Genotoxic effects of cadmium and influence on fitness components of Lymantria dispar caterpillars

Genotoxic effect of two environmentally safe doses of cadmium on the hepato-nephrocytic system of Bombus atratus forager workers

Eusocial bees are declining due to anthropogenic actions. Individuals can be exposed to contaminants like Cd, which have been found in pollen. Thus, we evaluated the potential genotoxicity of Cd to the hepato-nephrocitic system of Bombus atratus foraging workers exposed to environmentally safe doses of Cd (0.001 mg/kg and 0.003 mg/kg) during 72 h. To assess the genotoxicity of Cd, we conducted an alkaline comet assay. Doses of 0.001 mg/kg of Cd caused comets of levels 2 and 3, and 0.003 mg/kg of Cd induced comets of level 4, while controls exhibited regular nucleoids. Also, 0.003 mg/kg doses caused higher Damage Index, Damage Frequency, and Total Damage. Our results bring new evidence that 0.003 mg/kg Cd exerted genotoxicity to the HNS cells of B. atratus, probably affecting secondary metabolism and the detoxification capability of bees.

Chronic lead exposure prolongs the immature stages of brown-legged grain mite, Aleuroglyphus ovatus, in a long-term population study

An important aspect of environmental pollution, lead contamination is a widespread problem in several ecosystems. The present study aimed to evaluate the potential effects of low concentration lead stress on the development and reproduction of Aleuroglyphus ovatus. They were fed with artificial diet containing four different concentrations of lead (12.5, 25, 50, and 100 mg/kg). The results showed that there were both accelerating effect of lead (at low concentrations), as well as retarding effects (at high concentrations) on the development of the mite, and lead stress significantly prolonged the immature stages of A. ovatus and this inhibitory effect was greater with greater lead concentrations. The immature stages in the L group were shorter than those in the S group. In the S and L groups, the oviposition periods were significantly longer in the treatments with lower lead concentrations than in the control, while they were significantly shorter in those treatments of higher lead concentrations. Age-specific survival rate (lx) started to decline earlier in the S group, whereas there were no differences between the L group and CK. Age-specific fecundity rate (mx) peaked earlier in the S group than in CK, while mx peaked later in L1 and L2 than in CK. The rm value and net reproduction rate (R0) of treated A. ovatus decreased with increasing lead concentrations. Lower lead concentrations could promote population expansion while higher concentrations could inhibit population size. These results confirmed the developmental effect of lead stress on A. ovatus, highlighting that heavy metal contamination has negative effects on organisms in their natural environment.

Digestive enzyme activity and macromolecule content in the hemolymph of differentially adapted Lymantria dispar L. populations after short-term increases in ambient temperature

Global, unpredictable temperature increases have strong effects on all organisms, especially insects. Elucidating the effects of short-term temperature increases on midgut digestive enzymes (α-glucosidase, lipase, trypsin, and leucine aminopeptidase - LAP) and metabolic macromolecules in the hemolymph (proteins, lipids, and trehalose) of phytophagous pest larvae of Lymantria dispar is important for general considerations of insect adaptation to a warming climate and potential pest control options. We also wanted to determine whether the different adaptations of L. dispar populations to environmental pollution might affect their ability to cope with heat stress using larvae from the undisturbed, Kosmaj forest and disturbed, Lipovica forest. Heat treatments at 28 °C increased α-glucosidase activity in both larval populations, inhibited LAP activity in larvae from the polluted forest, and had no significant effect on trypsin and lipase activities, regardless of larval origin. The concentration of proteins, lipids, and trehalose in the hemolymph of larvae from the disturbed forest increased, whereas the population from the undisturbed forest showed only an increase in proteins and lipids after the heat treatments. Larval mass was also increased in larvae from the undisturbed forest. Our results suggest a higher sensitivity of digestive enzymes and metabolism to short-term heat stress in L. dispar populations adapted to pollution in their forest habitat, although climate warming is not beneficial even for populations from unpolluted forests. The digestive and metabolic processes of L. dispar larvae are substantially affected by sublethal short-term increases in ambient temperature.

