Higher LC50 Values Research Articles

Hexyltrimethylammonium ion enhances potential copper-chelating properties of ammonium thiomolybdate in an in vivo zebrafish model

Ammonium and hexyltrimethylammonium thiomolybdates (ATM and ATM-C6) and thiotungstates (ATT and ATT-C6) were synthesized. Their toxicity was evaluated using both in vitro and in vivo approaches via the zebrafish embryo acute toxicity assay (ZFET), while the copper-thiometallate interaction was studied using cyclic voltammetry, as well as in an in vivo assay. Cyclic voltammetry suggests that all thiometallates form complexes with copper in a 2:1 Cu:thiometallate ratio. Both in vitro and in vivo assays demonstrated low toxicity in BALB/3T3 cells and in zebrafish embryos, with high IC50 and LC50 values. Furthermore, the hexyltrimethylammonium ion played a crucial role in enhancing viability and reducing toxicity during prolonged treatments for ATM and ATT. In particular, the ZEFT assay uncovered the accumulation of ATM in zebrafish yolk, averted by the incorporation of the hexyltrimethylammonium ion. Notably, the copper-thiometallate interaction assay highlighted the improved viability of embryos when cultured in CuCl2 and ATM-C6, even at high CuCl2 concentrations. The hatching assay further confirmed that copper-ATM-C6 interaction mitigates inhibitory effects induced by thiomolybdates and CuCl2 when administered individually. These results suggest that the incorporation of the hexyltrimethylammonium ion in ATM increase its ability to interact with copper and its potential application as a copper chelator.

In-vitro Pharmacological Investigation of Ludwigia adscendens

Aims: This research objective was to investigate some in-vitro properties of methanol-extracted plant extracts of Ludwigia adscendens (the water primrose). The primary method of assessment for the methanolic extract of Ludwigia adscendens (MELA) was investigated for phytochemical screening. It was determined to look into the plant's potential for in vitro activities, such as antioxidant, antimicrobial, anti-inflammatory anti-arthritis, cytotoxic, thrombolytic and membrane stabilizing activity due to the pharmaceutical interest in its component parts.
 Methodology: Phytochemical screening was performed utilizing a battery of test reagents. Antioxidant, antimicrobial, anti-inflammatory, anti-arthritic, cytotoxic, thrombolytic and membrane stabilizing activities were measured at various doses using the DPPH Free Radical Scavenging Assay, the Disk Diffusion Method, Egg Albumin Protein Denaturation Assay, the Inhibition of Protein Denaturation Assay, the Brine Shrimp Lethality Bioassay, Clot lysis assay and heat induced and hypotonic induced haemolysis method.
 Results: The findings of research on MELA's phytochemical screening showed the presence of a wide range of various phytochemical components. The higher antioxidant activity of MELA is shown by its IC50 value of 85.76 µg/mL. Significant antibacterial action was shown by MELA. As compared to the standard ascorbic acid, this extract showed significantly greater anti-arthritic and anti-inflammatory effects. MELA exhibited much higher LC50 value which is 1.147 µg/mL than the typical vincristine-sulphate in a lethality test with brine shrimp. Comparatively speaking, this herb has quite powerful thrombolytic action. Significant membrane stabilizing action has also been shown by MELA.
 Conclusion: To wrap it up, it is clear that this plants phytochemical can be used for wide range of drug discovery field due to its potent pharmacological actions.

