Effects of soil acidification on the toxicity of organophosphorus pesticide on Eisenia fetida and its mechanism

Introducing high-performance star-shaped bimetallic nanotags into SERS aptasensor: An ultrasensitive and interference-free method for chlorpyrifos detection

Implementation of cost-effective, reliable, and efficient technologies for the sensitive, rapid, and accurate detection of pesticide residues in agriproducts presents a promising solution to the escalating food safety concerns. Herein, a high-performance surface-enhanced Raman scattering (SERS) aptasensor based on nanotag (AuNS@4-MBN@Ag-aptamer) was introduced for ultrasensitive, reliable, and interference-free detection of chlorpyrifos (CPF). This aptasensor featured star-shaped bimetallic nanotag as the principal Raman signal enhancement material and 4-mercaptobenzonitrile (4-MBN) as "biological-silent"-window reporter (at 2228 cm-1). Moreover, cDNA-linked Fe3O4@AuNPs (FA-cDNA) served as magnetic substrates to simplify the separation process of FA-cDNA-combined nanotags. In the aptasensor, the formation of FA-cDNA-aptamer-AuNS@4-MBN@Ag hybrids was hindered by CPF, and its Raman intensity decreased with increasing CPF concentration. Under optimal SERS conditions, the aptasensor exhibited a broad linear detection range from 2.5 × 102 to 5.0 × 104 pg⋅mL-1, with an impressively low limit of detection of 220.35 pg⋅mL-1 (signal-to-noise ratio = 3). The selectivity and reproducibility assessments highlighted its exceptional sensitivity and interference-free capabilities. Furthermore, practical applications on wheat and apples demonstrated satisfactory spiked recovery rates, ranging from 89.61% to 107.33% (relative standard deviation ≤ 14.55%). Consequently, the high-performance "biological-silent"-window nanotag-based aptasensor is a promising tool for monitoring trace CPF in complex matrices.

The interplay between temperature and an insecticide mixture modulates the stimulatory response of sublethally exposed Myzus persicae

Temperature can interact with chemical pesticides and modulate their toxicity. Sublethal exposure to pesticides is known to trigger hormetic responses in pests. However, the simultaneous effects of temperature and sublethal exposure to single or mixture-based insecticides on the insects' stimulatory responses are not frequently considered in toxicological studies. Here we investigated the combined effects of temperature on the lethal and sublethal responses of the green peach aphid Myzus persicae after exposure to commercial formulations of a neonicotinoid (thiamethoxam) and a pyrethroid (lambda-cyhalothrin) and their mixture. Firstly, the concentration-response curves of the insecticides were determined under four temperatures (15 °C, 20 °C, 25 °C, and 28 °C) by the leaf dipping method. Subsequently, the sublethal concentrations C0, CL1, CL5, CL10, CL15, CL20, and CL30 were selected to assess sublethal effects on aphids' longevity and reproduction under the same temperatures. The results showed that the mixture of thiamethoxam + lambda-cyhalothrin caused greater toxicity to aphids compared to the formulations with each active ingredient alone and that the toxicity was higher at elevated temperatures. Furthermore, the exposure to low concentrations of the mixture (thiamethoxam + lambda-cyhalothrin) and the separated insecticides induced stimulatory responses in the longevity and fecundity of exposed aphid females, but the occurrence of such hormetic responses depended on the insecticide type, its sublethal concentration, and the temperature as well as their interactions.

Determination of the binding affinities of OPEs to integrin αvβ3 and elucidation of the underlying mechanisms via a competitive binding assay, pharmacophore modeling, molecular docking and QSAR modeling

Organophosphate esters (OPEs) can cause adverse biological effects through binding to integrin αvβ3. However, few studies have focused on the binding activity and mechanism of OPEs to integrin αvβ3. Herein, a comprehensive investigation of the mechanisms by which OPEs bind to integrin αvβ3 and determination of the binding affinity were conducted by in vitro and in silico approaches: competitive binding assay as well as pharmacophore, molecular docking and QSAR modeling. The results showed that all 18 OPEs exhibited binding activities to integrin αvβ3; moreover, hydrogen bonds were identified as crucial intermolecular interactions. In addition, essential factors, including the -P = O structure of OPEs, key amino acid residues and suitable cavity volume of integrin αvβ3, were identified to contribute to the formation of hydrogen bonds. Moreover, aryl-OPEs exhibited a lower binding activity with integrin αvβ3 than halogenated- and alkyl-OPEs. Ultimately, the QSAR model constructed in this study was effectively used to predict the binding affinity of OPEs to integrin αvβ3, and the results suggest that some OPEs might pose potential risks in aquatic environments. The results of this study comprehensively elucidated the binding mechanism of OPEs to integrin αvβ3, and supported the environmental risk management of these emerging pollutants.

Copper toxicity on Eisenia fetida in a vineyard soil: a combined study with standard tests, genotoxicity assessment and gut metagenomic analysis

Copper (Cu) toxicity is a pressing concern for several soils, especially in organic viticulture. The objective of this work was to assess Cu toxicity on the non-target organism Eisenia fetida, employing both traditional and novel tools for early identification of Cu-induced damages. In addition to traditional tests like avoidance and reproductive toxicity experiments, other tests such as the single cell gel electrophoresis (SCGE) and gut microbiome analysis were evaluated to identify early and more sensitive pollution biomarkers. Four sub-lethal Cu concentrations were studied, and the results showed strong dose-dependent responses by the earthworm avoidance test and the exceeding of habitat threshold limit at the higher Cu doses. An inverse proportionality was observed between reproductive output and soil Cu concentration. Bioaccumulation was not detected in earthworms; soil concentrations of potentially bioavailable Cu were not affected by E. fetida presence or by time. On the contrary, the SCGE test revealed dose-dependent genotoxicity for the 'tail length' parameter already at the second day of Cu exposition. Gut microbiome analysis a modulation of microbial composition, with the most aboundant families being Pectobateriaceae, Comamonadaceae and Microscillaceae. Bacillaceae increased over time and showed adaptability to copper up to 165 mg/kg, while at the highest dose even the sensitive Acetobacteriaceae family was affected. The research provided new insights into the ecotoxicity of Cu sub-lethal doses highlighting both alterations at earthworms' cellular level and changes in their gut microbiota.

