Bioassay Studies Research Articles

Discovery of novel pyrazoline insecticides.

The pyrazoline insecticides, invented by Philips Duphar in the 1970s, provide excellent control of lepidopterans and coleopterans and introduced a novel mode of action (MoA) as sodium-channel-blocking insecticides, but were not commercialized due to unacceptable persistence. This MoA is less explored, with only two successfully commercialized insecticides derived from the pyrazoline class - the oxadiazine indoxacarb from FMC (developed by DuPont) and the semicarbazone metaflumizone, co-developed by BASF and Nihon Nohyaku. The design and synthesis of novel pyrazoline insecticides with improved biological efficacy and favorable environmental fate profile are described. Their structures are confirmed by proton nuclear magnetic resonance (1H-NMR) and liquid chromatography-mass spectrometry (LC-MS). Bioassay studies confirmed the insecticidal efficacy of the synthesized compounds against four key species: cotton boll weevil, tobacco budworm, diamondback moth and southern armyworm. Environmental fate profiles of a few representatives were evaluated, and MoA studies confirm that the MoA of these newly synthesized analogs (voltage-gated sodium channel block) is preserved. We used a chemistry-driven approach to explore position 5 on the pyrazoline core and a computationally-driven approach for bio-isosteric replacement of the aryl amide, leading to two novel pyrazoline sub-classes with improved insecticidal activities and favorable environmental fate profiles compared to PH 60-41 (the Philips Duphar compound). The MoA of these novel sub-classes was also confirmed as block of voltage-dependent sodium channels. © 2024 Society of Chemical Industry.

Design, Synthesis, and Insecticidal Activity of Novel meta-Diamide Compounds Bearing a Phthalimide as a Potential GABA Receptor Antagonist.

In pursuit of potent and environmentally benign insecticides targeting the γ-aminobutyric acid (GABA) receptor, a series of novel meta-diamide compounds bearing a phthalimide were rationally designed and synthesized. Bioassay studies revealed that most of the target compounds exhibited promising larvicidal activity against Mythimna separata (M. separata) and Plutella xylostella (P. xylostella). Notably, the most active compound N15 displayed exceptional potency with LC50 values of 3.82 and 3.42 mg·L-1 against M. separata and P. xylostella, respectively. Electrophysiological studies using Xenopus oocytes confirmed that compound N15 exerted its insecticidal activity by targeting the GABA receptors.

Host selection by thrips is affected by the floral volatile profile of sunflower.

Thrips, Frankliniella intonsa, is a highly polyphagous pest with a worldwide distribution. F. intonsa-infested sunflower seeds show marked visual damage. The study findings revealed that significantly more F. intonsa infested confection sunflower compared to oilseed sunflower, via olfactometer bioassay studies, we found that compared with the flower and pollen of oilseed sunflowers, those of confection sunflowers attract F. intonsa. Considering this discrepancy in the preference of F. intonsa on oilseed and confection sunflowers, the volatiles of the flower and pollens of two sunflowers were analysed bygas chromatography-mass spectroscopy. The behavioural responses of F. intonsa were assessed for these compounds using Y-tube bioassays. Geranyl bromide, a unique volatile component of oilseed sunflowers, induced an assertive approach-avoidance behaviour in F. intonsa, whereas the unique component ethyl isovalerate in confection sunflowers attracted F. intonsa. F. intonsa adults demonstrated significant attraction to the blends of confection sunflowers. Furthermore, field verification revealed that intercropping confection and oilseed sunflowers could effectively control F. intonsa. The study provided insights into the chemical cues used by F. intonsa in locating hosts. Therefore, oilseed sunflowers can be used as repellent plants to prevent F. intonsa invasion.

Comparative Bio Assay of New Generation Insecticides against Invasive Southeast Asian Thrips, Thrips parvispinus (Karny) (Thripidae:Thysanoptera)

