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Abstract

Contamination of soil with heavy metals has become an issue of concern on global scale. This study investigates the translocation of lead (Pb) along the soil - plant (eggplant and tomato) - mealybug (Dysmicoccus neobrevipes) - ladybird beetle (Cryptolaemus montrouzieri) food chain. Soil amendments used for this study were adjusted to 0, 25, 50 and 100 mg/kg of Pb (w/w). The results revealed significantly higher transfer of Pb in tomato when compared to eggplant. Bio-magnification of Pb (2–4 times) was observed for soil - root transfer whereas Pb was bio-minimized in later part of food chain (shoot – mealybug - ladybird transfer). A dose dependent increase in transfer of Pb across the multi-trophic food chain was observed for both host plants. A decrease in coefficients of Pb transfer (from root - shoot and shoot - mealybug) was observed with increase in Pb concentrations. Our results also showed removal of Pb from the bodies of ladybird beetle during metamorphosis. Further studies are required to explain the mechanisms or physiological pathways involved in the bio-minimization of Pb across the food chain.

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... The casparian strip prevents water stream and the Heavy metal enters the symplastic phase. Heavy metal transportation (in low concentrations) through root to APP have accounted for of immobilization by contrarily charged gelatins inside the root cell divider [106,107]. Insoluble Heavy metal salts hasten in intercellular spaces of root cells [107,108]. Essentially, Heavy metal amassing in plasma layers of root cells [107,109] or in rhizodermal vacuoles and cortical cells of roots. ...
... Heavy metal transportation (in low concentrations) through root to APP have accounted for of immobilization by contrarily charged gelatins inside the root cell divider [106,107]. Insoluble Heavy metal salts hasten in intercellular spaces of root cells [107,108]. Essentially, Heavy metal amassing in plasma layers of root cells [107,109] or in rhizodermal vacuoles and cortical cells of roots. Significant segment of Heavy metal is discharged from internal cells (endodermis) during the detoxification process by the plant. ...
... Insoluble Heavy metal salts hasten in intercellular spaces of root cells [107,108]. Essentially, Heavy metal amassing in plasma layers of root cells [107,109] or in rhizodermal vacuoles and cortical cells of roots. Significant segment of Heavy metal is discharged from internal cells (endodermis) during the detoxification process by the plant. ...
Chapter
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Food security is a major concern that requires sustained advancement both statistically and on the basis of Qualitative assessment. In recent years, antagonistic impacts of unforeseen toxins have impacted the quality of crops and have created a burden on human lives. Heavy metals (e.g., Hg, As, Pb, Cd, and Cr) can affect humans, adding to dreariness and in severe cases even death. It additionally investigates the conceivable geological routes of heavy metals in the surrounding subsystems. The top-to-the-bottom conversation is additionally offered on physiological/ atomic movement systems engaged with the take-up of metallic foreign substances inside food crops. At long last, the board procedures are proposed to recapture maintainability in soil-food subsystems. This paper reflects the contamination of the food crops with heavy metals, the way of transport of heavy metal to food crops, degree of toxicity after consumption and the strategies to maintain the problem.
... 13 Generally, the transfer efficiency of heavy metals between the pre and post trophic levels depends on the transfer coefficient, the ratio of heavy metal concentration in the receiver to the concentration in the source (donor). 20 In terms of transfer coefficient, the transfer efficiency of heavy metals can be controlled or regulated by bio-magnification and bio-minimization. 20,21 Bio-magnification refers to the phenomenon that heavy metals in the environment are gradually enriched and concentrated as they move from one trophic level to the other. ...
... 20 In terms of transfer coefficient, the transfer efficiency of heavy metals can be controlled or regulated by bio-magnification and bio-minimization. 20,21 Bio-magnification refers to the phenomenon that heavy metals in the environment are gradually enriched and concentrated as they move from one trophic level to the other. In contrast, bio-minimization refers to a reduction of the heavy metals concentration as they move to higher trophic levels. ...
... Whether the transfer mechanism is via bio-magnification or biominimization, it has been demonstrated that the transfer process of heavy metals from host plants to phytophagous insects varies amongst insect species investigated. 20 The difference between insect species could be due to their excretion capacity. For example, in the soil-mulberry-silkworm system, Pb transfer coefficients from the mulberry leaves to silkworm larvae were below one, meaning that there was a bio-minimization process; however, the transfer coefficients from silkworm larvae to their feces ranged from 13.02 to 39.35, about 108-983 times higher than those during the leaf to larvae transfer. ...
Article
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The development and physiological status of pest insects are important factors that affect the effectiveness of biological control. Current knowledge reveals that heavy metals can be transferred to phytophagous insects through food chains and cause various chronic toxicological effects on the growth and physiology of phytophagous insects. These findings potentially attribute heavy metal contamination to an environmental factor governing biocontrol efficiency against pest insects, pointing to an urgent demand to better understand the effects of heavy metal exposure on insect susceptibility to entomopathogenic microorganisms. Here we discuss the transfer characteristics of heavy metals along the food chains to phytophagous insects and conclude that heavy metal exposure may promote insect susceptibility to entomopathogenic microorganisms in the heavy metal‐contaminated regions. Furthermore, we propose a ‘combined effect’ hypothesis that combination of entomopathogenic agent and heavy metal stress can cause a much higher overall insect mortality than does the entomopathogenic agent or the heavy metal stress alone. This is a new and relatively unexplored area in the microbial‐based biocontrol research, which might have great potential for future optimization of biocontrol strategies against economically and ecologically important agricultural or forest pests in the heavy metal polluted areas. © 2020 Society of Chemical Industry
... The endoderm functions as a physical barrier to Pb translocation as water stream is blocked by casparian strip and, thus, Pb enters into the symplastic movement. The low Pb transportation from root to APP has been reported due to immobilization by negatively charged pectins within the root cell wall [2,84]. Insoluble Pb salts precipitate in intercellular spaces of root cells [70,84]. ...
... The low Pb transportation from root to APP has been reported due to immobilization by negatively charged pectins within the root cell wall [2,84]. Insoluble Pb salts precipitate in intercellular spaces of root cells [70,84]. Similarly, Pb accumulation in plasma membranes of root cells [61,84] or sequestration in the vacuoles of rhizodermal and cortical cells of roots is reported [68,84]. ...
... Insoluble Pb salts precipitate in intercellular spaces of root cells [70,84]. Similarly, Pb accumulation in plasma membranes of root cells [61,84] or sequestration in the vacuoles of rhizodermal and cortical cells of roots is reported [68,84]. The major portion of the absorbed lead is sequestered/excreted from endodermis cells during the plant detoxification process. ...
Article
Full-text available
Lead (Pb) toxicity has been a subject of interest for environmental scientists due to its toxic effect on plants, animals, and humans. An increase in several Pb related industrial activities and use of Pb containing products such as agrochemicals, oil and paint, mining, etc. can lead to Pb contamination in the environment and thereby, can enter the food chain. Being one of the most toxic heavy metals, Pb ingestion via the food chain has proven to be a potential health hazard for plants and humans. The current review aims to summarize the research updates on Pb toxicity and its effects on plants, soil, and human health. Relevant literature from the past 20 years encompassing comprehensive details on Pb toxicity has been considered with key issues such as i) Pb bioavailability in soil, ii) Pb biomagnification, and iii) Pb-remediation, which has been addressed in detail through physical, chemical, and biological lenses. In the review, among different Pb-remediation approaches, we have highlighted certain advanced approaches such as microbial assisted phytoremediation which could possibly minimize the Pb load from the resources in a sustainable manner and would be a viable option to ensure a safe food production system.
... The endoderm functions as a physical barrier to Pb translocation as water stream is blocked by casparian strip and, thus, Pb enters into the symplastic movement. The low Pb transportation from root to APP has been reported due to immobilization by negatively charged pectins within the root cell wall [2,84]. Insoluble Pb salts precipitate in intercellular spaces of root cells [70,84]. ...
... The low Pb transportation from root to APP has been reported due to immobilization by negatively charged pectins within the root cell wall [2,84]. Insoluble Pb salts precipitate in intercellular spaces of root cells [70,84]. Similarly, Pb accumulation in plasma membranes of root cells [61,84] or sequestration in the vacuoles of rhizodermal and cortical cells of roots is reported [68,84]. ...