Antioxidative enzymes, alkaline phosphatases and Hsp70 expression in larvae of Lymantria dispar (Lepidoptera: Erebidae) from unpolluted and polluted forests after chronic cadmium treatment

Long-term exposure of populations to pollution may result in enhanced ability to cope with environmental stress. To compare the responses of two Lymantria dispar populations living in unpolluted and polluted forests (UP and PP, respectively), we chronically exposed larvae to cadmium at concentrations of 50 and 100 μg Cd/g dry food (Cd1 and Cd2, respectively). We examined cadmium accumulation in the midgut and hemolymph, activities of superoxide dismutase (SOD), catalase (CAT), and alkaline phosphatases (ALP) in the midgut, as well as Hsp70 protein expression in the midgut, hemolymph, and brain and evaluated these parameters as biomarkers of cadmium contamination. Larvae from PP, fed a control diet, showed higher activity of SOD and increased Hsp70 expression compared with larvae from UP. Excessive amounts of Cd were accumulated in the midgut of all Cd-fed larvae, whereas Cd content in the hemolymph was elevated only in larvae from PP after Cd2 treatment. In larvae from UP, Cd2 treatment decreased the activity of CAT and induced the expression of Hsp70 in the midgut and hemolymph. In larvae from PP, exposure to both Cd concentrations strongly attenuated SOD and CAT activities, while Hsp70 expression was not induced in any organ/tissue. Cd did not affect ALP activity in either population. Midgut Cd content proved to be a suitable indicator of Cd contamination for both polluted and unpolluted habitats.

Effects of dietary fluoranthene on tissue-specific responses of carboxylesterases, acetylcholinesterase and heat shock protein 70 in two forest lepidopteran species

In this study, responses of carboxylesterases, acetylcholinesterase, and stress protein Hsp70 were examined in the midgut and midgut tissue, and brain of fifth instar larvae of Lymantria dispar L. and Euproctis chrysorrhoea L. following chronic exposure to dietary fluoranthene. Specific carboxylesterase activity increased significantly in the midgut tissue of E. chrysorrhoea larvae treated with a lower fluoranthene concentration. The specific patterns of isoforms expression, recorded in larvae of both species, enable efficient carboxylesterase activity as a significant part of defense mechanisms. Increased Hsp70 concentration in the brain of L. dispar larvae points to a response to the proteotoxic effects of a lower fluoranthene concentration. Decreased Hsp70 in the brain of E. chrysorrhoea larvae in both treated groups can suggest induction of other mechanisms of defense. The results indicate the importance of the examined parameters in larvae of both species exposed to the pollutant, as well as their potential as biomarkers.

Starvation and cadmium affect energy reserves and oxidative stress in individuals of Spodoptera exigua

Different factors, such as starvation and metal exposure, may affect development and cause oxidative stress in insects. Some host plants may contain a high concentration of cadmium due to their hyperaccumulating property. The negative effects of metals and hunger may be manifested by low availability of energetic substrates. This study aimed to assess whether the insect population with a history of long metal exposure may better manage metal stress or/and starvation at different developmental stages, with the use of energetic substrates. Two strains of Spodoptera exigua model organism were tested: control strain and cadmium strain (treated continuously for over 200 generations with subtoxic amounts of cadmium). The effects of different factors, individually and in combination, on the tested strains were assessed, first by determining the body weight of larvae and pupae and then by estimating the concentration of biomolecules (proteins, carbohydrates, lipids, or glycogen) in the 4th and 5th larval stages and in pupae, and the total antioxidant capacity and lipid peroxidation level in the 4th larval stage. Compared to control strain, cadmium strain individuals exhibited changes in the concentration of soluble carbohydrates and protein. This was partly related to earlier 1-day starvation. In particular, changes in carbohydrate concentration seemed to be a sensitive biomarker of metal stress, independent of the age of individuals and period of starvation. However, the increase in the total antioxidant capacity and the concentration of lipid peroxidation products in the 4th larval stage under the effect of cadmium was dependent on strain origin.

