Bioaccumulation and enantioselectivity of type I and type II pyrethroid pesticides in earthworm

Chirality in Insecticide Design and Efficacy

Chirality plays a crucial role in the design and efficacy of insecticides, significantly influencing their biological activity, selectivity, and environmental impact. Recent advancements in chiral insecticides have focused on enhancing their effectiveness, reducing toxicity to nontarget organisms, and improving environmental sustainability. This review provides a comprehensive overview of the current state of knowledge on chiral insecticides, including neonicotinoids, isoxazolines, and sulfiliminyls. We discuss the stereochemistry, synthetic development, mode of action, and environmental fate of these compounds. The review highlights the importance of chirality in optimizing insecticidal properties and underscores the need for continued research into novel chiral compounds and advanced synthesis technologies. By understanding the role of chirality, we can develop more effective and environmentally friendly insecticides for sustainable pest management.

Earthworm lipid content and size help account for differences in pesticide bioconcentration between species

The uptake and elimination kinetics of pesticides from soil to earthworms are important in characterising the risk of pesticides to soil organisms and the risk from secondary poisoning. However, the understanding of the relative importance of chemical, soil, and species differences in determining pesticide bioconcentration into earthworms is limited. Furthermore, there is insufficient independent data in the literature to fully evaluate existing predictive bioconcentration models. We conducted kinetic uptake and elimination experiments for three contrasting earthworm species (Lumbricus terrestris, Aporrectodea caliginosa, Eisenia fetida) in five soils using a mixture of five pesticides (log Kow 1.69 - 6.63). Bioconcentration increased with pesticide hydrophobicity and decreased with soil organic matter. Bioconcentration factors were comparable between earthworm species for hydrophilic pesticides due to the similar water content of earthworm species. Inter-species variations in bioconcentration of hydrophobic pesticides were primarily accounted for by earthworm lipid content and specific surface area (SSA). Existing bioconcentration models either failed to perform well across earthworm species and for more hydrophilic compounds (log Kow < 2) or were not parameterised for a wide range of compounds and earthworm species. Refined models should incorporate earthworm properties (lipid content and SSA) to account for inter-species differences in pesticide uptake from soil.

Oxidative stress and mitochondrial damage in lambda-cyhalothrin toxicity: A comprehensive review of antioxidant mechanisms

Lambda-cyhalothrin, also known as cyhalothrin, is an efficient, broad-spectrum, quick-acting pyrethroid insecticide and acaricide and the most powerful pyrethroid insecticide in the world. However, there is increasing evidence that lambda-cyhalothrin is closely related to a variety of toxicity drawbacks (hepatotoxicity, nephrotoxicity, neurotoxicity and reproductive toxicity, among others) in non-target organisms, and oxidative stress seems to be the main mechanism of toxicity. This manuscript reviews the oxidative and mitochondrial damage induced by lambda-cyhalothrin and the signalling pathways involved in this process, indicating that oxidative stress occupies an important position in lambda-cyhalothrin toxicity. The mechanism of antioxidants to alleviate the toxicity of lambda-cyhalothrin is also discussed. In addition, the metabolites of lambda-cyhalothrin and the major metabolic enzymes involved in metabolic reactions are summarized. This review article reveals a key mechanism of lambda-cyhalothrin toxicity-oxidative damage and suggests that the use of antioxidants seems to be an effective method for preventing toxicity.

Systematic assessment of cyflumetofen toxicity in soil-earthworm (Eisenia fetida) microcosms

Cyflumetofen was widely applied in agriculture with its excellent acaricidal effect. However, the impact of cyflumetofen on the soil non-target organism earthworm (Eisenia fetida) is unclear. This study aimed to elucidate the bioaccumulation of cyflumetofen in soil-earthworm systems and the ecotoxicity of earthworms. The highest concentration of cyflumetofen enriched by earthworms was found on the 7th day. Long-term exposure of earthworms to the cyflumetofen (10 mg/kg) could suppress protein content and increases Malondialdehyde content leading to severe peroxidation. Transcriptome sequencing analysis demonstrated that catalase and superoxide-dismutase activities were significantly activated while genes involved in related signaling pathways were significantly upregulated. In terms of detoxification metabolic pathways, high concentrations of cyflumetofen stimulated the number of Differentially-Expressed-Genes involved in the detoxification pathway of the metabolism of glutathione. Identification of three detoxification genes (LOC100376457, LOC114329378, and JGIBGZA-33J12) had synergistic detoxification. Additionally, cyflumetofen promoted disease-related signaling pathways leading to higher disease risk, affecting the transmembrane capacity and cell membrane composition, ultimately causing cytotoxicity. Superoxide-Dismutase in oxidative stress enzyme activity contributed more to detoxification. Carboxylesterase and glutathione-S-transferase activation play a major detoxification role in high-concentration treatment. Altogether, these results contribute to a better understanding of toxicity and defense mechanisms involved in long-term cyflumetofen exposure in earthworms.