... Insoluble Pb salts precipitate in intercellular spaces of root cells [70,84]. Similarly, Pb accumulation in plasma membranes of root cells [61,84] or sequestration in the vacuoles of rhizodermal and cortical cells of roots is reported [68,84]. The major portion of the absorbed lead is sequestered/excreted from endodermis cells during the plant detoxification process. ...
Article
Full-text available
Lead (Pb) toxicity has been a subject of interest for environmental scientists due to its toxic effect on plants, animals, and humans. An increase in several Pb related industrial activities and use of Pb containing products such as agrochemicals, oil and paint, mining, etc. can lead to Pb contamination in the environment and thereby, can enter the food chain. Being one of the most toxic heavy metals, Pb ingestion via the food chain has proven to be a potential health hazard for plants and humans. The current review aims to summarize the research updates on Pb toxicity and its effects on plants, soil, and human health. Relevant literature from the past 20 years encompassing comprehensive details on Pb toxicity has been considered with key issues such as i) Pb bioavailability in soil, ii) Pb biomagnification, and iii) Pb-remediation, which has been addressed in detail through physical, chemical, and biological lenses. In the review, among different Pb-remediation approaches, we have highlighted certain advanced approaches such as microbial assisted phytoremediation which could possibly minimize the Pb load from the resources in a sustainable manner and would be a viable option to ensure a safe food production system.
... Lead is a toxic element with serious health effects on humans and other biota. Plants serve as a route of exposure of Pb to herbivores while herbivores serve as a source of Pb transfer to organisms at higher levels in the food chain (Devkota and Schmidt 2000;Zhang et al. 2017). Aphids are harmful pests and can severely damage crop plants (Rehman et al. 2014). ...
... In the present study, soil spiked with different concentrations of Pb did not alter the total organic matter content, as expected and reported by Zhang et al. (2017) and Singh and Agarwal (2010). The increase in the total nitrogen content is due to the addition of Pb as a salt of nitrate (Pb (NO 3 ) 2 ). ...
... The TCs of Pb from root-shoot were lower than 1 (~0.54) and lower than those of soil-root. These results are in line with the findings of Liu et al. (2009), Shahid et al. (2011, Dar et al. (2015Dar et al. ( , 2017, Zhou et al. (2016) and Zhang et al. (2017), who reported the accumulation of Pb mostly in the roots of plants and only a small amount was translocated to aerial parts. Retention of Pb in roots and its lower root-shoot translocation may be due to immobilization or precipitation of Pb by negatively charged lignin and pectin or binding to mucilage uronic acids within the cell walls of roots (Arias et al. 2010;Islam et al. 2007), sequestration of Pb in the vacuoles of cortical and rhisodermal cells (Kopittke et al. 2007, accumulation of Pb in plasma membranes (Jiang and Liu 2010) or precipitation of insoluble salts of Pb in intercellular spaces (Malecka et al. 2009). ...
Article
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Lead (Pb) contamination of agroecosystems is a serious issue as Pb is a persistent pollutant that is retained in soil for long, causing toxicities to organisms. This study examines biotransfer of Pb from soils treated with different concentrations of Pb through a broad bean (Vicia faba L.)–aphid (Aphis fabae Scop.)–ladybird (Coccinella transversalis Fabricius) food chain and its consequent inference for natural biological control, the ladybird. The soil was amended with Pb at the rates of 0, 25, 50, 75 and 100 mg kg⁻¹ (w/w). The amount of Pb in plant, aphid and ladybird increased in a dose-dependent manner to Pb contents in the soil. The results showed that Pb biomagnified from soil to root with transfer coefficient always > 1. Biominimization of Pb occurred at the second trophic level in aphids and at the third trophic level in ladybirds as their respective transfer coefficients from shoot to aphid and aphid to ladybird were always < 1. The increased elimination of Pb via aphid excreta (honeydew) and pupal exuviae in a dose-dependent manner suggests that these are possible detoxification mechanisms at two different trophic levels which control Pb bioaccumulation along the food chain. The statistically significant (p ≤ 0.05) decreases in biomass and predation rate of predatory ladybirds at 100 mg kg⁻¹ Pb indicate that high dose of Pb in soil may have sub-lethal effects on ladybirds. Further studies at cellular and sub-cellular levels are needed to further document the potential mechanisms of achieving Pb homeostasis in ladybirds under Pb stress.
... Immobilization by negatively charged pectins within the root cell wall has been reported as the cause of the reduced Pb transportation from root to aerial parts of the plant like leaves and fruits. Insoluble Pb salts precipitate in root cell intercellular spaces (Zhang et al. 2017). Similarly, it has been found that Pb accumulates in the plasma membranes of root cells or is confined in the vacuoles of rhizodermal and cortical cells of roots (Zhang et al. 2017). ...
... Insoluble Pb salts precipitate in root cell intercellular spaces (Zhang et al. 2017). Similarly, it has been found that Pb accumulates in the plasma membranes of root cells or is confined in the vacuoles of rhizodermal and cortical cells of roots (Zhang et al. 2017). Consequently, through plants lead enters the food chain and may end up in the human body as well. ...
Chapter
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The contamination of the environment with heavy metals particularly lead (Pb) is highly contagious and an alarming situation in metropolitan regions with high anthropogenic pressure like vehicular and industrial active areas. Its tracer amount in the environment, soil, water, and biological systems can pose major issues for all living things, and its bioaccumulation in the food chain is particularly risky for the well-being of people and animals. It has been widely observed that human populations are exposed to lead contamination and are accumulating it as a result of a contaminated environment entering into the food chain. Though it is not an essential mineral element its plants can nevertheless absorb it from the contaminated area since it remains soluble in soil. Soil properties can have a significant impact on the behaviour and mobility of lead in the soil and the presence of lead in the soil can have several negative impacts on the soil–plant system. It is important to work with experts, such as soil scientists and environmental engineers, to determine the most effective strategy for tackling lead toxicity in the soil. In this chapter, our main focus is on the sources and mechanism of Pb in soil and plants because every environmental component contains a sizable proportion of lead, thus its management and remediation should be urgently required for better environmental health.KeywordsAgricultureEnvironmentLeadHeavy metalsPlantsSoil
... Most trace metal loss associated with metamorphosis occurs through 2 mechanisms, namely the excretion of meconium by the imago (Gintenreiter et al., 1993) and the loss of some of the larval trace metal body burden in the pupal exuviae (Green et al., 2003;Dar et al., 2015bDar et al., , 2017Zhang et al., 2017). Kazmirova and Ortel (2000) ascribed decreases in the concentration of Cd (33%), Pb (33-51%) and Cu (24-39%) during development of the dipteran Ceratitis capitata (common name: Mediterranean fruit fly) from pupa to adult principally to loss through the meconium. ...
... Loss via the exuviae can also be a very effective excretion mechanism, with up to 80% of Cu and 37% of Zn eliminated from the juvenile invertebrate by this mechanism (Andrzejewska et al., 1990). Typical losses for Cd, Pb and Zn appear to be much lower than this, with 2-19% of the larval body burden being removed (Green et al., 2003;Dar et al., 2015b;Dar et al., 2017;Zhang et al., 2017). ...
... Furthermore, examining the impact of heavy metals on organisms across various trophic levels via food chain transmission is a more effective approach for elucidating the enrichment and transmission patterns of heavy metals in plant-feeding herbivorous insects compared to a direct addition to diets or injection into insects. While some studies have explored the effects of heavy metals on organisms via soil-plant-phytophagous insect-predator food chains [22][23][24], the majority have focused on single-metal stress, thereby neglecting research from the perspective of combined stress. Consequently, it is of paramount importance to investigate the physiological and biochemical impacts of composite heavy metal stress on insects within food chain models. ...