Aims: Management of invasive southeast Asian thrips, Thrips parvispinus under laboratory conditions. Study Design: Completely Randomized Design. Place and Duration of Study: Regional Agricultural Research Station, Guntur, Andhra Pradesh during 2023. Methodology: Bio assays study was conducted with eleven insecticides for the Management of Thrips parvispinus under laboratory conditions following leaf dip method replicated thrice. Mortality and corrected mortality were assessed at 24 and 48 hours after treatment imposition by counting the number of dead and live adults. Results: Bio assay study revealed that the insecticide broflanilide 300 DC @ 64.0 ml/ha recorded significant high percent mortality of 93.3 at 48 hours after exposure. The insecticides fluxametamide 10 EC @ 400 ml/ha, tolfenpyrad 15 EC@ 1000 ml/ha, spinoterom 11.7 SC @ 500 ml/ ha and fipronil 5 SC @1000 ml/ha were at par with broflanilide 300 DC with 90.0, 90.0, 86.7 and 86.7 percent mortality, respectively. Lowest mortality of 6.0 percent was observed in untreated control where the leaves were agitated in distilled water. The corrected mortality was calculated and the insecticides broflanilide 300 DC (92.59 %), fluxametamide 10 EC (88.9), tolfenpyrad 15 EC (89.3), spinetoram 11.7 SC (85.9) and fipronil 5 SC @400 ml/acre (85.2) recorded high corrected mortality at 48 hours of post treatment.

A Repurposing Pipeline to Candidate-Suitable Inhibitors of Tyrosinase: Computational and Bioassay Studies.

Tyrosinase, a metalloprotein enzyme, plays a crucial role in melanin synthesis by hydroxylating L-tyrosine to L-dopa. However, the accumulation of melanin can lead to hyperpigmented spots, raising aesthetic concerns. In this study, we developed a pipeline to repurpose FDA-approved drugs as potential tyrosinase inhibitors. A structure-based screening study was conducted using 1,650 drugs to identify probable inhibitors based on binding energies. From the cluster analysis of binding interaction profiles, 16 compounds were selected as candidates. Montelukast emerged as the final candidate due to its favorable ADME properties. Bioassay evaluation revealed an IC50 value of 14.79±0.87 μM for Montelukast, compared to kojic acid (IC50=31.02±2.01 μM). Molecular dynamics simulation and g_MMPBSA free energy calculation studies were performed for the Tyrosinase-Montelukast complex. These findings enhance our understanding of Tyrosinase-Montelukast interactions and underscore Montelukast's potential as a tyrosinase inhibitor. This could have implications in dermatological applications and beyond, suggesting Montelukast as a promising candidate for further development in this regard.

Potent α-glucosidase inhibitors with benzimidazole-propionitrile hybridization; synthesis, bioassay and docking study.

Background: Diabetes is characterized by a lack of insulin and insensitivity to insulin. In 2013, the global diabetes population was 382million, with 90% of them having type 2 diabetes (non-insulin-dependent). It is predicted that this number will increase to 592million by 2035.Aim: Here, we aimed to synthesize a series of benzimidazole-based derivatives B1-B32 with α-glucosidase inhibition potential as antidiabetic agents.Methods: Compounds B1-B32 were prepared in three three-step reactions, and the structures were elucidated using spectroscopic methods, namely 1H NMR, 13C NMR, MS and IR. Enzyme inhibition and kinetic study were done using commercial assay kits, and molecular docking study using autodock4.Results: Bioassay data showed that twenty-four out of the thirty-two tested compounds exhibited IC50 values ranging from 44 to 745μM, surpassing the standard molecule, acarbose (IC50: 750μM). it was determined that the best compound, B10, functions as a competitive inhibitor. Additionally, a molecular docking study provided insights into the interactions between the four most promising compounds (B5, B6, B10 and B28) and the active site residues within the enzyme.Conclusion: The tested compounds are interesting α-glucosidase inhibitors, which indicates the benefit of more bioassay studies, especially in vivo studies.

Novel 5-alkenylthiothiazolidinone scaffold discovery as Multi-Chitinases inhibitors to arrest the molting of Asian corn borer

Chitinases are crucial enzymes in insect growth and development processes and have thus become potential targets for the control of insect pests. Rhodanine (5-alkenylthiothiazolidinone) is an important fragment with various biological activities in agriculture. Therefore, 24 novel 5-alkenylthiothiazolidinone derivatives were designed and synthesized by introducing a hydrophobic hydrocarbon chain and a benzylformamide group on the basis of the conserved binding cavity of three chitinases, OfChtI, OfChtII and OfChi-h. These 5-alkenylthiothiazolidinone analogs were found for the first time to have inhibitory effects on OfChtII, except for their ability to inhibit the other two known chitinases, OfChtI and OfChi-h. The inhibitory activities of the target compounds against OfChtI and OfChi-h ranged from 40 % to 95 % at a concentration of 100 μM. In particular, some compounds were also found to have an inhibitory rate of 50 % against OfChtII. Among them, the Ki values of the most potent compound 5e-9 were 5.82, 27.5 and 6.77 μM against OfChtI, OfChtII and OfChi-h, respectively. The inhibition mechanism studies revealed that both π stacking interactions and hydrophobic interactions were vital for the binding of Compound 5e-9 with the three chitinases. A lethal and sublethal bioassay study revealed that Compound 5e-9 could affect the growth and development of Asian corn borers. This work suggested that 5-alkenylthiothiazolidinone could be a novel inhibitor scaffold against multichitinase for the development of insect growth regulators.