Structural effects of sulfonamides on the proliferation dynamics of sulfonamide resistance genes in the sequencing batch reactors and the mechanism

Antibiotic resistance genes (ARGs) can be easily promoted by antibiotics, however, the structural effects of antibiotics on the proliferation of ARGs dynamic and the associated mechanisms remain obscure in, especially, activated sludge sequencing batch reactors. In the present study, the effects of 9 sulfonamides (SAs) with different structures on the proliferation dynamic of sulfonamide resistance genes (Suls) in the activated sludge sequencing batch reactors and the corresponding mechanisms were determined (30 days), and the results showed that the largest proliferation value (∆AR) of Suls dynamic for SAs (sulfachloropyridazine) was approximately 2.9 times than that of the smallest one (sulfadiazine). The proliferation of Suls was significantly related to the structural features (minHBint6, SssNH, SHBd and SpMax2_Bhm) that represent the biological activity of SAs. To interpret the phenomenon, a mechanistic model was developed and the results indicated that the biodegradation of SAs (T1/2) rather than conjugative transfer frequency or mutation frequency tends to be the key process for affecting Suls proliferation. T1/2 was proved to be dependent on the interactions between SAs and receptors (Ebinding), the cleavage mode (bond dissociation energy), and the site of nucleophilic assault. Besides, the metagenomic analysis showed that SAs posed significant effect on antibiotic resistome and Tnp31 played a vital role in the proliferation of Suls. Overall, our findings provide important insight into a theoretical basis for understanding the structural effects of SAs on the proliferation of ARGs in SBR systems.

Significant Differences in the Effects of Nitrogen Doping on Pristine Biochar and Graphene-like Biochar for the Adsorption of Tetracycline

To improve the adsorption efficiency of pollutants by biochar, preparing graphene-like biochar (GBC) or nitrogen-doped biochar are two commonly used methods. However, the difference in the nitrogen doping (N-doping) effects upon the adsorption of pollutants by pristine biochar (PBC) and GBC, as well as the underlying mechanisms, are still unclear. Take the tetracycline (TC) as an example, the present study analyzed the characteristics of the adsorption of TCs on biochars (PBC, GBC, N-PBC, N-GBC), and significant differences in the effects of N-doping on the adsorption of TCs by PBC and GBC were consistently observed at different solution properties. Specifically, N-doping had varied effects on the adsorption performance of PBC, whereas it uniformly improved the adsorption performance of GBC. To interpret the phenomenon, the N-doping upon the adsorption was revealed by the QSAR model, which indicated that the pore filling (VM) and the interactions between TCs with biochars (Ead-v) were found to be the most important two factors. Furthermore, the density functional theory (DFT) results demonstrated that N-doping slightly affects biochar's chemical reactivity. The van der Waals (vdWs) and electrostatic interactions are the main forces for TCs-biochars interactions. Moreover, N-doping mostly strengthened the electrostatic interactions of TCs-biochars, but the vdWs interactions of most samples remained largely unaffected. Overall, the revealed mechanism of N-doping on TCs adsorption by biochars will enhance our knowledge of antibiotic pollution remediation.

Environmental risk assessment of PPP application in European soils and potential ecosystem service losses considering impacts on non-target organisms

The use of Plant Protection Products (PPPs) is leading to high exposure scenarios with potential risk to soil organisms, including non-target species. Assessment of the effects of PPPs on non-target organisms is one of the most important components of environmental risk assessment (ERA) since they play crucial functions in ecosystems, being main driving forces in different soil processes. As part of the framework, EFSA is proposing the use of the ecosystem services approach for setting specific protection goals. In fact, the services provided by soil organisms can be impacted by the misuse of PPPs in agroecosystems. The aim of this work was to assess PPPs potential risk upon ecosystem services along European soils, considering impacts on earthworms and collembola. Four well-known (2 insecticides-esfenvalerate and cyclaniliprole- and 2 fungicides - picoxystrobin and fenamidone-) worst case application (highest recommended application) were studied; exploring approaches for linked observed effects with impacts on ecosystem services, accounting for their mode of action (MoA), predicted exposure, time-course effects in Eisenia fetida and Folsomia sp. and landscape variability. The selected fungicides exerted more effects than insecticides on E. fetida, whereas few effects were reported for both pesticides regarding Folsomia sp. The most impacted ecosystem services after PPP application to crops appeared to be habitat provision, soil formation and retention, nutrient cycling, biodiversity, erosion regulation, soil remediation/waste treatment and pest and disease regulation. The main factors to be taken into account for a correct PPP use management in crops are discussed.

Widespread use of toxic agrochemicals and pesticides for agricultural products storage in Africa and developing countries: Possible panacea for ecotoxicology and health implications

Chemicals used for storage majorly possess insecticidal activities - deterring destructive insect pests and microorganisms from stored agricultural produce. Despite the controversy about their safety, local farmers and agro-wholesalers still predominantly use these chemicals in developing countries, especially Africa, to ensure an all-year supply of agriproducts. These chemicals could have short- or long-term effects. Despite the state-of-the-art knowledge, factors such as poor education and awareness, limited agricultural subventions, quests for cheap chemicals, over-dosage, and many more are the possible reasons for these toxic chemicals' setback and persistent use in developing countries. This paper provides an up-to-date review of the environmental and ecological effects, as well as the health impacts arising from the indiscriminate use of toxic chemicals in agriproducts. Existing data link pesticides to endocrine disruption, genetic mutations, neurological dysfunction, and other metabolic disorders, apart from the myriad of acute effects. Finally, this study recommended several naturally sourced preservatives as viable alternatives to chemical counterparts and emphasized the invaluable role of education and awareness programs in mitigating the use in developing nations for a sustainable society.

Utility of a non-target screening method to explore the chlorination of similar sulfonamide antibiotics: Pathways and NCl intermediates

Sulfonamides (SAs) are ubiquitous antibiotics that are increasingly detected in aquatic environments and can react with free available chlorine to produce transformation products (TPs) during disinfection. However, the TPs generated during chlorination remains poorly understood. Here, a non-target screening method based on the PyHRMS program was used to assess the transformation pathways of five SAs, particularly the transient NCl intermediates, during a simulated chlorination process. We observed 210 TPs during SA chlorination using a non-target screening method based on high-resolution mass spectrometry, and the reaction mechanisms mainly included chlorine substitution, desulfonation, and hydroxylation. Among the TPs, 87 were tentatively proposed to be NCl intermediates as they instantly disappeared after quenching with Na₂S₂O₃. The MS² spectra of 13 of these potential NCl intermediates were obtained, and all displayed an [M-Cl]⁺ fragment. A diagnostic fragment ion (DFI) strategy was applied to explore the structural relationship between parent compounds and TPs. Based on the result, five SAs and 101 TPs (if their MS² spectra were available) could be connected through the same fragments, and this method was also proved effective in a real wastewater treatment plant effluent sample. We believe this novel method can help explore the TPs of organic compounds during chlorination in drinking water plants.

