The cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae), is an economically important pest in Egypt. This study examines the inheritance patterns, potential for resistance development, and fitness costs associated with chlorantraniliprole (CHL) resistance in S. littoralis. Laboratory selection over 15 generations resulted in a substantial resistance level, with a resistance ratio of 402.85-fold. Genetic analysis, including reciprocal crosses and backcrosses, revealed that CHL resistance is autosomal, polygenic, and exhibits incomplete dominance. The estimated realized heritability (h²) of resistance was 0.37, indicating a considerable potential for resistance development under selection pressure. Fitness assessments revealed no significant reproductive penalties associated with resistance; however, the resistant strain exhibited a significant developmental delay in the larval and pre-adult stages. These findings suggest that CHL resistance can rapidly evolve and persist in field populations, thereby complicating control efforts. The polygenic inheritance pattern underscores the complex genetic mechanisms underlying resistance, necessitating integrated management strategies. The reduced fitness costs further emphasize the importance of implementing proactive resistance management, such as rotating insecticides with different modes of action and integrating nonchemical control measures, to sustain the efficacy of CHL. Overall, this study provides critical insights into the genetic and biological dynamics of CHL resistance in S. littoralis, underscoring the urgency of vigilant resistance monitoring and strategic control practices to mitigate resistance and prolong the utility of CHL in pest management programs.
Pesticides have been widely used to ensure high productivity in monoculture systems. However, due to pathogen resistance and the need to improve the safety and sustainability of these substances, new compounds have emerged on the market. One example is pesticide mixtures, which aim to provide a broader spectrum of functionality within a single product. The azoxystrobin- and tebuconazole-based fungicide (ATBF) is a commercial premix fungicide containing two active ingredients. Nevertheless, studies investigating the effects of such mixtures on non-target organisms remain a significant gap in literature. Therefore, the main goal of this study was to investigate the toxicological effects of this fungicide mixture on the physiology and behavior of zebrafish. Developmental exposure (3–120 h post-fertilization [hpf]) to environmentally relevant concentrations was evaluated through assessments of survival, hatching, spontaneous movement, heart rate, and behavior (shoaling and antipredator response). Exposure to ATBF impaired survival, reduced spontaneous movement, altered heart rate, and affected shoaling behavior in zebrafish larvae. These findings highlight the importance of research on pesticide mixtures, as these products may exert additive or synergistic effects on aquatic fauna.
Honey bee (Apis mellifera) toxicity assessment is essential for environmental risk evaluation of agrochemicals, yet experimental data are costly and often limited, constraining the development of robust predictive models. This study investigates whether transfer learning via pretrained chemical language models can provide competitive QSAR performance for bee toxicity classification. Using the ApisTox dataset (1,035 compounds; 296 toxic and 739 non-toxic for bees), molecular representations were derived from SMILES in three ways: (i) PaDEL molecular descriptors, (ii) RDKit Morgan fingerprints, and (iii) MolFormer embeddings extracted from a publicly available reduced-scale pretrained checkpoint ( 100 M molecules; 10
The Corpus Christi Inner Harbor in Texas is a major center of industrial activity and contains high levels of persistent pollutants, including dioxins, furans, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). The Gulf killifish, Fundulus grandis, is an estuarine species inhabiting the Gulf of Mexico. F. grandis populations from the Houston Ship Channel (Galveston Bay, Texas) have been previously shown to be resistant to PCB-induced cardiac teratogenesis via a recalcitrant aryl hydrocarbon receptor (AHR) pathway. In this study, embryos from two F. grandis populations collected from the Corpus Christi Inner Harbor were exposed to varying doses of PCB-126 and evaluated for heart deformities at 144 h post fertilization. Both populations displayed significant resistance to PCB-induced cardiac teratogenesis compared to a reference population, representing the second documented cluster of adapted populations of F. grandis. Additionally, these populations exhibited lower basal cytochrome P4501A (CYP1A) activity (as measured via EROD assay) and reduced inducibility, indicating that a recalcitrant AHR pathway is at least partially responsible for the observed PCB resistance. Finally, we found that PCB-induced cardiac teratogenesis and CYP1A induction were highly correlated at the population level; however, individual CYP1A activity did not predict cardiac deformity. We propose a theoretical model in which inter-individual variation in CYP1A response explains this discrepancy and offers a conceptual framework for understanding individual variation within adapted populations. Collectively, these findings provide new insight into the mechanisms underlying adaptive responses to persistent pollutants and further establish F. grandis as a valuable model for evolutionary toxicology.
