Toxic Effects Of Herbicides Research Articles

Coupling multifactor dominated the biochemical response and the alterations of intestinal microflora of earthworm Pheretima guillelmi due to typical herbicides.

The excessive application of herbicides on farmlands can substantially reduce labor costs and increase crop yields, but can also have undesirable effects on terrestrial ecosystems. To evaluate the ecological toxicity of herbicides, metolachlor and fomesafen, two typical herbicides that are extensively used worldwide were chosen as target pollutants, and the endogeic earthworm Pheretima guillelmi, which is widely distributed in China, was selected as the test organism. A laboratory-scale microcosmic experiment was set, and energy resources, enzymes, and the composition and connections of intestinal microorganisms in earthworms were determined. Both herbicides depleted the energy resources of the earthworms, especially glycogen contents; increased the levels of antioxidant enzymes; and inhibited acetylcholinesterase. Moreover, the richness and diversity of the intestinal bacterial community of the earthworms were suppressed. Additionally, the bacterial composition at the genus level changed greatly and the connections between dominant bacteria increased dramatically. Most interactions among the bacterial genera belonging to the same and different phyla showed mutualism and competition, respectively. Importantly, metolachlor with higher toxicity had a transitory effect on these indicators in earthworms, whereas fomesafen, with lower toxicity but stronger bioaccumulation potential, exerted a sustaining impact on earthworms. Collectively, these results indicate that the toxic effects of herbicides on terrestrial organisms should be comprehensively considered in combination with biological toxicity, persistence, bioaccumulation potential, and other factors.

Research Progress on the Remediation Technology of Herbicide Contamination in Agricultural Soils

Asthe most-used pesticides in the agricultural production process, herbicides are mainly applied to protect crops from weeds. However, with the increased global demand for food, the dosage of herbicides is rising annually, and the efficacy of herbicides is getting stronger, which can cause some environmental issues including the accumulation, migration and transformation, and toxic effects of herbicides in agricultural soils. According to the characteristics of herbicide contamination and regional agricultural production, developing green and low-carbon technologies to reduce the ecological risks of herbicides to the soil-crop systems is a current concern in the ecological environment field. In this paper, relevant studies in recent years on herbicide pollution management in agricultural soils were identified and reviewed, the research progress and application cases of remediation technologies for herbicide pollution was analyzed and demonstrated, and future research and development tendency regarding the remediation of herbicides pollution was also prospected. Current remediation technologies for herbicides mainly include bioremediation technologies (e.g., microbial remediation, enzyme remediation, and phytoremediation), adsorption, and immobilization technologies (e.g., biochar-based materials). The bioremediation technologieswere rather mature and had been applied to the herbicide-contaminated soil in fields. Additionally, many successful bioremediation cases have been reported. Moreover, in order to enhance the remediation effect on herbicide pollution in agriculture soils, remediation technologies have been gradually developed from a single model to a coupled model with physical,chemical, and biological technology, which can maximize the synergy of the multi-technology application.

Phytotoxicity of the novel compound 3-hydroxy-4-oxo-β-dehydroionol and compound 3-oxo-α-ionone from Albizia richardiana (Voigt.) King & Prain

To protect our environment from the toxic effect of herbicides, it is necessary to reduce the application of synthetic herbicides for controlling weeds in crop fields as well as to increase the use of natural herbicides produced from plant sources. Phytotoxic compounds obtained from plant species have gained attention as an alternate biological method for managing weeds. Albizia richardiana was previously reported to contain a number of phytotoxic substances. Therefore, we carried out this study to investigate more allelopathic substances in Albizia richardiana leaves. Aqueous methanol extracts of Albizia richardiana leaves were significantly inhabited the seedling growth of the two test species (alfalfa and timothy) in a concentration-dependent manner. The two most active substances were separated through different chromatographic steps and characterized as a novel compound 3-hydroxy-4-oxo- β -dehydroionol [( E )-6-hydroxy-3-(3-hydroxybut-1-en-1-yl)-2,4,4-trimethylcyclohexa-2,5-dien-1-one], and compound 3-oxo- α -ionone [3,5,5-trimethyl-4-(3-oxo-1-butenyl)-2-cyclohexen-1-one]. The novel compound 3-hydroxy-4-oxo- β -dehydroionol showed relatively stronger growth inhibitory potential compare to the compound 3-oxo- α -ionone and significantly restricted the seedling growth of crees and timothy. The required concentration for 50% reduction in the growth ( I 50 values) of the cress and timothy seedlings varied from 63.78 to 141.61 μ M for 3-hydroxy-4-oxo- β -dehydroionol and 1059.60 to 1616.10 μ M for 3-oxo- α -ionone. The results indicate that these two allelopathic compounds may be responsible for the phytotoxicity of Albizia richardiana leaves. • Isolation and identification of a novel compound 3-hydroxy-4-oxo- β -dehydroionol. • Characterization of another compound 3-oxo- α -ionone and determined their phytotoxicity. • Albizia richardiana might play a vital to control weeds and protect the environment.