Toxicity comparison of atrazine on Eisenia fetida in artificial soil and three natural soils

Atrazine has been widely used in the world and caused environmental pollution, especially soil pollution. When assessing the toxicity of atrazine in soil, most studies used standardized artificial soils, while few studies focused on the real soil environments. In the present study, three natural soils and artificial soil were selected as test soils to study and compare the toxicities of atrazine to Eisenia fetida. Acute toxicity of atrazine was determined by filter paper and soil tests. In chronic toxicity study, after atrazine exposure, the content of reactive oxygen species in Eisenia fetida significantly increased and showed a dose-response relationship. The activity changes of three antioxidant enzymes and glutathione transferase showed that atrazine had obvious oxidative stress effect on earthworms. The contents of malondialdehyde and 8-hydroxy deoxyguanosine in 0.1 and 1 mg/kg atrazine treatment groups were significantly higher than the control, indicating that medium and high concentrations of atrazine could cause lipid and DNA damage in Eisenia fetida. The acute toxicity results and the integrated biomarker response index for chronic toxicity indicated that the toxicity order of atrazine was: red clay > fluvo-aquic soil > artificial soil > black soil, and that the toxicity of atrazine in artificial soil was not representative of its toxicity in real soil environment. The results of correlation analysis showed that three soil property parameters of organic carbon, organic matter and sand were most related to the toxicity of atrazine.

Ecotoxicity of parathion during its dissipation mirrored by soil enzyme activity, microbial biomass and basal respiration

The application of parathion (PTH) in agriculture can result in its entry into the soil and threaten the soil environment. Monitoring the PTH residues and assessing toxicity on soil health are of paramount importance to the public. Herein, the dissipation of PTH and concomitant influence on microbial activities [FDA hydrolase (FDA‒H), microbial biomass carbon (MBC) and basal respiration (BR)] in coastal solonchaks were investigated. Results showed that the dissipation of PTH in tested soil declined linearly, and the half-lives varied from 5.6 to 56.8 days, depending on pollutant concentrations. The FDA‒H activity and MBC were negatively affected by PTH pollution and exhibited a significantly positive correlation. Two‒way ANOVA analysis demonstrated that microbial activities were affected not only by PTH dose and incubation time but also by their interactions. The integrated biomarker response (IBR/n) index values on day 120 were between 1.02 and 2.89, larger than those on day 1 during PTH dissipation. This implied that the soil quality did not recover though there was no PTH residue in the soil at the end of the experiment. These findings suggested that microbial activities integrated with IBR/n index could elucidate the hazardous impacts of PTH dissipation on biochemical cycling and microorganisms in soil.

Predicting environmental concentrations and the potential risk of Plant Protection Products (PPP) on non-target soil organisms accounting for regional and landscape ecological variability in european soils

Plant Protection Products (PPP) raise concerns as their application may cause effects on some soil organisms considered non-target species which could be highly sensitive to some pesticides. The European Food and Safety Authority (EFSA), in collaboration with the Joint Research Centre (JRC) of the European Commission, has developed guidance and a software tool, Persistence in Soil Analytical Model (PERSAM), for conducting soil exposure assessments. EFSA PPR Panel has published recommendations for the risk assessment of non-target soil organisms. We have used PERSAM for calculating PPPs predicted environmental concentrations (PECs); and used the estimated PEC for assessing potential risks using Toxicity Exposure Ratios (TER) for selected soil organisms and good agricultural practices. Soil characteristics and environmental variables change along a latitudinal axis through the European continent, influencing the availability of PPP, their toxicity upon soil biota, and hence, impacting on the risk characterization. Although PERSAM includes as input geographical information, the information is aggregated and not further detailed in the model outputs. Therefore, there is a need to develop landscape based environmental risk assessment methods addressing regional variability. The objective was to integrate spatially explicit exposure (PECs) and effect data (biological endpoints i.e. LC₅₀, NOEC, etc.) to estimate the risk quotient (TER) of four PPP active substances (esfenvalerate, cyclaniliprole, picoxystrobin, fenamidone) on non-target species accounting European landscape and agricultural variability. The study was focused on the effects produced by the above-mentioned pesticides on two soil organisms: E. fetida earthworms and Folsomia sp. collembolans. After running PERSAM assuming a worst case application of PPPs, PECs in total soil and pore water were obtained for different depths in northern, central and southern European soils. With this data, soil variability and climatic differences among soils divided in three large Euroregions along a latitudinal transect (Northern, Central, Southern Europe) were analysed. Summarising, a trend to accumulate higher PECs and TERs in total soil was observed in the north decreasing towards the south. Higher PECs and TERs could be expected in pore water in southern soils, decreasing towards the north. The risk disparity between pollutant concentrations at different soils compartments should be taken into account for regulatory purposes, as well as the potential landscape variabilities among different Euroregions.

Nano-bio interfacial interactions determined the contact toxicity of nTiO2 to nematodes in various soils

The biological effect of soilborne nanoparticles (NPs) is a manifestation of soil-NMs-bio interactions. Soil factors are known to restructure NPs surfaces and thus influence the nanotoxicity. However, the mechanisms by which environmental factors affecting nano-bio interactions to aggravate or alleviate nanotoxicities are poorly understood. Herein, we compared the toxicity of TiO₂ NPs (nTiO₂) in five soils using the model nematode (Caenorhabditis elegans), and investigated the variation of nano-bio interactions under different conditions. A correlation analysis showed that pH and dissolved organic matter (DOM) were dominant regulators of nTiO₂ toxicity. At the nano-bio interface, low pH (5.0) led to nTiO₂ adhesion to micron-sized furrows and aggravated dermal wrinkling, while humid acid (HA) alleviated these impacts. Mechanically, low pH increased nTiO₂ adhesion through enhanced electrostatic attraction and subsequent stimulation of mucin and collagen synthesis, resulting in a positive feed cycle of pH-dependent contact nanotoxicity. HA not only prevented nTiO₂ adhesion onto the epidermis due to its negative charge, but also relieved the overstimulation of stress response pathways, thereby alleviating nanotoxicity. These findings broaden our knowledge of how NPs induce contact toxicity in soil invertebrates through specific biointerfacial interactions, and highlight the important role of DOM in alleviating the combined hazards of NPs and soil acidification.