Biomonitoring of organic pollutants in pet dog plasma samples in North-Western Spain

Most of organic pollutants (OPs) have the ability to interfere with biological systems causing negative effects in living beings, including humans. In the last decades, pets have been used as bioindicators of human exposure because they share the same habitat with their homeowners. We sought to determine levels of approximately 70 OPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated biphenyl ethers (PBDEs), organophosphate pesticides (OPPs), polycyclic aromatic hydrocarbons (PAHs) and pyrethroids (PYRs) in plasma samples from 39 pet dogs from Ourense (north-western Spain). The results revealed that PAHs were the dominant OPs (mean value 175 ± 319 ng/g lipid weight (lw)), followed by PYRs (132 ± 352 ng/g lw), PCBs (122 ± 96 ng/g lw), OCPs (33 ± 17 ng/g lw), PBDEs (19 ± 18 ng/g lw) and OPPs (2.1 ± 2.7 ng/g lw) in plasma samples. We have previously detected the target OPs in hair samples of pets, collected simultaneously and similar trend of some OPs has been observed. Moreover, pyrene and chrysene showed correlations between levels detected in both matrices.

Organophosphate Pesticides and Pyrethroids in Farmland of the Pearl River Delta, China: Regional Residue, Distributions and Risks

A regional-scale survey was conducted to assess the occurrence, distribution, and risk of two extensively used pesticides (organophosphate pesticides and pyrethroids) in agricultural soils from the Pearl River Delta (PRD), South China. All target organophosphate pesticides (OPPs) and pyrethroids (PYs) were detected in the soil samples and both with a detection rate of 100%. The residues of the sum of six OPPs and the sum of four PYs were in the range of LOD-991 ng/g and 8.76-2810 ng/g, respectively. Dimethoate was the dominant OPPs, and fenpropathrin was the predominant PYs in the soils of the PRD region. With intensive agricultural activities, higher residues of OPPs and PYs in soils were detected closer to the seaside, among which Zhuhai city and Huizhou city suffered more serious combined pesticide pollution. The vertical compositional profiles showed that dimethoate could be detected through each soil layer in the PRD region's nine cities. The human exposure estimation of OPPs showed insignificant risks to the local population. In contrast, cypermethrin and fenpropathrin showed a potential ecological risk of 2.5% and 3.75% of the sampling sites, respectively. These results can facilitate those commonly used pesticide controls and promote sustainable soil management.

Bacterial remediation of pesticide polluted soils: Exploring the feasibility of site restoration

For decades, reclamation of pesticide contaminated sites has been a challenging avenue. Due to increasing agricultural demand, the application of synthetic pesticides could not be controlled in its usage, and it has now adversely impacted the soil, water, and associated ecosystems posing adverse effects on human health. Agricultural soil and pesticide manufacturing sites, in particular, are one of the most contaminated due to direct exposure. Among various strategies for soil reclamation, ecofriendly microbial bioremediation suffers inherent challenges for large scale field application as interaction of microbes with the polluted soil varies greatly under climatic conditions. Methodically, starting from functional or genomic screening, enrichment isolation; functional pathway mapping, production of tensioactive metabolites for increasing the bioavailability and bio-accessibility, employing genetic engineering strategies for modifications in existing catabolic genes to enhance the degradation activity; each step-in degradation study has challenges and prospects which can be addressed for successful application. The present review critically examines the methodical challenges addressing the feasibility for restoring and reclaiming pesticide contaminated sites along with the ecotoxicological risk assessments. Overall, it highlights the need to fine-tune the available processes and employ interdisciplinary approaches to make microbe assisted bioremediation as the method of choice for reclamation of pesticide contaminated sites.

Enantiomer-Specific Study of Fenpropathrin in Soil-Earthworm Microcosms: Enantioselective Bioactivity, Bioaccumulation, and Toxicity

In this study, the enantiomer-specific bioactivity, bioaccumulation, and toxicity of fenpropathrin (FEN) enantiomers were investigated in soil-earthworm microcosms. The bioactivity order was S-FEN > rac-FEN > R-FEN for Spodoptera litura and Conogethes punctiferalis. Moreover, S-FEN was 12.0 and 32.2 times more toxic than rac-FEN and R-FEN to earthworms, respectively. S-FEN degraded faster than R-FEN with the enrichment of R-FEN in the soil environment. Furthermore, the peak-shaped accumulation curves for FEN enantiomers were observed, and R-FEN was preferentially bioaccumulated by earthworms. As compared to R-FEN, S-FEN induced greater changes in the activities of detoxification enzymes, antioxidant enzymes, and malondialdehyde content, which suggested that earthworms exhibited enantioselective defense responses to S-FEN and R-FEN. Integrated biomarker response results indicated that S-FEN exhibited higher toxic effects on earthworms than R-FEN. Finally, molecular simulation revealed that the greater interaction forces between S-FEN and sodium channel protein could be the primary reason for the enantioselective bioactivity and toxicity of FEN enantiomers. This study comprehensively highlights the enantiomer-specific bioactivity, bioaccumulation, toxicity, and mechanism of FEN in soil-earthworm microcosms at the enantiomer level. Our findings will contribute to a better risk assessment of FEN in the soil ecosystem.