Phytochemical Profile And Toxicity Testing Of African Leaf Extract (Vernonia Amygdalina Delile) With Liquid Variation Scavenger Method Brine Shrimp Lethality Test (BSLT)

Background: The African leaf (Vernonia amygdalina Delile) is one of the plants used as a traditional medicine, one of which is anti-cancer. Aim: The study aims to identify compound groups, toxic effects and LC50 values of African leaf extracts with variations in the leaf fluid. Method: In this study, African leaves were extracted using a maseration method with three fluids namely n-hexane, ethyl acetate and 70% ethanol. The extract was qualitatively studied by the group of chemical compounds and toxicity tests were conducted using the method of Brine Shrimp Lethality Test. (BSLT). Result: The results of this study showed that n-hexane extract contains flavonoid and glycoside compounds. Ethyl acetate extract has a flavonoid compound, saponins and glucosides. The results of a linear regression analysis showed that 70% ethanol extract was an extract with the highest LC50value with a LC50 value of 31.80 ppm, an ethyl acetate extracts with LC50 values of 51.70 ppm and n-hexane extracts with LC50, with a 91.88 ppm value of LC50. Conclusion: This study showed that the three extracts included a strong toxic ketegori with a range of 0-100 ppm.

Determining the Median Lethal Concentration (LC50) and Seedling Growth Effects of MARDI Nano-fertilizer on Rock melon (Cucumis melo)

New fertilizer formulations and nitrogen delivery systems are needed to address deteriorating nutrient-use-efficiency and environmental hazards due to farmers' dependency on chemical fertilizers. Nanofertilizers (NF) made from tailored smart nano materials are a viable alternative to inefficient and harmful traditional fertilizers. Nanotechnology and NFs may help solve chemical fertilizers formulation difficulties. To boost rock melon yields, MARDI has created a nano-fertilizer made from nano-emulsions. The relations between seed germination inhibition (%) of rock melon seed and different concentrations of MARDI nano-fertilizer showed that when nano-fertilizer concentrations increased from 10 to 45% with inhibition 3.3% to 100%, seed germination decreased. The LC50 value was calculated at 32.2% equal to 322,000 ppm, with upper and lower limits at 25.346% and 40.953%, 96 hrs after treatments, indicating the formulation is not toxic with a high LC50 value. In order to further study the effects of the created nano-fertilizer on the growth of rock melon plants across the adult, reproductive, and developmental stages, it is suggested that future field trials work use a concentration of 0.5% of the developed MARDI nano-fertilizer.

In-vitro and In-vivo Pharmacological Evaluation of Persicaria lapathifolia Available in Bangladesh

Purpose: The purpose of this research was to examine the effects of Persicaria lapathifolia (Pale smartweed) leaf and bark extracts prepared with methanol on in vitro activities like antioxidant, antimicrobial, anti-arthritis, anti-inflammatory, and cytotoxic, as well as on some in vivo activities like analgesic and neuropharmacological properties in animal model.
 Methodology: The primary method for the methanolic extract of Persicaria lapathifolia leaf (MEPLL) and methanolic extract of Persicaria lapathifolia bark (MEPLB) were investigated for phytochemical screening. It was determined to look into the plant's potential for in vitro activities, such as phytochemical screening, antioxidant, anti-arthritis, anti-inflammatory, anti-bacterial, and cytotoxic, due to the pharmaceutical interest in its component parts. Its described effects on its in vivo analgesic and neuropharmacological activities in animal models are significant compared to the standard. This research was conducted between July 2022 and November 2022 in the Stamford University Bangladesh, Dhaka, Laboratory of Physiology and Pharmacology, Department of Pharmacy, and Laboratory of Microbiology. Antioxidant, anti-arthritic, anti-inflammatory, antibacterial, cytotoxic, analgesic, and neuropharmacological activities of MEPLL and MEPLB were investigated. Phytochemical screening was performed utilizing a variety of test reagents. Antioxidant, total phenolic content, anti-arthritic, anti-inflammatory, antibacterial, and cytotoxic activities were measured at various doses using the DPPH Free Radical Scavenging Assay, the Folin-Ciocalteu technique, the Inhibition of Protein Denaturation Assay, Egg Albumin Protein Denaturation Assay, the Disk Diffusion Method, and the Brine Shrimp Lethality Bioassay. The analgesic effectiveness was evaluated by using acetic acid to elicit writhing in Swiss albino mice and then testing the animals on a hot plate. Locomotor activity was measured by open field and hole cross tests as part of the neuropharmacological investigation.
 Results: Research performed on MEPLL and MEPLB's phytochemical screening yielded results that revealed the presence of a variety of different phytochemical components. In comparison to MEPLL's IC50 value of 1.49 µg/mL, MEPLB's value of 30.45 µg/mL indicates its superior antioxidant activity. Both extracts demonstrated significant anti-arthritic and anti-inflammatory effectiveness in comparison to the standard drug. When compared to MEPLB, MEPLL exhibited much more antibacterial activity. In a lethality test using brine shrimp, MEPLL and MEPLB both had much higher LC50 values than the standard vincristine sulfate. Their respective values were 1.42 and 0.66 µg/mL. In contrast, MEPLL inhibited peripheral nociception in the acetic acid-induced writhing nociceptive paradigm with percent inhibitions of 60.72 and 67.56, respectively, while MEPLB inhibited 48.22 and 67.28, respectively, at the aforementioned doses. In addition, the hot plate test revealed a significant analgesic effect. The extract was also shown to have a more negative impact on motor coordination in the Open Field and Hole Cross Tests than the standard Diazepam.
 Conclusion: This research demonstrates a relationship between the existence of anti-oxidative, anti-arthritis, and anti-bacterial activities, as well as a strong cytotoxic, analgesic, and neuropharmacological activity, which substantiates all previously made claims against Persicaria lapathifolia.