Article
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Heavy metal pollution is a serious global environmental issue. It threatens human and ecological health. Heavy metals can accumulate in the soil over extended periods and inevitably transfer through the food chain to herbivorous insects and their natural enemies, leading to various adverse effects. This study aimed to investigate the stress responses and biochemical metabolic changes of aphids and one of aphids’ predators, ladybugs, under cadmium (Cd) and lead (Pb) stress by constructing a food chain of Vicia faba L., Megoura crassicauda, and Harmonia axyridis. The results showed that aphids and ladybugs had a notable accumulation of Cd2+ and Pb2+. Insects can adapt to heavy metal stress by regulating their energy metabolism pathways. Glycogen content in the first filial generation (F1) aphids decreased significantly, glucose content in the second filial generation (F2) to the fourth filial generation (F4) adult aphids significantly increased, and trehalose content in the F1 adult aphids increased significantly. Moreover, the relative expression levels of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) in the F1 adult aphids were significantly higher than those in the control group, and the expression levels of TPS genes in the second filial generation to the fifth filial generation (F2 to F5) aphids decreased, suggesting that insects can resist heavy metal stress by regulating trehalose metabolism. The fertility of female aphids in all treatment groups was reduced compared to the control group. Additionally, the relative expression level of vitellogenin (Vg) was down-regulated in all aphid generations except the F1 aphids. There was interaction between heavy metal concentration and aphid generation, and it significantly affected the number of aphids’ offspring and the expression of the aphid Vg gene. The developmental duration of the ladybugs from the second to fourth instars was prolonged, and the weight decreased significantly from the prepupa to the adult stages. These results contribute to understanding the effects of Cd2+–Pb2+ accumulation on phytophagous insects and higher trophic levels’ natural enemies, laying the foundation for protecting natural enemies and maintaining ecosystem stability.
... According to the studies of Zhang et al. (2017) and Naikoo et al. (2019), the concentrations of lead treatment were set at 12.5 (T1), 25 (T2), 50 (T3), 100 (T4), and 200 (T5) mg/L, respectively (Table S1). This experiment used tap water treatment as control (T0). ...
... Additionally, there is evidence of the presence of Cd in bee products (honey, propolis, and beeswax) associated with bees collecting pollen from plants in contaminated areas (Bogdanov 2006, Silici et al. 2016). Previous studies have also shown that tomatoes had a higher translocation of Pb in the trophic chain (soil-plant-herbivorous insect-predator insect) with the Cryptolaemus montrouzieri beetle (Zhang et al. 2017). In the current study, the TTF value for the tomato-to-D. ...
Article
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The presence of toxic metals in vegetables of daily consumption is a concern for human health. Little is known about the concentration of toxic metals in vegetables sold in markets in Quito, Ecuador, and the corresponding risk to the population. This study aimed to measure the concentration of cadmium (Cd), and lead (Pb) in tomatoes, carrots, and lettuce, to estimate the risk for human health, and to determine the trophic transfer factor using Drosophila melanogaster flies. Vegetable samples were obtained from four local markets in Quito to measure the concentration of Cd and Pb (expressed in mg/kg of dry weight) in the vegetables by microwave-assisted acid digestion and atomic absorption spectrophotometry. Drosophila melanogaster flies were fed with contaminated vegetables to determine de trophic transfer factor of metals in the trophic chain. Our results showed the highest accumulation of Pb and Cd occurred in lettuce. In all cases, the Pb and Cd concentrations exceeded the maximum levels established by the Food and Agriculture Organization. However, the daily intake of metals and the health risk index showed no risk from daily consumption. Pb’s trophic transfer factor was excessively high in the tomato-fed flies, showing transference and accumulation in the flies. Cadmium concentration in tomato-fed flies was also the highest among the three vegetables. The trophic chain transfer of toxic metals from vegetables to Drosophila has been observed through a high accumulation of these metals in flies, and this suggests a negative impact on both human health and ecosystems.
... Trace metals in the soil can be concentrated in the plants, which insects then feed on and carry trace elements into their bodies (Zhang et al., 2017). Thus, the extensive diet of Silver-eared Mesia will enrich a mass of trace elements into the body, making its intestinal microbiota under trace element stress environment. ...
Article
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The complex gut bacterial communities have a major impact on organismal health. However, knowledge of the effects of habitat change on the gut microbiota of wild birds is limited. In this study, we characterized the gut microbiota of two different subspecies of the Silver-eared Mesia (Leiothrix argentauris), the native subspecies (L. a. rubrogularis) and immigrant subspecies (L. a. vernayi), using 16S rRNA gene high-throughput sequencing. These two subspecies live in a trace metal-contaminated area, and L. a. vernayi was trafficked. They are an excellent system for studying how the gut microbiome of wild animal changes when they move to new habitats. We hypothesized that the immigrant subspecies would develop the same adaptations as the native subspecies in response to habitat changes. The results showed that there were no significant differences in the composition, diversity, or functional metabolism of gut microbiota between native and immigrant subspecies under the combined action of similar influencing factors (the p values of all analyses of variance >0.05). In addition, the composition and functional metabolism of gut microbiota in two subspecies showed adaptation against trace metal damage. Linear discriminant analysis effect size (LEfSe) analysis revealed that Massilia in the intestinal microbiota of immigrant subspecies was significantly higher than that of native subspecies, suggesting that immigrant subspecies suffered habitat change. Finally, we found that these two subspecies living in the mining area had an extremely high proportion of pathogenic bacteria in their gut microbiota (about 90%), much higher than in other species (about 50%) living in wild environment. Our results revealed the adaptation of intestinal microbiota of immigrant Silver-eared Mesias under heavy metals stress, which would provide guidance for biodiversity conservation and pollution management in mining area.
... In the 1990s, Cordyceps fumosorosea (Wize, 1904) (formerly known as Isaria fumosorosea Wize) [40] was reportedly the most common entomopathogenic fungi in Asia, Russia, the USA, South America, and India. Under favorable conditions, C. fumosorosea can cause a significant reduction in insect pest populations [41]. Apart from its efficacy and low cost of production, the use of C. fumosorosea has other advantages, including broader insecticidal activity, a diversified host range, and safety for humans and other non−target organisms [42]. ...
Article
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Ultraviolet-C (UV-C) radiation significantly impacts living organisms. UV-C radiation can also be used as a pest management tool. Therefore, this study was designed to investigate the effect of UV-C radiation on the physiology and gene expression level of Plutella xylostella, a destructive vegetable pest. Results showed that, after exposure to UV-C radiation for 3, 6, 12, and 24 h, the activity of SOD (superoxide dismutase) and CAT (catalase) of P. xylostella increased, while the activity of PPO (polyphenol oxidase), POD (peroxidase), AChE (acetylcholinesterase), CarE (carboxylesterase), and ACP (acid phosphatase) decreased with increased exposure time. Correlation coefficient analyses indicated that the activity of CAT correlated positively, while PPO and CarE correlated negatively, with exposure time. Gene regulation analysis via qRT-PCR confirmed a significant increase in regulation in CAT, CarE, and PPO-related genes. We also investigated the effect of UV-C exposure on the virulence of Cordyceps fumosorosea against P. xylostella. Here, results indicated that when the fungal treatment was applied to larvae before UV-C radiation, the virulence of C. fumosorosea was significantly reduced. However, this decline in virulence of C. fumosorosea due to UV-C exposure remained only for one generation, and no effect was observed on secondary infection. On the other hand, when larvae were exposed to UV-C radiation before fungal application, the mortality rate significantly increased as the exposure time to UV-C radiation increased. From the current study, it could be concluded that UV-C exposure suppressed the immunity to P. xylostella, which later enhanced the virulence of entomopathogenic fungi. Moreover, the study also suggested that UV irradiation is an effective pest management tool that could be incorporated into pest management strategies, which could help reduce pesticide application, be economically beneficial for the farmer, and be environmentally safe.
... et le Pb(Naikoo et al., 2019;Zhang et al., 2017), ces deux composés ne semblent pas avoir été biomagnifiés. Ainsi, même pour un système linéaire et maitrisé, le phénomène de bioamplification semble variable selon les ETM et selon des facteurs intrinsèques aux espèces de plantes et d'insectes considérées. ...
Thesis
Les contaminations entrainent des dégradations générant des dysfonctionnements des sols et des atteintes à leurs fonctions écologiques. Le phytomanagement, qui utilise des espèces végétales pour extraire, contenir ou dégrader des polluants, apparaît comme une solution adaptée pour produire de la biomasse végétale tout en favorisant la réhabilitation de ces sols délaissés. Les approches récentes s’accordent sur l'importance des associations végétales dans l’optimisation de ces dispositifs. Ce projet de thèse s’articule autour d’un dispositif agroforestier novateur, associant la grande ortie (Urtica dioica L.) à une plante modèle dans le domaine, le peuplier. Dans des plantations de peuplier, l’ortie offre de nouvelles perspectives liées à son aptitude à se développer spontanément sur des sites contaminés et à la qualité de sa fibre végétale, utilisables pour la fabrication de biomatériaux.A partir de deux sites ateliers contaminés par les éléments trace métalliques (ETM) et différentes approches disciplinaires, ces travaux ont permis i) de mieux comprendre le fonctionnement de cedispositif peuplier-ortie à l’interface rhizosphérique et sa réponse aux ETM via des approches de barcoding environnemental et de métabolomique ciblée ii) d’appréhender le rôle des plantes modèles dans la restauration écologique de ces sites au travers d’études phytosociologique et entomologique et évaluer l’implication des communautés associées dans les flux d’ETM par uneapproche écotoxicologique, et finalement iii) de caractériser et optimiser le potentiel économique de ce dispositif selon une approche agroécologique. Enfin, cette thèse ambitionne d’être un travail de référence pour les futurs projets de phytomanagement basés sur des associations arbres – orties.