Multi-walled carbon nanotubes impact on the enantioselective bioaccumulation and toxicity of the chiral insecticide bifenthrin to zebrafish (Danio rerio)

The effects of different multi-walled carbon nanotubes on the enantioselective bioaccumulation and toxicity of the chiral pesticide bifenthrin to zebrafish were investigated in this work. The results showed that MWCNTs and MWCNTs-COOH did not affect the preferential bioaccumulation of 1R-cis-BF in zebrafish following exposure to cis-BF enantiomers for 28 days, but which increased cis-BF accumulation amount by 1.03-1.48 times. Further research demonstrated that the genes related to immunity, endocrine activity and neurotoxicity showed enantioselective expression in different zebrafish tissues, and sex-specific differences were observed. The levels of c-fos, th, syn2a, 17β-hsd and cc-chem were expressed as 1.09-2.84 times higher in females and males treated with 1R-cis-BF than in the 1S-cis-BF-treated groups. However, in the presence of MWCNTs or MWCNTs-COOH, c-fos, th, syn2a, 17β-hsd and cc-chem levels were expressed as 1.53-14.92 times higher in females and males treated with 1S-cis-BF than in 1R-cis-BF-treated groups, which indicated that enantioselective expression was altered. The effects of different types of MWCNTs on the enantioselective bioaccumulation and toxicity of BF in zebrafish have little difference. In summary, the presence of MWCNTs or MWCNTs-COOH increased the impact of BF on zebrafish. Therefore, the risks posed by coexisting nanomaterials and chiral pesticides in aquatic environments should be considered.

Effects of biochar on the fate of conazole fungicides in soils and their bioavailability to earthworms and plants

The study showed novel findings about changes in the fate and bioavailability of conazole fungicides (CFs) after biochar (BC) addition to soil. Two contrasting soils (low- and high-sorbing of CF; L soils, H soils) were amended by three BCs (low-, moderate-, and high-sorbing of CF; L-BC, M-BC, H-BC) at 0.2% and 2% doses. Epoxiconazole (EPC) and tebuconazole (TBC) were then added to the soil-BC mixtures, and their degradation, bioaccumulation in earthworms (Eisenia andrei), and bioconcentration in lettuce (Lactuca sativa) were studied for three months. Also, stir bar sorptive extraction (SBSE) was performed to determine CF (bio)accessibility. The EPC and TBC degradation in the soil-BC mixtures followed usually the first-order decay kinetics. The BC addition prevalently decreased the pesticides degradation in the L soil mixtures but often increased it in the H soil mixtures. In general, EPC degraded less than TBC. BC type and dose roles in the pesticides degradation were unclear. The BC addition significantly reduced pesticide uptake to the earthworms in the L soil mixtures (by 37-96%) and in the H soil mixtures (by 6-89%) with 2% BC. The BC addition reduced pesticide uptake to the lettuce roots and leaves significantly-up to two orders of magnitude, and this reduction was strong in H soil mixtures at 2% of BC. The BC addition reduced the CF (bio)accessibility measured by SBSE in all L soil mixtures and some H soil mixtures with 2% BC. Although not significant, it also seems that the pesticide bioaccumulation, bioconcentration, and (bio)accessibility were decreasing according to the BC type (L-BC > M-BC > H-BC). The pesticide concentrations in the earthworms and lettuce correlated significantly to the SBSE results, which indicates this technique as a possible predictor of biotic uptake. Our results showed that the interactions were hard to predict in the complex soil-BC-pesticide system.