Healing Wounds Efficiently with Biomimetic Soft Matter: Injectable Self-Healing Neutral Glycol Chitosan/Dibenzaldehyde-Terminated Poly(ethylene glycol) Hydrogel with Inherent Antibacterial Properties.

The high prevalence of acquiring skin wounds, along with the emergence of antibiotic-resistant strains that lead to infections, impose a threat to the physical, mental, and socioeconomic health of society. Among the wide array of wound dressings developed, hydrogels are regarded as a biomimetic soft matter of choice owing to their ability to provide a moist environment ideal for healing. Herein, neutral glycol chitosan (GC) was cross-linked via imine bonds with varying concentrations of dibenzaldehyde-terminated polyethylene glycol (DP) to give glycol chitosan/dibenzaldehyde-terminated polyethylene glycol hydrogels (GC/DP). These dynamic Schiff base linkages (absorption peak at 1638 cm-1) within the hydrogel structure endowed their ability to recover from damage as characterized by high-low strain exposure in continuous step strain rheology. Along with their good injectability and biodegradability, the hydrogels exhibited remarkable inhibition against E. coli, P. aeruginosa, and S. aureus. GC/DP hydrogels demonstrated high LC50 values in vivo using zebrafish embryos as a model system due to their relative biocompatibility and a remarkable 93.4 ± 0.88% wound contraction at 30-dpw against 49.1 ± 3.40% of the control. To the best of our knowledge, this is the first study that developed injectable glycol chitosan/dibenzaldehyde-terminated polyethylene glycol self-healing hydrogels for application in wound healing with intrinsic bacteriostatic properties against the three bacteria.

The effect of chlorantraniliprole on the transcriptomic profile of Spodoptera frugiperda: a typical case analysis for the response of a newly invaded pest to an old insecticide.