Implications of long-term exposure of a Lymantria dispar L. population to pollution for the response of larval midgut proteases and acid phosphatases to chronic cadmium treatment

Cadmium (Cd) presence in terrestrial ecosystems is a serious threat that requires continuous development of biomonitoring tools. Ideally, a suitable biomarker of exposure should respond to the toxicant consistently in different populations regardless of previous exposure to pollution. Here we considered the activities and isoform patterns of certain proteases and acid phosphatases (ACP) in the midgut of Lymantria dispar larvae as well as the integrated biomarker response (IBR) for application in Cd biomonitoring. We compared the responses of caterpillars originating from unpolluted and polluted localities after they had been chronically subjected to dietary Cd (50 and 100 μg Cd/g dry food). The population inhabiting the unpolluted forest was far more sensitive to Cd exposure as the activities of total proteases, trypsin (TRY) and leucine aminopeptidase (LAP) were mostly reduced while the activities of total and non-lysosomal ACP were increased. Non-lysosomal ACP activity was elevated in larvae from the contaminated site in response to the higher Cd concentration. Exposure to the metal resulted in numerous alterations in the pattern of enzyme isoforms, but the responses of the two populations were similar except that larvae from the polluted locality were more tolerant to the lower Cd concentration. Non-lysosomal ACP activity and the appearance of ACP isoforms 4 and 5 together with the IBR index are the most promising indicators of Cd presence, potentially applicable even in populations with a history of exposure to pollution. TRY and total ACP activities could be used to monitor populations at uncontaminated localities.

Sensitivity of midgut physiological parameters of Lymantria dispar L. larvae to benzo[a]pyrene in populations with different multigeneration contact to environmental pollutants

Accumulation of organic pollutants in the environment calls for sensing physiological parameters adequate to indicate the presence of contaminants and their effects on ecosystems. Evidence points to the importance of insect adaptations in their habitats for the assessment of sensitive biomarkers so we examined the influence of origin and multigenerational adaptations of the Lymantria dispar larvae to chronic benzo[a]pyrene (B[a]P) treatment under laboratory conditions. The main aim was to compare reactions of larvae from unpolluted and polluted forests using alkaline phosphatase (ALP), acid phosphatase (ACP), and carboxylesterase (CE) specific activities in the midgut, including electrophoretic isoform patterns; midgut expression levels of Hsp70, larval development time (DT), and midgut mass (MM), after chronic exposure to 5 and 50 ng of B[a]P/g dry food weight. The biomarker potential of these parameters regarding larval pre-exposure history to pollution was estimated by principal component analysis (PCA). B[a]P treatment resulted in inhibition of ALP activity, a rise of CE activity, and reduction of MM in larvae from the unpolluted forest, while the population from the polluted forest showed significant elevation of Hsp70 expression in the midgut, prolonged DT, and reduction of MM. PCA confirmed variations in responses of the selected parameters regarding population origin. The obtained results provide insight into insect population variability concerning physiological responses to pollutants. It is indicative that all investigated physiological parameters of L. dispar larvae showed origin-dependent responses to long-term presence of B[a]P, which may be of great importance in ecotoxicological research.