Expression, Characterization, Fermentation, Immobilization, and Application of a Novel Esterase Est804 From Metagenomic Library in Pesticide Degradation

Esterase, as a type of powerful catabolic enzyme for the degradation of pyrethroid pesticides (PYRs), appears promising in improving the quality of crops and the environment contaminated by pesticide residues. The purpose of this research is to provide a detailed introduction to the enzymatic properties, optimal production and immobilization conditions, and the degradation ability of Est804 for PYRs. The study on enzymatic properties indicated that Est804 was an alkaline esterase with an optimal pH of 8.0 and a broad optimal temperature in the range of 35-50°C. The optimal activity of free Est804 was calculated to be 112.812 U, and the specific enzyme activity was 48.97 U/mg. The kinetic parameters of Est804 were K _m = 0.613 mM, k _cat = 12,371 s^-1, and V _m = 0.095 mM/min. The results of the fermentative optimization demonstrated that the optimal conditions included 1.5% of inoculation amount, 30 mL of liquid volume, 28°C of the fermentation temperature, and 18 h of the fermentation time. The optimal medium consists of 15.87 g of yeast powder, 8.00 g of glycerol, and 9.57 g of tryptone in 1 L of liquid. The optimized enzyme activity was 1.68-fold higher than that before optimization. Immobilized Est804 exhibited the highest activity under the optimum preparation conditions, including 0.35 g of chitosan dosage, 0.4 mL of an enzyme, and 4 h at 40°C for adsorption. The degradation rates of Cypermethrin (CYP), fenpropathrin (FE), and lambda-cyhalothrin (LCT) by Est804 within 30 min were 77.35%, 84.73%, and 74.16%, respectively. The present study indicated that Est804 possesses great potential for the treatment of pesticide residues on crops and environmental remediation, conducive to the development of SGNH family esterase against pyrethroid accumulation.

Conazole fungicides epoxiconazole and tebuconazole in biochar amended soils: Degradation and bioaccumulation in earthworms

Biochar usage in agriculture becomes increasingly important for the improvement of soil properties. However, from the perspective of pesticides, biochar can influence exposure to pesticides of both target and non-target organisms and also pesticides' fate in soil. Our study investigated degradation and bioaccumulation (in the Eisenia andrei earthworm) of two conazole fungicides, epoxiconazole and tebuconazole, added to high- and low-sorbing soils (by means of fungicides' sorption measured beforehand) amended with low-, moderate- and high-sorbing biochars at 0.2% and 2% doses. We aimed to investigate the effects of contrasting soil and biochar properties, different doses of biochar in soil-biochar mixtures, and different compounds on the degradation and bioaccumulation. We also wanted to explore if the beforehand determined sorption of fungicides on individual soils and biochars is manifested somehow in their degradation and/or bioaccumulation in soil-biochar mixtures. The biochars' presence in the soils promoted the degradation of fungicides with a clear effect of dose and soil, but less clear effect of biochar or compound. The bioaccumulation factors were higher in low-sorbing soil variants and also decreased with increasing biochar dose. For low-sorbing soil variants, the bioaccumulation was also influenced by the type of biochar corresponding to its sorbing potential and the possible effect on the bioavailability of the fungicides. Our results show that mixing of biochars with soils changes the fate and bioaccumulation of the conazole fungicides. However, the sorption results from original materials are not straightforwardly manifested in the more complex soil-biota system.

Naringenin Attenuates Toxicity and Oxidative Stress Induced by Lambda-cyhalothrin in Liver of Male Rats

BACKGROUND AND OBJECTIVES

Extensive use of Lambda-cyhalothrin (LTC), a synthetic pyrethroid insecticide, has been associated with serious health problems to the non-target organisms including mammals. The present study investigated the protective effect of naringenin (NGN), an antioxidant flavonoid, against the toxicity induced LTC in the liver of male rats.

MATERIALS AND METHODS

Five groups of rats were assigned as follows; control group, LTC group (6.12 mg kg-1, 1/10 LD50), LTC-NGN group (6.12 mg kg-1 LTC and 50 mg kg-1 NGN), NGN-LTC group (50 mg kg-1 NGN and 6.12 mg kg-1 LTC) and NGN group (50 mg kg-1). Doses were administrated orally for 21 consecutive days.

RESULTS

Administration of LTC induced liver damage as indicated by the increase in the activities of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase and in the level of total bilirubin in serum. LTC also induced a significant elevation in the levels of serum total lipids, total cholesterol, triglycerides and low-density lipoproteins while high-density lipoproteins decreased. Furthermore, LTC significantly disturbed the oxidant/antioxidant balance in the liver as shown by the elevation in lipid peroxidation, lipid hydroperoxides, protein carbonyl content and conjugated dienes with a concomitant inhibition in the major antioxidants such as reduced glutathione and the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase. Both post-treatment and pre-treatment with NGN significantly modulated the LTC-induced hepatotoxicity and oxidative stress in rat's liver and pretreatment was found to be more effective in improving most of the studied parameters in both serum and liver tissue.

CONCLUSION

NGN could be used as a safe dietary supplement to protect against the toxicity and oxidative stress associated with the use of LTC.