... For example, the accumulation of metal ions in Beta vulgaris is higher in summers than in winter due to the relatively high transpiration rates (Sharma et al., 2007). From plants, the metal can enter into higher trophic levels of food chains such as insects, herbivores, and humans, resulting in the ecosystem and food chains imbalance (Zhang et al., 2017). HM toxicity reduces the growth of plants in terms of dry weight and height, which can be improved by plant symbiotic association with ectomycorrhizal (ECM) fungi. ...
Article
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Soil heavy metal (HM) pollution, which arises from natural and anthropogenic sources, is a prime threat to the environment due to its accumulative property and non-biodegradability. Ectomycorrhizal (ECM) symbiosis is highly efficient in conferring enhanced metal tolerance to their host plants, enabling their regeneration on metal-contaminated lands for bioremediation programs. Numerous reports are available regarding ECM fungal potential to colonize metal-contaminated lands and various defense mechanisms of ECM fungi and plants against HM stress separately. To utilize ECM–plant symbiosis successfully for bioremediation of metal-contaminated lands, understanding the fundamental regulatory mechanisms through which ECM symbiosis develops an enhanced metal tolerance in their host plants has prime importance. As this field is highly understudied, the present review emphasizes how plant’s various defense systems and their nutrient dynamics with soil are affected by ECM fungal symbiosis under metal stress, ultimately leading to their host plants ameliorated tolerance and growth. Overall, we conclude that ECM symbiosis improves the plant growth and tolerance against metal stress by (i) preventing their roots direct exposure to toxic soil HMs, (ii) improving plant antioxidant activity and intracellular metal sequestration potential, and (iii) altering plant nutrient uptake from the soil in such a way to enhance their tolerance against metal stress. In some cases, ECM symbiosis promotes HM accumulation in metal stressed plants simultaneous to improved growth under the HM dilution effect.
... There is no recommended limit for Sn intake. Heavy metals in food can be due to various reasons such as polluted and/or contaminated soil, pesticides, fertilizers and geographical location ( Zhang et al., 2017 ). Table 2 shows that nuts have a high content of lipids, which are considered beneficial to health, such as monounsaturated fatty acids (MUFAS) and polyunsaturated fatty acids (PUFAS). ...
Article
The purpose of this review is to demonstrate how the unexplored nuts native to Brazil can contribute positively to biodiversity and human nutrition. This review presents data on the composition of macronutrients, micronutrients, and bioactive compounds of non-conventional nuts native from Brazil (baru, chichá, gurguéia, monguba, pracaxi and sapucaia). The knowledge about these underutilized raw materials is important to stimulate their production, commercialization and consumption, as well as generate interest among researchers from various scientific fields. Non-conventional nuts are rich in lipids such as unsaturated fatty acids, phytosterols, and tocopherols. In addition, they provide high levels of energy, fiber, minerals, and amino acids. Bioactive compounds such as phenolic acids and flavonoids were identified and quantified from non-conventional nuts. Several of these nuts are native from Brazil and have the potential for further research that encourage their production, commercialization, consumption and use the valorization of co-products as ingredients in foods.
... Transfer coefficient (TC) of Cd from aphids to ladybirds were valued below 1, indicating biominimization of these heavy metals in predatory ladybirds. These results correspond to previous studies by several researchers (Dar et al., 2017;Wang et al., 2017;Zhang et al., 2017). Ladybirds feed voraciously in the fourth instar larval stage (Naikoo et al., 2019a); therefore, Cd accumulation mainly occurs in the fourth instar larval stage (Gintenreiter et al., 1993). ...
Article
Cadmium is a highly mobile toxic heavy metal and a serious hazard to the biosphere. We studied uptake, accumulation and elimination of cadmium in a soil - faba bean - aphid - ladybird food chain. The soil in the study was amended with Cd at concentrations 0, 5, 10, 20 and, 30 mg kg⁻¹ (w/w). We noted significant Cd transfer in a dose-dependent manner. Cadmium biomagnified in faba bean roots and aphids while biominimized in ladybirds as revealed by their respective transfer coefficients. The concentration-dependent removal of Cd from aphids through excretion via honeydew as well as through pupal exuviae of ladybirds during metamorphosis links to possible mechanisms of Cd detoxification at these trophic levels, which regulates the bioaccumulation of Cd along the food chain. These findings press for the advance studies to find and understand the physiological pathways and mechanisms leading to bio-minimization of Cd across the food chain.
... Lead (Pb) is one of the most frequently encountered heavy metals in polluted environments and is now ubiquitous in the biosphere (De Vleeschouwer et al., 2007;Shu et al., 2015;Huang et al., 2019). Pb contamination is a significant public health problem because Pb is easily bio-accumulated in plants (Zu et al., 2004;Robinson et al., 2008;Ali et al., 2020), and there is a greater potential for trophic transfer along the food chain (Zhuang et al., 2009;Zhang et al., 2017;Naikoo et al., 2019). ...
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... Many studies reveal that Pb mostly remains in the roots of plants and only a small fraction is translocated to aboveground parts (Małecka et al. 2008;Metanat et al. 2019). The low Pb transportation from roots to aboveground parts has been assigned to its immobilization by negatively charged pectins present in the root cell wall and accumulation of Pb in plasma membranes of root cells (Zhang et al. 2017). However, the above reasons do not explain the low movement from roots to aboveground parts as plant species such as Brassica pekinensis translocate sufficient Pb to shoots from roots without affecting metabolic functions (Xiong, Zhao, and Li 2006). ...
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... In this study none of the samples exceeded the values considered as toxic by the Agency for Toxic Substances and Disease Registry and Codex Alimentarius Commission. Heavy metals in food derive from several sources such as soil polluted by heavy metals (where they may stay for longer periods because of their higher affinity with organic matter), pesticides and fertilizers (Zang, Wang, Ashraf, Qiu, & Ali, 2017). Table 3 shows some characteristics of identity and quality of the sapucaia nut oil. ...
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Chapter
Trace elements (TEs) could have hazardous effects on soil and plants, therefore imposing maximum admissible restrictions on their concentrations in soil by governments or organizations. These limits are usually classified into many groups, depending on the soil usage, soil qualities, or both. The goal of this chapter was to investigate and assess the toxic effect of TEs in soil by identifying potential health issues in soils with maximum permissible values and managing their toxicity effects. The soil-to-human pathway was examined, and we identified three primary TE exposures: household, commercial, and farming. The limits of arsenic have been shown to provide a relative high-risk quotient (HQi) that tends to underestimate its risk. Other TE restrictions such as Cd, Cu, Pb, and Zn often lead to low HQi, which means that limitations are somewhat overprotective in those circumstances. This chapter also covers the management and remediation opportunities available to solve this crucial problem.
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Phytotoxic effects of a single heavy metal on different crops are widely reported; however, consequences of combined metal toxicity on maize are rarely investigated. In this study, a pot experiment was conducted to assess the phytotoxic effects both Al and Cr on morphophysiological and biochemical traits, photosynthetic gas exchange capacities, metal uptake, and translocation in different plant parts. Plants were exposed to Al3+ (100 μM), Cr6+ (100 μM), and Al3+ + Cr6+ (100 + 100 μM), and data were collected at pre- and post-silking stages while uncontaminated pots were served as control (Ck). Results depicted that both Al and Cr impaired maize growth and yield response and inhibited photosynthesis and gas exchange attributes i.e., transpiration, stomatal conductance, inter-cellular CO2, as well as water use efficiency (WUE) and intrinsic water use efficiency (WUEi). Moreover, Al and Cr toxicities caused lipid peroxidation and membrane damage while activated antioxidative defense system in terms of superoxide dismutase (SOD), peroxidaes (POD), and catalase (CAT) and mediated reduced glutathione contents (GSH). Increased proline and reduced protein contents were also observed with a combined metal toxicity. Interestingly, Cr proved to be more toxic than Al whereas affects were more apparent where both Al and Cr were applied simultaneously. Plant exposure to both Al and Cr increased metal contents in different plant parts, while maximum metal contents were recorded in roots followed by stem, leaves, corn ear, and grains. Overall severity in phytotoxic effects was observed as Al+Cr > Cr > Al > Ck. Additionally, values of combined application of both Al + Cr were higher than those of the linear sum of Al and Cr alone, suggesting that synergistic effects of Al + Cr were more toxic than their individual effects. Hence, combined metal toxicity proved more damaging for maize than individual metal stress.