Influence of pre-exposure time on the toxicities of different temperature effect insecticides to Apolygus lucorum (Hemiptera: Miridae)

Temperature can have influences on the toxicities and efficacies of insecticides. Therefore, it is important to accurately evaluate the temperature effect (TE) on the toxicities of insecticides to insects. Previous studies have shown that the pre-exposure of insects to temperatures before their contact with insecticides, caused variations in their toxicities. However, most of these studies focused on the TE of the insecticides post-treatment. In this study we hypothesized that pre-exposure time of insect at different temperature can influence the toxicities of insecticides. We then evaluated the influence of different pre-exposure time (0, 2, 4, 8, 12 and 24 h) on toxicities of three different temperature effect insecticides (TEIs) to Apolygus lucorum at 15, 25 and 35°C respectively. We found that all toxicities of three TEIs to A. lucorum did not vary with pre-exposure time at 25°C. The LC₅₀ of hexaflumuron (positive TEI) only decreased (from 1800.06 to 237.40 mg/L) at 15°C, with an increase in the pre-exposure time. Whereas the LC₅₀ of β-cypermethrin (negative TEI) decreased from 225.43 to 60.79 mg/L at 35°C. These results also showed that the temperature coefficients (TCs) of the toxicities were influenced by pre-exposure time at different temperatures. For hexaflumuron, all the TCs at 25°C and 35°C decreased, as the pre-exposure time increased. For β-cypermethrin, the TCs decreased significantly only at 35°C. The toxicity and TCs of phoxim (non-effect TEI) showed no obvious fluctuation at the tested temperatures. These results showed that when the pre-exposure times were extended, the toxicities of the positive / negative TEI showed an increase at the temperature where the pest was less sensitive to the insecticides. These results can be applied to determine the toxicities / bioactivities of different insecticides accurately at different temperatures.

A highly sensitive bio-barcode immunoassay for multi-residue detection of organophosphate pesticides based on fluorescence anti-quenching

Balancing the risks and benefits of organophosphate pesticides (OPs) on human and environmental health relies partly on their accurate measurement. A highly sensitive fluorescence anti-quenching multi-residue bio-barcode immunoassay was developed to detect OPs (triazophos, parathion, and chlorpyrifos) in apples, turnips, cabbages, and rice. Gold nanoparticles were functionalized with monoclonal antibodies against the tested OPs. DNA oligonucleotides were complementarily hybridized with an RNA fluorescent label for signal amplification. The detection signals were generated by DNA-RNA hybridization and ribonuclease H dissociation of the fluorophore. The resulting fluorescence signal enables multiplexed quantification of triazophos, parathion, and chlorpyrifos residues over the concentration range of 0.01-25, 0.01-50, and 0.1-50 ng/mL with limits of detection of 0.014, 0.011, and 0.126 ng/mL, respectively. The mean recovery ranged between 80.3% and 110.8% with relative standard deviations of 7.3%-17.6%, which correlate well with results obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The proposed bio-barcode immunoassay is stable, reproducible and reliable, and is able to detect low residual levels of multi-residue OPs in agricultural products.

A two-step strategy for simultaneous dual-mode detection of methyl-paraoxon and Ni (Ⅱ)

Exogenous pollution of Chinese medicinal materials by pesticide residues and heavy metal ions has attracted great attention. Relying on the rapid development of nanotechnology and multidisciplinary fields, fluorescent techniques have been widely applied in contaminant detection and pollution monitoring due to their advantages of simple preparation, low cost, high throughput and others. Most importantly, synchronous detection of multi-targets has always been pursued as one of the major goals in the design of fluorescent probes. Herein, we firstly develop a simultaneous sensing method for methyl-paraoxon (MP) and Nickel ion (Ni, Ⅱ) by using carbon based fluorescent nanocomposite with ratiometric signal readout and nanozyme. Notably, the designed system showed excellent effectiveness even when the two pollutants co-exist. Under the optimum conditions, this method provides low limits of detection of 1.25 µM for methyl-paraoxon and 0.01 µM for Ni (Ⅱ). To further verify the reliability, recovery studies of these two analytes were performed on ginseng radix et rhizoma, nelumbinis semen, and water samples. In addition, smartphone-based visual analysis has been introduced to expand its applicability in point of care detection. This work not only expands the application of the dual-mode approach to pollutant detection, but also provides insights into the analysis of multiple pollutants in a single assay.

Factors Influencing Soil Nitrification Process and the Effect on Environment and Health

To meet the global demand for food, several factors have been deployed by agriculturists to supply plants with nitrogen. These factors have been observed to influence the soil nitrification process. Understanding the aftermath effect on the environment and health would provoke efficient management. We review literature on these factors, their aftermath effect on the environment and suggest strategies for better management. Synthetic fertilizers and chemical nitrification inhibitors are the most emphasized factors that influence the nitrification process. The process ceases when pH is <5.0. The range of temperature suitable for the proliferation of ammonia oxidizing archaea is within 30 to 37oC while that of ammonia oxidizing bacteria is within 16 to 23oC. Some of the influencing factors excessively speed up the rate of the nitrification process. This leads to excess production of nitrate, accumulation of nitrite as a result of decoupling between nitritation process and nitratation process. The inhibition mechanism of chemical nitrification inhibitors either causes a reduction in the nitrifying micro-organisms or impedes the amoA gene's function. The effects on the environment are soil acidification, global warming, and eutrophication. Some of the health effects attributed to the influence are methemoglobinemia, neurotoxicity, phytotoxicity and cancer. Biomagnification of the chemicals along the food chain is also a major concern. The use of well-researched and scientifically formulated organic fertilizers consisting of microbial inoculum, well-treated organic manure and good soil conditioner are eco-friendly. They are encouraged to be used to efficiently manage the process. Urban agriculture could promote food production, but environmental sustainability should be ensured.

Acidic Neutralization by Indigenous Bacteria Isolated from Abandoned Mine Areas

Soil acidification has been a serious problem in abandoned mine areas, and could be exacerbated by acid deposition with the release of mine wastes. In this study, three different indigenous bacterial consortia were isolated from abandoned mines in South Korea, from which the potential for acid neutralization of microorganisms was evaluated. They were all able to neutralize acidity within 24 h in the liquid nutrient medium. Moreover, a strong positive correlation (R = +0.922, p < 0.05) was established between the ammonium ion (NH4+) production yield and the resulting pH, indicating that NH4+ served as an important metabolite for biological neutralization. Serratialiquefaciens, Citrobacter youngae, Pseudescherichia vulneris, and Serratia grimesii had higher acid neutralization ability to generate NH4+ by the metabolism of nitrogen compounds such as carboxylation and urea hydrolysis. Therefore, acidic soils can be expected to be ameliorated by indigenous microorganisms through in situ biostimulation with the adequate introduction of nitrogenous substances into the soil environments.