Pyrethroid bioaccumulation in field-collected insecticide-resistant Hyalella azteca

Wild-type Hyalella azteca are highly sensitive to pyrethroid insecticides and typically do not survive exposure; however, pyrethroid bioaccumulation by insecticide-resistant H. azteca is an important potential risk factor for the transfer of pyrethroids to higher trophic species in aquatic systems. In the current study, four populations of pyrethroid-resistant H. azteca with corresponding sediment samples were sampled throughout the year, and nine-current use pyrethroids (tefluthrin, fenpropathrin, bifenthrin, cyhalothrin, permethrin, cyfluthrin, cypermethrin, esfenvalerate and deltamethrin) were measured. Bifenthrin was detected in every pyrethroid-resistant H. azteca tissue sample, up to 813 ng/g lipid, while cyhalothrin and permethrin were detected in fewer (18 and 28%, respectively) samples. Concurrent sampling of the sediment showed total pyrethroid concentrations exceeding toxic unit thresholds for non-resistant H. azteca survival, and confirmed the ubiquitous presence of bifenthrin at each site and sampling event. Bifenthrin concentrations in H. azteca tended to be higher in samples collected in winter months, and seasonal factors, such as temperature and rainfall, may have contributed to the noted differences in bioaccumulation. Finally, the bifenthrin and permethrin biota-sediment accumulation factors (BSAF) for pyrethroid-resistant H. azteca were similar to the BSAF values for less sensitive invertebrates, and therefore the development of resistance may enable an additional pathway for trophic transfer of pyrethroids in species that would otherwise be too sensitive to survive the exposure.

Non-invasive biomonitoring of organic pollutants using feather samples in feral pigeons (Columba livia domestica)

A large portion of organic pollutants (OPs) represent a potential hazard to humans and living beings due to their toxic properties. For several years, birds have been used as biomonitor species of environmental pollution. Polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated biphenyl ethers (PBDEs), organophosphate pesticides (OPPs), polycyclic aromatic hydrocarbons (PAHs) and pyrethroids (PYRs) were assessed in body feather samples of 71 feral pigeons (Columba livia domestica) collected from Asturias and Galicia (NW Spain). The percentage of detection for all chemical groups were above 90% in studied birds. The general pattern was dominated by PAHs (mean value ± standard deviation (SD) 32 ± 15 ng/g) followed by OCPs (3.8 ± 1.1 ng/g), PYRs (3.4 ± 3.8 ng/g), PCBs (1.6 ± 1.0 ng/g), OPPs (1.3 ± 0.70 ng/g) and PBDEs (0.80 ± 0.30 ng/g). Significant differences were observed between age, location and gender suggesting different sources of exposure and accumulation pathways.

Soil dissipation and bioavailability to earthworms of two fungicides under laboratory and field conditions

The representativeness of laboratory studies of the fate of pesticides in soil in field conditions is questionable. This study aimed at comparing the dissipation and bioavailability to earthworms of two fungicides, dimoxystrobin (DMX) and epoxiconazole (EPX), over 12 months under laboratory and field conditions. In both approaches, the fungicides were applied to the same loamy soil as a formulated mixture at several concentrations. We determined total DMX and EPX concentrations in the soil using exhaustive extraction, their environmental availability using mild extraction and their bioavailability through internal concentrations in exposed earthworms. The initial fungicide application appeared as much better controlled in terms of dose and homogeneity in the laboratory than in the field. One year after application, a similar dissipation rate was observed between the laboratory and field experiments (ca 80% and 60% for DMX and EPX, respectively). Similarly, the ratio of available/total concentrations in soil displayed the same trend whatever the duration and the conditions (field or lab), EPX being more available than DMX. Finally, the environmental bioavailability of the two fungicides to earthworms was heterogeneous in the field, but, in the laboratory, the bioaccumulation was evidenced to be dose-dependent only for DMX. Our findings suggest that the actual fate of the two considered fungicides in the environment is consistent with the one determined in the laboratory, although the conditions differed (e.g., presence of vegetation, endogeic earthworm species). This study allowed better understanding of the fate of the two considered active substances in the soil and underlined the need for more research dedicated to the link between environmental and toxicological bioavailability.

Behavior of imidazolinone herbicide enantiomers in earthworm-soil microcosms: Degradation and bioaccumulation

Imidazolinone herbicides are a group of chiral herbicides that are widely used to control weeds in crops. Despite their wide use, few studies on the behavior of enantiomers in terrestrial systems have been reported. In this study, the bioaccumulation of imazamox, imazapic, and imazethapyr enantiomers in earthworm and their degradation in soils were assessed using earthworm-soil microcosms. The bioaccumulation of the three herbicides in earthworm was not significantly enantioselective. Imazamox and imazethapyr did not significant stereoselective degradation in soil (p > 0.05), while the enantioselectivity of the degradation of imazapic was significant (p < 0.05). Furthermore, biota to soil accumulation factor (BSAF) values were also calculated for three herbicides. Relationships between BSAF values and organic matter content of soil and log K_OW of herbicides were investigated. The BSAFs values were negatively correlated with the log K_OW of herbicides, and were positively correlated with organic matter content of soil in earthworm-soil microcosms. These relationships indicated that chemical hydrophobicity (K_ow) and organic matter content of soil were good predictors to estimate the bioavailability of imidazolinone herbicides to earthworm.

