important ecological role by regulating invertebrate populations. Biological control using spiders may represent a sustainable method of controlling agricultural pest species and reducing the amount of pest damage on crops. However, pesticide application on agricultural crops may directly or indirectly impact spider foraging in the crop. In particular, pesticides may have mutagenic effects on spiders, negatively affecting the spider population abundance and transferring these effects to the next generation. Recent studies have reported that low-dose pesticides kill pests, but promote the predation of natural enemies. Therefore, revealing the mechanism behind low-dose pesticides on natural enemies is critical to improving predator ability, exploring the potential control of insect predators and coordinating bio- and chemical control.Our aim was to investigate the effect of low-dose pesticides on spider predation behavior and reveal the underlying mechanisms. Pardosa astrigera was treated with a low-dose of imidacloprid using the drug-film method. We determined the sensitivity of P. astrigera, the predation effect of P. astrigera on B. brassicae and the activity of acetylcholinesterase (AChE), glutathione S-transferase (GSTs), superoxide dismutase (SOD), catalase (CAT) and midgut proteinase. The results showed that under different concentrations of imidacloprid, the predacious functional response of spiders on aphids belonged to the Holling type. Compared with the control, the theoretical maximal consumption increased, searching efficiency decreased and the prey handling time declined with increasing aphid density. Therefore, low-dose pesticide levels resulted in enhanced predation by spiders. When P. astrigera was treated with a low-dose of pesticide, this species showed a reduction in AChE and GSTs activity compared with the control (P < 0.05), suggesting spider activity was inhibited. The inhibition was enhanced with increasing pesticide concentration and weakened with prolonged treatment. SOD, CAT and midgut proteinase activity were induced significantly at the low-dose of 1, 3 and 5mg/L(P < 0.050, but decreased gradually with increased concentration and extended treatment, with activity close to the control. After low-dose pesticide treatment, P. astrigera showed inhibited AChE activity, leading to reduced AChE sensitivity, less decomposition of AChE in nerve transfer and increased spider activity. Increased GSTs, SOD and CAT activity induced by low-dose pesticide, accelerated the spiders' metabolism, stimulating predatory behavior. Enhanced midgut proteinase activity may benefit food digestion and nutrient absorption. The low-dose pesticide regime may enhance the predatory behavior of P. Astrigera via three main pathways. First, it enhances the instant attack rate, shortens prey handling time and increases the amount of prey per day. Second, it affects physiological enzyme activity, inhibits to a degree the metabolic detoxification enzyme subject of: low doses of imidacloprid causing a reduction in AChE sensitivity of the neurotransmitter acetylcholine decomposition, resulting in higher spider excitability; increased protection enzyme, such as GSTs, SOD, CAT, function oxidases (MFOs) and esterase, resulting in the acceleration of spider metabolism, stimulating predator behavior. Third, on the physiological activity of digestive enzymes, low doses of pesticides activate protein midgut digestive enzymes, improving the digestion and absorption function of prey. In summary, certain concentrations of pesticide promote the predation function of P. astrigera against prey, changing spider behavior through a series of physiological and biochemical reactions. 参考文献 相似文献 引证文献

Microbial degradation of imidacloprid and toxicological analysis of its biodegradation metabolites in silkworm (Bombyx mori)

This work presents the degradation of neonicotinic pesticide imidacloprid by an isolated bacterium Klebsiella pneumoniae strain BCH1. The bacterium was capable of degrading imidacloprid up to 78% within 7days at 30°C under static conditions. Effect of various physico-chemical parameters like pH, temperature and increasing pesticide concentration on biodegradation rate were tested. Biodegradation was monitored by various analytical techniques like TLC, HPLC, GC–MS and FTIR. The metabolites produced after imidacloprid degradation were characterized and identified as nitrosoguanidine, imidacloprid guanidine and 6-chloronicotinic acid by gas chromatography and mass spectroscopy. Toxicity testing of imidacloprid and its degraded metabolites was performed using silkworm (Bombyx mori) as a model animal. Various biochemical parameters viz. antioxidant enzyme status (catalase and superoxide dismutase), lipid peroxidation, protein oxidation and genotoxicity assay were performed to assess the toxicity of imidacloprid and its biodegradation metabolites.