Organism and molecular-level responses of superoxide dismutase interaction with 2-pentanone

2-Pentanone is an excellent organic solvent and extractant, which is widely used in industrial production. 2-Pentanone is harmful to soil organisms when it enters the soil. However, current studies have not clarified the response of the antioxidant enzyme superoxide dismutase (SOD) to 2-Pentanone and its mechanism. In this study, the response of earthworm antioxidant enzyme SOD to 2-Pentanone and its molecular mechanism was investigated at organism molecular levels. The results showed that the SOD activity of earthworms under 2-Pentanone stress was significantly inhibited, and the inability of superoxide anion radicals (·O₂^-) to be scavenged in time might be one of the reasons for the increase of lipid peroxidation. Under 2-Pentanone exposure conditions, catalase (CAT), an antioxidant enzyme closely related to SOD, and the total antioxidant capacity (T-AOC) of earthworms were activated to resist oxidative damage. On the other hand, the observation of earthworm microstructure provided evidence of a direct risk of 2-Pentanone on earthworm body wall tissues. Molecular-level assays have shown that 2-pentanone altered the secondary structure of SOD, which further led to the loosening of the SOD backbone structure and the extension of the polypeptide chain. On the other hand, 2-pentanone quenched the endogenous fluorescence of SOD in the form of static quenching and formed the 2-pentanone/SOD complex. Molecular simulation results suggested that 2-pentanone tended to bind on the surface of SOD rather than close to the active site, and it is speculated that the alteration of SOD structure is the key reason for the change in its activity. This study enriches the toxicological data of 2-Pentanone on soil organisms, thus responding to the current concerns about its ecological risk.

Probing the biological toxicity of pyrene to the earthworm Eisenia fetida and the toxicity pathways of oxidative damage: A systematic study at the animal and molecular levels

Pyrene (Pyr), a widely used tetracyclic aromatic hydrocarbon, enters soil in large quantities and causes environmental pollution due to its production and mining. In order to systematically study the biotoxicity of pyrene to model organisms Eisenia fetida in soil, experiments were carried out from four dimensions: animal, tissue, cell and molecule. Experimental results proved that the mortality rate increased with increasing concentration and time of exposure to pyrene, while the mean body weight and spawning rate decreased. Meanwhile, when the pyrene concentration reached 900 mg/kg, the seminal vesicle and longitudinal muscle of the earthworm showed obvious atrophy. Experimental results at the cellular level showed that pyrene induced cell membrane damage and Ca²⁺ influx triggered mitochondrial membrane depolarization and a surge in ROS levels. Oxidative stress causes damage to proteins and lipids and DNA inside cells. When the mortality rate was 91.67 %, the Olive Tail Movement (OTM) of the comet experiment reached 15. The results of molecular level tests showed that pyrene inhibited the activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) mainly by changing the microenvironment and secondary structure of amino acid Tyr 108. The weakened function of direct antioxidant enzymes may be the root cause of the excessive increase of reactive oxygen species (ROS) in cells. The systematic approach used in this study enriches the network of toxic pathways in toxicological studies, and basic data on the biological toxicity of pyrene can provide support for future soil contamination detection.

Influences and mechanisms of nanoparticles on pentachloronitrobenzene accumulation by earthworms

Pesticides and nanoparticles may coexist in soil; however, influences of nanoparticles on accumulation of pesticides in terrestrial organisms are still unclear. This study aims to investigate the influences and mechanisms of metal oxide nanoparticles (nano ZnO and nano CuO) on accumulation of pentachloronitrobenzene (PCNB) in earthworms and their combined toxicity. The earthworms were cultivated in the soil spiked with nanoparticles (10, 50, 250 mg/kg) and PCNB (100 μg/kg) for 21 days. The concentrations of PCNB in earthworms in binary exposure treatments (PCNB + ZnO and PCNB + CuO) reached 2.47 and 3.13 times of that in individual PCNB exposure treatment, indicating that nanoparticles facilitated the accumulation of PCNB in earthworms. The contents of reactive oxygen species (ROS) in earthworms in treatments PCNB + ZnO 250 and PCNB + CuO 250 reached 379 and 316 fluorescence intensity/mg Protein, respectively, which were significantly higher than that in control group (183 fluorescence intensity/mg protein), indicating that nanoparticles would cause oxidative stress to earthworms. Earthworm coelomocytes were extracted from healthy earthworms and cultivated in culture media in cytotoxicity tests. Changes of intracellular ROS contents and cell viability suggested that PCNB and nanoparticles caused serious oxidative damage to earthworm coelomocytes, thus leading to the damage of cell membrane and cell death. In in vivo tests, changes of biomarkers (ROS and malondialdehyde) demonstrated that these pollutants injured the earthworms. Increased accumulation of PCNB in binary exposure treatments was due to the damage of body cavity caused by nanoparticles. This study provides a novel hypothesis for nanoparticles facilitating organic pollutants entering terrestrial organisms and determines whether nanoparticles would bring about greater environmental risks of other pollutants.

Enantioselective degradation of the organophosphorus insecticide isocarbophos in Cupriavidus nantongensis X1T: Characteristics, enantioselective regulation, degradation pathways, and toxicity assessment

The chiral pesticide enantiomers often show selective efficacy and non-target toxicity. In this study, the enantioselective degradation characteristics of the chiral organophosphorus insecticide isocarbophos (ICP) by Cupriavidus nantongensis X1^T were investigated systematically. Strain X1^T preferentially degraded the ICP R isomer (R-ICP) over the S isomer (S-ICP). The degradation rate constant of R-ICP was 42-fold greater than S-ICP, while the former is less bioactive against pest insects but more toxic to humans than the latter. The concentration ratio of S-ICP to R-ICP determines whether S-ICP can be degraded by strain X1^T. S-ICP started to degrade only when the ratio (C_S-ICP/C_R-ICP) was greater than 62. Divalent metal cations could improve the degradation ability of strain X1^T. The detected metabolites that were identified suggested a novel hydrolysis pathway, while the hydrolytic metabolites were less toxic to fish and green algae than those from P-O bond breakage. The crude enzyme degraded both R-ICP and S-ICP in a similar rate, indicating that enantioselective degradation was due to the transportation of strain X1^T. The strain X1^T also enantioselectively degraded the chiral organophosphorus insecticides isofenphos-methyl and profenofos. The enantioselective degradation characteristics of strain X1^T make it suitable for remediation of chiral organophosphorus insecticide contaminated soil and water.