Enantioselective degradation of chiral fungicides triticonazole and prothioconazole in soils and their enantioselective accumulation in earthworms Eisenia fetida

Triticonazole and prothioconazole are widely used systemic agricultural triazole fungicides both with a chiral center. In this work, the enantioselective degradation of triticonazole and prothioconazole in three types of soils were investigated under native conditions using reversed phase liquid chromatography-tandem mass spectrometry with a Chiralcel OD-RH column. The results indicated that the enantioselective degradation was observed with S-triticonazole and R-prothioconazole preferentially degraded and the degradation rate was fast with a half-life within 6 days. It was also found that the presence of earthworms can accelerate the degradation and further enhance degradation enantioselectivity of triticonazole and prothioconazole in soils. Moreover, the enantioselective of triticonazole and prothioconazole in earthworms were studied. The results showed that the bioaccumulation was enantioselective with R-triticonazole and S-prothioconazole preferentially accumulated, which was similar to the soil. Our findings suggest that the enantioselective toxicity and potential effects of the metabolites should be considered for more accurate assessment of ecological risks of triticonazole and prothioconazole to target and non-target species.

Insight Into Microbial Applications for the Biodegradation of Pyrethroid Insecticides

Pyrethroids are broad-spectrum insecticides and presence of chiral carbon differentiates among various forms of pyrethroids. Microbial approaches have emerged as a popular solution to counter pyrethroid toxicity to marine life and mammals. Bacterial and fungal strains can effectively degrade pyrethroids into non-toxic compounds. Different strains of bacteria and fungi such as Bacillus spp., Raoultella ornithinolytica, Psudomonas flourescens, Brevibacterium sp., Acinetobactor sp., Aspergillus sp., Candida sp., Trichoderma sp., and Candia spp., are used for the biodegradation of pyrethroids. Hydrolysis of ester bond by enzyme esterase/carboxyl esterase is the initial step in pyrethroid biodegradation. Esterase is found in bacteria, fungi, insect and mammalian liver microsome cells that indicates its hydrolysis ability in living cells. Biodegradation pattern and detected metabolites reveal microbial consumption of pyrethroids as carbon and nitrogen source. In this review, we aim to explore pyrethroid degrading strains, enzymes and metabolites produced by microbial strains. This review paper covers in-depth knowledge of pyrethroids and recommends possible solutions to minimize their environmental toxicity.

Enantioselective Distribution, Degradation, and Metabolite Formation of Myclobutanil and Transcriptional Responses of Metabolic-Related Genes in Rats

Myclobutanil (MT), a chiral fungicide, can be metabolized enantioselectively in organisms. In this work, the associated absorption, distribution, metabolism and transcriptional responses of MT in rats were determined following a single-dose (10 mg·kg^-1 body weight) exposure to rac-, (+)- or (-)-MT. The enantiomer fractions (EFs) were less than 0.5 with time in the liver, kidney, heart, lung, and testis, suggesting preferential enrichment of (-)-MT in these tissues. Furthermore, there was conversion of (+)-form to (-)-form in the liver and kidney after 6 h exposure to enantiopure (+)-MT. Enrichment and degradation of the two enantiomers differed between rac-MT and MT-enantiomers groups, suggesting that MT bioaccumulation is enantiomer-specific. Interestingly, the degradation half-life of MT in the liver with rac-MT treatment was shorter than that with both MT-enantiomer treatments. One reason may be that the gene expression levels of cytochrome P450 1a2 ( cyp1a2) and cyp3a2 genes in livers treated with rac-MT were the highest among the three exposure groups. In addition, a positive correlation between the expression of cyp2e1 and cyp3a2 genes and rac-MT concentration was found in livers exposed to rac-MT. Simultaneously, five chiral metabolites were detected, and the enantiomers of three metabolites, RH-9090, RH-9089, and M2, were separated. The detected enantiomers of (+)-MT metabolites were in complete contrast with those of (-)-MT metabolites. According to the results, a metabolic pathway of MT in male rats was proposed, which included the following five metabolites: RH-9089, RH-9090, RH-9090 Sulfate, M1, and M2. The possible metabolic enzymes were marked in the pathway. The findings of this study provide more specific insights into the enantioselective metabolic mechanism of chiral triazole fungicides.

Toxic effects of Lambda-cyhalothrin, on the rat thyroid: Involvement of oxidative stress and ameliorative effect of ginger extract

•

Lambda-cyhalothrin leads to histpathological changes and DNA damage in thyroid gland.

