Lethal Concentration Values Research Articles

Evaluation of Hemolysis Activity of Zerumbone on RBCs and Brine Shrimp Toxicity

Zerumbone is a well-known compound having anti-cancer, anti-ulcer, anti-inflammatory and anti-hyperglycemic effects. During its use for the disease treatment, the membrane of erythrocyte can be affected by consumption of this bioactive compound. The current study was the first report of investigation of the hemolytic activities on human erythrocytes and cytotoxic profile of zerumbone. The toxicity of zerumbone on human erythrocytes was determined by in vitro hemolytic assay. Brine shrimp lethality assay was used to evaluate the cytotoxic effect of zerumbone at concentrations 10, 100 and 1000 μg/mL. The human erythrocyte test showed no significant toxicity at low concentrations, whereas hemolytic effect was amplified up to 17.5 % at the highest concentration. The half lethal concentration (LC50) value of zerumbone against brine shrimp was less than 1000 µg /mL (LC50=190 µg/ml) showing the significant toxic nature of this compound. These results provide a baseline in terms of the toxicity of therapeutic formulations from this compound to membrane erythrocytes with a great attention to the highest concentrations, which paves promise for drug development.

Effect of N- 3, 4-Dichlorophenyl -N, N-Dimethylurea (Diuron) Herbicide to Serum Biochemistry of Clarias gariepinus

Assessing the effect of Diuron herbicide on post juvenile African catfish (Clarias gariepinus) using specific biochemical markers could provide vital information concerning the health status with regards to electrolyte determination. The fishes were subjected to different concentrations of diuron of (0.5, 0.75, 1.0, 1.25, and 1.5mgL-1 respectively) for 96hrs and the alterations in the serum enzymes, metabolites and ion level were determined. The lethal concentration (LC50) value of the herbicide was 1.0mg L-1 for 96h of exposure. During the experiment different behavioural changes were observed and recorded and blood samples were collected after 96hours of experiment to check for the effect of fish exposed to different concentration of diuron herbicide and the parameters observed were serum enzymes (ALT, ALP, AST and LDH). Biochemical examination was also carried out to know the changes in Total protein, glucose and cortisol level. Ion level examination was carried out to assess changes in sodium (Na+), potassium (K+) and chloride (Cl-). It was observed that there were significant differences (P˂0.05) in the serum enzymes analysis, biochemical examination and ion level examination and these parameters revealed differences with varying concentrations of diuron herbicide. Thus, diuron possesses toxicity effects on C. gariepinus
 Keywords: Herbicide, Clarias gariepinus, serum enzymes

Viability and reconstitution of delta-endotoxins from Bacillus thuringiensis var. israelensis extracts after forty\u2009years of storage against Aedes aegypti (Diptera: Culicidae)

BackgroundBacillus thuringiensis subsp. israelensis (Bti) produces insecticidal endotoxins known as Cry and Cyt. Its efficiency and specificity make it the most widely used substance as a biopesticide for controlling disease from vector insects, such as mosquitoes, responsible for important human diseases such as malaria, filariasis, dengue, and yellow fevers. To date, it is proven difficult to develop a commercial product that has more than 2 years of shelf life, and there is little information on the viability of these commercial proteins under prolonged storage conditions.ResultsThis study aimed to evaluate biological activity of reconstituted Bti endotoxins after 40 years of storage against the mosquito Aedes aegypti larvae. Five concentrations of Bti extracts were used for bioassays against 3rd and 4th instars of A. aegypti larvae. All reconstituted endotoxins from stored extracts showed a potency increase. The strain HD-500 from extract 3260 was the most effective insecticide (LC50 = 0.0014 mg/l), followed by 3756 (LC50 = 0.0037 mg/l). These strains were particularly notable, increasing their larvicidal potency one hundredfold and one thousandfold, respectively. Protein profiles in polyacrylamide gels revealed a greater presence of Cyt toxins compared to the stored Bti extracts, which maintained their activity at high concentrations.ConclusionThe reconstituted Bti strains presented a great biological activity against A. aegypti larvae, specially extract 3260 (median lethal concentration (LC50) value = 0.0014 mg/l). This considerable larvicidal activity after 40 years under storage was an encouraging signal for the development of future formulation strategies regarding their useful life. The stability of extracts of stored endotoxins produced by Bti decreased significantly, particularly Cyt1A protein, which is responsible for their synergistic activity.