Proteomic response of wheat embryos to fosthiazate stress in a protected vegetable soil

A proteomic analysis of wheat defense response induced by the widely used organophosphorus nematicide fosthiazate is reported. Seed germination and two-dimensional gel electrophoresis (2-DE) experiments were performed using a Chinese wheat cultivar, Zhenmai No. 5. Root and shoot elongation decreased but thiobarbituric acid reactive substances (TBARS) content in embryos increased with increasing pesticide concentration. More than 1000 protein spots were reproducibly detected in each silver-stained gel. Thirty-seven protein spots with at least 2-fold changes were identified using MALDI-TOF MS/MS analysis. Of these, 24 spots were up-regulated and 13 were down-regulated. Proteins identified included some well-known classical stress responsive proteins under abiotic or biotic stresses as well as some unusual responsive proteins. Ten responsive proteins were reported for the first time at the proteomic level, including fatty acyl CoA reductase, dihydrodipicolinate synthase, DEAD-box ATPase-RNA-helicase, fimbriata-like protein, waxy B1, rust resistance kinase Lr10, putative In2.1 protein, retinoblastoma-related protein 1, pollen allergen-like protein and S-adenosyl-L-methionine:phosphoethanolamine N-methyltransferase. The proteins identified were involved in several processes such as metabolism, defense/detoxification, cell structure/cell growth, signal transduction/transcription, photosynthesis and energy. Seven candidate proteins were further analyzed at the mRNA level by RT-PCR to compare transcript and protein accumulation patterns, revealing that not all the genes were correlated well with the protein level. Identification of these responsive proteins may provide new insight into the molecular basis of the fosthiazate-stress response in the early developmental stages of plants and may be useful in stress monitoring or stress-tolerant crop breeding for environmentally friendly agricultural production.

Biodegradation of acephate using a developed bacterial consortium and toxicological analysis using earthworms (Lumbricus terrestris) as a model animal

This study reports on degradation of the organophosphorus pesticide acephate by a developed bacterial consortium ER, consisting of the bacterial isolates Exiguobacterium sp. BCH4 and Rhodococcus sp. BCH2. The consortium was capable of degrading acephate up to 75.85%, with an initial concentration of 50 mg l−1 within 6 days at 30 °C under static conditions. The effect of various physicochemical parameters, such as pH, temperature, and increasing pesticide concentration on the biodegradation rate, were tested. Biodegradation was monitored by HPLC, FTIR, and GC-MS. The metabolites produced after acephate degradation were characterized and identified as O,S-dimethyl hydrogen thiophosphate (m/z 142), S-methyl dihydrogen thiophosphate (m/z 127), and methyl dihydrogen phosphate (m/z 111), by gas chromatography and mass spectroscopy. Toxicity testing of acephate and its degraded metabolites was performed using the earthworm Lumbricus terrestris as the model animal. The toxicity of acephate and its biodegradation metabolites was tested using various biochemical parameters, such as antioxidant enzyme status (catalase (CAT) and superoxide dismutase (SOD)), lipid peroxidation, protein oxidation, and genotoxicity assay; the eventual conclusion was that the consortium ER possessed significant potential for degradation and detoxification of acephate.

Malathion toxicity in Nile tilapia, Oreochromis niloticus - A haemotological and biochemical study

Deliberate or accidental contamination of ponds by widely utilized organophophorous (OP) insecticides, such as malathion is a potential problem for aquaculture in tropical countries. The aim of the study was to investigate the toxic effects of malathion (0, 0.5, 1.0, 1.50 and 2 mg L−1) toxicity in the Nile tilapia (Oreochromis niloticus; 15.0 cm length and 50.0 g weight) by correlation of acute toxicity (LC50) studies with biochemical and hematological parameters. Tilapia were very sensitive to malathion (96 h LC50 2ppm). The LC50 for malathion (48 and 96 h) was 2.0 and 1.5 ppm, respectively. The fish shows quick response to malathion. In comparison with controls, sublethal levels of these pesticides led to a significant decrease (P<0.05) in final body weight. The erythrocyte count, haematocrit value and haemoglobin content of Nile tilapia were Glycogen, and protein in fish muscle gradually decreased with increased pesticide concentrations. On the other hand, total production, net returns and profitability of reared fish decreased with increase in concentrations of pesticides. Key words: Tilapia, malathion, toxicity, mortality, haemotological, biochemical.