•

Lambda-cyhalothrin induces oxidative stress by decreasing the levels of thyroid hormones and antioxidant enzyme in erythrocytes.

•

Ginger prevents the toxicity effect of Lambda-cyhalothrin and DNA damage in the thyroid gland.

•

Ginger decreases the histopathological changes, abnormal level of thyroid hormones and antioxidant enzymes in the thyroid gland caused by LCT.

Lambda-cyhalothrin (LCT) is a synthetic pyrethroid that is widely used to control insecticide. Ginger is a traditional plant that is widely used as a spice or folk medicine. This study evaluates the antioxidant effect of ginger extract on thyroid toxicity induced by LCT in albino rats. Adult Rats were divided into 4 experimental groups: Group 1: control, Group 2: oral ginger treatment (24 mg/ml, 3 days/week for 4 weeks), Group 3: oral LCT treatment (1/100 LD₅₀, 3 days/week for 4 weeks), Group 4: oral LCT and ginger mixture treatment. The histological results of LCT group showed degenerated follicles with reduced colloids, congestion of blood vessels and hyperaemia between the follicles. Histochemically, depletion of glycogen and proteins was recorded in follicular cells and colloids. The biochemical results of LCT treated group revealed a decrease in T3, T4, SOD and CAT, while TSH and MDA were increased. The comet assay showed that LCT significantly induced DNA damage in the thyroid gland. However, treating rats with LCT plus ginger led to an improvement in the histological structure of the thyroid, with noticeable increases in glycogen and protein deposition. Also, LCT plus ginger increase in T3, T4 and the antioxidant enzymes SOD and COT were detected concomitantly with a decrease in TSH and MDA as well as a significant reduction in DNA damage. LCT affected the thyroid function and structure. On the other hand, ginger has a preventative effect against the histological damage and biochemical toxicity caused by the (LCT) insecticide.

Uptake kinetics of pesticides chlorpyrifos and tebuconazole in the earthworm Eisenia andrei in two different soils

Agriculture is today indispensably connected with enormous use of pesticides. Despite tough regulation, their entrance into soil cannot be excluded and they might enter soil organisms and plants and continue further to terrestrial food chains. This study was conducted to investigate the bioaccumulation of two pesticides currently used in large amounts, the insecticide chlorpyrifos (CLP) and the fungicide tebuconazole (TBZ). Their detailed uptake kinetics in the model earthworm species Eisenia andrei were measured in two arable soils differing in organic carbon content (1.02 and 1.93% respectively). According to our results, a steady state was reached after 3-5 days for both pesticides and soils. The values of bioaccumulation factors calculated at the steady state ranged from 4.5 to 6.3 for CLP and 2.2-13.1 for TBZ. Bioaccumulation factors were also calculated as the ratio of uptake and elimination rate constants with results comparable with steady-state bioaccumulation factors. The results suggested that the degradation and bioaccumulation of tested compounds might be influenced by other factors than only total organic carbon (e.g. clay content). The lower K_oc and hydrophobicity of TBZ relative to CLP probably led to higher availability of TBZ through pore water exposure. On the other hand, CLP's higher hydrophobicity probably caused an increase in availability by its additional uptake via ingestion. To enable a proper ecological risk assessment of current pesticides in soils, it is necessary to accurately determine their bioaccumulation in soil invertebrates. We believe that our study not only brings such information for two specific pesticides but also addresses key methodological issues in this area.

Stereoselective degradation and thyroid endocrine disruption of lambda-cyhalothrin in lizards (Eremias argus) following oral exposure

The disturbance of the thyroid system and elimination of chiral pyrethroid pesticides with respect to enantioselectivity in reptiles have so far received limited attention by research. In this study, bioaccumulation, thyroid gland lesions, thyroid hormone levels, and hypothalamus-pituitary-thyroid axis-related gene expression in male Eremias argus were investigated after three weeks oral administration of lambda-cyhalothrin (LCT) enantiomers. In the lizard liver, the concentration of LCT was negatively correlated with the metabolite-3-phenoxybenzoic acid (PBA) level during 21 days of exposure. (+)-LCT exposure induced a higher thyroid follicular epithelium height than (-)-LCT exposure. The thyroxine levels were increased in both treated groups while only (+)-LCT exposure induced a significant change in the triiodothyronine (T3) level. In addition, the expressions of hypothalamus-pituitary-thyroid axis-related genes including thyroid hormone receptors (trs), deiodinases (dios), uridinediphosphate glucuronosyltransferase (udp), and sulfotransferase (sult) were up-regulated after exposure to the two enantiomers. (+)-LCT treatment resulted in higher expression of trs and (-)-LCT exposure led to greater stimulation of dios in the liver, which indicated PBA-induced antagonism on thyroid hormone receptors and LCT-induced disruption of thyroxine (T4) deiodination. The results suggest the (-)-LCT exposure causes higher residual level in lizard liver while induces less disruption on lizard thyroid activity than (+)-LCT.