Toxicity of Alkyl Sulfate Surfactant Detergent (AS) to Larvae of Vannamei Shrimp (Litopenaeus vannamei) From Marine Waters, District of Lingga Timur, Lingga Regency

The coastal area of East Lingga Subdistrict, Lingga Regency has been designated by the Lingga Regency government as the center for the development of shrimp pond cultivation. This study aims to determine the level of toxicity of the surfactant alkyl sulfate (AS) detergent to post larvae (PL) of Vannamei shrimp (Litopenaeus vannamei). An acute test was performed on PL10 samples exposed to AS media for 96 hours. Then the Median Lethal Concentration (LC50) value was calculated for 4 times (24 hours, 48 hours, 72 hours, and 96 hours). Furthermore, the PL-15 sample was AS in the sub chronic test, then the sample was exposed to AS media for 24 hours, then the growth rate and changes in the gill organ structure of the PL samples were observed. From the test results, it is known that the LC50 values in the AS test for the 24th, 48th, 72th, and 96th times of the shrimp larvae samples obtained LS50 values were 33.6 mg/l, 29.4 mg/l, respectively. 24.3 mg/l, and 22.8 mg/l. Subsequently, an increase in AS concentration by 17.11 mg/l in the rearing medium resulted in a decrease in the growth rate of post larvae. The acute and sub chronic testing period showed changes in the behavior of post-larvae samples. The histopathological observations found damage to the structure of the sample gill organs and hepatopancreas. Symptoms of damage to the structure of the gills began to appear at AS concentrations of 25.58 mg/l at time 96 and 72 with an LC50 value of 34.99 mg/l. Furthermore, it was also seen at an AS concentration of 9.78 mg/l at time 24. The results of this study found that AS toxicity to Vannamei larvae increased with increasing concentration and exposure time.

Field evaluation of toxicity of plant extracts against vector of filariasis Culex quinquefasciatus Say, 1823 (Diptera: Culicidae)

Mosquito control has been facing backlashes due to the emergence of resistant varieties against synthetic insecticides. The bioactivity of five plant extracts viz., Poncirus trifoliate, Murraya paniculata, Citrus bergamia, Aegle marmelos and Limonia acidissima was studied against the filarial vector of Culex quinquefasciatus Say, 1823. Larvicidal assays were conducted under laboratory condition to evaluate the 24 h LC50 and LC90 of the selected plants against 3rd instar larvae of Cx. quinquefasciatus. The lethal concentration (LC50 and LC90) values ranged from 76.26 to 208.32 mg/L and 191.85 to 477.16 mg/L, respectively. The result of larvicidal test suggests that the larvicidal activity of the L. acidissima and P. trifoliate extracts were highly influenced. Test results showed that the flavonoid compounds exhibited larvicidal activity against 3rd instar Cx. quinquefasciatus mosquitoes. Percent reduction was recorded with an LC50 concentration of L. acidissima and P. trifoliate. A field study was carried out to evaluate larvicidal activity on 24 h, 48 h and 78 h period and percentage of larval and pupal reduction due to L. acidissima and P. trifoliate extracts in the unused cement tank and mini water pool in Puthanampatti, Tiruchirappalli district. The field tested plant extracts proved to have various activities against different life stages of Cx. spp. Therefore, flavonoid compounds from L. acidissima and P. trifoliate plant can be a potential candidate for use in the development of commercial mosquito larvicidal products that may be an alternative to conventional synthetic chemicals, particularly in integrated vector control applications.