Efficient Green Solvent Extraction and Bioassay Studies of Favipiravir in Rat Dried Blood Spots Using Ionic Liquid-based Dispersive Liquid-liquid Microextraction (IL-DLLME) Coupled with HPLC-PDA: Application to Bioequivalence Studies

Background: Favipiravir is an antiviral drug having pyrazine group moiety. It is a reliable and an efficient green solvent, and a highly recoverable bio-sampling method is required for it. It is widely used in COVID-19 treatment for the prevention of the spread of viral infections in the body. Objective: This proposed green solvent (ionic liquid)-based bioassay study aimed to quantify favipiravir in rat-dried blood spots using Dispersive Liquid-liquid Microextraction (IL-DLLME). Methods: The proposed bioassay separation was achieved through an isocratic elution mode using a hybrid silica-based ODS column (250 × 4.6 mm; 5 μm), a column temperature of 25°C, an injection volume of 10 μL, a flow rate of 1.0 mL/min, and a detector wavelength set at 310 nm. The run time was less than 10 minutes. Mobile phase was delivered with acetonitrile, methanol, and 10 mM Na2HPO4 at pH 4.0 ± 0.5, (15: 20: 65, v/v/v). In a microtube, 50 mL of Ionic Liquid (IL), 500 μL of disperser ACN, 50 μL of 10% NaCl, and IS (20 ng mL-1) were added to perform the Dried Blood Spot (DBS) sample extraction methodology. The advantages of the proposed methodology have been found to include minimum hematocrit effect and an adequate blood volume for testing, easy transportation, and significant extraction recovery. The sample analysis has been carried out using HPLC-PDA with oseltamivir used as an internal standard. Results: We have investigated the important variables, i.e., salt concentration (10% NaCl, analyte recovery being higher) and disperser solvent [50μL of BMIHP plus 500 μL of ACN (v/v) yielding the highest recovery], in the extraction process. Extraction Recovery (ER) and Enrichment Factor (EF) were also evaluated using the IL-DLLME method. The calibration curve examined a range of 0.5-150 μg/mL, with a lower Limit of Quantification (LOQ) being 0.5 μg/mL in QC as well as calibration samples, respectively. Conclusion: Significant bioanalytical validation has been performed and all the parameters have been evaluated systematically as per bioanalytical method validation protocols, i.e., US FDA- 2018 guidelines. The following analytical parameters have been covered: standard curve, limit of quantification, range, recovery, stability, accuracy, precision, sensitivity, ER, EF, and selectivity. The developed bioassay method has been successfully applied in the pharmacokinetic studies of rats and successfully applied in bulk drugs.

Sulfated Aeruginosins from Lake Kinneret: Microcystis Bloom, Isolation, Structure Elucidation, and Biological Activity.

Aeruginosins are common metabolites of cyanobacteria. In the course of re-isolation of the known aeruginosins KT608A and KT608B for bioassay studies, we isolated three new sulfated aeruginosins, named aeruginosins KT688 (1), KT718 (2), and KT575 (3), from the extract of a Microcystis cell mass collected during the 2016 spring bloom event in Lake Kinneret, Israel. The structures of the new compounds were established on the basis of analyses of the 1D and 2D NMR, as well as HRESIMS data. Marfey's method, coupled with HR ESI LCMS and chiral HPLC, was used to establish the absolute configuration of the amino acid and hydroxyphenyl lactic acid residues, respectively. Compounds 1-3 were tested for inhibition of the serine protease trypsin, and compounds 1 and 2 were found to exhibit IC50 values of 2.38 and 1.43 µM, respectively.