Multi-biomarker approach and IBR index to evaluate the effects of different contaminants on the ecotoxicological status of Apis mellifera

The honeybee, Apis mellifera L. (Hymenoptera: Apidae), a keystone pollinator of wild plant species and agricultural crops, is disappearing globally due to parasites and diseases, habitat loss, genetic constraints, beekeeper management issues and to the widespread use of pesticides. Besides insecticides, widely studied in this species, honeybees are also exposed to herbicides and fungicides and heavy metals whose lethal and sublethal effects need to be investigated. In this context, our study aimed to evaluate the effects of fungicides and of heavy metals on honeybees and to develop and apply a multi-biomarker approach that include an Integrated Biological Index (IBRv2) to assess the toxicological status of this species. Biomarkers of neurotoxicity (AChE and CaE), metabolic alteration (ALP, and GST) and immune system (LYS, granulocytes) were measured, following honeybees' exposure to cadmium or to a crop fungicide, using the genotoxic compound EMS as positive control. A biomarker of genotoxicity (NA assay) was developed and applied for the first time in honeybees. At the doses tested, all the contaminants showed sublethal toxicity to the bees, highlighting in particular genotoxic effects. The data collected were analyzed by an IBRv2 index, which integrated the seven biomarkers used in this study. IBRv2 index increased with increasing cadmium or fungicide concentrations. The IBRv2 represents a simple tool for a general description of honeybees ecotoxicological health status. Results highlight the need for more in-depth investigations on the effects of fungicides on non-target organisms, such as honeybees, using sensitive methods for the determination of sublethal effects. This study contributes to the development of a multi-biomarker approach to be used for a more accurate ecotoxicological environmental monitoring of these animals.

Energy reserves, oxidative stress and development traits of Spodoptera exigua Hübner individuals from cadmium strain

Cadmium as a common environmental stressor may exert highly toxic effects on herbivorous insects. The question was whether possible elevation of an oxidative stress and imbalance of energetic reserves in insects may depend on developmental stage, sex and insect population's multigenerational history of exposure to cadmium. So, the aim of this study was to compare of the development traits, total antioxidant capacity, lipid peroxidation, RSSR to RSH ratio and the concentration of carbohydrates, glycogen, lipids and proteins in whole individuals (larvae or pupae) of Spodoptera exigua originating from two strains: control and selected over 120 generations with sublethal metal concentration (44 Cd mg per dry weight of diet). Generally, the increase of the protein, carbohydrates, glycogen concentration and lipid peroxidation decrease with age of the larvae were found. Revealed cases of a higher mobilisation of carbohydrates and proteins, and changes in total antioxidant capacity or lipid peroxidation, in individuals being under metal exposure, occurred in strain-depended mode. Short-term Cd exposure effect was connected with possible higher engagement of proteins and glycogen in detoxification processes, but also higher concentration of lipid peroxidation. In turn, for long-term Cd exposure effect lower lipids concentration and higher thiols usage seemed to be more specific.

Cd exposure-induced growth retardation involves in energy metabolism disorder of midgut tissues in the gypsy moth larvae

Cadmium, a common environmental contaminant in both terrestrial and aquatic ecosystems, presented a serious hazard to growth and development of phytophagous insects. For better understanding the toxicology of Cd exposure on phytophagous insects, the physiological and molecular mechanisms underlying the energy metabolism disorder in midgut tissue of gypsy moth larvae fed on Cd-amended artificial diets (3.248 or 44.473 mg Cd/kg fresh food) were investigated. Our results showed that compared with control, Cd exposure at both two levels triggered detriment effects on growth indexes, and with the increase of exposure concentrations, the adverse effects were significantly exacerbated. Larval growth and nutritional indexes (except approximate digestibility) showed a strong positive correlation, indicating that growth retardation in the gypsy moth larvae under Cd stress was tightly related to the food utilization. The key genes at mRNA level in glycolysis/gluconeogenesis, citrate cycle pathway and starch/sucrose metabolism pathway also presented a significant and positive correlation with growth indexes, once again demonstrating that energy metabolism was the key factor that controls the growth and development of the gypsy moth larvae under Cd stress. Antioxidant system collapse and oxidative damage, a chief cause of histopathological alterations in midgut tissue, consist of the physiological basis of energy metabolism disorder in Cd-treated gypsy moth larvae. Together, these results suggest that histopathological alterations or oxidative damage of tissue structure significant disturbed physiological functions of midgut tissue in gypsy moth larvae exposed to Cd stress, as reflected via food utilization or energy metabolism disorder, and eventually resulted in larval growth retardation.