Toxicity assessment of green synthesized Cu nanoparticles by cell-free extract of Pseudomonas silesiensis as antitumor cancer and antimicrobial

Spherical homogeneous 32 nm, protein coated Pseudomonas silesiensis strain A3 CuNPs was investigated for their cytotoxicity effect as well as antimicrobial and antitumor activity. CuNPs cytotoxicity was estimated using human normal lung cell lines (Wi38) against CuNPs with concentrations ranging from 25 to 150 μg/mL using neutral red uptake assay. The cytotoxicity study revealed that the bacterial CuNPs had an impact on Wi38 cell viability at concentrations of 25, 50, 100 and 150 μg/mL CuNPs were 95.8, 91.1, 89.2 and 82.3%, respectively, with a strong correlation coefficient (r = 0.94) and a CuNPs IC50 value of 1057.0 μg/mL. CuNPs exhibit a broad-spectrum antimicrobial activity against various microorganism species, including fungi and Gram positive and negative bacteria using the agar-well diffusion method. The findings revealed that the most sensitive pathogens were Staphylococcus aureus ATCC5638 and Aspergillus flavus ATCC 9643 which tended to have a high inhibition zone diameter (50 and 47 mm, respectively). The minimum inhibitory concentration (MIC) of CuNPs was 50 μg/mL. The minimum lethal concentration (MLC) values were 50 and 75 μg/mL for S. aureus ATCC 5638 and A. flavus ATCC 9643, respectively. MLC/MIC ratio was ≤2, suggesting the CuNPs had a bactericidal or fungicidal effect on both pathogenic strains. Results also indicated that bacterial CuNPs at varying concentrations of 25, 50, 100 and 150 μg/mL were such a good antitumor agent against A549 lung carcinoma cell lines with an IC50 value of 137.5 μg/mL and a cell viability of 89.3, 79.6, 64.9 and 44.1%, respectively. The results also suggested that the biosynthesized-CuNPs were an antimicrobial and anticancer agent that could be used in future in food preservation, biomedicine and pharmaceutical fields.

Origanum vulgare ssp. hirtum Essential Oil as a Natural Intrinsic Hurdle against Common Spoilage and Pathogenic Microbes of Concern in Tomato Juice

The aim of the present study was to assess the commercial potential of the Origanum vulgare ssp. hirtum essential oil (OEO) as a natural intrinsic hurdle against common spoilage and pathogenic microbes in tomato juice. The main volatile compounds of the OEO identified by gas chromatography mass spectrometry (GC/MS) analysis were thymol and carvacrol, accounting for approximately 48% and 27%, respectively. Its activity against common food spoilage and pathogenic microbes was confirmed and the minimum inhibitory concentration (MIC), non-inhibitory concentration (NIC), and minimum lethal concentration (MLC) values were determined. OEO effectiveness was further validated in commercial tomato juice. Supplementation of tomato juice with OEO at concentrations lower than the MIC (350 ppm) resulted in significant delay of food spoilage and extension of the product’s shelf-life, as well as in inhibition of Listeria monocytogenes, Clostridium difficile, Saccharomyces cerevisiae, and Aspergillus niger growth after deliberate inoculation in both room and refrigerated temperatures. In conclusion, the results suggested that OEO may be used as an efficient intrinsic inhibitor of food spoilage and growth of pathogenic microbes in tomato juice.

Need for growing non-Bt cotton refugia to overcome Bt resistance problem in targeted larvae of the cotton bollworms, Helicoverpa armigera and Pectinophora gossypiella

BackgroundThe effectiveness of Bacillus thuringiensis (Bt) cotton against target arthropod larvae is decreasing day by day. The comparative effect of Bt expression among Bt cotton varieties and different plant parts was observed against the cotton bollworms: Helicoverpa armigera and Pectinophora gossypiella larvae.ResultsIn the present study, larval mortality of H. armigera was higher than P. gossypiella among selected Bt cultivars. Median lethal concentration (LC50) values were 8.91, 13.4, 14.0, and 36.4 for P. gossypiella, while 5.91, 4.04, 2.37, and 8.26 for H. armigera of FH-142, MNH-886, IR-3701, and FH-Lalazar, respectively. These values depicted that P. gossypiella had more Bt resistance problem than H. armigera larvae. The host range of both targeted insect larvae was different from each other due to the polyphagous feeding nature of the larvae of H. armigera that feed on different host plants, but P. gossypiella attacked only cotton with monophagous feeding habit. It was also notable from results that Bt expression in reproductive parts where the attacked pink bollworm was lower than the American bollworm, so the former had the maximum chance of resistance due to repeated exposure to Bt.ConclusionsIt was concluded that farmers be advised to follow the practice of growing non-Bt as a refuge crop to reduce the problem of Bt resistance in the target arthropod species.

