Toxicity of imidacloprid to the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

Imidacloprid is a neonicotinoid insecticide with neurotoxic action that, as a possible alternative for commonly used organophosphorus pesticides, has gained registration in about 120 countries for use in over 140 agricultural crops. Only few data are available on its toxicity for soil invertebrates. We therefore assessed the effects of imidacloprid on survival, weight gain, feeding rate, total protein content, glutathione S-transferase activity (GST), and digestive gland epithelial thickness in juveniles and adults of the terrestrial isopod Porcellio scaber. After two weeks of feeding on imidacloprid-dosed food, weight gain (NOEC 5 microg/g dry food) and feeding rate (NOEC 10 microg/g) in juveniles, and feeding rate (NOEC<10 microg/g) and digestive gland epithelial thickness (NOEC<10 microg/g) in adults were most affected. In juveniles induction of GST activity and increase of total protein content per wet animal weight was detected at 5 microg/g dry food, whereas in adults a reduction of GST was observed at 25 microg/g (NOEC 10 microg/g). An estimate of actual intake rates suggests that imidacloprid affects isopods at similar exposure concentrations as insects. The toxicity of imidacloprid was similar to that of the organophosphorus pesticide diazinon, tested earlier using the same methods [Stanek, K., Drobne, D., Trebse, P., 2006. Linkage of biomarkers along levels of biological complexity in juvenile and adult diazinon fed terrestrial isopod (Porcellio scaber, Isopoda, Crustacea). Chemosphere 64, 1745-1752]. At actual environmental concentrations, diazinon poses a higher risk to P. scaber. Due to its increasing use in crop protection and higher persistence in soil, imidacloprid might however, be potentially more dangerous after long-term application. We conclude that toxicity testing with P. scaber provides relevant, repeatable, reproducible and comparable toxicity data that is useful for the risk assessment of pesticides in the terrestrial environment.     

Long-term Hg pollution induced Hg tolerance in the terrestrial isopod Porcellio scaber (Isopoda, Crustacea)

The aim of our work was to assess the pollution-induced community tolerance (PICT) of isopod gut microbiota and pollution-induced isopod population tolerance (PIPT). Animals collected from a chronically Hg polluted and an unpolluted location were exposed for 14 days to 10microg Hg/g dry food under laboratory conditions. The lysosomal membrane stability, hepatopancreas epithelium thickness, feeding activity and animal bacterial gut microbiota composition were determined. The results confirm the hypothesis that the response to short-term Hg exposure differs for animals from the Hg polluted and the unpolluted field locations. The animals and their gut microbiota from the Hg polluted location were less affected by Hg in a short-term feeding experiment than those from the unpolluted environment. We discuss the pollution-induced population tolerance of isopods and their gut microbiota as a measure of effects of long-term environmental pollution. The ecological consequences of such phenomena are also discussed.     

Linkage of biomarkers along levels of biological complexity in juvenile and adult diazinon fed terrestrial isopod (Porcellio scaber, Isopoda, Crustacea)

In parallel laboratory experiments, we determined the effect of a typical representative of organophosphorous pesticides, diazinon, on AChE activity, lipid, protein and glycogen content, weight change, feeding activity and mortality of juvenile and adult terrestrial isopods Porcellio scaber (Isopoda, Crustacea). Organophosphorous pesticides (OP) are among the most extensively used pesticides, which have replaced organochlorine pesticides. OPs inhibit the enzyme acetylcholinesterase (AChE), resulting in neurotoxicity. They have more widespread effects on non-target organisms than do organochlorine pesticides. The aim of this study was to link effect of diazinon on target enzyme to energy reserves and to integrated biomarker responses in juvenile and adult P. scaber. The non-observed effect concentration (NOEC) for AChE activity after diazinon exposure in two weeks toxicity study with isopods was below 5 microg/g diazinon. There was a good agreement between concentrations at which AChE and survival were affected (10 microg/g diazinon in juveniles, 100 microg/g diazinon in adults). We revealed a link among AChE activity, protein content and mortality. Glycogen and lipid content, feeding activity and weight change were not affected in two weeks diazinon exposure up to 100 microg/g diazinon. Juveniles were affected at concentrations that were an order of magnitude lower than those provoking similar effects on adults. Recommendations are made for future toxicity studies with terrestrial isopods.     