A verification of correlation between chemical monitoring and multi-biomarker approach using clam Ruditapes philippinarum and scallop Chlamys farreri to assess the impact of pollution in Shandong coastal area of China

Biogeochemical monitoring coupled with multi-biomarker approach were performed for the assessment of marine environment, using clam Ruditapes philippinarum and scallop Chlamys farreri to indicate contamination status in sediments and seawater respectively. The bivalves were collected from three stations, Jiaozhou Bay, Rushan Bay and Laizhou Bay, of Shandong coastal area. A series of contaminants (PAHs and TBBPA) and biomarkers (AhR, EROD, GST, SOD, GPx, CAT, DNA damage) were measured. Multi-biomarker pollution index (MPI) and integrated biomarker response (IBR) were carried out to evaluate contamination status and both indexes showed that Rushan Bay was most polluted, where the pollution level of sediments reached "highly polluted" in August, followed by Jiaozhou Bay and Rushan Bay which reached "lightly polluted". The correlation of IBR values with contaminants' concentrations was verified through the Pearson correlation coefficient (p < 0.05), consolidating this scientific assessment method for marine environment.

Effect of fluoranthene on antioxidative defense in different tissues of Lymantria dispar and Euproctis chrysorrhoea larvae

This study examined the effect of long-term exposure to environmentally relevant concentrations of dietary fluoranthene (6.7 and 67 ng / g dry food weight) on defense mechanisms of the polyphagous forest insects Lymantria dispar L. and Euproctis chrysorrhoea L. The activities and expression of isoforms of superoxide dismutase (SOD) and catalase (CAT), the activities of glutathione S-transferase (GST) and glutathione reductase (GR), and total glutathione content (GSH) were determined in the whole midgut and midgut tissue, while SOD and CAT activities were assessed in hemolymph of the larvae. The results showed significant changes of enzyme activities, with more pronounced responses in larval midgut tissues, and between-species differences in patterns of response. Significantly increased activity of SOD was recorded in the whole midgut and midgut tissue of L. dispar larvae, as well as in midgut tissue of E. chrysorrhoea larvae. Fluoranthene increased CAT activity in midgut tissue of L. dispar larvae, and in the whole midgut and midgut tissue of E. chrysorrhoea larvae. Different expression patterns were detected for enzyme isoforms in tissues of larvae exposed to dietary fluoranthene. Total GSH content and GST activity increased in E. chrysorrhoea larval midgut tissue. Significantly decreased SOD activity in hemolymph of L. dispar larvae, and opposite changes in CAT activity were recorded in the hemolymph of larvae of two insect species. The tissue-specific responses of enzymes to dietary fluoranthene, recorded in each species, enabled the larvae to overcome the pollutant induced oxidative stress, and suggest further assessment of their possible use as early-warning signals of environmental pollution.

Parameters of oxidative stress, cholinesterase activity, Cd bioaccumulation in the brain and midgut of Lymantria dispar (Lepidoptera: Lymantriidae) caterpillars from unpolluted and polluted forests

Cadmium (Cd) can display a variety of different effects on living organisms. The objectives of the present study were to investigate Cd bioaccumulation and differences in parameters of oxidative stress (activities of the enzymes: superoxide dismutase, catalase, glutathione reductase, ascorbate peroxidase, glutathione S-transferase, and amounts of non-enzymatic free sulfhydryl groups and total glutathione) and cholinesterase activity in larval brain and midgut tissues of the polyphagous forest insect Lymantria dispar collected from unpolluted and polluted oak forests. Fourth instar L. dispar caterpillars from the unpolluted forest had higher body mass but accumulated more Cd in comparison to caterpillars from the polluted forest. In both populations the midgut was more sensitive than the brain to the prooxidative effects of Cd. Enzyme activities and amounts of non-enzymatic parameters tended to be greater in midgut tissues than in the brain, except for cholinesterase activity. Parameters of oxidative stress had higher values in caterpillar tissues from the polluted than from the unpolluted oak forest. The observed differences between the two natural populations point to the importance of knowing the history of population exposure to environmental pollution when monitoring forest ecosystems.