Inheritance mode and metabolic mechanism of the sulfoximine insecticide sulfoxaflor resistance in Oxycarenus hyalinipennis (Costa).

Dusky cotton bug (DCB), Oxycarenus hyalinipennis (Costa) (Hemiptera: Lygaeidae), is a key insect pest of cotton. It causes huge losses to cotton and many other economically important crops. Sulfoxaflor is a newly introduced systemic insecticide that is effective against many sap-feeding insect pests such as aphids, whiteflies and true bugs. The present study was designed to characterize the inheritance of sulfoxaflor resistance in DCB. Moreover, the role of synergists in reducing sulfoxaflor resistance in DCB was also assessed. A field population of DCB has developed 1132.0-fold resistance to sulfoxaflor after 11 selected generations in the laboratory. Nonsignificant difference of reciprocal crosses was observed depending on the LC50 (median lethal concentration) values (95% confidence intervals overlapped), suggesting an autosomal mode of sulfoxaflor resistance inheritance. The degree of dominance of 0.7 for F1 (Sulfo-Sel Pop ♀ × Lab-Pop♂) and 0.6 for F1 '(Sulfo-Sel Pop ♂ × Lab-Pop♀), respectively, suggested that sulfoxaflor resistance was incompletely dominant. According to the monogenic model, the number of genes involved to induce sulfoxaflor resistance revealed that sulfoxaflor resistance was polygenic in nature. The realized heritability (h2 ) value for sulfoxaflor resistance was 0.2. The synergists experiment indicated that esterases were involved in the sulfoxaflor resistance mechanism in DCB. The current results indicate that there is autosomal, incompletely dominant and polygenic inheritance of sulfoxaflor resistance in DCB. Our results would be helpful in delaying sulfoxaflor resistance against DCB in the field. © 2021 Society of Chemical Industry.

Morphological and molecular identification of four Purpureocillium isolates and evaluating their efficacy against the sweet potato whitefly, Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae)

BackgroundEntomopathogenic fungi are widely distributed and well described within the fungal kingdom. This study reports the isolation, characterization, and virulence of 4 Purpureocillium lilacinum isolates against the sweet potato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae).ResultsFour strains of Purpureocillium lilacinum (XI-1, XI-4, XI-5, and J27) were isolated from soil samples from different localities of China. The morphological studies observed that four strains showed essentially the same morphological characteristics. After 7 days of cultivation, the colonies were purple, round, and bulged. Conidia were single-celled, oval to spindle-shaped, chain-like, and the spore size was about 2.0–2.3 × 3.1–4.0 μm. The genome-based identification results showed that ITS sequences of XI-1 (GenBank accession # MW386433), XI-4 (GenBank accession # MW386434), XI-5 (GenBank accession # MW386435), and J27 (GenBank accession # MW386436) were similar to another P. lilacinum. The newly identified strains of P. lilacinum proved pathogenicity to B. tabaci under laboratory conditions. In addition, the P. lilacinum isolate XI-5 was the most virulent one against different nymphal instars of whitefly having median lethal concentration (LC50) values of 4.99 × 106, 4.82 × 105, and 2.85 × 106 conidia/ml, respectively, 7 days post application.ConclusionThe newly isolated strains of P. lilacinum can be developed as a potential biopesticide against the whitefly although extensive field bioassays as well as development of proper formulation are still required.