UTILIZING COMBINATION OF HERBICIDE COMMAND AND GROWTH STIMULATORS MELAFEN AND EMISTIM C FOR TOBACCO SEEDLING GROWING

Efficiency of combination of soil herbicide Command (CE 0.02 ml/m2) and growth stimulators Melafen and Emistim S for tobacco seedling growing in sheltered ground has been studied. Before studies inhibition properties of herbicide on first stage of tobacco growing were found. For decreasing effect of herbicide ’s depression and increasing growing processes researches during greenhouse and field stages have been carried. It has been found that soaking seeds in solution of growth stimulator Melafen (concentration 0.05 %) and Emistim S (concentration 0.00001 %) during 3 hours in combination with further treatments on basic stages of seedling development (cotyledon and ready for transplanting before pulling out) led not only to decreasing toxic effect of herbicide but also increasing qualitative properties of tobacco plants. Growth stimulators led to increasing length of plants from collar to growing point by 46-62 %, to end of tips - by 20-35 %, above ground plant mass - by 42 - 86 %, root mass - by 32 %. It was also noticed 28 - 36 % increasing outcome of standard seedlings from m2 in time of transplanting. Due to prolonged effect of Melafen and Emistim S seedlings transplanted into field were with increased surviving properties. Later, due to increased growing rate it was noticed increasing leaf area by 9-18 % and productivity - by 16-24 %. Economic effect due to utilizing growth stimulators Melafen and Emistim S during seedling stage reaches 360 and 470 rubles/m2 and during field stage - 66 and 98 th.rubles/ha respectively. Offered elaboration can be utilized for protecting systems of different agricultural plants where utilizing soil herbicides is recommended. Also quality of cured tobacco grown with stimulators had been improved.

Cichoric acid attenuates the toxicity of mesotrione. Effect on in vitro skin cell model

There is an important need to increase knowledge regarding the interactions between environmental contaminants and other compounds. Pesticides are an important group of food contaminants. By contrast, cichoric acid (CA) belongs to the category of desirable food ingredients with antioxidant and cytotoxic effects. The aim of the presented study was to test if CA may constitute a food ingredient, which eliminate stimulatory effect of pesticides on skin cancer cells and toxic effect of herbicides on fibroblasts. Therefore, we conducted cytotoxicity studies of environmentally relevant pesticide concentrations and the mixture of both compounds in melanoma and fibroblasts cells. We studied if CA combined with mesotrione change the oxidative stress parameters and apoptotic activity in treated cells. Obtained results indicate that CA exhibits cytotoxic activity against mesotrione-induced skin cancer development by influencing oxidative stress parameters and apoptosis. On the other hand CA inhibits prooxidative and proapoptotic activity of mesotrione in fibroblasts. Presented methods and obtained results could be a useful tool in the analysis of environmental contaminants toxicity and possible preventive activity of antioxidative plant- origin compounds.

Bacterial responses to environmental herbicide pollutants (glyphosate and paraquat)

The toxic effect of herbicides on non- target microorganisms may influence degradation of organic matter resulting in changes to nutrient cycling. In the present study, different strains of bacteria incubated in media containing different concentrations of glyphosate and paraquat were assessed over a period of two incubation terms. The deleterious impact of the herbicide was observed as glyphosate and paraquate treatments led to a reduction in the bacterial population. Analysis of the colony- forming unit (CFUs) showed a declining in microbial growth from 0 to 24 hours of incubation in all concentrations of glyphosate followed by a steady declining rate of the bacterial population after 48 h. The greatest bacterial population developed in media containing concentrations of glyphosate and paraquat was observed with strains S13.3, while strains S55 and S35 showed the lowest biomass production in response to all concentrations of glyphosate and paraquat. Based on the results obtained, strain S13.3 was determined to be resistant to the herbicides examined and may be useful for bioremediation of these compounds in soil.