Chlorantraniliprole is a diamide insecticide widely used in China over the last 15 years. The fall armyworm (FAW), Spodoptera frugiperda, newly invaded China in 2019. The response of FAW to chlorantraniliprole deserves more attention, in the context of many destructive lepidopteran species are resistant to diamide insecticides and the patent on core chemical of chlorantraniliprole in China expired in August 2022. This study investigated the response profile in larvae under chlorantraniliprole-induced (LC50) stress using methods of bioassay, RNA-Seq and qPCR. We observed growth inhibition and lethal effects in FAW larvae, but at a relatively high LC50 value compared to other several pests. Additionally, under chlorantraniliprole-induced stress, 3309 unigenes were found to be differentially expressed genes. The impacted genes included 137 encoding for detoxification enzymes, 29 encoding for cuticle proteins, and 20 key enzymes involved in the chitin metabolism, which all associated with metabolic resistance. Finally, we obtained the single nucleotide polymorphisms (SNPs) of two RyR genes, which are the target proteins for chlorantraniliprole. We also investigated the causes of the high LC50 value in our FAW, which possibly related to the stabilized 4743M on SNP frequency of RyR. These findings documented the genetic background of RyR of FAW and indicated that application of chlorantraniliprole has a high risk of controlling FAW in China. In brief, our results provide a better understanding of the mechanisms of chlorantraniliprole toxicity and detoxification in FAW, and will aid in monitoring the development of resistant strains for a newly pest to an old insecticide.

Baicalein prevents stress-induced anxiety behaviors in zebrafish model.

Baicalein is a flavonoid mainly obtained from plants with wide range of biological activities, including neuroprotection. An acute and unexpected chronic stress (UCS) protocol has recently been adapted to zebrafish, a popular vertebrate model in brain research. The present study was aimed to evaluate baicalein's anti-anxiety potential in a zebrafish model by induction, which included neuropharmacological evaluation to determine behavioural parameters in the novel tank diving test (NTDT) and light-dark preference test (LDPT). The toxicity was also assessed using the brine shrimp lethality assay, and the 50% lethal concentration (LC50) was determined. The animals were then stressed for 7days before being treated with different doses of baicalein (1 and 2mg/L) for another 7days in UCS condition. Due to acute stress and UCS, the frequency of entries and time spent in the 1) top region and 2) light area of the novel tank reduced significantly, indicating the existence of elevated anxiety levels. The biological activity of baicalein was demonstrated by its high LC50 values (1,000μg/ml). Additionally, baicalein administration increased the frequency of entries and duration spent in the light region, indicating a significant decrease in anxiety levels. Overall, the present results showed that baicalein has a therapeutic advantage in reversing the detrimental consequences of UCS and acute stress, making it is a promising lead molecule for new drug design, development, and therapy for stress.

Variation in the toxicity of a novel meta-diamide insecticide, broflanilide, among thrips pest species and developmental stages.

Thrips pests cause increasing damage to crops around the world. Widespread usage of some insecticides against thrips has now led to the evolution of resistance to several active ingredients, and new insecticides are required. This study examined the toxicity of the novel insecticide broflanilide to multiple populations of several thrips pests. Bioassays showed that thrips populations had LC50 values ranging from 0.5 to almost 300 mg·L-1 . A population of Frankliniella occidentalis had the highest LC50 value at 290.63 mg·L-1 , while a population of Echinothrips americanus had the lowest LC50 value at 0.51 mg L-1 . LC50 values among seven populations of Thrips palmi ranged from 2.5689 to 23.6754 mg·L-1 , indicating intraspecific variation in toxicity. In this species, the toxicity of broflanilide was relatively higher in adults than in larvae. More than 90% of eggs of T. palmi could not develop into larvae when treated with 5-50 mg L-1 broflanilide. Compared to five commonly used insecticides, broflanilide showed relatively high toxicity to T. palmi. Field control tests with T. palmi showed that control efficacy (from 90.44% to 93.14%) was maintained from day three to day 14 after treatment with 22.5 and 45 ga.i hm-1 broflanilide. Broflanilide is potentially a useful insecticide for controlling Thrips hawaiiensis, Frankliniella intonsa, Megalurothrips usitatus. E. americanus, and some populations of T. palmi. However, the variation in toxicity of this insecticide to different species, populations, and developmental stages indicates that target species and life stages may need to be carefully considered. © 2022 Society of Chemical Industry.