Acute toxicity and sublethal effects of sodium laureth sulfate on oxidative stress enzymes in benthic oligochaete worm, Tubifex tubifex

The present study was performed to determine the acute toxicity of sodium laureth sulfate (SLES) and its sublethal effects on oxidative stress enzymes in benthic oligochaete worm Tubifex tubifex. The results showed that 96 h median lethal concentration (LC50) value of SLES for Tubifex tubifex is 21.68 mg/l. Moreover exposed worms showed abnormal behaviours including incremented erratic movement, mucus secretion, and decreased clumping tendency at acute level. Percentage of autotomy additionally increased significantly (P < 0.05) with the increasing dose of toxicant at 96 h exposure. Sublethal concentrations of SLES (10% and 30% of 96 h LC50 value) caused paramount alterations in the oxidative stress enzymes. Superoxide dismutase (SOD), reduced glutathione (GSH), glutathione S-transferase (GST), and glutathione peroxidase (GPx) exhibited a striking initiatory increment followed by a resulting descending pattern. Moreover, during exposure times, catalase (CAT) activity and malondialdehyde (MDA) level increased markedly with incrementing concentrations of SLES. However, the effects of sodium laureth sulfate on Tubifex tubifex were characterized and portrayed by the development of a correlation matrix and an integrated biomarker response (IBR) assessment. These results indicate that exposure to this anionic surfactant alters the survivability and behavioral response at acute level and modifies changes in oxidative stress enzymes at sublethal level in Tubifex tubifex.

EVALUACIÓN DEL RIESGO AMBIENTAL DE LA MEZCLA DE ALFA-CIPERMETRINA E IMIDACLOPRID SOBRE LA LOMBRIZ DE TIERRA (EISENIA FETIDA) (SAVIGNY, 1826)

En el presente estudio, se evaluó el riesgo ambiental (ERA) de la alfa-cipermetrina y del imidacloprid, individualmente y en mezcla, sobre Eisenia fetida (Savigny, 1826). La concentración letal media (CL50) para la alfa-cipermetrina y el imidacloprid fue de 341,1 mg·kg-1 y 2,34 mg·kg-1 a los 14 d de exposición, respectivamente, siendo más tóxico el imidacloprid. Se observó una reducción en el peso seco y húmedo en E. fetida, para ambos plaguicidas. La mezcla de alfa-cipermetrina e imidacloprid no permitió calcular la CL50 para la mortalidad; sin embargo, los valores subletales de NOEC (concentración a la cual no se observa efecto) y LOEC (concentración más baja a la cual se observa efecto), para el peso húmedo y seco de E. fetida, presentaron diferencias significativas con el control. Las unidades tóxicas (UT) mostraron un comportamiento antagónico entre la alfa-cipermetrina y el imidacloprid. La prueba de evasión arrojó un mayor efecto de la mezcla de alfa-cipermetrina e imidacloprid, lo que no ocurrió con los ensayos con los plaguicidas individuales. En general, el alfa-cipermetrina y el imidacloprid son considerados compuestos altamente tóxicos y no representaron un riesgo significativo a nivel agudo en base a la mortalidad de E. fetida, pero se observaron efectos subletales por afectación del crecimiento.

Volatile fatty acids from whey volatilome as potential soil fumigants to control Meloidogyne incognita

Organic residues emit volatile organic compounds (VOCs) that are toxic to plant-parasitic nematodes (PPNs). In this study, we demonstrated that whey produced by cow milk emit VOCs that are toxic to Meloidogyne incognita second-stage juveniles (J2), causing immobility above 80% and significant (P < 0.05) mortality compared to controls. The analysis of the volatilome done by gas chromatography coupled with mass spectrometry revealed 28 compounds, predominantly carboxylic acids and esters. Four of those volatile fatty acids (VFAs), namely acetic acid, octanoic acid, ethyl octanoate, and isovaleric acid, were chosen to further studies. The four tested VFAs were toxic to M. incognita J2, with lethal concentration values required to kill 50% of the nematode population (LC50), ranging from 134.30 to 236.08 μg mL−1. However, on eggs, only acetic acid and ethyl octanoate were consistent with J2 hatch inhibition, reaching 80% at a concentration of 1000 μg mL−1. In a greenhouse assay, when the VFAs were applied as soil fumigant, M. incognita infectivity and reproduction were significantly (P < 0.05) reduced compared to the negative control (water). Among them, ethyl octanoate application reduced (P < 0.05) the number of eggs to the level of the commercial fumigant dazomet. Overall, the volatile compounds released by whey were toxic to M. incognita J2 and contained a great diversity of molecules. Among the VFAs, ethyl octanoate stood out and showed the potential to be used in future field studies.