Potential Impacts of Climate Change on the Toxicity of Pesticides towards Earthworms

This review examined one of the effects of climate change that has only recently received attention, i.e., climate change impacts on the distribution and toxicity of chemical contaminants in the environment. As ecosystem engineers, earthworms are potentially threatened by the increasing use of pesticides. Increases in temperature, precipitation regime changes, and related extreme climate events can potentially affect pesticide toxicity. This review of original research articles, reviews, and governmental and intergovernmental reports focused on the interactions between toxicants and environmental parameters. The latter included temperature, moisture, acidification, hypoxia, soil carbon cycle, and soil dynamics, as altered by climate change. Dynamic interactions between climate change and contaminants can be particularly problematic for organisms since organisms have an upper and lower physiological range, resulting in impacts on their acclimatization capacity. Climate change variables such as temperature and soil moisture also have an impact on acidification. An increase in temperature will impact precipitation which might impact soil pH. Also, an increase in precipitation can result in flooding which can reduce the population of earthworms by not giving juvenile earthworms enough time to develop into reproductive adults. As an independent stressor, hypoxia can affect soil organisms, alter bioavailability, and increase the toxicity of chemicals in some cases. Climate change variables, especially temperature and soil moisture, significantly affect the bioavailability of pesticides in the soil and the growth and reproduction of earthworm species.

Effects of antibiotics on enhanced biological phosphorus removal and its mechanisms

Many kinds of antibiotics are continuously discharged into wastewater and typically cause a great decrease in sewage treatment performance, whereas mechanisms of differences in the impacts of commonly used antibiotics on phosphate removal are still elusive. Thus, an enhanced biological phosphorus removal (EBPR) system, as an effective method of phosphate removal, was developed, and its performance in the treatment of artificial wastewater containing antibiotics at short- (8 h) and long-term (15 days) exposure was investigated. The results show that phosphorus removal was consistently inhibited by the addition of antibiotics with a significant difference (P < 0.05). To interpret the phenomena, mechanistic equations were developed, and the results indicate that for short-term tests, the difference was mainly caused by the suppression of polyhydroxyalkanoate (PHA) degradation and the activity of polyphosphate kinase (PPK), resulting in the different inhibition of the soluble orthophosphorus (SOP) uptake process. For long-term tests, the difference in SOP uptake was principally caused by the inhibition of PHA degradation and the activity of PPK, whereas the difference in SOP release resulted from the inhibition of activities of exopolyphosphatase (PPX) and adenylate kinase (ADK). Moreover, micro-mechanisms of such inhibition were identified from molecular docking and electrostatic potential.

Soil acidification enhancing the growth and metabolism inhibition of PFOS and Cr(VI) to bacteria involving oxidative stress and cell permeability

Soil acidification is causing more and more attention, not only because of the harm of acidification itself, but also the greater harm to bacteria brought by some pollutants under acidic condition. Therefore, the toxicities of two typical soil pollutants (perfluorooctane sulfonate (PFOS) and chromium (Cr(VI)) to growth and metabolisms of soil bacteria (Bacillus subtilis as modol) were investigated. Under acidic condition of pH = 5, Cr(VI), PFOS and PFOS + Cr(VI) show stronge inhibition to bacteria growth up to 24.3%, 42.3%, 41.6%, respectively, and this inhibition was about 2-3 times of that at pH = 7. Moreover, acid stress reduces the metabolism of bacteria, while PFOS and Cr(VI) pollution futher strengthens this metabolic inhibition involving oxidative stress and cell permeability. The activities of dehydrogenase (DHA) and electron transport system (ETS) at pH = 5 exposed to Cr(VI), PFOS and combined PFOS + Cr(VI) was 21.5%, 16.9%, 23.2% and 8.9%, 32.2%, 19.1% lower than the control, respectively. However, the relative activity of DHA and ETS at pH = 7 are 5-8 and 2-13 times of that at pH = 5, respectively. Isoelectric point, cell surface hydrophobicity and molecular simulation analysis show that the corresponding mechanism is that acidic conditions enhance the interaction between bacteria and PFOS/Cr(VI) through hydrogen bonding, hydrophobic and electrostatic interactions. The results can guide the remediation of acid soil pollution, and provide a reference for the combined toxicity evaluation of heavy metals and micro-pollutants in acid soil.

Adsorption of sulfonamides on biochars derived from waste residues and its mechanism

Waste residues have been prepared as biochar (BC) adsorbents to remove sulfonamides (SAs) at low cost, but the mechanisms of the differences in the SA adsorption performance of different BCs are not clear. Thus, the adsorption characteristics of two SAs (sulfadiazine and sulfathiazole) on three BCs derived from waste residues (sewage sludge (SB), pig manure (PB), and rice straw (RB)) were investigated. The results showed that the adsorption mechanism was chemisorption and RB was the preferred BC under the different tested conditions (pH, Ca²⁺, and humic acid), followed by PB and SB. To interpret the phenomena, FTIR, XRD, and XPS analyses were performed and results indicated that SB had the lowest C content, and there was a very significant difference in the concentrations of the two O functional groups (C˭O and C‒O) for PB and RB (P < 0.01). Density functional theory calculations revealed that the mechanisms of SA adsorption onto BCs were mainly through π-π electron donor acceptor interactions and H bonds. There was no significant difference in the π interactions between the SAs-BC containing C‒O (BC(OH)) and the SAs-BC containing C˭O (BC(C˭O)), whereas the H bond strength of SAs-BC(OH) was much stronger than that of SAs-BC(C˭O).

New frontiers and prospects of metal-organic frameworks for removal, determination, and sensing of pesticides

Pesticides have been widely used in agriculture to control, reduce, and kill insects. Humans are also being using pesticides to control insidious animals in daily life. By these practices, a huge volume of pesticides is introduced to the environment. Despite broad-spectrum applicability, pesticides also have hazardous effects on both humans and animals at high and low concentrations. Long-term exposure to pesticides can cause different diseases, like leukemia, lymphoma, and cancers of the brain, breasts, prostate, testis, and ovaries. Reproductive disorders from pesticides include birth defects, stillbirth, spontaneous abortion, sterility, and infertility. Therefore, the application of determination and treatment methods for pre-concentration and removal of these toxic materials from the environment appears a vital concern. To date, different materials and approaches have been employed for these purposes. Among these approaches, multifunctional metal-organic frameworks (MOFs)-assisted adsorption and determination processes have always been in the spotlight. These facts are due to exclusive properties of MOFs in terms of the crystallinity, large surface area, high chemical, and physical stability, and controllable structure as well as unique features of adsorption and determination process in terms of simple, easy, cheap, available method and ability to use in large and industrial scales. In the present work, we illustrate the exceptional features of MOFs as well as the possible mechanism for the adsorption of pesticides by MOFs. The use of these fantastic materials for pre-concentration and removal of pesticides are extensively explored. In addition, the performance of MOFs was compared with other adsorbents. Finally, the new frontiers and prospects of MOFs for the determination, sensing, and removal of pesticides are presented.