Anti-Anaemic Activity and Potential Toxicity of Extracts of Four Tinctorial Plants Used in the Treatment of Anemia in Benin: <i>Gossypium barbadense, Sorghum bicolor, Hibiscus sabdariffa</i> and <i>Justicia secunda</i>

Justicia secunda, Sorghum bicolor, Gossypiun barbadense and Hibiscus sabdariffa are dye plants traditionally used in Benin for the treatment of anemia. This work is part of the therapeutic valorization of dyes from these plants. Its objective is to characterize their composition in chemical groups and evaluate their harmlessness and their anti-anaemic property in laboratory rats. Anemia was induced in Wistar rats by phenylhydrazine hydrochloride followed by treatment by gavage with hydroethanolic extracts of the plants studied. Phytochemical screening of these extracts made it possible to characterize the major chemical groups, in particular alkaloids, polyphenols including tannins, flavonoids and leucoanthocyanins, as well as reducing compounds and saponosides in the plants studied. Cytotoxic analysis of these extracts on Artemia salina shrimp larvae revealed globally high LC50 values of between 3.14 and 4.64 mg/mL, which testify a priori to the harmlessness of these extracts. The administration of the hydroethanolic extract of each plant to anaemic rats at doses of 2000 mg/kg/d promoted, after 15 days, an increase in hemoglobin levels, the number of red blood cells and hematocrit, going to more than 90% recovery of the hematological parameters involved. The highest rate, 99.06% being that of the species Justicia secunda followed closely by Sorghum bicolor (96.80%) compared to 93.93% obtained by treatment with the Ranferon-12 positive control used. Indeed, these results confirm the therapeutic indication of these plants in the resorption of anemia in traditional medicine.

Brine shrimp lethality test of various Cinnamomum iners (Lauraceae) barks extracts

Cinnamomum iners (Lauraceae) is a traditional plant that widely used to relieve headache, breathingand appetite problems. This plant has been used over the centuries on several illnesses with bacterialsymptoms such as fevers, digestive ailments and coughs. However, lack of scientific studies havebeen conducted to identify its toxicity. Thus, an evaluation on the toxicity of this plant extracts iscrucial to support its therapeutic claims as well as to ensure that there was no side effects toconsumers. Various extracts from C. iners barks were screened for their toxicity against brineshrimp using the brine shrimp lethality test. All extracts exhibited very high LC50 (50% lethalconcentration) values greater than 1mg/ml (1000 ?g/ml) with the hexane extracts showed thehighest toxicity to the brine shrimp with LC50 value of 1306.79 ?g/ml, while the lowest toxicitywas the ethyl acetate extract at 3370.13 ?g/ml. This finding corroborates the traditional uses of thisplant and could be developed as another alternative natural sources in treating various diseases.

Phosphoproteomic Characterization of Primary AML Samples and Relevance for Response Toward FLT3-inhibitors.

Phosphoproteomic Characterization of Primary AML Samples and Relevance for Response Toward FLT3-inhibitors.

Annual analysis of field-evolved insecticide resistance in Bemisia tabaci across China.

Over recent decades, many efficacious insecticides have been applied for control of Bemisia tabaci, one of the most notorious insect pests worldwide. Field-evolved insecticide resistance in B. tabaci has developed globally, but remains poorly understood in China. In this study, a total of 30 field samples of the whitefly Bemisia tabaci from eight provinces of China were collected in 2015 to 2018. Twenty-four of the populations were identified as Mediterranean, 'Q' type (MED), three were Middle East-Asia Minor 1, 'B' type (MEAM1), and three were mixtures of MED/ MEAM1. After identifying whether they belong to MED or MEAM1, the selected individuals were used in bioassays assessing insecticide resistance to abamectin, thiamethoxam, spirotetramat, cyantraniliprole, and pyriproxyfen. Our results showed that all populations in the eight regions had little or no resistance to abamectin; abamectin resistance was highest in the Hunan (Changsha) and Hubei (Wuhan) regions and was lowest in the island region of Hainan (Sanya). The resistance of B. tabaci to spirotetramat, cyantraniliprole, and pyriproxyfen increased each year. The resistance to thiamethoxam remained low because of the high LC50 value for the laboratory strain. These findings suggest that a rotation system using efficacious B. tabaci insecticides with differing mode of actions ought to be implemented for sustainable control to reduce the potential of resistance development. This study provides important data to support the integrated pest management and insecticide resistance management of B. tabaci in China. © 2021 Society of Chemical Industry.