In vitro evaluation of antimicrobial efficacy of silver zeolite against common oral pathogens.

Antimicrobial efficacy and toxicity analysis of 5 different concentrations of silver zeolite (SZ) compound against 5 common oral pathogens Streptococcus mutans, Streptococcus pyogenes, Lactobacillus sp., Staphylococcus aureus, Candida albicans. The antimicrobial efficacy of 5 different concentrations of SZ was tested against 5 common oral pathogens using the agar well diffusion method and the MIC and MBC values were determined using the micro broth dilution method. The toxicity of all 5 different concentrations was evaluated using brine shrimp assay and lethal concentration (Lc50) value was determined. At 10 μg/mL the antimicrobial activity of SZ was almost negligible. The antimicrobial activity was observed in an increasing trend against all the test microorganisms as the concentration increased. At 75 & 100 μg/mL the zone of inhibitions was more than the control. Furthermore, MIC and MBC values of SZ with concentrations 25, 50, 75, and 100 μg/mL were determined and recorded. SZ was equally effective against all the test organisms. The LC25 (lethal concentration25) value was 1.6 μg/mL, whereas the LC50 value was 1.77 μg/mL and the LC75 value was 1.90 μg/mL, calculated from the probit computational method. SZ has the potential to change the ongoing system and bring about a revolution as an antimicrobial drug. However, the dose must be regulated as it can be toxic in higher concentrations. SZ compounds with the correct study of physicochemical properties and toxicity analysis can increase their pharmacological use and market value.

Fumigant and repellent potentials of Mentha pulegium L. and Citrus limon L. (Burm) essential oils against Tribolium confusum Duval. (Coleoptera: Tenebrionidae)

This study aims to investigate the chemical composition of essential oils (EOs) extracted from the aerial parts of pennyroyal (Mentha pulegium L.) and lemon peels (Citrus limon L.) and evaluate the fumigant toxicity and repellency against the most important and destructive stored product beetle in Algeria (T. confusum). Chemical analysis of the essential oil of M. pulegium showed that pulegone (62.24%), sabinene (5.51%) and menthol (16.5%) were the main essential components, while C. limon essential oil had limonene (66.93%) as the main compound, followed by β-pinene (4.52%), citral (3.09%) and β-Bisabolen (2.67%). The results show that the fumigant toxicity varies according to the concentration of essential oils, the median lethal concentration (LC50) values of Mentha pulegium and Citrus limon were 92.89 and 818.5 μl/Lair on T. confusum respectively. In addition, significant pest repellent activity was demonstrated with pennyroyal where repellent effects reached 80 and 90% (Class V) after 60 min exposure against the beetle at all concentrations (0.126, 0.314, 0.628 and 0.942 μL/cm2). The data obtained indicate that pennyroyal EOs show a higher toxicity and repellent activity against adults of T. confusum comparing to those of C. limon.

Slight induction and strong inhibition of Heterodera glycines hatching by short-chain molecules released by different plant species.