Effects of dietary fluoranthene on nymphs of Blaptica dubia S. (Blattodea: Blaberidae)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants which exert detrimental effects on living beings. Considering the health risk associated with exposure to these pollutants, their presence in food increases efforts to establish early-warning indicators of pollution. We aimed to examine the effects of environmentally relevant concentrations of fluoranthene (0.2 ng and 18 ng/g dry weight of diet) on the activities of midgut antioxidant and detoxification enzymes in Blaptica dubia. Significant changes of superoxide dismutase and catalase activities, recorded at the higher fluoranthene concentration regardless of the exposure time, suggest that they may be used as biomarkers of PAH pollution. Increased GST activity and decreased total GSH content, detected upon acute exposure to the lower concentration, indicate processes of detoxification. Reorganization of B. dubia mechanisms of defense in response to oxidative stress caused by exposure to dietary PAH point to the necessity for further examination of fluoranthene actions.

Leaves, berries and herbivorous larvae of bilberry Vaccinium myrtillus as sources of metals in food chains at a Cu-Ni smelter site

Ericaceous dwarf shrubs, such as bilberry, Vaccinium myrtillus, have an important role in nutrient cycling of boreal forests, but in metal polluted environments they also form a link between heavy metal pool of the soil, primary consumers and upper trophic levels. From the viewpoint of metal transfer in a food chain, we document metallic element (As, Ca, Cd, Co, Cu, Mn, Mo, Ni, Pb, Se, Zn) concentrations in leaves, berries and herbivorous larvae of V. myrtillus around a Finnish copper-nickel smelter and compare those with levels in relatively unpolluted reference sites, and with levels documented in soil and feces (a proxy of dietary levels) of an insectivorous bird, the pied flycatcher, Ficedula hypoleuca. Herbivorous larvae of the autumnal moth, Epirrita autumnata (Lepidoptera: Geometridae), grown experimentally on V. myrtillus, showed slower growth rate but not higher mortality in the polluted area. In general, metal levels in leaves, berries and larvae were higher in the polluted area and comparable to those reported at other smelter sites in Europe. The levels of the main toxic metals (As, Cd, Cu, Ni, Pb) followed the general pattern: soil > bird feces > leaves > larvae = berries, and levels in V. myrtillus, E. autumnata and F. hypoleuca reflected soil metal levels. The lowest levels were found in those matrices that are most important sources of food for birds and humans, i.e. leaf-eating larvae and berries, reducing a risk of toxic effects.

The impact of ocean acidification and cadmium on the immune responses of Pacific oyster, Crassostrea gigas

Seawater acidification (OA) and cadmium (Cd) has the potential to lead to immunosuppression effect on marine bivalves. However, the interaction between these two environmental stressors on immune system of marine bivalves has received limited attention. In order to evaluate the defense responses of oysters under the combined exposure to OA and cadmium, the oysters Crassostrea gigas were exposed to 10 μg/L Cd at three pH levels (8.1, 7.8 and 7.6) for 31 days. Results showed that OA exposure alone led to increased DNA damage, apoptosis rate and ROS production of hemocytes. However, inhibited phagocytosis rate, combined with increased DNA damage, apoptosis rate and ROS production of hemocytes were observed in oysters under exposure to Cd exposure alone or combined with OA. Significant interactive effects between OA and Cd were observed on ROS production and DNA damage of hemocytes. In addition, there is generally significant increase in the mRNA expression of genes related to immune-related TLR pathway and two immune factors (TNF and integrin beta-1B) in Cd-exposed oysters at pH 7.6. The results revealed that even though the mRNA expression of genes related to immune responses (TLR pathway and immune factors) was stimulated to counteract the immunosuppression caused by acidified seawater and Cd, depressed hemocyte function perhaps sensitized oysters to potential pathogen infection.