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The effect of lead on accumulation of Pb; mineral composition in roots, shoots and leafs; growth-development; chlorophyll and water content of tomato (Solanum lycopersicum L. cv. Falcon) seedlings was tested under doses of 0-control, 75, 150 and 300 mg L -1 Pb. Lead accumulation was defined by elevated concentrations as 75 to 300 mg L -1 Pb in root, shoot and leaf tissues. Element uptake by roots, shoots and leafs was negatively affected by in raised lead concentrations, especially in 300 mg L -1 Pb. Root elongation and plant height; root, shoot and leaf fresh and dry biomass; leaf area were negatively affected by increasing lead concentrations. Tissue water content (TWC), growth tolerance index (GTI), chlorophyll a, chlorophyll b and total chlorophyll content limited by lead toxicity.
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Using the examples of cadmium and lead, the review considers the various toxic effects exerted by these heavy metals. Putative specific and nonspecific mechanisms of the toxic effects of the heavy metals and plant responses are discussed together with the issue of Cd and Pb accumulation in various plant organelles, cells, tissues, and organs. The basic mechanisms providing for plant resistance to excess Cd and Pb are elucidated. These data are used to schematically outline the changes in plant metabolism produced by these heavy metals.
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The ever-increasing environmental pollution necessitates organisms to develop specific defense systems in order to survive and function effectively. Lead is taken up by plants mainly through roots and over 96% are accumulated there.Pea plants were cultivated hydroponically for 4days with 0.1, 0.5 and 1mM Pb(NO3)2. Uptake of lead ions from nutrient solution and accumulation in root stems and leaves during 96-h cultivation was estimated. The root tip cells were observed with transmission electron microscope to analyse their ultrastructure and lead localization. Pb was accumulated in the cell wall, cell membrane, vacuoles, mitochondria and peroxisomes. The fractions of mitochondria and peroxisomes were isolated from pea roots purified by means Percoll gradient, and were observed by means of electron microscope with the attachment for X-ray microanalysis. Visible deposits containing Pb were observed in both cell organelles.
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Plants are the target of a wide range of pollutants that vary in concentration, speciation, and toxicity. Such pollutants mainly enter the plant system through the soil (Arshad et al. 2008) or via the atmosphere (Uzu et al. 2010). Among common pollutants that affect plants, lead is among the most toxic and frequently encountered (Cecchi et al. 2008; Grover et al. 2010; Shahid et al. 2011). Lead continues to be used widely in many industrial processes and occurs as a contaminant in all environmental compartments (soils, water, the atmosphere, and living organisms). The prominence of environmental lead contamination results both from its persistence (Islam et al. 2008; Andra et al. 2009; Punamiya et al. 2010) and from its present and past numerous sources. These sources have included smelting, combustion of leaded gasoline, or applications of lead-contaminated media (sewage sludge and fertilizers) to land (Piotrowska et al. 2009; Gupta et al. 2009; Sammut et al. 2010; Grover et al. 2010). In 2009, production of recoverable lead from mining operations was 1690, 516, and 400 thousand metric tons by China, Australia, and the USA, respectively (USGS 2009).
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Electron microscopy (EM) techniques enable identification of the main accumulations of lead (Pb) in cells and cellular organelles and observations of changes in cell ultrastructure. Although there is extensive literature relating to studies on the influence of heavy metals on plants, Pb tolerance strategies of plants have not yet been fully explained. Allium sativum L. is a potential plant for absorption and accumulation of heavy metals. In previous investigations the effects of different concentrations (10(-5) to 10(-3) M) of Pb were investigated in A. sativum, indicating a significant inhibitory effect on shoot and root growth at 10(-3) to 10(-4) M Pb. In the present study, we used EM and cytochemistry to investigate ultrastructural alterations, identify the synthesis and distribution of cysteine-rich proteins induced by Pb and explain the possible mechanisms of the Pb-induced cellular defense system in A. sativum. After 1 h of Pb treatment, dictyosomes were accompanied by numerous vesicles within cytoplasm. The endoplasm reticulum (ER) with swollen cisternae was arranged along the cell wall after 2 h. Some flattened cisternae were broken up into small closed vesicles and the nuclear envelope was generally more dilated after 4 h. During 24-36 h, phenomena appeared such as high vacuolization of cytoplasm and electron-dense granules in cell walls, vacuoles, cytoplasm and mitochondrial membranes. Other changes included mitochondrial swelling and loss of cristae, and vacuolization of ER and dictyosomes during 48-72 h. In the Pb-treatment groups, silver grains were observed in cell walls and in cytoplasm, suggesting the Gomori-Swift reaction can indirectly evaluate the Pb effects on plant cells. Cell walls can immobilize some Pb ions. Cysteine-rich proteins in cell walls were confirmed by the Gomori-Swift reaction. The morphological alterations in plasma membrane, dictyosomes and ER reflect the features of detoxification and tolerance under Pb stress. Vacuoles are ultimately one of main storage sites of Pb. Root meristematic cells of A. sativum exposed to lower Pb have a rapid and effective defense system, but with the increased level of Pb in the cytosol, cells were seriously injured.
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Agro-ecosystem contamination by the heavy metals present in different agricultural products is a serious challenge faced by the living organisms. This study explains the cadmium (Cd) transfer from soils contaminated with different cadmium concentrations through a plant (eggplant and tomato) - mealybug (Dysmicoccus neobrevipes) - predator (Cryptolaemus-montrouzieri) food chain. The soils were amended with Cd at the rates of 0, 12.5, 25 and 50 mg/kg (w/w). Our findings showed that considerably higher Cd transfer through tomato plant. Cadmium was biomagnified during soil-root transfer while bio-minimization of Cd was observed for shoot-mealybug – ladybird transfer. Our results further showed sequestration of Cd during the metamorphosis of ladybird beetle whilst transfer of Cd through soil-plant-mealybug-ladybird multi-trophic food chain increased in a dose dependent manner. Our results emphasize the need of further studies to elaborate possible mechanisms of Cd bio-minimization by plants, mealybugs and ladybirds observed during this study.
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The present study investigated the uptake, translocation, and accumulation of chromium (Cr⁶⁺) and aluminum (Al³⁺) in maize and their induced variations in morpho-physiological and biochemical attributes as well as growth behavior and yield formation. Plants were grown in pots supplied with heavy metals, alone and in combination (chromium (Cr), aluminum (Al) and chromium + aluminum (Cr + Al)) while pots without adding Cr or Al were regarded as control. Metal stress considerably reduced growth and yield related attributes as well as photosynthetic pigments of maize. However, production of hydrogen peroxide (H2O2), thiobarbituric acid and activities of ascorbate peroxidase, glutathione reductase, glutathione peroxidase, and ascorbic acid were substantially increased under Cr and Al stress. A significant increase in soluble sugars and total phenolic contents were recorded in plants exposed to Cr and Al stress. Furthermore, all physiological attributes were increased with plant age except chlorophyll. Interestingly, Cr alone was proved more toxic to maize than Al alone. Cr and Al accumulation varied significantly (p ≤ 0.05) among different plant organs as roots > stem > leaves > corn ear > grains, whereas degrees of translocations were higher from stem to other plant parts than roots to stem. Accumulation of Cr and Al in either above- or below-ground plant parts are negatively correlated with grains and biological yield. The overall trend of metal stress on plant growth and yield were perceived as: Cr + Al > Cr > Al > control. Furthermore, synergistic effects of Cr + Al were more prominent than the individual effects of Cr and Al alone.