COMPARATIVE STUDIES ON ANTIDIABETIC, ANALGESIC, AND CYTOTOXIC EFFECT OF ETHANOLIC EXTRACTS OF AMARANTHUS GANGETICUS L. AND ALTERNANTHERA SESSILIS L.

Objective: The present study was designed to evaluate and compare antidiabetic, analgesic, and cytotoxic properties of Lal shak (Amaranthus gangeticus L.) and Chanchi shak (Alternanthera sessilis L.). We carried out this work to explore the medicinal uses of very common and cheap leafy plant vegetables among the people of all classes.
 Methods: The antidiabetic activity was evaluated and compared by studying the effect of ethanolic extract of A. gangeticus (EEAG) and ethanolic extract of A. sessilis (EEAS) against blood glucose level of alloxan-induced diabetic mice in every 6 h for 24 h. To evaluate and compare analgesic and cytotoxic activity, different tests such as acetic acid-induced writhing test, hot plate test, and brine shrimp lethality bioassay test had been performed.
 Results: The mice were treated with both plants extract at a dose of 200 mg/kg body weight in case of antidiabetic activity test. Blood glucose level was examined and found that there was a significant reduction of blood glucose level with EEAG (p<0.05) and EEAS (p<0.001) in comparison with their respective diabetic control group. Although both plant extracts reduced the blood glucose level, the glucose reducing effect was higher in EEAS. Both the plants showed significant (p<0.05) peripheral analgesic activity in treated mice but no significant central analgesic activity. EEAG showed higher peripheral analgesic activity than EEAS. In brine shrimp lethality bioassay, both the plants showed higher LC50 value thus cytotoxicity occurs at very higher dose and safe to administer.
 Conclusion: In this study, both the plants showed sufficient antidiabetic property and higher LC50 value, thus administration of leafy vegetable Lal shak and Chanchi shak may be useful for diabetic people. Chanchi shak may be more helpful for diabetic people than Lal shak.

Evaluation of toxicity and teratogenicity of anti-psychotic drugs followed by determination of anti-psychotic property of Mangifera indica bark through behavioral assay on Danio rerio model

Psychosis is a gathering of genuine sicknesses that influence the brain. About 2% of the populace experiences psychosis worldwide. As of now accessible advertised medications like , has some genuine antagonistic impacts. there is no agreeable cure available for avoidance and the executives of psychosis. Thus, the interest in natural medication is expanding. We have correlated the toxicity of various synthetic drugs ( and ) with that of the mango bark extract and assessed the proficiency of the natural medicines by building up social test on model followed by the investigation of the chemical drugs just as herbal medications. Bradycardia, increased amount of deaths in embryos were observed during the toxicity monitoring of chemical medications, and in terms of bending of tail, , loss of blood circulation and death of eggs were also found in acute toxicity study. On the other hand, the mango bark did show a very high range LC50 value inferring low toxicity of the extract. Also, the extract did not show any significant and gave good results in the assay. With such high rate of toxicity and effect of chemical drugs on the fish embryo, it can be estimated to show some in humans too, as we have the right amount of similar genes with that of thus an alternative to such chemical drugs can be the mango bark extract which showed low toxicity rate and almost negligible and even its anti-psychotic property is not compromised. with further modifications and investigations, the mango bark extract can be thought of as an alternative to that of the current chemical drugs with the elimination of unnecessary .