The influence of metal speciation on the bioavailability and sub-cellular distribution of cadmium to the terrestrial isopod, Porcellio dilatatus

Cadmium is a non-essential toxic metal that is able to bioaccumulate in both flora fauna and has the potential to biomagnify in some food chains. However, the form in which cadmium is presented to consumers can alter the bioavailability and possibly the internal distribution of assimilated Cd. Previous studies in our laboratory highlighted differences in Cd assimilation among isopods when they were provided with a plant-based food with either Cd biologically incorporated into plant tissue or superficially amended with ionic Cd(2+). Cd is known for its high affinity for sulphur ligands in cysteine residues which form the basis for metal-binding proteins such as metallothionein. This study compares Cd assimilation efficiency (AE) in Porcellio dilatatus fed with food amended with either cadmium cysteinate or cadmium nitrate in an examination of the influence of Cd speciation on metal bioavailability followed by an examination of the sub-cellular distribution using a centrifugal fractionation protocol. As hypothesized the AE of Cd among isopods fed with Cd(NO(3))(2) (64%, SE=5%) was higher than AE for isopods fed with Cd(Cys)(2) (20%, SE=3%). The sub-cellular distribution also depended on the Cd species provided. Those isopods fed Cd(Cys)(2) allocated significantly more Cd to the cell debris and organelles fractions at the expense of allocation to metal-rich granules (MRG). The significance of the difference in sub-cellular distribution with regard to toxicity is discussed. This paper demonstrates that the assimilation and internal detoxification of Cd is dependent on the chemical form of Cd presented to the isopod.     

Factors determining amounts of fluoride in woodlice Oniscus asellus and Porcellio scaber, litter and soil near an aluminium reduction plant

Amounts of fluoride were measured in whole woodlice Oniscus asellus and Porcellio scaber, together with associated soil and litter, from 17 sites near an aluminium reduction plant at Holyhead, Anglesey, in North Wales. There was a strong positive correlation between amounts of fluoride in woodlice, soil and litter in all comparisons (P<0.02). Highest and lowest fluoride concentrations in woodlice differed by a factor of >50. Where both woodlice species occurred together at the more polluted sites, fluoride levels in Oniscus asellus were generally twice as high as those found in Porcellio scaber. At any given site, amounts of environmental fluoride were determined partly by distance and direction from the pot-rooms of the plant (a function of prevailing winds), modified by the presence of trees which acted as collectors for gaseous and particulate fluoride.     

Reduced nitrogen in ecology and the environment

Since the beginning of the 19th century humans have increasingly fixed atmospheric nitrogen as ammonia to be used as fertilizer. The fertilizers are necessary to create amino acids and carbohydrates in plants to feed animals and humans. The efficiency with which the fertilizers eventually reach humans is very small: 5-15%, with much of the remainder lost to the environment. The global industrial production of ammonia amounts to 117 Mton NH(3)-Nyear(-1) (for 2004). By comparison, we calculate that anthropogenic emissions of NH(3) to the atmosphere over the lifecycle of industrial NH(3) in agriculture are 45.3 Mton NH(3)-Nyear(-1), about half the industrial production. Once emitted ammonia has a central role in many environmental issues. We expect an increase in fertilizer use through increasing demands for food and biofuels as population increases. Therefore, management of ammonia or abatement is necessary.     

Long-term Hg pollution-induced structural shifts of bacterial community in the terrestrial isopod (Porcellio scaber) gut

In previous studies we detected lower species richness and lower Hg sensitivity of the bacteria present in egested guts of Porcellio scaber (Crustacea, Isopoda) from chronically Hg polluted than from unpolluted environment. Basis for such results were further investigated by sequencing of 16S rRNA genes of mercury-resistant (Hg^r) isolates and clone libraries. We observed up to 385 times higher numbers of Hg^r bacteria in guts of animals from polluted than from unpolluted environment. The majority of Hg^r strains contained merA genes. Sequencing of 16S rRNA clones from egested guts of animals from Hg-polluted environments showed elevated number of bacteria from Pseudomonas, Listeria and Bacteroidetes relatives groups. In animals from pristine environment number of bacteria from Achromobacter relatives, Alcaligenes, Paracoccus, Ochrobactrum relatives, Rhizobium/Agrobacterium, Bacillus and Microbacterium groups were elevated. Such bacterial community shifts in guts of animals from Hg-polluted environment could significantly contribute to P. scaber Hg tolerance.     