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The translocation of lead (Pb) in the soil-mulberry-silkworm food chain and the process of Pb detoxification in the mulberry-silkworm chain were investigated. The amount of Pb in mulberry, silkworm, feces and silk increased in a dose-responsive manner to the Pb contents in the soils. Mulberry roots sequestered most of the Pb, ranging from 230.78 to 1209.25mgkg(-1). Over 92% of the Pb in the mulberry leaves was deposited in the cell wall, and 95.29-95.57% of the Pb in the mulberry leaves was integrated with oxalic acid, pectates and protein, and it had low bioavailability. The Pb concentrations in the silkworm feces were 4.50-4.64 times higher than those in the leaves. The synthesis of metallothioneins in three tissues of the silkworms was induced to achieve Pb homeostasis under Pb stress. These results indicated the mechanism involved in Pb transfer along the food chain was controlled by the detoxification of Pb in different trophic levels. Planting mulberry and rearing silkworm could be a promising approach for the remediation of Pb-polluted soils due to the Pb tolerance of mulberry and silkworm. Copyright © 2015. Published by Elsevier Ltd.
Article
The effects of four host plants (Agave sisalana, Ag. americana var. marginata, Ananas comosus Baili and An. comosus Smooth Cayenne) on the biology of the mealybug Dysmicoccus neobrevipes Beardsley were studied in the laboratory at 26 ± 1 °C, 75–90% RH and 14:10 (L:D) photoperiod. The development, survivorship, longevity, reproduction and life table parameters of D. neobrevipes differed among the host plants. The shortest developmental period (from the first instar nymph to adult) was recorded on An. comosus Smooth Cayenne (22.4 days for females and 21.3 days for males), whereas the longest was recorded on An. comosus Baili (25.6 days for females and 24.7 days for males). The highest survivorship was found on An. comosus Baili (98% for both females and males) and the lowest was on Ag. americana var. marginata (39.6% for females and 50% for males). Meanwhile the sex ratio and fecundity were highest and the pre-lay period was shortest on Ag. sisalana. The longest longevity of females was 62.5 days on An. comosus Baili, whereas the other host plants did not differ significantly with grand mean longevities of 51.0 days for females, while the longest and shortest longevities of males were 4.6 days and 2.3 days on Ag. americana var. marginata and Ag. sisalana, respectively. Values for net reproductive rate, intrinsic rate of increase and finite rate of increase were highest on Ag. sisalana, whereas the mean generation time was shortest on An. comosus Smooth Cayenne. The results indicated that Ag. sisalana is the most suitable host for D. neobrevipes among the four tested plants. When reared on Ag. sisalana, D. neobrevipes had a short developmental period (females 22.7 days and males 23.8 days), high reproduction (418 nymphs/female) and a high intrinsic rate of increase (0.106). Results of this study indicated that host plant can largely influence the population dynamics of D. neobrevipes, and our findings are useful in understanding the roles of host plants in integrated management of this pest, including exploitation of these host plants in push-pull control.
Article
A DTPA soil test was developed to identify near‐neutral and calcareous soils with insufficient available Zn, Fe, Mn, or Cu for maximum yields of crops. The extractant consists of 0.005 M DTPA (diethylenetriaminepentaacetic acid), 0.1 M triethanolamine, and 0.01 M CaCl 2 , with a pH of 7.3. The soil test consists of shaking 10 g of air‐dry soil with 20 ml of extractant for 2 hours. The leachate is filtered, and Zn, Fe, Mn, and Cu are measured in the filtrate by atomic absorption spectrophotometry. The soil test successfully separated 77 Colorado soils on the basis of crop response to Zn, Fe, and Mn fertilizers. Critical nutrient levels must be determined separately for each crop using standardized procedures for soil preparation, grinding, and extraction. The critical levels for corn using the procedures reported herein were: 0.8 ppm for Zn, 4.5 ppm for Fe, and tentatively 1.0 ppm for Mn, and 0.2 ppm for Cu. Development of the soil test was based, in part, on theoretical considerations. The extractant is buffered at pH 7.30 and contains CaCl 2 so that equilibrium with CaCO 3 is established at a CO 2 level about 10 times that of the atmosphere. Thus, the extractant precludes dissolution of CaCO 3 and the release of occluded nutrients which are normally not available to plants. DTPA was selected as the chelating agent because it can effectively extract all four micronutrient metals. Factors such as pH, concentration of chelating agent, time of shaking, and temperature of extraction affect the amount of micronutrients extracted and were adjusted for maximum overall effectiveness.
Article
summaryLead transport has been characterized in corn (Zea mays L. cv. Fiesta) and ragweed (Ambrosia artemisiifolia L.), and the Pb phytoextraction efficiency of these species has been compared with that of Tritiaim aestivum, Thlaspi rotundifolium, Thlaspi caerulescens and Brassica juncea, using both nutrient solutions and Pb-contaminated soils. Our results demonstrated that plant species differ significantly in Pb uptake and translocation. In short term (60 min) experiments, Pb uptake by ragweed roots was threefold higher than that by corn roots. After 2 wk of Pb (100/yM) exposure in hydroponics, root-Pb concentration was 24000 mg kg−1 for ragweed and 4900 mg kg−1 for corn. In contrast to root-Pb concentration, shoot-Pb concentration was significantly higher in corn (560 mg kg−1) than in ragweed (30 mg kg-1). At an external Pb concentration of 20/IM, corn concentrated Pb in shoots by 90-fold, and ragweed concentrated Pb in shoots by 20-fold over the solution Pb concentration. Of the 11 species/cultivars tested using both nutrient solutions and Pb-contaminated soils, corn accumulated the highest shoot-Pb concentration. Using this corn cultivar, we investigated the role of synthetic chelates in Pb phytoextraction. Addition of HEDTA (2.0 g kg−1 soil) to a Pb-contaminated soil (total soil Pb 2500 mg kg−1) resulted in a surge of Pb accumulation in corn. The shoot Pb-concentration was increased from 40 mg kg−1 for the control (-HEDTA) to 10600 mg kg−1 for the HEDTA-treated soil. To our knowledge, this is the highest shoot Pb concentration reported in the literature for plants grown on Pb-contaminated soils. Our results suggest that in combination with sou amendment, some agronomic crops, such as corn, might be used for the clean-up of Pb-contaminated soil.
Article
Accumulation, and therefore toxicity, of trace metals in invertebrates may be affected by potential interactive effects that can occur amongst different metallic elements. However, there is little data on the nature and effects of such interactions in terrestrial systems. This work reports the interactions among Cu, Ni and Zn during accumulation by the beetle Coccinella septempunctata. Test animals were treated with 500mgkg(-1) of each metal singularly and in combination for 15d. The effects of treatment with a single metal had no effect on the baseline concentrations of the other two. Time-response relationships for Cu and Ni after treatment with one metal were curvilinear, demonstrating that the metals were initially accumulated, but after ∼8d regulatory mechanisms became effective. This resulted in decreasing concentrations in test animals despite continued treatment. In contrast, the time-response relationship for Zn was linear. Treatment with metals in combination markedly altered the time-response relationships with all three metals showing a linear trend and the slope of the Zn relationship increasing significantly. After 15d of exposure this had the effect of increasing the metal concentration in animals exposed in combination compared to those exposed singularly by 144% to 38.3mgkg(-1) for Cu, 141% to 27.5mgkg(-1) for Ni and 55% to 311mgkg(-1) for Zn. For all metals, differences amongst treatments were significant, indicating that inter-element interactions can enhance the concentration of trace metals in C. septempunctata.
Article
Accumulation of lead (Pb), cadmium (Cd), and copper (Cu) (from food) by the fruit fly (Ceratitis capitata Wiedemann; Diptera, Tephritidae) and the transfer of the metals to the internal solitary pupal parasitoid Coptera occidentalis Muesebeck (Hymenoptera, Proctotrupoidea, Diapriidae) were investigated experimentally by exposing host larvae to contaminated diets. Each metal was added to the diet at two concentrations: Cd, 50 and 100 μg/g; Pb and Cu, 400 and 800 μg/g diet dry weight. Whole-body concentrations of the applied metals and of zinc (Zn) in the host and parasitoid were determined by atomic absorption photospectrometry. Concentration factors (CFs) for all metals (based on initial dietary concentrations) were lower at the higher food contamination level. Cadmium (CF = 3.2–7.05) and Zn (CF = 2.79–7.05) were accumulated by fruit fly larvae more efficiently than were Pb (CF = 0.95–1.02) and Cu (CF = 0.35–0.78, except control: 37.2). Considerable quantities of the metals taken up by host larvae and retained in their pupae were eliminated via the meconium after eclosion of flies (Cd, 33%; Pb, 33–51%; Cu 24–39% of pupal metal burdens). Low proportions of the host metal content were transferred to the parasitoid (0.4–5.6% and 0.3–1.4% to pupae and adults, respectively, depending on the applied metal). The remaining amounts of the metals were detected in the host puparia that remained after wasp eclosion. Vitality and fecundity of the parasitoid were not impaired by host metal contamination. Thus, the parasitic wasp probably possesses an efficient regulatory mechanism that mediates excretion of toxic metals before pupation and that diminishes the potential hazard of high metal loads in the host.