New management tools are necessary to reduce the damage caused by the soybean cyst nematode (SCN), Heterodera glycines. Identification of molecules that can stimulate second-stage juveniles (J2) hatching in an environment without food may contribute to that. In in vitro experiments, we evaluate the effect of volatile organic compounds (VOCs) released by soybean (Glycine max), bean (Phaseolus vulgaris), ryegrass (Lolium multiflorum), and alfalfa (Medicago sativa) on H. glycines egg hatching. VOCs released by all plant species significantly (p < 0.05) increased egg hatching. Short-chain molecules released by leaves and roots of soybean and bean increased the hatching up to 71.4%. The analysis of the volatilome done by gas chromatography coupled with mass spectrometry revealed 44 compounds in the plant emissions. Four of them, namely 3-octanol, 1-hexanol, hexanal and linalool were tested individually as hatching inductors. Under concentrations of 200, 600, and 1,000 µg/ml there was no hatching induction of H. glycines J2 by these compounds. On the other hand, in these concentrations, the compounds 3-octanol and 1-hexanol caused hatching reduction with values similar to the commercial nematicide carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methyl carbamate). In subsequent tests, the compounds 1-hexanol and 3-octanol showed lethal concentration values required to kill 50% of thenematode population (LC50) of 210 and 228 µg/ml, respectively, in the first experiment and, 230 and 124 µg/mlin the second one. Although we have not identified any molecules acting as hatching factor (HF), here we present a list (44 candidate molecules) that can be explored in future studies to find an efficient HF.

In vivo visualization assay to evaluate the effects of maternal exposure to mercury on offspring bioaccumulation in the oriental river prawn (Macrobrachium nipponense)

Mercury (Hg) is a persistent pollutant that accumulates in aquatic animals. However, studies related to understand how gonad tissue of this species responds to mercury exposure and elucidation of mercury bioaccumulation in crustacean offspring by cross-generational, are still sparse. The present study aimed to assess the bioaccumulation of Hg2+in vivo in prawn offspring by a specific aggregation-induced emission fluorogen (AIEgen). The 96 h median lethal concentration (LC50) values of mercury to the juveniles were 0.072 mg/L. Hg2+ reduced growth performance, damaged oocyte quality, and inhibited ovary maturation, thus inhibiting gonadal maturation in intact prawns. F1 offspring were exposed to Hg2+ by direct transfer from their F0 parents, as shown by the distribution of mercury in gonads and fertilized eggs. In the medium containing oriental river prawn larvae, the Hg2+ concentration decreased rapidly, indicating fast initial larval uptake of Hg2+. Due to metal ion triggered AIE activity, analysis of fluorescence images showed that prawn offspring accumulated Hg2+ via maternal transfer, and there was a relationship among the photoluminescence intensity, the AIEgen concentration, and mercury levels. The quantitative detection of Hg2+ absorption from prawn larvae by the AIEgen represents a novel analytical technique to understand the dynamics of Hg2+ between maternal and offspring.

Acute and chronic toxicity tests of systemic insecticides, four neonicotinoids and fipronil, using the tadpoles of the western clawed frog Silurana tropicalis

Extensive use of neonicotinoids and fipronil, which are popular systemic insecticides used in Japanese rice paddies, has raised concerns about their impacts on nontarget aquatic organisms such as amphibians. This study employed premetamorphic tadpoles of Silurana tropicalis and addressed the toxicity of four neonicotinoids (acetamiprid, clothianidin, dinotefuran, and imidacloprid) and fipronil. Acute toxicity tests were conducted under a 96-h semistatic exposure regime and median lethal concentration (LC50) values were calculated at 24-h intervals. All LC50 values of the four neonicotinoids exceeded 100 mg/L, suggesting their low acute toxicity to amphibians. Fipronil yielded much lower LC50 values (3.00–1.34 mg/L) and was highly toxic compared to the four neonicotinoids. Additionally, exposure to fipronil at >1 mg/L induced axial malformations, suggesting its teratogenicity. However, the LC50 values of fipronil were three orders of magnitude higher than the realistic concentrations in paddy water. Chronic toxicity tests were conducted with morphometric, gravimetric, and thyroid-histological endpoints. Premetamorphic tadpoles were exposed to each insecticide at two test concentrations: 0.1 and 1.0 mg/L for the four neonicotinoids; and 1/100 and 1/10 of the 96-h LC50 value for fipronil. Exposure to each insecticide continued until all tadpoles in the control reached late prometamorphic stages or the initial stage of metamorphic climax. At test termination, all insecticides showed no significant differences in any of the endpoints between the respective controls and chemical exposure groups. Overall, our results suggest that these insecticides alone do not directly affect amphibians through their larval stages at concentrations that likely occur in paddy water.