Inoculation with arbuscular mycorrhizal fungi and addition of composted olive-mill waste enhance plant establishment and soil properties in the regeneration of a heavy metal-polluted environment

A greenhouse experiment was carried out in order to investigate the effects of arbuscular mycorrhizal (AM) fungi inoculation and the use of composted olive waste (COW) in the establishment of Tetraclinis articulata and soil properties in a heavy metal-polluted soil. The treatments assayed were as follows: AM?+?0 % COW, AM?+?1 % COW, and AM?+?3 % COW. The higher doses of COW in combination with AM fungi increased shoot and root biomass production of T. articulata by 96 and 60 %, respectively. These treatments trended to improve the soil properties evaluated, highlighting the C compounds and N as well as the microbiological activities. In relation to the metal translocation in T. articulata, doses of COW applied decreased the Cr, Ni, and Pb contents in shoot, as well as Cr and As in root, although the most of them reached low levels and far from phytotoxic. The COW amendment aided Glomus mosseae-inoculated T. articulata plants to thrive in contaminated soil, mainly through an improvement in both nutrients uptake, mainly P and soil microbial function. In addition, the combined use of AM fungi plus COW could be a feasible strategy to be incorporated in phytoremediation programs because it promotes soil properties, a better performance of plants for supporting the stress in heavy metal-contaminated soils derived from the mining process, and also can be a good way for olive-mill waste disposal.     

Distribution and persistence of carbaryl in some terrestrial and aquatic components of a forest environment

Abstract

An oil‐based formulation of carbaryl (1‐naphthyl N‐methyl‐carbamate) (Sevin‐2‐Oil) was applied twice by a fixed‐wing aircraft at a dosage rate of 280 g of A.I./ha/application to a coniferous forest near Allardville, New Brunswick. The highest concentrations of the chemical in fir foliage, litter and forest soil 1 h after application were respectively 4.20, 1.21 and 0.59 ppm (fresh weight). The residues dissipated rapidly and the DT50 values obtained from the depletion curves were 2.3 d for foliage and 1.5 d for litter and soil samples. Very low levels (<0.1 ppm) of carbaryl persisted in foliage and litter beyond the 10 d sampling period. The maximum residue level found in stream water was 0.314 ppm and more than 50% of it had dissipated within 1 h. Low but detectable levels (0.001 ppm) of the chemical persisted in water until the end of the 10 d sampling period. Sediment samples contained a maximum level of 0.04 ppm, which dissipated below the detection limit within 5 h. Brook trout and slimy sculpins captured in the stream 1 d after the spray contained on average about 0.04 ppm of carbaryl and none of it was found in 3 d postspray samples.     

Energy reserves and accumulation of metals in the ground beetle Pterostichus oblongopunctatus from two metal-polluted gradients

Living in an area chronically polluted with metals is usually associated with changes in the energy distribution in organisms due to increased energy expenses associated with detoxification and excretion processes. These expenses may be reflected in the available energy resources, such as lipids, carbohydrates, and proteins. In this context, the energy status of Pterostichus oblongopunctatus (Coleoptera: Carabidae) was studied in two metal pollution gradients near Olkusz and Miateczko ?l?skie in southern Poland. Both regions are rich in metal ores, and the two largest Polish zinc smelters have been operating there since the 1970s. Beetles were collected from five sites at each gradient. Zinc and cadmium concentrations were measured in both the soil and the beetles. The possible reduction in energy reserves as a cost of detoxifying assimilated metals was evaluated biochemically by determining the total lipid, carbohydrates, and protein contents. At the most polluted sites, the Zn concentration in the soil organic layer reached 2,906 mg/kg, and the Cd concentration reached 55 mg/kg. Body Zn and Cd concentrations increased with increasing soil Zn and Cd concentrations (p?=?0.003 and p?=?0.0001, respectively). However, no relationship between pollution level and energetic reserves was found. The results suggest that populations of P. oblongopunctatus inhabiting highly metal-polluted sites are able to survive without any serious impact on their energy reserves, though they obviously have to cope with elevated body metal concentrations.     

Lead impact on nutrition, energy reserves, respiration and stress protein (hsp 70) level in Porcellio scaber (Isopoda) populations differently preconditioned in their habitats