Enantiomeric separation of type I and type II pyrethroid insecticides with different chiral stationary phases by reversed-phase high-performance liquid chromatography

The enantiomeric separation of type I (bifenthrin, BF) and type II (lambda-cyhalothrin, LCT) pyrethroid insecticides on Lux Cellulose-1, Lux Cellulose-3, and Chiralpak IC chiral columns was investigated by reversed-phase high-performance liquid chromatography. Methanol/water or acetonitrile/water was used as mobile phase at a flow rate of 0.8 mL/min. The effects of chiral stationary phase, mobile phase composition, column temperature, and thermodynamic parameters on enantiomer separation were carefully studied. Bifenthrin got a partial separation on Lux Cellulose-1 column and baseline separation on Lux Cellulose-3 column, while LCT enantiomers could be completely separated on both Lux Cellulose-1 and Lux Cellulose-3 columns. Chiralpak IC provided no separation ability for both BF and LCT. Retention factor (k) and selectivity factor (α) decreased with the column temperature increasing from 10°C to 40°C for both BF and LCT enantiomers. Thermodynamic parameters including ∆H and ∆S were also calculated, and the maximum R_s were not always obtained at lowest temperature. Furthermore, the quantitative analysis methods for BF and LCT enantiomers in soil and water were also established. Such results provide a new approach for pyrethroid separation under reversed-phase condition and contribute to environmental risk assessment of pyrethroids at enantiomer level.

Degradation Processes of Pesticides Used in Potato Cultivations

Potato is one of the most important crops, after maize, rice and wheat. Its global production is about 300 million tons per year and is constantly increasing. It grows in temperate climate and is used as a source of starch, food, and in breeding industry.Potato cultivation requires application of numerous agro-technical products, including pesticides, since it can be affected by insects, weeds, fungi, and viruses. In the European Union the most frequently used pesticides in potato cultivations check are: thiamethoxam, lambda-cyhalothrin and deltamethrin (insecticides), rimsulfuron (herbicide) and metalaxyl (fungicide).Application of pesticides improves crop efficiency, however, as pesticides are not totally selective, it affects also non-target organisms. Moreover, the agrochemicals may accumulate in crops and, as a consequence, negatively influence the quality of food products and consumer health. Additional risks of plant protection products are related to their derivatives, that are created both in the environment (soil, water) and in plant organisms, since many of these compounds may exhibit toxic effects.This article is devoted to the degradation processes of pesticides used in potato crop protection. Attention is also paid to the toxicity of both parent compounds and their degradation products for living organisms, including humans. Information about the level of pesticide contamination in the environment (water, soil) and accumulation level in edible plants complement the current knowledge about the risks associated with widespread use of thiamethoxam, lambda-cyhalothrin and deltamethrin, rimsulfuron and metalaxyl in potato cultivation.

Tissue distribution, metabolism and hepatic tissue injury in Chinese lizards (Eremias argus) after a single oral administration of lambda-cyhalothrin

Lambda-cyhalothrin (LCT) is a widely used pyrethroid with neurotoxicity. However, little is known about the toxicokinetics of LCT in reptiles. In this study, the absorption, distribution, metabolism and excretion of LCT in Chinese lizards (Eremias Argus) were determined following a single dose (10 mg kg^-1) treatment. In the liver, brain, gonads and skin, LCT levels peaked within several hours and then decreased rapidly. However, the concentration of LCT gradually increased in the fat tissue. More than 90% of the LCT dose was excreted in the faeces. One LCT metabolite, 3-phenoxybenzoic acid (PBA), was detected in lizard plasma and tissues. PBA preferentially accumulates in the brain and plasma. The half-life of PBA in the brain was 3.2 days, which was 35.4-fold greater than that of LCT. In the plasma, the concentration of PBA was significantly higher than that of LCT. The bioaccumulation of LCT in tissues was enantioselective, and the enantiomeric fractions (EF) ranged from 0.72 to 0.26. The preferential accumulation of enantiomers changed according to exposure time, but the reasons behind this phenomenon were not clear. For pathological analysis, vacuolation of the cytoplasm and large areas of necrosis were observed in the liver sections after 168 h of dosing. The liver tissues exhibited both decreases in the hepatosomatic index and histopathological lesions during the exposure period. In this study, the effect concentration of LCT in lizards was 200-fold lower than its LD₅₀ value used in risk assessments for birds. These results may provide additional information for the risk assessment of LCT for reptiles and indicate that birds may not be an ideal surrogate for reptile toxicity evaluation.