The present study investigated the joint effects of β-lactam antibiotics and silver nanoparticles (Ag NPs) on Chlorella vulgaris (C. vulgaris). The results show that when a single analyte was treated with amoxicillin (AM), aztreonam (AZ) and Ag NPs, the growth of C. vulgaris significantly decreased with increasing exposure concentration. The 96 h median effect concentration (EC50) was determined, and the toxicity of the three substances decreased in the order of Ag NPs > AZ > AM. In the cotreatments, the joint effects of Ag NPs and antibiotics on C. vulgaris were synergistic. Similarly, scanning electron microscopy (SEM) images also revealed that compared with coexposure, single-analyte exposure caused less damage to C. vulgaris. Grey correlation analysis was employed to assess the impact of combined β-lactam antibiotics and Ag NPs on the aforementioned indicators. Our findings contribute greatly to a better understanding of the joint effects of β-lactam antibiotics and Ag NPs on aquatic organisms and can provide solid evidence for ecological risk assessment of the coexistence of β-lactam antibiotics and Ag NPs in aquatic environments.
Although microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) are widespread in aquatic environments, their combined effects in freshwater systems remain poorly understood. This gap is relevant because green algae, frequently exposed to MPs, play an important role in PAHs bioremediation. This study evaluated how MPs influence the toxicity of benzo[a]pyrene (BaP) in the green microalga Raphidocelis subcapitata. A full-factorial design was used to expose algal cells to three concentrations of low-density polyethylene MPs (5, 50, and 500 mg L⁻¹), tested alone or in combination with the BaP median effective concentration (EC50-72 h) determined for this species. Experiments lasted 72 ± 2 h under controlled temperature, agitation, and light. The isolated and combined effects of MPs and BaP were analyzed using Generalized Linear Models. The EC50 of BaP was 21 µg L⁻¹ (20–25 µg L⁻¹) and the range provided refers to 95
Glyphosate and atrazine are among the most extensively applied herbicides worldwide and are often detected together in aquatic environments due to their concurrent agricultural use. This study investigated their individual and combined effects on Allium cepa at environmentally realistic concentrations: 62.5–1000 µg L⁻¹ for glyphosate and 0.25–4 µg L⁻¹ for atrazine. Five mixtures were also tested: M1 (62.5 + 0.25), M2 (125 + 0.5), M3 (250 + 1), M4 (500 + 2), and M5 (1000 + 4). Multiple endpoints were analyzed, including germination, root elongation, mitotic index, chromosomal and mitotic abnormalities, cell-cycle phase distribution, sub-G₁ fraction, fluorescence intensity, light-scattering parameters (FSC, SSC), membrane integrity (Evans Blue assay), and mitochondrial activity (TTC assay). Both herbicides and mixtures triggered cytotoxic and genotoxic responses, though most mixtures did not exceed the toxicity of the individual compounds, suggesting non-interactive or saturable mechanisms. Mixture M5, containing concentrations comparable to those reported in agricultural surface waters, produced stronger responses for some biomarkers. Flow-cytometric and mitochondrial endpoints were the most responsive following mitotic index and chromosomal aberrations. On the other hand, germination, root elongation, and membrane integrity showed limited sensitivity. Overall, the data indicate that even concentrations within current environmental guidelines can impair cellular function in A. cepa. This study provides a novel integrated assessment of glyphosate, atrazine, and their mixtures at environmentally relevant concentrations by combining classical A. cepa cytogenotoxicity assays with flow cytometry, membrane integrity, and mitochondrial activity biomarkers.