The impact of lead on food consumption, energy metabolism and the stress protein (hsp 70) level was investigated in the woodlouse Porcellio scaber (Isopoda), a common representative of the saprophagous soil macrofauna. To examine possible acclimation or tolerance to lead in woodlice from a contaminated habitat, animals of two populations, one deriving from a lead-contaminated artillery range and one from an uncontaminated control stand, were exposed to a series of lead concentrations under otherwise constant laboratory conditions for a maximum of 80 days. The applied lead concentrations (at a maximum 7945 mg/kg food dry wt) did not have any significant quantitative effect on the food consumption of the isopods, although the population pre-exposed in the artillery range showed a tendency toward a higher food uptake than the control population. After 80 days of exposure, both populations showed an equal trend toward increasing their respiration as lead concentrations, that they had been fed on, were increased. Accordingly, the glycogen content of the body, in both populations, was elevated with increasing lead concentrations in the food. This effect was more pronounced in the pre-exposed isopod population than in the one from the control stand. The non-pre-exposed isopods showed a general tendency toward a lower protein content of their bodies than the pre-exposed ones, although no effect of the lead on this parameter could be statistically proven. The ability of the artillery range isopods to synthesise stress proteins (hsp 70) in response to lead contamination decreased at much lower lead concentrations in their food than in the non-pre-exposed control population, even though the artillery range isopods seemed to be equally or even slightly better equipped with energy storage products. Even though the better nutrient status of these animals might refer to some lead tolerance of the pre-exposed population, the stress protein data suggest that a metal-resistant Porcellio population did not evolve in this lead-contaminated site.     

Biogeochemical transformation of greenhouse gas emissions from terrestrial to atmospheric environment and potential feedback to climate forcing

Environmental Science and Pollution Research - Carbon dioxide (CO2) is mainly universal greenhouse gas associated with climate change. However, beyond CO2, some other greenhouse gases (GHGs) like...     

Environmental hazard screening of a metal-polluted site using pressurized liquid extraction and two in vitro bioassays

Rapid screening methods can improve the cost effectiveness, throughput, and quality of risk assessments of contaminated sites. In the present case study, the objective was to evaluate a combination of pressurized liquid extraction and 2 in vitro bioassays for the hazard assessment of surface soil sampled from 46 points across a pyrotechnical industrial site. Pressurized liquid extraction was used to rapidly produce soil-water extracts compatible with 2 high-capacity bioassays. Hazard assessment using combined toxicological and chemical screening revealed zones with relatively high potential risks of metal pollution. Multivariate data analysis provided indications that significant inhibition in the bioassays was correlated with levels of metals in the extracts, suggesting an elevated toxic potential from certain metals. Low pH and high concentrations of dissolved organic carbon were associated with increased cytotoxicity of extracts, indicating that these factors influence metal bioavailability. The cytotoxicity observed was more strongly correlated to metal concentrations in the extracts than in the soil, suggesting that measurements of total metal concentrations in soils do not provide good indications of the soil's potential toxicity.     

Transfer of selenium from prey to predators in a simulated terrestrial food chain

Little is known about the accumulation and effects of selenium in reptiles. We developed a simplified laboratory food chain where we fed commercial feed laden with seleno-D,L-methionine (30 microg/g dry mass) to crickets (Acheta domestica) for 5-7 d. Se-enriched crickets (approximately 15 microg/g Se [dry mass]) were fed to juvenile male and female lizards (Sceloporus occidentalis) for 98 d while conspecifics were fed uncontaminated crickets. Lizards fed contaminated prey accumulated Se concentrations ranging from 9.3 (in female carcass) to 14.1 (in female gonad) microg/g compared to <1.5 microg/g in tissues of controls. Female gonad concentrations approached the highest of thresholds for reproductive toxicity in oviparous vertebrates. However, we observed no consistent effect of dietary treatment on sublethal parameters or survival. Our simplified food chain proved to be an ecologically relevant method of exposing lizards to Se, and forms the foundation for future studies on maternal transfer and teratogenicity of Se.     

A synthesis of the arctic terrestrial and marine carbon cycles under pressure from a dwindling cryosphere

The current downturn of the arctic cryosphere, such as the strong loss of sea ice, melting of ice sheets and glaciers, and permafrost thaw, affects the marine and terrestrial carbon cycles in numerous interconnected ways. Nonetheless, processes in the ocean and on land have been too often considered in isolation while it has become increasingly clear that the two environments are strongly connected: Sea ice decline is one of the main causes of the rapid warming of the Arctic, and the flow of carbon from rivers into the Arctic Ocean affects marine processes and the air–sea exchange of CO₂. This review, therefore, provides an overview of the current state of knowledge of the arctic terrestrial and marine carbon cycle, connections in between, and how this complex system is affected by climate change and a declining cryosphere. Ultimately, better knowledge of biogeochemical processes combined with improved model representations of ocean–land interactions are essential to accurately predict the development of arctic ecosystems and associated climate feedbacks.     