Screening of indigenous Bacillus thuringiensis for dipteran active cry gene profiles and potential toxicity against melon fruit fly, Zeugodacus cucurbitae (Coquillett)

BackgroundMelon fruit fly, Zeugodacus cucurbitae Coquillett (Diptera: Tephritidae), is a devastating polyphagous pest attacking large number of fruits and vegetables causing huge economic yield losses across the world. Management of this notorious pest is very challenging as the larvae feed inside the fruit. Hence, the present research study aimed to screen the indigenous Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) strains causing toxicity to larvae and to identify the insecticidal toxicity-related genes present in respective strains. In the present study, 50 indigenous B. thuringiensis (Bt) strains along with one reference strain were screened against second-instar larvae Z. cucurbitae. All the strains were analyzed for presence of 21 dipteran active cry genes.ResultsMortality in Z. cucurbitae larvae due to Bt strains ranged from 16 to 92%. PCR results revealed that each strain tested positive for a minimum of three cry genes to maximum of nine cry genes. Among the cry genes, cry1A, cry2A, cry1C, cry19, cry11 and cry70 were detected in high frequency of 100, 88, 84, 74, 58 and 54%, respectively. Bioassay studies revealed that ten out of fifty strains displayed more than 50% mortality. Hence, these ten strains, along with the reference strain, were further tested for mortality for the calculation of the median lethal concentration (LC50). The LC50 values ranged between 38.48 and 105.18 μg/ml. The lowest LC50 found for the strain NBAIR Bt107 was 38.48 μg/ml and was on par with the reference strain (Bti 4Q1) (31.3 μg/ml).ConclusionIndigenous Bt strains displayed a toxicity against the larvae of Z. cucurbitae. The probable dipteran active cry genes responsible for toxicity were interpreted. Thus, the Cry toxins from Bt can play a very important role in the management of Z. cucurbitae.

Determination of target site mutations and detoxification enzymes in the abamectin resistance of spider mite Tetranychus urticae collected from cotton fields of Türkiye

The two-spotted spider mite, Tetranychus urticae (Koch, 1836) (Acari: Tetranychidae) causes significant problems in cotton fields. The pest has developed resistance to abamectin, which is used intensely against spider mite populations. A discriminating dose was applied to T. urticae populations collected from Aydın, Adana, Şanlıurfa, and Diyarbakır provinces between 2019 and 2021, where there is significant cotton production and intensive acaricide applications. Populations with a mortality rate of less than 80% at the discriminating dose applied to field populations were included in the bioassay study. Then, the 10 most resistant populations were determined based on their LC50 and LC90 values. It was observed that there was high resistance (HR) in two T. urticae populations collected from Diyarbakır (DIY28 and DIY2) with LC50 values of 24.5 and 33.81 mg L-1, respectively 113 and 156-fold and one population collected from the province of Aydın (AYD4) LC50 value of 23.5 mg L-1 and 109-fold. As a result of the comparisons with a susceptible population in biochemical studies, it was determined that the carboxylesterase (CarE) enzyme of these populations (except for SAN6, SAN7, SAN8, ADA9, and ADA11) had more than 2-fold higher activity compared to the glutathione enzyme (GST), and they were in statistically different groups. When the GST enzyme activities were examined, it was found that the enzyme activities were generally low, except for the ADA11 and ADA16 populations (3.73 and 2.3-fold). In terms of the target site resistance, it was observed that there was no target site mutation (G314D and I321T-G326E) in the glutamate-gated chloride channels (Units GluCl 1 and 3) in these highest 10 resistant populations. It can be said that the resistance levels determined for abamectin from the obtained populations were determined to be low. In brief, out of the total 44 populations brought in and tested, only 30 populations were considered resistant with a mortality rate below 80% after the applied discriminating dose. It was determined that 6.8% of these 30 populations had HR, 31.8% had medium resistance (MR), and 29.5% had low resistance (LR). When examining by regions, it was found that high resistance populations were more prevalent in Diyarbakır and Aydın (15.4% and 10%, respectively) provinces, while the highest percentage of MR populations was found in Şanlıurfa, at 90%. Abamectin still acts as an effective acaricide. However, it is recommended to use acaricides with different modes of action to prevent possible emergence of resistance cases.

Design, synthesis, antimicrobial activity, and mechanism of novel 3-(2,4-dichlorophenyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives.