The current work seeks to evaluate the effectiveness of Cataglyphis saviginyi and Tentyrum sp as indicators of pollution in the city’s main industrial regions by analyzing their enzymatic activity and primary metabolites. Soil samples were collected at each site under investigation to analyze soil characteristics and heavy metal content. C. saviginyi and Tentyrum sp were collected across four consecutive seasons (2023–2024) to investigate enzymatic (GPT, GOT, ALP, ACP, LDH) and metabolic (lipid, protein, carbohydrate) biomarkers. The physicochemical properties of the soil differed substantially between the industrial areas and the control site. Soil heavy metal buildup was highest at industrial sites (1 and 4) compared to the control site, with the order being Zn > Cr > Cd > Cu. Heavy metal pollution indices were determined. Increased industrial activity from metal industries, ceramics, and chemical painting companies defines this area, as seen by the high Cdeg, mCd, PI, and PLI values derived for industrial sites 1 and 4. While C. saviginyi and Tentyrum sp deconcentrated and released Cr, Cd, and Zn into the soil via the biological accumulation factor (BAF), Cu acted as a macro-concentrator. Compared with the control site, industrial environments were shown to increase levels of GPT, GOT, LDH, ACP, protein, and carbohydrates in C. saviginyi. However, lipid and ALP activity was suppressed. at industrial sites, Tentyrum sp carbohydrate content was higher than at control sites, but GPT, GOT, ALP, ACP, LDH, protein, and lipid activities were all suppressed. Consequently, enzymatic and metabolic biomarkers proved to be sensitive indicators for assessing industrial heavy metal pollution in desert ecosystems.
The persistence of pharmaceutical compounds in aquatic environments and their limited removal by conventional treatment processes necessitate evaluating organism-level effects of long-term exposure using biomarkers. To determine how carbamazepine (CBZ), commonly detected in environmental waters, modulates immune and oxidative stress responses in the freshwater mussel Unio delicatus, individuals (n = 160) were exposed to sublethal CBZ concentrations for 21 and 45 days under semi-static conditions. Exposure concentrations were set at 199 µg/L (D1), 995 µg/L (D2), and 1.99 mg/L (D3), corresponding to 1
The study aimed to examine the possible impact of environmentally persistent pharmaceutical pollutants at environmentally relevant concentrations. Intriguingly, the Novel Tank Behavior Test did not reveal significant differences in anxiety-related behaviors. However, the Social Interaction Test unveiled a substantial reduction in social interaction, particularly notable in zebrafish treated with carbamazepine (CBZ). Furthermore, the Mirror Biting Behavior Test illustrated a complex picture, with CBZ inducing heightened aggression while Metformin (MET) treatment resulted in reduced aggression. The study also delved into light and dark zone preferences, revealing that CBZ-treated fish spent significantly more time in both zones, whereas MET-treated fish exhibited a preference for the dark zone. These behavioral findings were complemented by biochemical analyses, which unveiled gender-specific variations in acetylcholinesterase (AChE) activity. Males consistently exhibited increased AChE activity across all treatment groups, while females displayed unique responses, with TMP and MET-treated females showing increases and CBZ-treated females exhibiting a decrease. Additionally, Superoxide Dismutase (SOD), Catalase (CAT), and Glutathione S-Transferase (GST) activities exhibited intricate responses to pharmaceutical treatments, with variations based on gender and specific pharmaceutical agents used. While the 7-day exposure duration and environmentally relevant concentrations used in this study offer valuable insights into acute effects, future research with longer exposure durations may provide insights into chronic consequences in aquatic ecosystems.