Changes in cell-type composition in digestive gland of slugs and its influence in biomarkers following transplantation between a relatively unpolluted and a chronically metal-polluted site

Changes in cell-type composition (CCTC) is a general phenomenon that takes place in the digestive gland epithelium of stressed molluscs. The aim of the present work was to determine whether CCTC is a reversible process in the digestive gland of sentinel slugs chronically exposed to metal pollution and how CCTC affects metal accumulation parameters and different cell and tissue biomarkers of exposure and effect. Slugs (Arion ater) from an abandoned zinc mine were transferred to a relatively unpolluted site and the other way around for 3, 10 and 28 d. The volume density of black silver deposits (Vv_BSD) after autometallography, and metallothionein (MT) levels were used as biomarkers of exposure to metals and CCTC and lysosomal responses were selected as effect biomarkers. Results indicated that slugs were sensitive to recent metal pollution; however, slugs chronically exposed to metals presented some characteristic features and were less responsive to pollution cessation without signs of CCTC reversal.     

Bioaccumulation of cadmium by the freshwater isopod Asellus aquaticus (L.) from aqueous and dietary sources

Experiments were conducted to determine the kinetics and relative importance of aqueous and dietary uptake of cadmium by the freshwater isopod Asellus aquaticus (L.). Test animals were exposed during 30 days to aqueous Cd in a continuous flow system (exposure levels: 0.2 - 10 microg litre(-1)) and kept on a diet of previously contaminated Elodea sp. (range of Cd concentrations: 2-350 microg g(-1), dry weight). Preceding semi-static experiments on dosage-control of the dietary factor revealed a rapid uptake of Cd by Elodea, with relatively high concentration factors (CF), which ranged from 4.8 to 5.5 (dry weight log (CF) after 16 days). For Asellus uptake from water appeared to be the predominant route. Highly significant bioconcentration of cadmium from water was observed in the animals, even at exposure levels below 1.0 microg litre(-1). In the various treatments, direct uptake from water accounted for 50-98% of the body burdens after 30 days exposure. The experimental results were described with a first order one-compartment bioaccumulation model. Model parameter estimates (mean +/- standard error) were obtained for rate constant of uptake (560 +/- 110 day(-1)), rate constant of elimination (0.032 +/- 0.017 day(-1)) and assimilation efficiency of Cd uptake from food (1.1 +/- 0.7%). The (dry weight) bioconcentration factor (BCF) and bioaccumulation factor (BAF) for extrapolated steady state conditions were estimated at 18 000 (BCF) and 0.08 (BAF). Experiments conducted at two different pH levels (5.9 versus 7.6) revealed no significant effects of pH on the uptake of aqueous Cd by the isopods. The results are discussed in relation to their potential significance to the field situation.     

Development of a terrestrial vertebrate model for assessing bioavailability of cadmium in the fence lizard (Sceloporus undulatus) and in ovo effects on hatchling size and thyroid function

In the terrestrial environment, standardized protocols are available for measuring the exposure and effects of contaminants to invertebrates, but none currently exist for vertebrates. In an effort to address this, we proposed that developing lizard embryos may be used as a terrestrial vertebrate model. Lizard eggs may be particularly susceptible to soil contamination and in ovo exposure may affect hatchling size, mortality, as well as thyroid function. Toxicant-induced perturbations of thyroid function resulting from in ovo chemical exposure may result in toxicity during the critical perinatal period in reptiles. Fertilized Eastern fence lizard (Sceloporus undulatus) eggs were placed in cadmium (Cd)-spiked expanded perlite (0, 1.48, 14.8, 148, 1480, 14 800 μg Cd/g, nominal concentrations), artificially incubated at 28 °C, and examined daily for mortality. Whole lizard hatchlings as well as failed hatches were homogenized in ethanol and the homogenate was divided for Cd body residue analysis and thyroid hormone (triiodothyronine (T₃) and thyroxine (T₄)) analyses. Acute mortality was observed in the two highest doses (1480 and 14 800 μg Cd/g). Cadmium body residues showed a higher internal concentration with increasing exposure concentration indicating uptake of Cd. There was a decrease in T₃:T₄ ratio at the highest surviving dose (148 μg Cd/g), however, there were no differences observed in hatchling size measured as weight and snout-vent length, or in whole body thyroid hormone levels. In summary, this study has shown Cd amended to a solid phase representing soil (perlite) can traverse the thin, parchment-like shell membrane of the fence lizard egg and bioaccumulate in lizard embryos. We believe this study is a good first step in investigating and evaluating this species for use as a model.