Acute toxicity of calcium hypochlorite (65% chlorine disinfectant) on the liver, brain, and gill of Clarias gariepinus fingerlings (Burchell, 1822)

The acute toxicity of Calcium Hypochlorite was investigated on the water quality and histopathology of liver, brain and gill of Clarias gariepinus fingerlings. Fish with average weight and length of 5.5 ± 0.8g and 7.8 ± 0.5cm were stocked at 10 fish per tank and fed with 45% crude protein diets. The experimental fish was exposed to a photoperiod of 12 hours daylight and 12 hours darkness. After the range finding test, the fingerlings were exposed to test concentrations of treatments 0.000 mg/L (A), 0.011 mg/L (B), 0.033 mg/L (C), 0.055 mg/L (D) and 0.077 mg/L (E) and was replicated trice. The Lethal Concentration value (LC50) for the disinfectant was 0.033mg/L. Behavioural changes such as erratic swimming, frequent jumping and gasping for air at the surface was observed in the exposed fish. Histopathology of the brain showed different stages of spongiosis and necrosis; gills showed thickening of the lamellae and necrosis while the liver showed varying congestion in the exposed fish. The observed changes in behaviour and histopathology were normal in the control fish and increased with increase in concentration of disinfectant to the exposed fish. It is therefore essentia

Toxicity and Biological Effects of Beauveria brongniartii Fe0 Nanoparticles against Spodoptera litura (Fabricius).

Simple SummaryMetal-based nanoparticles of different microbial pest control agents have been effective against several pests. This study reports the synthesis of Beauveria brongniartii based Fe0 nanoparticles (Fe0NPs) and their bio-efficacy against Spodoptera litura that was observed during this study. The median lethal concentration (LC50) of Fe0NPs against S. litura after 7 days was 59 ppm, whereas the median survival time (LT50) for 500 ppm concentrations of Fe0NPs was 2.93 days. B. brongniartii Fe0NPs caused a significant reduction in feeding and growth parameters as well as detoxifying enzyme production by S. litura at the end of the experimental period. These findings suggest that B. brongniartii Fe0NPs can potentially be used in environmentally friendly S. litura management programs.Nanotechnology has clear potential in the development of innovative insecticidal products for the biorational management of major insect pests. Metal-based nanoparticles of different microbial pest control agents have been effective against several pests. Synthesis of Beauveria brongniartii based Fe0 nanoparticles (Fe0NPs) and their bio-efficacy against Spodoptera litura was observed during this study. Beauveria brongniartii conidia were coated with Fe0NPs and characterized by applying a selection of different analytical techniques. Ultraviolet (UV) spectroscopy showed the characteristic band of surface plasmon at 430 nm; Scanning electron microscopy (SEM) images showed spherical shaped nanoparticles with a size ranging between 0.41 to 0.80 µm; Energy-dispersive X-ray (EDX) spectral analysis revealed characteristic Fe peaks at 6.5 and 7.1 Kev; the X-ray diffractogram showed three strong peaks at 2θ values of 45.72°, 64.47°, and 84.05°. The bioassay studies demonstrated that mortality of 2nd instar S. litura larvae following Fe0NPs treatment increased with increasing concentrations of Fe0NPs at different time intervals. The median lethal concentration (LC50) values of Fe0NPs against S. litura after seven days of fungal treatment was 59 ppm, whereas median survival time (LT50) values for 200 and 500 ppm concentrations of Fe0NPs against S. litura seven days post-treatment were 5.1 and 2.29 days, respectively. Beauveria brongniartii-Fe0NPs caused significant reductions in feeding and growth parameters (relative growth rate, relative consumption rate, and efficiency of conversion of ingested food) of S. litura. Beauveria brongniartii Fe0NPs induced reduction in glutathione-S-transferase activities throughout the infection period whereas activities of antioxidant enzymes decreased during later periods of infection. These findings suggest that B. brongniartii Fe0NPs can potentially be used in biorational S. litura management programs.