This study presents the first integrated assessment of spatial–vertical MPs distribution, polymer degradation, and ecotoxicological risk in the upstream stretches of Thamirabarani River and Punnakayal Estuary, a biodiversity-sensitive system adjacent to the Gulf of Mannar. Triplicate samples were collected from five sites (three riverine, two estuarine) across three environmental matrices: surface water (0–20 cm), subsurface water (4 m depth), and surface sediments. MPs were detected in all samples, with highest abundance in surface water (28 ± 2 items L⁻¹), followed by subsurface water (19 ± 4 items L⁻¹) and sediments (19 ± 1 items kg⁻¹). One-way ANOVA confirmed significant vertical stratification (p < 0.05), while spatial variation across sites was not statistically significant. Fibres predominated (> 53
Chiral fungicides are commonly applied as racemic mixtures, although their enantiomers may differ in environmental behavior and biological uptake. This study investigated the enantioselective bioaccumulation of three widely used triazole fungicides—in four aquatic species representing different ecological traits. Two standardized test organisms (Danio rerio and Daphnia magna) were evaluated together with two native South American taxa (Cnesterodon decemmaculatus and Hyalella curvispina) to compare stereoselective patterns between model and regionally relevant species. Enantiomer-specific bioconcentration factors (BCFs), enantiomeric fractions (EFs), and differences between organism and water-phase stereochemical composition were jointly evaluated. Overall bioconcentration was low to moderate across all species; however, enantiomer-resolved analyses revealed species- and compound-dependent differences that were not evident from racemic assessments alone. Fish generally exhibited higher total BCF values, whereas invertebrates showed greater variability in stereoselective enrichment patterns despite lower overall accumulation. Native taxa also displayed distinct enantioselective behaviors not always mirrored by standardized species. These findings demonstrate that stereochemical discrimination may occur even under conditions of relatively limited bioaccumulation and support the inclusion of enantiomer-resolved approaches and regionally relevant organisms in comparative ecotoxicological assessments of chiral fungicides.
The current study aims to investigate the median lethal concentration (LC50 at 96 h) of lead for the female sea urchin Paracentrotus lividus. Adult urchins were exposed to six gradually increasing concentrations (0.5, 1, 2, 4, 8 and 10 mg/L) of lead for 96 h. The mortality of the urchins was directly proportional to the lead concentration, and the LC50 value at 96 h was 3.6 mg/L. Additionally, lead concentration and the bioconcentration factor (BCF) in the gonads of control sea urchins and urchins exposed to two selected concentrations (0.5 and 1 mg/L) were determined after 96 h of exposure. The results showed high levels of this metal in the gonads of P. lividus, with BCF values of 35.59 and 92.85 for the two concentrations, respectively. In addition, the effects on non-enzymatic and enzymatic biomarkers, vitellogenin (VTG), glutathione (GSH) and catalase (CAT), were evaluated at baseline (0 h), 24, 48, 72 and 96 h of exposure under laboratory conditions. The results demonstrated significant decreases in CAT activity, as well as in GSH and VTG levels, compared with those of the control. These findings suggest that acute exposure to lead can cause deleterious effects on the survival, reproductive and physiological aspects of P. lividus, which varied depending on the degree of pollution.
Copper (Cu) is a widespread aquatic contaminant, but the integrated intestinal responses of adult zebrafish to sub-chronic waterborne Cu exposure remain insufficiently characterized. Adult zebrafish (initial body weight, 0.29 ± 0.02 g; total length, 3.11 ± 0.15 cm) were exposed for 14 days to nominal Cu concentrations of 0, 0.04, 0.08, and 0.16 mg/L, and terminal growth, intestinal Cu accumulation, histopathology, and gut microbiota were evaluated. Compared with the control, terminal body weight decreased significantly in the medium- and high-exposure groups by 7.07
Both biochar and nano-zero-valent iron (nZVI) are increasingly used to remediate soils polluted with heavy metals, such as the toxic Cr(VI). However, how soil microbiomes respond to biochar and nZVI applied in Cr(VI)-contaminated soil has not yet been clarified. The current study compared the effects of bare nZVI (B-nZVI) and starch-stabilized nZVI (S-nZVI) at 100 and 1000 mg/kg on soil enzyme activity and microbial communities in Cr(VI)-contaminated soil growing mung bean amended with or without 1
Ecological risk assessments estimate chemical exposures in wildlife from contaminant concentrations within their surrounding environment. This approach precludes a detailed understanding of interactions between biota and contaminant sources. It also overlooks how the uneven and irregular use of space by animals influences variability in exposure. Here, we conducted a meta-analysis to examine whether site-specific variability in lead exposure was associated with the home range size and movement-related traits of terrestrial bird species. We constructed a series of linear models to test the effect of ecological and environmental predictors on variability in lead exposure, which we quantified using the coefficient of variation for site-specific feather lead concentrations. Accounting for variance across study, site, species, and phylogeny, we show that birds with larger home ranges exhibited more variable levels of lead exposure than those with more restricted movement patterns. This relationship was moderated by foraging niche and was significant in ground foraging birds but non-significant in generalists and arboreal-aerial foragers, which may relate to differences in dietary lead sources and niche complexity. Site-specific variability in feather lead concentrations was further structured by feather type, with contour feathers exhibiting lower variability than wing, tail, or mixed feather samples. Our findings highlight how the use of space at varying scales might influence divergent patterns of chemical exposure in terrestrial birds. We discuss how incorporating movement-related traits into wildlife risk assessments can reduce uncertainties associated with spatial variability in exposure and improve the ecological relevance of monitoring outcomes.