Management of Aedes aegypti using green silver nanoparticles and botanical extracts

The excessive use of insecticides has led to development of resistance in Aedes aegypti and negative impact on environment and non-target organisms. To overcome these problems, emphasis is being laid for alternatives, therefore, in the present study, the toxicity of eight plant extracts and their green synthesized nanoparticles were evaluated against A. aegypti. Clove extracts caused the maximum mortalities of 92% and 90% of 3rd and 4th instar larvae of A. aegypti followed by ginger causing 90% and 78% mortalities respectively. On the other hand, the minimum mortalities of these larvae were caused by neem and garlic extracts. In case of green silver nanoparticles, the maximum mortalities of 3rd and 4th instar larvae of A. aegypti were caused by clove followed by ginger while the minimum mortalities were caused by nanoparticles of datura followed by garlic. All the green silver nanoparticles caused mortalities of both the instars of the mosquito above 80% with few exceptions. Datura extracts showed the minimum LC50 values after 72 hours of application followed by neem against the 3rd and 4th instar larvae of A. aegypti. The highest LC50 value was observed in case of ginger followed by clove and eucalyptus. In case of silver nanoparticles, the minimum LC50 values after 72 hours were recorded in case of datura, neem and garlic while the values were the maximum in case of clove and ginger. The LC50 values decreased with the passage of time.

Efficacies of some isolates of Lecanicillium lecanii to control Tribolium castaneum (Col., Tenebrionidae)

The entomopathogenic fungi are safe and ecofriendly biocontrol agents which can be applied against stored product pests. In this study, potentials of some Iranian isolates of Lecanicillium lecanii (PAL6, PAL7 and PAL8) and Lecanicillium muscarium to control Tribolium castaneum (AGM5) were investigated under laboratory conditions. For this purpose, the LC50 and LT50 values of each isolates to adults of the beetle were estimated. Results showed that all of the isolates were virulent to the pest. The estimated LC50 values were ranged from 2.8 × 106 to 6.13 × 1022 (conidia/mL). The lowest and the highest LC50 values were estimated for L. lecanii (PAL7) and L. mucarium (isolate AGM5), respectively. The LT50 values varied from 4.99 to 13.65 days. The LT50 values were decreased by increasing conidial concentrations of each isolate. Moreover, at each conidial concentration, the LT50 values for L. lecanii isolate PAL8 were significantly lower than other isolates. Totally, among the isolates, L. lecanii isolate PAL7 (at concentration 107 conidia/mL) is the most promising isolate. The laboratory study is preliminary, and further experiments under field condition are required before any recommendations.

Bt-toxin susceptibility and hormesis-like response in the invasive southern armyworm (Spodoptera eridania)

Bacillus thuringiensis (Bt) varieties of soybean and cotton have been widely adopted in South America, but defoliation by the southern armyworm Spodoptera eridania (Lepidoptera: Noctuidae) has increased in these crops. This issue may be linked to the low inherent susceptibility of the larvae to some Bt toxins. However, this hypothesis was not yet tested, nor was the potential sublethal effects of the toxins on larval development of southern armyworm. Here we determined the response of southern armyworm larvae exposed to Bt toxins representative of those used in soybean and cotton cultivars. In concentration-response bioassays, whereas a low median lethal concentration (LC50) value was found for Cry2Aa (11 ng/cm2), higher LC50 values were found for Cry1F (>3000 ng/cm2) and Cry1Ac (>10000 ng/cm2). Larval growth of the southern armyworm showed a hormesis-like response when the larvae were reared on artificial diet containing increasing Cry1Ac concentrations. Such enhanced larval growth was also observed when fresh foliage of Cry1Ac soybean or its lyophilized tissue in an artificial diet were fed to the larvae. Although the foliage of the dual-toxin Bt cotton producing Cry1Ac + Cry2Ab killed all larvae, its lyophilized leaf tissue caused no significant larval mortality when diluted 25 times. These results indicate that southern armyworm larvae have low inherent susceptibility to Cry1Ac and Cry1F toxins, while the Cry1Ac Bt toxin can enhance its larval growth. In addition, Cry1Ac + Cry2Ab Bt cotton may not meet the high-dose condition for the southern armyworm. These findings have important implications for pest management of the southern armyworm, which is discussed.