Effects of Cd accumulation on cutworm Spodoptera litura larvae via Cd treated Chinese flowering cabbage Brassica campestris and artificial diets

By exposing herbivorous cutworm Spodoptera litura (Lepidoptera: Noctuidae) larvae to Cadmium (Cd) stress via Cd treated cabbages Brassica campestris and artificial diets, we investigated effects of Cd accumulation in larvae on their survival and food utilization. The results showed that Cd transferred from soils contaminated with different Cd concentrations through cabbages-larvae, and be mainly accumulated in larvae guts. There was a dose-response relationship between Cd accumulations in larvae cuticle, head, guts and Cd concentrations in artificial diets, and the highest one was found in the guts, regardless of generations. High Cd stress (10 mg kg^-1 Cd in soil, 40.6, 81.2 mg kg^-1 Cd in artificial diets) had inhibited effects on larvae growth and food utilization, whereas low Cd stress (Lvbao 701 planted in 2.5 mg kg^-1 Cd soil, 4.06 mg kg^-1 Cd in artificial diets) showed stimulated effect. Cd accumulations in the guts were significantly negative correlated with efficiency of conversion of ingested food (ECI) and relative growth rate (RGR) of larvae feeding on Cd treated diets or cabbages while were significantly positive correlated with relative consumption rate (RCR). Therefore, after S. litura larvae feed on Cd treated natural food or artificial diets, Cd could be transferred to different tissues, and mainly accumulated in the guts, which significantly affected growth and food utilization. Additionally, Cd stress via Cd treated artificial diets presented less detrimental effects on S. litura larvae than via Cd treated cabbages.

Adsorption of Cd (II) on Modified Granular Activated Carbons: Isotherm and Column Study

In this work, equilibrium and dynamic adsorption tests of cadmium Cd (II) on activated carbons derived from different oxidation treatments (with either HNO₃, H₂O₂, or NaOCl, corresponding to GACoxN, GACoxP, and GACoxCl samples) are presented. The oxidation treatments determined an increase in the surface functional groups (mainly the acidic ones) and a decrease in the pH_PZC (except for the GACoxCl sample). A slight alteration of the textural parameters was also observed, which was more significant for the GACoxCl sample, in terms of a decrease of both Brunauer-Emmett-Teller (BET) surface area and micropore volume. Adsorption isotherms were determined for all the adsorbents and a significant increase in the adsorption performances of the oxidized samples with respect to the parent material was observed. The performances ranking was GACoxCl > GACoxP > GACoxN > GAC, likely due to the chemical surface properties of the adsorbents. Dynamic tests in a fixed bed column were carried out in terms of breakthrough curves at constant Cd inlet concentration and flow rate. GACoxCl and GACoxN showed a significantly higher value of the breakpoint time, likely due to the higher adsorption capacity. Finally, the dynamic tests were analyzed in light of a kinetic model. In the adopted experimental conditions, the results showed that mass transfer is controlled by internal pore diffusion, in which surface diffusion plays a major role.