Plant pathogens cause substantial crop losses annually, posing a grave threat to global food security. Fungicides have usually been used for their control, but the rapid development of pesticide resistance renders many ineffective, therefore the search for novel and efficient green pesticides to prevent and control plant diseases has become the top priority in crop planting. The results of bioassay studies indicated that most of the target compounds showed certain antimicrobial activity in vitro. In particular, compound X7 showed high inhibitory activity against Xanthomonas oryzae pv. oryzae (Xoo), with an EC50 value of 27.47 μg mL-1, surpassing conventional control agents such as thiazole zinc (41.55 μg mL-1) and thiodiazole copper (53.39 μg mL-1). Further studies on molecular docking showed that X7 had a strong binding affinity with 2FBW. The morphological change observed by scanning electron microscopy indicated that the surface of Xoo appears wrinkled and cracked under X7 treatment and a total of 2662 proteins were identified by label-free proteomic analysis. Three experiments have elucidated the mechanism whereby X7 induced considerable changes in the physiological and biochemical properties of Xoo, which in turn affected the reproduction and growth of bacteria. This work represents a pivotal advancement, offering important reference for the research and development therapeutics in combating plant pathogens. © 2024 Society of Chemical Industry.

Performance evaluation of sugarcane bagasse biochar based fixed bed column for removal of triclosan from aqueous solution in presence of humic acid: Mechanism, kinetics and safety

Triclosan (TCS), an emerging pollutant emerges as a notable contributor to adverse impacts on aquatic organisms owing to its widespread use during COVID19. The current study aims to investigate the efficiency of sugarcane bagasse biochar (SBB) for removal of triclosan (TCS), an emerging pollutant in aquatic ecosystems in presence of humic acid from aqueous solution through batch and column studies. In batch study, SBB prepared at pyrolysis temperature of 400 °C showed highest adsorption of TCS. Langmuir isotherm model showed highest adsorption of 68.49 mg g−1 at pH 7.0. A 90 % reduction in TCS was accomplished with 0.625 g L−1 of SBB-400 °C. Adsorption kinetic modelling was well fitted to pseudo-second order model signifying that rate of adsorption on SBB-400 °C mainly depends on chemisorption. TCS removal was not significantly inhibited in presence of 5, 10 and 25 mg L−1humic acid concentrations. Column experiments of continuous flow biochar-bed column with the aqueous solution spiked with TCS (100 mg L−1) at a flow rate of 50 mL min−1 showed 99 % removal efficiency. Thomas model and Yoon-Nelson model signified the breakthrough behaviour of TCS adsorption on the column and the experimental data were in good agreement with the expected values. Bioassay studies on Chlorella vulgaris exhibited that percentage inhibition (8 %) in algal cell counts was significantly less in the SBB treated TCS water when compared with control (untreated water containing TCS). The designed column is highly efficient, effective and eco-friendly approach for TCS removal.

Investigating the Cardio-protective Activity of Agaricus bisporus in Wistar Rats Induced with Myocardial Infarction

Myocardial infarction is now recognized as one of the chronic diseases and the leading cause of death across the globe. The use of plants abundant in our environment, especially Agaricus bisporusprovides a cheap alternative to combat this common foe of mankind. Hence, this study was carried out to evaluate the cardio-protective effect of the leaf extract of Agaricus bisporus in isoproterenol-induced myocardial infarction. Fresh sample of Agaricus bisporus were purchased from a market at Asaba, Delta State, Nigeria. The samples were thereafter shredded with a knife and oven-dried at 40oC and pulverized and extracted, using Solvent-solvent (ethanol and water) (7:3) via maceration for 72 hr. The filtrate was evaporated to dryness to obtain the ethanol extract which was used for further bioassay study. The animals were administered with the extract of A. bisporus orally for fourteen consecutive days at a divided dose of 100 mg/kg, 200 mg/kg and 400 mg/kg body weights and thereafter 0.2 ml isoproterenol (ISO) at 150 mg/kg was injected intraperitoneally at an interval of 24 h on the 15th and 16th day. Subsequently, the blood pressures were monitored and blood collected for bioassay studies. Assay of High density lipoprotein cholesterol (HDL-c), low density lipoprotein cholesterol (LDL-c), triglyceride (TG) and total cholesterol (TC) levels as well as activities of lactate dehydrogenase (LDH), were carried out with standard assay kit sourced from Randox laboratories Ltd, United Kingdom with maximum adherence to the manufacturer’s instruction. Results showed a significant increase (P<0.05) in high density lipoproteins (HDL) levels and lactate dehydrogenase (LDH) activities with a significant decrease (P>0.05) in low density lipoproteins (LDL) and triglyceride levels in a dose-dependent manner (100<200<400 mg/kg body weight) among the extract treated groups when compared to the untreated control group. Conversely, total cholesterol levels of extract treated groups showed no significant difference when compared with the untreated control group.The findings of this work have shown that extract of Agaricus bisporus could help to mitigate cardiovascular diseases and could be used to produce plant based products to combat myocardial infarction, thereby improving general wellbeing.