Remediation of organophosphorus pesticide polluted soil using persulfate oxidation activated by microwave

Contaminated sites from pesticide industry have attracted global concern due to the characteristics of organic pollution with high concentrations and complete loss of habitat conditions. Remediation of organophosphorus pesticide polluted soil using microwave-activated persulfate (MW/PS) oxidation was investigated in this study, with parathion as the representative pesticide. Approximately 90 % of parathion was degraded after 90 min of MW/PS oxidation treatment, which was superior to those by single PS or MW treatment. Relatively greater performances for parathion degradation were obtained in a relatively larger PS dosage, higher microwave temperature, and lower organic matter content. Appropriate soil moisture favored parathion degradation in soil. SO₄^-, OH, O₂^-, and ¹O₂ generated in the MW/PS system all contributed to parathion degradation. Multiple spectroscopy analyses indicated that PO and PS bonds in parathion were destroyed after MW/PS oxidation, accompanied by generation of hydroxylated and carbonylated byproducts. The soil safety after parathion degradation was assessed via model prediction. Furthermore, MW/PS oxidation also exhibited great performance for degradation of other organophosphorus pesticides, including ethion, phorate, and terbufos.

Impact of hydrochar and biochar amendments on sorption and biodegradation of organophosphorus pesticides during transport through Danube alluvial sediment

This work investigates the transport behaviour of selected organophosphorus pesticides, OPPs (chlorpyrifos, CP; chlorpyrifos-methyl, CPM; chlorfenvinphos, CF) through Danube alluvial sediment in the presence of hydrochars and biochars. The investigated hydrochar, obtained at three different temperatures (180 °C, 200 °Cand 220 °C), originated from sugar beet shreds (SBS) and Miscanthus×giganteus (MIS). Results are described by conventional advective-dispersive equation (ADE). Retardation coefficients (R_d) for all OPPs were in the range 6.2-16. Biodegradation was 4.15 and 1.80 for CPM and CP, respectively, while for CF biodegradation did not occur. The addition of carbon rich materials increases retardation of all OPPs in the range from 4 to 18 times depending on the material. Column experiment results indicated that biodegradation of OPPs occurred (up to λ = 13). In order to confirm that biodegradation occurred in the column experiments, we isolated OPPs degrading microorganisms for the first time from the alluvial sediment. A strain capable of degrading CP and CPM was isolated and identified as Bacillus megaterium BD5 based on biochemical properties, MALDI TOF and 16S rRNA analysis (99.54% identity). The results demonstrate that hydrochars, biochars and isolated degrading bacteria may be effective agents for reducing the mobility of or removing OPPs in contaminated soils or sediments.

In vivo monitoring and exposure potency assessment of phase I metabolism of fenthion in vegetables

In this study, the phase I metabolism of fenthion was monitored in three common vegetables in different chamber situations via an in vivo solid-phase microextraction method. The phase I metabolic pathways of fenthion were evaluated based on the in vivo monitoring results and their comparisons among the chamber situations. Enzyme catalysis was found to play a basic and dominant role, whereas light catalysis could promote subsequent transformations that were difficult for enzyme catalysis. Moreover, according to the concentrations of the metabolites and their toxicity, the total concentrations and total toxicity weighted concentrations were calculated to reveal actual residual levels. The relative total and weighted exposure potency values were calculated to account for the fact that only the parent pesticide was considered in the diet exposure risk assessment. In result, both total and weighted approaches indicated a much higher exposure risk. Present study uncovered the potential pesticide exposure risk associated with phase I metabolism and highlighted the toxicity weighted approach, both of which more realistically reflect the exposure risk than the parent compound concentration does. In general, this study may facilitate further illustrating the phase I metabolism of ubiquitous agricultural pesticides, and provide a more realistically understanding of their exposure risk.

New parameters for the quantitative assessment of the proliferation of antibiotic resistance genes dynamic in the environment and its application: A case of sulfonamides and sulfonamide resistance genes

Antibiotic resistance genes (ARGs) have been widely detected around the world and are generally viewed as emerging pollutants with environmental persistence. The proliferation of ARGs can be easily promoted by antibiotics. However, the dynamics of ARGs in the environment are still unable to be quantified using a single parameter, which is vital to evaluating the ability of ARGs to spread by antibiotics and effectively controlling ARGs. A new parameter, termed the relative area ratio of sample to control (ΔA^R), was developed based on the quantitative features determined by ARG-time curves in soils contaminated with sulfonamides (SAs) and verified by quantitative structure-activity relationships (QSARs) models. The results showed that ΔA^R can not only be used to accurately quantify the characteristics of SAs resistance genes (Suls) over time but also be applied to reveal the relationships between the proliferation of Suls and important factors (i.e., concentrations and chemical structures). Moreover, the ΔA^R-based QSARs model indicated that bioavailability and the frequency of conjugative transfer, rather than the ability of induced mutations in bacteria, tend to be key processes of the characteristics of the proliferation of Suls. Therefore, ΔA^R is a useful parameter to perform environmental risk assessments of ARG proliferation in the environment.

Ecotoxicological effects of petroleum-contaminated soil on the earthworm Eisenia fetida

Petroleum is an important industrial raw material that enters the soil during production and use and is harmful to soil organisms. To evaluate the toxicity of petroleum-contaminated soil, earthworms (Eisenia fetida) were used as model organisms for soil ecotoxicity studies. We found that earthworm weight and cocoon production decreased significantly after exposure to petroleum-contaminated soil. In addition, soil contaminated with high concentrations of petroleum can cause damage to the DNA within earthworm seminal vesicles. Superoxide dismutase (SOD), catalase, and peroxidase activities were significantly inhibited when earthworms were exposed to petroleum-contaminated soil, indicating that oxidative stress was induced by petroleum pollutants. The mRNA levels of annetocin precursor, a reproduction-related gene, was significantly inhibited after petroleum exposure. The mRNA levels of translationally controlled tumour protein (TCTP) and SOD exhibited a concentration-dependent relationship, and their relative expression increased with petroleum concentration.