In natural ecosystems, aquatic organisms are intermittently exposed to a complex cocktail of contaminants. Current hazard assessments use only a continuous exposure profile for chemicals, with limited knowledge on the effects of intermittent exposures with mixtures. The study aimed to explore interactive effects of binary mixture of Hg and Cd on metal accumulation in M. edulis compared to each metal alone during intermittent exposure, using biomarkers that characterizes oxidative stress and overall physiological effects. Mytilus edulis were intermittently exposed (2 days exposure, 2 days in clean seawater) to either control (no metals), 50 µg l⁻¹ of mercury (Hg) or cadmium (Cd) alone, or a 50 µg l⁻¹ Hg plus 50 µg l⁻¹ Cd mixture for 14 days. Tissues were collected on days 0, 2, 4, 8, and 14 for metal analysis, and for biochemistry/haematology and histology at the end of the exposure. Significantly higher haemolymph Hg concentrations in Hg alone ( 280 µg l-1) than in the mixture ( 110 µg l-1), suggesting an antagonistic effect of Cd on Hg uptake. Gill Cd concentrations were higher in the mixture ( 110 µg g-1 dw) compared to Cd alone ( 70 µg g-1 dw) indicating a synergistic effect of Hg on Cd accumulation. However, across all other tissues, the sum of individual metals was not significantly different from the mixture (Student’s t-test, p > 0.05), indicating additive effects. Intermittent exposure did not induce oxidative stress (thiobarbituric acid reactive substance, TBARS, remained 2–3 nmol mg protein-1), although some glutathione depletion occurred in the Hg exposure. Histological observations of gills and digestive gland were similar across treatments, but the pathological effects were generally greater in the digestive gland from the mixture than each metal alone, with some potentially synergistic effects. Haemolymph protein (mean ± SE, mg ml⁻¹) was significantly increased in Hg alone (0.79 ± 0.13) compared to control (0.45 ± 0.13), Cd alone (0.33 ± 0.06), and the mixture (0.38 ± 0.07). Sub-lethal effects included increased haemolymph protein and digestive gland inflammation. In conclusion, the accumulation of Hg and Cd in the tissues were generally additive, although there were some metal and tissue-specific differences in biochemistry, and synergistic pathological effects in the tubules of the digestive gland.