Herbicides and Earthworm population

Vermibiotechnology is the technique for management of biological wastes in to valuable rich nutrients vermicompost which is the best alternative of chemicals fertilizers for growth and productivity of crops. Since last decade abundant used of chemical fertilizers and herbicides have been made our soil sick and problematic. Herbicides are the plant growth hormones or chemicals generally use by large to small farmers for remove unwanted weeds devoid any proportional ratio. The earthworms are a bio-indicator of soil habitat. The continuous use of herbicides decreased the earthworm population in soil which ultimately declined the natural soil fertility. In this review summarized the toxic effect of herbicides on the earthworm population in different combinations of feed materials along with soil.

Toxic Effect of Herbicide 2,4-D on the Earthworm Eutyphoeus waltoni Michaelsen

The toxicity of herbicide 2,4-D (2′-4′ dicholoro phynoxy acetic acid) was studied on earthworms in different combinations of biological wastes and different types of soils as feed materials under laboratory conditions. Eutyphoeus waltoni were exposed to different concentrations of 2,4-D (200, 300, 400, 450 mg/kg) in feed material (i.e., buffalo dung, wheat straw and gram bran) and different concentrations of 2,4-D (150, 300, 350, 400 mg/kg) in different types of soil (i.e., loamy soil, clay soil and sandy soil). Observations were recorded from 24 h up to 240 h. It was observed that the toxic effect of herbicide 2,4-D on the earthworm Eutyphoeus waltoni was both time and dose dependent. Maximum toxicity was observed in the sandy soil, whereas minimum in the feed material of buffalo dung with gram bran. There was no mortality observed in control.

Toxic effect of herbicides used for water hyacinth control on two insects released for its biological control in South Africa

The integrated control of water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae) has become necessary in South Africa, as biological control alone is perceived to be too slow in controlling the weed. In total, seven insect biological control agents have been released on water hyacinth in South Africa. At the same time, herbicides are applied by the water authorities in areas where the weed continues to be troublesome. This study investigated the assumption that the two control methods are compatible by testing the direct toxicity of a range of herbicide formulations and surfactants on two of the biological control agents released against water hyacinth, the weevil, Neochetina eichhorniae Warner (Coleoptera: Curculionidae) and the water hyacinth mirid, Eccritotarsus catarinensis (Carvalho) (Hemiptera: Miridae). A number of the formulations used resulted in significant mortality of the mirid and the weevil. Products containing 2,4-D amine and diquat as active ingredients caused higher mortality of both agents (up to 80% for the mirid) than formulations containing glyphosate. Furthermore, when surfactants were added to enhance herbicide efficiency, it resulted in increased toxicity to the insects. We recommend that glyphosate formulations should be used in integrated control programmes, and that surfactants be avoided in order to reduce the toxic nature of spray formulations to the insect biological control agents released against water hyacinth.

Abiotic Reduction Reactions of Dichloroacetamide Safeners: Transformations of “Inert” Agrochemical Constituents

Safeners are so-called "inert" constituents of herbicide formulations added to protect crops from the toxic effects of herbicides. We examined the reactivity of three dichloroacetamide safeners and 12 structural analogues [all neutral compounds of the form Cl(2)CXC(═O)NRR'; X = H, Cl; R-groups include alkyl, branched alkyl, n-allyl, and cyclic moieties] in one homogeneous and two heterogeneous reductant systems: solutions of Cr(H(2)O)(6)(2+), suspensions of Fe(II)-amended goethite, and suspensions of Fe(II)-amended hematite. Analyses of reaction products indicate each safener can undergo stepwise hydrogenolysis (replacement of chlorine by hydrogen) in each system at near-neutral pH. The first hydrogenolysis step generates compounds similar (in one case, identical) to herbicide active ingredients. Rates of product formation and (when reactions were sufficiently fast) parent loss were quantified; reaction rates in heterogeneous systems spanned 2 orders of magnitude and were strongly influenced by R-group structure. The length of n-alkyl R-groups exerted opposite effects on hydrogenolysis rates in homogeneous versus heterogeneous systems: as R-group size increased, reduction rates in heterogeneous systems increased, whereas reduction rates in the homogeneous system decreased. Branched alkyl R-groups decreased hydrogenolysis rates relative to their straight-chain homologues in both homogeneous and heterogeneous systems. Reaction rates in heterogeneous systems can be described via polyparameter linear free energy relationships employing molecular parameters likely to influence dichloroacetamide adsorption. The propensity of dichloroacetamide safeners to undergo reductive transformations into herbicide-like products challenges their classification as "inert" agrochemical ingredients.

Toxicity assessment of herbicides quizalafop-p-ethyl and clodinafop towards Rhizobium pea symbiosis.