Article
The forest pest insect Lymantria dispar L. (gypsy moth) was reared on an artificial diet contaminated independently with four metals at two different concentrations (2 and 10 g/g Cd, 4 and 20 g/g Pb, 10 and 50 g/g Cu, 100 and 500 gg Zn). Whole body metal concentrations were determined in each larval stage, pupae, imagoes, and F1 generation first instars and also of the corresponding exuviae, headcapsules, and faeces. The pattern of metal accumulation in successive developmental stages was metal and concentration (Cu, Zn) specific. Pb was barely assimilated by the larvae (concentration factor L. dispar larval weight. These relationships were also concentration dependent. F1-generation first instar larvae showed significantly higher metal contamination than controls, reflecting the metal burdens of the parental generation.
Article
An agricultural soil in southern England was amended with a single application of sewage sludge from a municipal source at rates of 0, 5, 7.5, 10, 15 and 20 t ha−1 dry solids. Soil concentrations of Cd and Zn in the field plots ranged from 0.109 to 0.180 mg kg−1 and 26.3 to 34.3 mg kg−1, respectively, dependent on sewage sludge application rate. Concentrations of Cd and Zn in the shoots of winter wheat grown were dependent on the rate of sewage sludge application to the soil. Concentrations of Cd in the ears of wheat were not dependent on sewage sludge application rate, whilst Zn concentrations were dependent. Grain aphids (Sitobion avenae) collected from the host plants accumulated concentrations of Cd and Zn up to 0.386 mg Cd kg−1 and 319 mg Zn kg−1 (eight and 10 times greater, respectively, than the concentrations on the ears on which they were feeding). Regression analysis demonstrated that the concentrations of Cd and Zn in S. avenae could be predicted from the concentrations of these metals in the soil. The retention characteristics of the sludge amended soils and control soils for Cd and Zn were assessed by batch adsorption experiments. From the sorption data it was observed that the sewage sludge amended soils showed no significant change in Cd affinity when compared to the controls soils. However, for Zn, the reduction in the Freundlich distribution coefficient of the isotherms of the sludge treated soils were significant when compared to the control soils — indicating a reduced affinity for Zn at these relatively low sewage sludge application rates.
Article
Arbuscular mycorrhizal (AM) fungi contribute to plant growth, mediating the uptake of mineral elements. In polluted areas, AM also binds toxic heavy metals to roots. In this study, mesquite plants (Prosopis sp.), associated with Glomus deserticola, were treated for 15 days (in hydroponics) with lead at 0, 10, 50, or 100 mg L−1, and chromium(III) and (VI) at 0, 20, 40, 75, or 125 mg Cr L−1. All Cr ion concentrations and the highest Pb concentration reduced shoot size compared to the control. Toxic effects (yellowish leaves, leaf decay) were observed after seven treatment days. However, Pb and Cr(III) treated plants recovered upon conclusion of experimental period. Total amylase activity in leaves increased upon the addition of Pb and Cr. The inductively coupled plasma-optical emission spectroscopy results showed that plants treated with Pb at 50 mg L−1 accumulated in roots, stems, and leaves: 61947, 9584, and 478 mg Pb kg−1; whereas plants treated with Cr(III) and Cr(VI) at 125 mg L−1 accumulated 28815, 6055, and 647; and 13767, 5010, and 2530 mg Cr kg−1. The transmission electron microscopy (TEM) micrographs showed the presence of G. deserticola within roots. X-ray mapping demonstrated higher Cr and Pb deposition in xylem and phloem cells. Results suggest that G. deserticola improves metal tolerance/accumulation in mesquite.
Article
Geogenic, as well as anthropogenic heavy metals from distant sources, gradually increase the level of toxic metals in natural environments and these will be increasingly taken up by the plants and transferred further up the food chain. The level of different heavy metals (Hg, Cd, Pb) was studied in the producers (food plants) and consumers [four species of acridid grasshoppers: Calliptamus italicus (L.), Oedipoda caerulesens (L.), O. germanica (Latr.) and Chorthippus(Glyptobothrus) crassiceps(Ramme, 1926)] of a grassland located 1200 m above the sea level in the Taigetos Mountains, Peloponnesus, Greece. The concentrations of heavy metals in the food plants and grasshoppers were in the order Pb > Cd > Hg and the mean concentration of Pb was about 55 and 20 times the concentrations of Hg and Cd, respectively. The solely herbivorous C.(G.) crassiceps had a significantly higher Hg-concentration than in the food plants, but it did not exceed that of Cd and Pb. Cd-concentration in the grasshoppers was significantly higher than in food plants, and female grasshoppers had higher Cd accumulation than males. Lead accumulation in grasshoppers was always lower than in their food plants. The accumulation factors of these elements in the grasshoppers were found in the order Cd > Hg > Pb, thus showing greater affinity to Cd accumulation. Significantly higher concentration of Hg in both sexes of C.(G.) crassiceps than in other three grasshoppers proved this species to be a comparatively better bioindicator of Hg pollution. Elevated concentrations of Cd in both, females and males of all four grasshopper species suggested that any grasshopper, irrespective of the sex, could equally play the role of bioindicator. Studies on the bioaccumulation and biotransfer of different heavy metals showed that the organisms of such distantly located ecosystems were also exposed to measurable amounts of toxic heavy metals.
Article
An agricultural soil was amended with sewage sludge at rates equivalent to 0, 10 and 30 t (dry solids) ha−1 and the subsequent transfer of zinc and cadmium through a soil–plant–arthropod system was investigated. Zinc concentration in soil, wheat and aphids increased significantly with sludge amendment rate. Zinc was biomagnified during transfer along the pathway, resulting in concentrations in the aphids four times greater than in the soil. Cadmium concentration in the soil was also significantly elevated by the addition of sludge, but there was no significant difference in cadmium concentration in the shoots of wheat plants. Cadmium concentration in aphids followed the pattern found in plants, but again, differences between treatments were not significant. Aphids collected from the plants were subsequently fed to fourth instar Coccinella septempunctata. Consumption of these aphids did not result in significant differences between treatments in the body burden of newly emerged adult C. septempunctata for either metal. Sequestration of cadmium in the pupal exuviae had a greater effect on the body burden of newly emerged adult ladybirds than for zinc. Results are discussed in relation to possible risks posed by the transfer of trace metals via the soil–plant–arthropod system to predatory arthropods.
Article
Use of sewage sludge in agriculture is an alternative disposal technique for this waste. The present field study was conducted to assess the suitability of sewage sludge amendment in soil for rice (Oryza sativa L. cv. Pusa sugandha 3) by evaluating the heavy metal accumulation, growth, biomass and yield responses of plants grown at 0, 3, 4.5, 6, 9, 12 kgm(-2) sewage sludge amendment (SSA) rate. Sewage sludge amendment modified the physico-chemical properties of soil, thus increasing the availability of heavy metals in soil and consequently with higher accumulation in plant parts. Root length decreased, whereas shoot length, number of leaves, leaf area and total biomass increased significantly when grown under various SSA rates. Yield of rice increased by 60%, 111%, 125%, 134% and 137% at 3, 4.5, 6, 9 and 12 kgm(-2) SSA, respectively, as compared to those grown in unamended soil. Sewage sludge amendment rates above 4.5 kgm(-2) though increased the yield of rice, but caused risk of food chain contamination as concentrations of Ni and Cd in rice grains were found to be above the Indian safe limits (1.5 mgkg(-1)) of human consumption above 4.5 kgm(-2) SSA and of Pb (2.5 mgkg(-1)) above 6 kgm(-2) SSA. Since aboveground parts of the rice also showed higher concentration than the permissible levels of Ni, Cd and Pb at 4.5 kgm(-2) SSA rate, it cannot be used as fodder. The rice husk may be used as bioresource for energy production. Efforts should be made to treat the effluents from small scale industries before discharge into the sewerage system.