Acute toxicity of glyphosate on various life stages of calanoid copepod, Pseudodiaptomus annandalei

Copepods are one of the most important primary producers and biodiversity indicators. They are also highly susceptible to various toxicants. In this study, glyphosate (Roundup®), a widely used herbicide was used to investigate the toxicity effect on calanoid copepods, Pseudodiaptomus annandalei, focused on their nauplius, copepodid, and adult stages. Different concentrations of glyphosate (i.e. 0 - as control, 0.05, 0.1, 0.4, 1.6, 6.4 and 25.6 mg/L) were used to elucidate the tolerance level of P. annandalei. The survival rate of copepod was recorded at the intervals of 24, 48, 72 and 96 h after glyphosate exposure. The analysis was performed using probit test to determine the sub-lethal concentrations. Our results revealed that LC50 of the nauplius stage was recorded as 3.47, 3.02, 1.86 and 1.10 mg/L at 24, 48, 72 and 96 h, respectively. Higher LC50 values were recorded at 4.36 mg/L for 24 h, 3.09 mg/L for 48 h, 2.00 mg/L for 72 h, and 1.12 mg/L for 96 h at the copepodid stage. Generally, adult copepods showed a higher level of tolerance to glyphosate among all stages, whereby at this stage LC50 values were recorded as 11.70 mg/L for 24 h,10.23 mg/L for 48 h, 7.41 mg/L for 72 h, and 3.61 mg/L for 96 h, respectively. Our results indicated that prolong exposure time of glyphosate could increase the susceptibility of P. annandalei to the herbicide. Nauplii are the most sensitive group among all. This study showed that glyphosate could post significant eco-toxicological impact to the non-targeted organism.

Sublethal Effects of Four Insecticides on the Seven-Spotted Lady Beetle (Coleoptera: Coccinellidae).

To further develop integrated pest management (IPM) strategies against two sucking insect pests, Aleurocanthus spiniferus (Quaintanca) (Hemiptera: Aleyrodidae) and Toxoptera aurantii Boyer (Hemiptera: Aphididae), in Chinese tea plantations, it is important to evaluate the effects of insecticides on biological control agents, such as the seven-spot lady beetle, Coccinella septempunctata L. (Coleoptera: Coccinellidae). Therefore, we tested the toxicity and sublethal effects of spirotetramat, clothianidin, lambda-cyhalothrin, and bifenthrin on C. septempunctata. The side effects of the active ingredients of the insecticides were evaluated with residual contact tests on the larvae of C. septempunctata in the laboratory. Spirotetramat and clothianidin exhibited lower lethality to C. septempunctata as shown by the higher LC50 values and had higher selectivity for A. spiniferus and T. aurantii based on the selective toxicity ratios being superior to other tested insecticides. Spirotetramat also did not affect survival, longevity, fecundity, and egg hatching of C. septempunctata. Clothianidin and bifenthrin prolonged the duration of larval development stages of C. septempunctata obviously. Clothianidin at >2.5 mg/liter, lambda-cyhalothrin at >0.03 mg/liter, and bifenthrin at >0.125 mg/liter significantly reduced the survival and pupation rates of C. septempunctata larvae. Furthermore, spirotetramat at 3.125 mg/liter was harmless (IOBC class 1) to larvae of this coccinellid species. Based on the results, spirotetramat was innocuous to C. septempunctata larvae compared with clothianidin, lambda-cyhalothrin, and bifenthrin. Therefore, spirotetramat might be incorporated into IPM programs in combination with C. septempunctata for control of A. spiniferus and T. aurantii in the tea plantations.