Cadmium and high temperature effects on brain and behaviour of Lymantria dispar L. caterpillars originating from polluted and less-polluted forests

Insects brain as a part of nervous system is the first-line of fast stress response that integrate stress signals to regulate all aspects of insect physiology and behaviour. The cadmium (Cd) bioaccumulation factor (BF), activity of the neurotoxicity biomarker acetylcholinesterase (AChE), dopamine content, expression and amount of Hsp70 in the brain and locomotor activity were evaluated in the 4th instar of Lymantria dispar L. caterpillars fed a Cd supplemented diet and reared in an optimal temperature regime (23 °C) and/or exposed to high temperature (28 °C). The insects originated from two forests, one close to "Nikola Tesla" thermoelectric power plant, Obrenovac (polluted population), and the other Kosmaj mountain (less-polluted population, far from any industrial region). The Cd BF was higher in the less-polluted than in the polluted population especially at the high ambient temperature. AChE activity and dopamine content were changed in the brains of L. dispar from both populations in the same manner. Hsp70 concentration in caterpillar brains showed opposite trends, a decrease in the less-polluted and an increase in the polluted population. Locomotor activity was modified in both Lymantria dispar populations, but the pattern of changes depended on the stressors and their combined effect. ACh activity and dopamine content are sensitive parameters to Cd exposure, regardless of pollutant experience, and might be promising biomarkers in monitoring forest ecosystems.

Influence of dietary cadmium exposure on fitness traits and its accumulation (with an overview on trace elements) in Lymantria dispar larvae

Bioaccumulation and excretion of heavy metals in insects is only partially clarified. We have investigated cadmium accumulation in the feces, head and integument of Lymantria dispar (Lepidoptera: Lymantriidae) larvae exposed to chronic dietary intake of cadmium. The aim of the experiment was to establish modalities of metal accumulation, primarily cadmium, as well as changes in fitness traits in two insect populations receiving 50 or 100μgCd/g dry food. The egg-masses originated from two localities: a protected nature reserve (unpolluted population) and an area near a busy highway (polluted population) in Serbia. At both added dietary levels cadmium concentration was highest in feces. Small alterations in metal concentrations after both cadmium treatments were detected in the integument. It was established that irrespective of population origin, the modality of decline of larval mass and relative growth rate (RGR) was similar. Concentrations of Cu and Zn in the integument were approximately the same regardless of dietary cadmium intake. However, cadmium accumulation in the examined tissues, as well as variability of fitness traits depended on population origin and cadmium concentration. In larvae from both populations not given contaminated food the head was the organ with the greatest accumulation of trace elements. Our results reveal how invasive phytophagous insects cope with high metal concentrations in their food by body mass (RGR) reduction and energy allocation towards processes that enable accumulation of cadmium and other trace elements in different tissues.

Baseline and oxidative DNA damage in marine invertebrates

Anthropogenic pollutants produce oxidative stress in marine organisms, directly or following generation of reactive oxygen species (ROS), potentially resulting in increased accumulation of DNA strand breaks quantified. The aim of this study is to quantify baseline levels of DNA strand breaks in marine species from four phyla and to assess relative sensitivity to oxidative stress as well as ability to recover. DNA strand breaks were determined using a formamidopyrimidine DNA glycosylase (Fpg)-amended comet assay in circulating cells from blue mussel (Mytilus edulis), shore crab (Carcinus maenas), sea star (Asterias rubens), and vase tunicate (Ciona intestinalis). Lymphocytes from Atlantic cod (Gadus morhua) were used as a reference. In addition to immediate analysis, cells from all species were exposed ex vivo to two concentrations of hydrogen peroxide (H₂O₂) at 25 or 250 μM prior to assay. Mean baseline DNA strand breaks were highest for cells from sea star (34%) followed by crab (25%), mussel (22%), tunicate (17%), and cod (14%). Circulating cells from invertebrates were markedly more sensitive to oxidative stress compared to cod lymphocytes. DNA strand breaks exceeded 80% for sea star, crab, and mussel cells following exposure to the lowest H₂O₂ concentration. There was no recovery for cells from any species following 1 hr in buffer. This study provides an in-depth analysis of DNA integrity for ecologically important species representing 4 phyla. Data indicate that circulating cells from invertebrates are more sensitive to oxidative stress than cells from fish as evidenced by DNA strand breaks. Future studies need to address the extent to which DNA strand breaks may exert consequences for body maintenance costs in marine invertebrates.