Cry Toxins from <i>Bt</i> Bollgard II® Cotton Seeds: An Affordable Source for Insect Bioassays

The relative expression of Bacillus thuringiensis (Bt) Cry1Ac and Cry2Ab toxins from seeds of Bt Bollgard II® cotton was quantified using Enzyme Linked Immunosorbent Assays (ELISA) method. The ELISA technique involves binding a sample or calibrator to a solid-phase antibody, forming a "sandwich complex" with an enzyme-labeled antibody. The resulting enzyme substrate reaction produces a product proportional to the antigen concentration. The study reveals that each gram of Bt Bollgard II® seed powder contains 3.25 μg Cry1Ac and 182.32 μg Cry2Ab, with Cry2Ab expression 56 times higher. Variability in Cry protein expression is influenced by factors like temperature, genetic background, and plant maturity. The research emphasizes the importance of Bt plants, particularly Bt Bollgard II® seed powder as a valuable source for studying insect responses to combined Cry1Ac + Cry2Ab expression in bioassay studies.

Impact of Treated Castor Leaves on Growth and Productivity of Eri Silkworms: A Bioassay Study

One of the most common foliar diseases in castor cultivation for ericulture is Cercospora leaf spot, caused by Cercospora ricinella Sacc. & Berl. which seriously damages leaves meant as food for eri silkworms. Deterioration in the quality or quantity of castor leaves primarily hampers the health of eri silkworm, which ultimately affects the economic parameters of the cocoons produced by them. A bioassay study was conducted during 2019-2021 at College of Sericulture, Assam Agricultural University, Jorhat, Assam, to check the effects of feeding castor leaves, treated with treatments found promising for eco-friendly management of Cercospora leaf spot of castor. Eight treatments with three replications were taken for the experiment which included a phytoextract of Tulsi (Ocimum sanctum) @ 5%, a bio agent (Trichoderma viride) @ 5% and a fungicide (Copper oxychloride) @ 0.2 % and their combinations, applied as foliar spray at 15 days interval after 30 days of transplanting. These treated leaves were fed as first feed to the 3rd instar silkworms after maintaining 25-30 days as safe period. Silkworms fed with castor leaves treated with T.viride + Tulsi extract showed the best results in overall health (ERR 91.66%, Fecundity 391, Shell ratio 13.44%) followed by worms fed with leaves treated with Tulsi extract + T. viride + COC (ERR 80.55%, Fecundity 370, Shell ratio 12.59%).

First Report of <i>Metarhizium Rileyi</i> Infecting Fall Army Worm <i>Spodoptera Frugiperda</i> (J E Smith) From Nepal

The fall army worm (FAW) Spodoptera frugiperda (Noctuidae: Lepidoptera) is an invasive polyphagous pest that prefers maize crop in the newly invaded regions like Africa, Asia, Australasia, and some Pacific Islands and was recorded in Nepal in the year 2019. Surveys were conducted in the maize fields to collect various natural enemies for utilization in the management of FAW. Several larvae infected with an unidentified fungus were collected and subjected to morphological and molecular analysis for identification as Metarhizium rileyi. In bioassay studies we observed percent larval mortality at 1x108 conidia/ml suspension. This is the first report of M. rileyi infecting S. frugiperda from Nepal.

Assessment of Insecticide Resistance in Spodoptera litura (Fabricius) in Vegetable Crop Ecosystem