Amphibians are among the most threatened groups of vertebrates worldwide, and the increasing release of emerging contaminants such as microplastics (MPs) and nanoparticles (NPs) poses a growing ecological risk to these organisms. This study evaluated the semi-chronic effects of polyethylene microplastics (60 mg/L) (PE-MPs) and titanium dioxide nanoparticles (10 µg/L) (TiO2 NPs), individually and in combination (Mix), on oxidative stress and detoxification biomarkers in the gills and liver of bullfrog tadpoles (Aquarana catesbeiana, in Gosner stages 25–26). Tadpoles were exposed for 15 days, and biochemical parameters (ethoxyresorufin-O-deethylase – EROD, glutathione-s-transferase - GST, superoxide dismutase - SOD, catalase - CAT, lipid peroxidation - LPO, protein carbonyls - PCO, and glucose levels) were quantified. In the gills, the Mix group significantly increased SOD and CAT activities, indicating sustained antioxidant responses associated with the formation of reactive oxygen species (ROS). In the liver, GST activity was elevated only in the Mix group, while LPO levels increased in all contaminant-exposed groups, demonstrating oxidative damage to membranes. Conversely, hepatic glucose concentrations decreased exclusively in the MP group, suggesting disturbances in energy metabolism potentially linked to contaminant bioaccumulation. Principal Coordinates Analysis (PCoA) and Integrated Biomarker Response indices (IBRv2) revealed organ-specific and treatment-dependent effects, with more pronounced biochemical alterations in the liver and stronger integrated responses in the MPs and Mix treatments. Altogether, these results demonstrate that MPs and NPs induce distinct oxidative and metabolic dysfunctions in tadpoles, with synergistic effects emerging under combined exposure. These findings highlight the importance of assessing mixtures of emerging contaminants and underscore the vulnerability of amphibian larvae to environmentally realistic pollution scenarios.
Mercury (Hg), and specifically methylmercury (MeHg), is a contaminant of global concern to humans and wildlife, but there is still limited understanding of its effects on many taxa. Amphibians are closely associated with water, where Hg is converted to MeHg, and high concentrations of MeHg can reduce survival of amphibians in the wild. However, limited non-lethal proxies exist for estimating MeHg bioaccumulation in amphibian larvae, which could be used to reduce destructive sampling and allow sampling of imperiled species. We evaluated whether tail clips were indicative of whole-body MeHg concentrations of larval amphibians, whether dragonflies were an effective bioindicator of Hg concentrations of larval amphibians, and compared MeHg bioaccumulation in predatory caudate (salamanders, newts) and non-predatory anuran (frogs, toads) larvae. Tail-clip and whole-body MeHg concentrations were strongly correlated, especially for caudates. There was high variability among sites and species, but caudates had higher MeHg than anurans, and MeHg concentrations of caudates and anurans were strongly correlated. Dragonflies were a weak indicator of MeHg for anurans but strong indicators for larval caudates, likely because caudates and dragonflies are carnivorous and occupy similar trophic positions. Our study revealed that sampling tails can be an effective non-destructive index of whole-body MeHg for larval amphibians and demonstrates differences in MeHg bioaccumulation related to trophic position in larval amphibians and dragonflies. All post-embryo life stages for a broad suite of amphibian species can now be sampled non-lethally for MeHg, allowing for a broader examination of population-level effects and focus on imperiled species that cannot be sampled destructively.
Southern Brazil is a key agricultural region in South America, where wetland ecosystems are increasingly impacted by irrigated rice cultivation. Amphibians are particularly sensitive to environmental contamination due to their permeable skin and biphasic life cycle, making them effective bioindicators of ecosystem health. This landscape forms a mosaic of croplands and natural habitats, exposing wildlife to agrochemical contamination. In this study, we evaluated erythrocyte nuclear abnormalities (NAs) in the arboreal amphibian Dendropsophus sanborni and the aquatic amphibian Pseudis minuta, both inhabiting natural and agricultural wetlands in southern Brazil. Our results revealed significantly higher frequencies of NAs in individuals from agricultural environments across all evaluated biomarkers, indicating a generalized increase in genomic instability. Both micronuclei (MN) and nuclear abnormalities excluding MN (ENAs) increased in agricultural areas, reflecting different dimensions of genotoxic stress. Pseudis minuta consistently exhibited higher frequencies of abnormalities than D. sanborni and showed stronger responses to habitat type, highlighting the role of ecological traits and exposure pathways in modulating susceptibility to contaminants. Temporal variation was observed for several biomarkers, with higher frequencies occurring during periods coinciding with the onset of agricultural activities. These findings demonstrate that agricultural intensification promotes widespread cellular damage in wetland amphibians and emphasize the importance of integrating multiple biomarkers and species with contrasting ecological traits in biomonitoring programs. Such approaches are essential to improve the detection of sublethal effects of agrochemical exposure and to support conservation strategies in agricultural landscapes.