Assessing Soil Acidification of Croplands in the Poyang Lake Basin of China from 2012 to 2018

Soil acidification, caused by intensified fertilizer application and acid deposition, has threatened the sustainability of agricultural ecosystems and soil quality in parts of China since the 1980s. However, little is known about the spatio-temporal change of soil pH in cropland at a large basin scale. Poyang Lake Basin of China was selected as the study area to identify the spatio-temporal change of cropland pH and detect potential soil acidification factors. A total of 507 and 503 topsoil samples were collected in 2012 and 2018, respectively, and methods including one-way analysis of variance (ANOVA), Pearson’s correlation analyses, and Inverse Distance Weighted (IDW) were applied. Results showed that soil pH ranged from 3.96 to 7.95 in 2012 and from 3.34 to 8.19 in 2018, with most samples being acidic (pH < 7) in both sets of data. The two soil datasets showed a significant decline (p < 0.05) of 0.1 pH units over the past six years and several soil samples that exhibited obvious uptrends in the groups of pH < 4.5 and 4.5–5.0 from 2012 to 2018. Overall, the distribution patterns of pH at the two sampling dates were similar, whereas local details of the pH spatial distribution patterns differed. While we found a significant correlation (p < 0.05) between soil pH and aspect, elevation and slope showed no significant correlation with pH. ANOVA showed that pH values in the water density (river or lake network density) range of 6.27–19.94 were significantly higher (p < 0.05) than the other water densities. Large amounts of precipitation with low pH values were found to significantly influence soil pH, whereas N-fertilizer inputs exerted limited effects on soil pH over the entire study area. These findings provided new insights on soil acidification assessment and potential factor detection at the basin scale.

Spectrophotometric detection of fenthion in foods after extraction by magnetic zirconia

A magnetic material, Fe₃O₄@ZrO₂, was used to enrich an organophosphorus pesticide, fenthion. After enrichment the Fe₃O₄@ZrO₂ was treated with NaOH to elute and hydrolyze fenthion. The hydrolysis products, orthophosphate ions, combine to molybdate ions to yield molybdophosphoric acid, which was further reduced with SnCl₂ to obtain a blue phosphatemolybdate. The content of orthophosphate ions as well as fenthion can be determined through the spectrophotometric method. Adsorption and elution conditions were optimized to obtain an enrichment factor of 12.5. The proposed composite method was successfully used to analyze the fenthion residues on the skin of cucumber and apple samples. The limit of detection was as low as 0.037 mg/Kg, which was close to that of the gas chromatography-mass spectrometer method. The method was simple, rapid, and economic, suitable for the rapid screen of fenthion and the other organophosphorus pesticide in mass samples.

Solid-phase microextraction of organophosphorous pesticides from food samples with a nitrogen-doped porous carbon derived from g-C3N4 templated MOF as the fiber coating

A nitrogen-doped metal organic framework (MOF) based porous carbon (C-(C₃N₄@MOF)) was produced by the carbonization of a graphitic carbon nitride (g-C₃N₄) templated MOF (NH₂-MIL-125). The C-(C₃N₄@MOF) was then coated on a stainless steel wire by sol-gel technique to serve as a solid-phase microextraction (SPME) fiber coating. The coated fiber was studied for the extraction of fourteen organophosphorous pesticides (OPPs) from different fruit and vegetable samples followed by gas chromatography-mass spectrometer (GC-MS) detection. The C-(C₃N₄@MOF) coated fiber exhibited a high extraction capability for the OPPs. Both single factor optimization and response surface analysis (Box-Behnken Design) methods were implemented to optimize the experiment conditions for the extraction. The results indicated that the linear response for the fourteen OPPs was in the range from 0.69 to 3000 ng g^-1 and the coefficients of determination (r²) ranged from 0.9981 to 0.9998. The limits of detection (LODs, S/N = 3) ranged from 0.23 to 7.5 ng g^-1. The method recoveries (R) of the fourteen OPPs for spiked fruit and vegetable samples were between 82.6% and 118%, with the relative standard deviations (RSDs) varying from 2.8% to 11.7%. The fiber can be reused over 100 times without a significant loss of extraction efficiency.

The activity prediction of indole inhibitors against HCV NS5B polymerase

Non-structural viral protein 5B (NS5B) is a viral protein in hepatitis C virus. Although various inhibitors against NS5B have been found, the activity prediction of similar untested inhibitors is still highly desirable. In this respect, the Tchebichef moments (TMs) calculated from the images of molecular structures were regarded as the independent variables while the inhibitory activity (pIC₅₀ ) was the dependent variable, and the predictive model was established by means of stepwise regression. The R-squared of leave-one-out cross-validation (Q² ) for the training set and the R-squared of prediction ( R p 2 ) for external independent test set were 0.919 and 0.927, respectively. The obtained model was also evaluated strictly. Compared with the multivariate curve resolution with alternating least squares (MCR-ALS) and the QSAR approaches derived from the literature, the proposed method is more accurate and reliable. This study not only provides an effective approach to predict the biological activity of RNA replication's inhibitors, but also extends the QSAR modeling technique.

The influence of temperature on the toxicity of insecticides to Nilaparvata lugens (Stål)

The toxicity of insecticides is associated with a variety of factors including temperature, and global warming is bound to lead to the outbreak of pests; therefore, it is important to study the influence of temperature on insecticide toxicity and pest control. In this study, the influence of temperature on the toxicity of insecticides to Nilaparvata lugens (BPH) was determined. The results showed that the sensitivity of BPH to cycloxaprid (LC₅₀ = 42.5-0.388 mg/L), nitenpyram (LC₅₀ = 3.49-0.187 mg/L), triflumezopyrim (LC₅₀ = 0.354-0.0533 mg/L) and chlorpyrifos (LC₅₀ = 36.3-7.41 mg/L) increased significantly when the temperature changed from 18 °C to 36 °C. BPH sensitivity to etofenprox (LC₅₀ = 9.04-54.2 mg/L) was also affected by temperature. Additionally, the feeding amount and the activities of three detoxification enzymes [cytochrome P450 (P450), glutathione S-transferase (GST) and carboxylesterase (CarE)] of BPH at different temperatures were also measured. The feeding amounts were positively correlated with temperature increases while the activities of P450 and GST were significantly inhibited. The correlation analysis showed that changes in P450 activity (but not GST activity) were closely related to the sensitivity of BPH to cycloxaprid, nitenpyram, chlorpyrifos, and etofenprox according to the variation in temperatures. This study provides a theoretical basis for the rational use of chemical pesticides under the global warming trend and provides a reference for the integrated management of BPH in the field.