One of the most prevalent insect pests is the tobacco caterpillar or Spodoptera litura (Fabricius), which results in significant crop losses developed resistance against different insecticides over time. This laboratory experiment was carried out in the Department of Entomology, College of Agriculture, Rajendranagar, Professor Jayashankar Telangana State Agricultural University (PJTSAU), Hyderabad during Karif, 2022. The susceptible population was reared in laboratory continuously for ten generation without exposing it to insecticides. The susceptibility of field populations of S. litura that were collected from many vegetable crops in the intense vegetable crop cultivating mandals i.e., Chevella and Maheshwaram of Rangareddy district to commonly used insecticides viz., chlorantraniliprole, emamectin benzoate and flubendamide was then compared with a laboratory reared susceptible population The bioassay studies revealed that the LC50 values of these insecticides were significantly higher in the field population collected from Chevella and Maheshwaram compared to the susceptible laboratory population. Based on the LC50 values the Resistant ratio (RR) was calculated for the field populations. It was found that Chevella population developed 35.34 folds resistance and Maheshwaram population also developed nearly 34.90-fold resistance against emamectin benzoate. Both Chevella and Maheshwaram populations were found to develop moderate resistance of 28.23 and 27.35-fold against flubendamide and comparatively lower resistance of 21.05 and 23.44-fold resistance against chlorantraniliprole when compared to susceptible population. These findings further helps in developing better IRM strategies.

Gene flow and spontaneous mutations are responsible for imidazolinone herbicide-resistant weedy rice (Oryza sativa L.)

For more than two decades, weedy rice (Oryza sativa L.) has been controlled in rice fields by using imidazolinone (IMI) herbicide-resistant rice technology (Clearfield®). Outcrossing in weedy rice populations and spontaneous mutations are potential problems with herbicide-resistant crop management technologies, such as the IMI-resistant rice. The aim of this study was to characterize the mechanism of IMI herbicide resistance in weedy rice through dose-response bioassay study and evaluating amino acid substitutions in acetolactate synthase (ALS) protein. A total of 118 suspected IMI-resistant weedy rice samples, which survived in the field after an IMI herbicide application, were collected at harvest time from Türkiye in 2020 and 2021. Single-dose imazamox application experiment revealed that 38 plants survived herbicide treatment. The imazamox resistance of the surviving plants was confirmed by dose-response experiment. ALS gene region underwent a sanger DNA partial sequencing. No substitution was found in 10 samples, however, amino acid substitutions were found in 26 samples with S563N, one sample with S653T, and one sample with E630D. The S653N point is the same substitution point that serves as the origin of resistance for the Clearfield® rice varieties that are commonly cultivated in the region. It has been hypothesized that the gene flow from IMI-resistant rice may be the cause of resistance in the IMI resistant weedy rice samples with S653N. The other substitution, S653T, were considered spontaneous mutation to IMI resistance. Interestingly, the S653T mutation was detected for the first time in weedy rice. The mechanism of resistance of 10 resistant weedy rice was not confirmed in this study, however, it may be a non-target resistance or another mutation point in target site, but evidently, they did not acquire resistance by gene flow from IMI-resistant rice. It has been concluded that the effectiveness of IMI-resistant rice technology in controlling weedy rice has drastically decreased due to possible gene flow, spontaneous mutation and non-target resistance. In addition to cultural controls like clean seed, clean machinery and crop rotation, other herbicide-tolerant rice systems such as Provisia® and Roxy-RPS® rice are needed to create a diverse weedy rice management ensemble available for rice production and move towards sustainable rice farming.

Synthesis of New Fatty N-Acylamino Amides from 3,4-Dichloroaniline with Crop Protection Activity

A series of biologically active N-acylamino amides were synthesized from readily available amino acids and common fatty acids from oil seeds, including the pharmacophoric group in the family of herbicides propanil, linuron, and diuron. The esterification followed by N-acylation with long-chain fatty acids was carried out with O-(benzotriazole-1-yl)-N,N,N’,N’-tetramethyluronium tetrafluoroborate (TBTU) as activating agent. The N-acylamino esters were synthesized and isolated in good yields (70-98%), which after the hydrolysis step, provided the N-acylamino acids. Finally, new N-acylamino amides were obtained from the reaction with 3,4-dichloroaniline in the presence of TBTU and N,N-diisopropylethylamine (DIPEA), in yields between 24-83%. Bioassays were conducted against arthropod strawberry pests Chaetosiphon fragaefolii, Duponchelia fovealis, and Drosophila suzukii, without any registered compound for use in strawberry crops in Brazil. The bioassay studies showed promising results, with mortality percentages ranging from 20-80%, and the best relative mortality by N-oleyl glycinamide, suggesting a possible fatty chain-amino acid synergistic bioactivity. Overall, this study provides an efficient and sustainable method for synthesizing biologically active N-acylamino amides from abundant natural sources, with potential applications in the development of ecofriendly agrochemicals.