Article
A greenhouse trial investigated the uptake of cadmium and zinc by the bird-cherry oat aphid (Rhopalosiphum padi) feeding on wheat grown on sewage sludge amended soil. The trial was conducted at application rates of 0, 5, 7.5, 10, 15 and 20 tonnes ha(-1) dry solids. Concentrations of Cd and Zn were within current UK limits for potentially toxic elements in soils amended with sewage sludge. Cd and Zn in wheat plants were significantly greater than controls. Batches of aphids feeding on the wheat also showed a significant increase in the uptake of Cd and Zn. This study demonstrates a potential route of exposure to Cd and Zn for the predators of cereal aphids.
Article
The concentrations of lead, zinc, copper and cadmium accumulated by 12 emergent-rooted wetland plant species including different populations of Leersia hexandra, Juncus effusus and Equisetum ramosisti were investigated in field conditions of China. The results showed that metal accumulation by wetland plants differed among species, populations and tissues. Populations grown in substrata with elevated metals contained significantly higher metals in plants. Metals accumulated by wetland plants were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance widely exists in them. That some species/populations could accumulate relatively high metal concentrations (far above the toxic concentration to plants) in their shoots indicates that internal detoxification metal tolerance mechanism(s) are also included. The factors affecting metal accumulation by wetland plants include metal concentrations, pH, and nutrient status in substrata. Mostly concentrations of Pb and Cu in both aboveground and underground tissues of the plants were significantly positively related to their total and/or DTPA-extractable fractions in substrata while negatively to soil N and P, respectively. The potential use of these wetland plants in phytoremediation is also discussed.
Article
The transfer characteristics of Cd and Pb from soils to the edible parts of six vegetable species were calculated from plant and corresponding surface soil samples collected from the fields in Fujian Province, southeastern China. The soil-to-plant transfer factors (TF) calculated from both total and DTPA-extractable Cd and Pb in the soils decreased with increasing total or DTPA-extractable Cd and Pb, indicating that the TF values of Cd and Pb depend on the soil metal content. For most plants studied, there was a significant relation between the TF values and the corresponding soil metal concentrations (total or DTPA-extractable) that was best described by an exponential equation (y=axb). We recommend that the representative TF value for a given crop-metal system should be estimated from the regression models between the transfer factors and the corresponding soil metal concentrations and at a given soil metal concentration.
Article
The effect of transpiration (high and low) on Pb uptake by leaf lettuce and on water soluble low molecular weight organic acids (LMWOAs) in rhizosphere has been studied. After two weeks of growth the plants were cultured in greenhouse for more four weeks and two days. Pb(NO(3))(2) solutions of different concentrations (100, 200, and 300 mg l(-1) of Pb) were then added to the quartz sand pots of different plants and studies were initiated. Blank experiments (without treating the quartz sand pots with Pb(NO(3))(2) solutions) were also run in parallel. No significant differences in the growth of the plants with the concentrations of added Pb(NO(3))(2) solutions were observed by both low and high transpirations at the end of the 0, 3rd, and 10th days of studies. The total evaporation of the volatiles during 10 days did not depend on the concentration of Pb(2+) but with high transpiration the rate of evaporation was significantly higher than with low transpiration. Uptake of Pb by shoots and roots of the plants was found to be proportional to the concentration of various Pb(NO(3))(2) solutions added and more accumulation was observed in roots than in shoots at the end of 3rd and 10th days. High transpiration created more Pb uptake than low transpiration did. One volatile acid, propionic acid and nine non-volatile acids, lactic, glycolic, oxalic, succinic, fumaric, oxalacetic, D-tartaric, trans-aconitic, and citric acids in rhizosphere quartz sands were identified and quantified by gas chromatography (GC) analysis. D-Tartaric and citric acids were major among the non-volatile acids. The amount of LMWOAs in rhizosphere quartz sands increased with the higher amount of Pb uptake and also with the duration of studies. The total quantities of the LMWOAs in the rhizosphere quartz sands were significantly higher under high transpiration with 300 mg l(-1) Pb solution addition at the end of 10th day. The present study shows prominent correlation between transpiration and uptake of heavy metal and interesting correlation between Pb contaminated level and quantity of water soluble LMWOAs in rhizosphere quartz sands. The latter thus deserves of further studies.
Article
Metal contaminants in garden and allotment soils could possibly affect human health through a variety of pathways. This study focused on the potential pathway of consumption of vegetables grown on contaminated soil. Five cultivars each of six common vegetables were grown in a control and in a soil spiked with Cd, Cu, Pb and Zn. Highly significant differences in metal content were evident between cultivars of a number of vegetables for several of the contaminants. Carrot and pea cultivars exhibited significant differences in accumulated concentrations of Cd and Cu with carrot cultivars also exhibiting significant differences in Zn. Distinctive differences were also identified when comparing one vegetable to another, legumes (Leguminosae) tending to be low accumulators, root vegetables (Umbelliferae and Liliaceae) tending to be moderate accumulators and leafy vegetables (Compositae and Chenopodiaceae) being high accumulators.
Article
A concentration as low as 1 microM lead (Pb) is highly toxic to plants, but previous studies have typically related plant growth to the total amount of Pb added to a solution. In the present experiment, the relative fresh mass of cowpea (Vigna unguiculata) was reduced by 10% at a Pb2+ activity of 0.2 microM for the shoots and at a Pb2+ activity of 0.06 microM for the roots. The primary site of Pb2+ toxicity was the root, causing severe reductions in root growth, loss of apical dominance (shown by an increase in branching per unit root length), the formation of localized swellings behind the root tips (due to the initiation of lateral roots), and the bending of some root tips. In the root, Pb was found to accumulate primarily within the cell walls and intercellular spaces.
Article
The mechanism of oxidative burst induced by lead in Vicia faba excised roots was investigated by luminol-dependent chemiluminescence. Results showed that lead triggered a rapid and dose-dependent increase in chemiluminescence production. In this study, specific inhibitors of putative reactive oxygen species (ROS) sources were used to determine the mechanism of lead-induced ROS generation. This generation was sensitive to dephenylene iodonium (DPI), quinacrine and imidazole, some inhibitors of the NADPH-oxidase and not inhibited by other putative ROS sources inhibitors. Data reported in this work clearly demonstrated the pivotal role of NADPH-oxidase-like enzyme in early steps of lead-induced oxidative burst. To investigate the respective implication of calmodulin and protein kinase (PK) in lead-induced NADPH-oxidase activation, excised roots were treated with the calmodulin inhibitor W7 or with the PK inhibitor staurosporine. The chemiluminescence generation inhibition by these inhibitors illustrated the role of PK in lead-induced NADPH-oxidase activation and revealed a calmodulin-dependent step. Using the calcium entry blocker La(3+) or different concentrations of calcium in the extra-cellular medium, our data highlighted the implication of Ca(2+) channel in lead-induced oxidative burst.
Metal Stress in Plants, From Molecules to Ecosystems
  • M Greger
Greger, M., 1999. Metal availability and bio-concentration in plants. In: Prasad, M.N.V., Heavy, Hagemeyer, J. (Eds.), Metal Stress in Plants, From Molecules to Ecosystems. Springer, Hong Kong, pp. 1-28.
Sources and Impacts of Past, Current and Future Contamination of Soil Appendix 1: heavy Metals SP0547. (Defra Science Directorate) Department for Environment Food and Rural Affairs
  • F A Nicholson
  • B J Chambers
Nicholson, F.A., Chambers, B.J., 2008. Sources and Impacts of Past, Current and Future Contamination of Soil Appendix 1: heavy Metals SP0547. (Defra Science Directorate) Department for Environment Food and Rural Affairs, London, UK.
Effect of rate of prey, Planococcus citri (Risso) on the fecundity of mealybug predator
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  • K Sreedharan
  • P K Bhat
Reddy, K.B., Sreedharan, K., Bhat, P.K., 1991. Effect of rate of prey, Planococcus citri (Risso) on the fecundity of mealybug predator, Cryptolaemus montrouzieri Mulsant. J. Coffee Res. 21, 149-150.