In modern conventional agriculture, herbicides are frequently used to prevent yield losses due to weeds. Herbicides also affect negatively the productivity of legumes. With these considerations, we evaluated the effects of soil applications of different concentrations of quizalafop-p-ethyl and clodinafop on the performance of Rhizobium inoculated pea, grown in clay pots. In this study, the concentration of herbicides higher than the recommended rates of quizalafop-p-ethyl and clodinafop adversely affected the dry matter accumulation, symbiotic properties, grain yield and nutrient status of pea plants. Toxicity of quizalafop-p-ethyl and clodinafop to pea plants increased progressively with increase in rates of herbicides. Of the two herbicides, quizalafop-p-ethyl was more toxic than clodinafop. In contrast, when herbicide tolerant Rhizobium strain MRP1 was also used with herbicide, it increased the measured parameters at all concentrations. A maximum increase of 11%, 17%, 46%, 33%, 21% and 7% in the root N, shoot N, root P, shoot P, seed yield and seed protein, respectively, was observed when MRP1 was used with 120 microg quizalafop-p-ethyl kg(-1) soil while with 1,200 microg clodinafop kg(-1) soil it increased the root N, shoot N, root P, shoot P, seed yield and seed protein by 20%, 9%, 56%, 56%, 29% and 7%, respectively, compared with the un-inoculated but herbicide treated control. This study suggested that the toxic effects of herbicides on pea plants could be attenuated by applying growth promoting herbicide tolerant strain of Rhizobium under herbicide stressed soil environment.

Deleterious effect of herbicides on waterhyacinth biocontrol agents Neochetina bruchi and Alternaria alternata

The integration of biological and herbicidal methods is advocated to manage waterhyacinth, but this can only be achieved when herbicides are nontoxic to the biocontrol agent. Therefore, laboratory experiments were conducted to determine the toxic effect of herbicides on the insect biocontrol agent, the waterhyacinth weevil, Neochetina bruchi Hustache, and phytopathogen, Alternaria alternata, with two commonly used herbicides, glyphosate and 2,4-dichlorophenoxy acetic acid at three recommended doses. The herbicides were sprayed on the waterhyacinth weevils and added to the nutrient media of A. alternata. 2,4-D caused higher weevil mortality (6.7, 13.3 and 15.6%) as compared to glyphosate (3.3, 5.6 and 11.1%), at three doses over 72 h. There was also a decrease in feeding in the herbicide treated leaves. When the weevils were allowed to move freely between the herbicide treated and untreated plants, higher orientation of the weevils was found on the untreated waterhyacinth than on the treated ones. Neither of the two herbicides actually killed the fungus but both inhibited its growth. Glyphosate though, delayed mycelial growth yet stimulated sporulation while 2,4-D inhibited both growth and sporulation. Glyphosate at low concentration did not affect the virulence of A. alternata, while fungi grown on 2,4-D amended plates lost their virulence.

Herbicides and Forest Biodiversity: An Alternative Perspective

Effects of herbicide use on forest biodiversity was the topic of a special section in the winter 2004 issue of The Wildlife Society Bulletin. In acknowledging public concerns regarding the toxic effects of herbicides, several of the contributing authors argued that these effects are negligible and that intensifying wood production would be beneficial for forest biodiversity and conservation by reducing habitat conversions. We contend there are other important environmental consequences; hence, responding to increased opportunities for selling wood products by augmenting supply through intensifying production should not be the only option. We argue that it is also important to develop mechanisms to reduce the demand for forest products. We believe the focus of the special section was too narrow, particularly with respect to benefiting biodiversity, because herbicide use also intensifies the export of wood products and, thus, nutrients. Other factors that must be considered include soil acidification caused by biomass export and fertilizer application, as well as additional acidification resulting from aerial emissions. In addition, because of mineral cycle dynamics constraints, intensively managed forests may not be sustainable for wood production, and less so for forest-dependent animals. Extensively exploited forests may deplete mineral reserves, and any intensification likely would speed up the declines. We believe the indirect impact from herbicides through accelerating mineral export and loss needs to be addressed, in particular how it may affect mammals' ability to accumulate essential trace elements. We contend using fertilizer applications as a corrective measure at the landscape level would be cost-prohibitive. Thus, heralding that herbicides, a tool to intensify wood production, benefit forest biodiversity appears premature, given the time scale of forest growth and soil development.

The toxic effect of herbicides, PCP and Randox, on fish

The toxic effect of herbicides, PCP and Randox, on fish