Larvicidal Activity Research Articles

Impact of Nanoparticles Synthesized From Azadirachta indica (A. Juss) for Targeted Control of Malarial, Dengue, and Filariasis Vectors With Minimized Aquatic Toxicity

ABSTRACTIn the present study, biogenic silver nanoparticles (AgNPs) synthesized using Azadirachta indica leaf extract were evaluated for their toxic effects on both target and non‐target species. The botanical synthesized nanoparticles were tested against Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus and non‐targeted species Artemia salina and Eudrilus eugeniae at 24 h posttreatment. AgNPs were characterized using the following analytical techniques: UV‐Vis spectroscopy, FT‐IR, x‐ray diffraction (XRD), energy‐dispersive x‐ray spectroscopy (EDX), and scanning electron microscope (SEM) analysis. Results showed that AgNPs caused larvicidal activity with 90.66% mortality in An. stephensi, 97.33% in Ae. aegypti, and 93.33% in Cx. quinquefasciatus at 24 h posttreatment. A. indica‐derived AgNPs had lower LC50 (lethal concentration 50) and LC90 (lethal concentration 90) values of 44.803 and 252.886 ppm/mL in An. stephensi, 18.358 and 189.553 ppm/mL in Ae. Aegypti, and 36.492 and 219.800 ppm/mL in Cx. quinquefasciatus, respectively. Furthermore, AgNPs demonstrated lower toxicity effects with 50.66% mortality in A. salina and 38.66% mortality in E. eugeniae at 24 h posttreatment. Additionally, they exhibited lower LC50 and LC90 values of 240.996 and 533.618 ppm/mL in A. salina and 301.122 and 548.944 ppm/kg in E. eugeniae at 24 h posttreatment, respectively. The findings conclude that green‐synthesized AgNPs from plants offer a promising, cost‐effective, and target‐specific alternative for eco‐friendly mosquito larvicides. Future work should focus on developing these plant‐based agents with minimal non‐target toxicity to support sustainable pest control. Further research may explore large‐scale applications and assess the long‐term environmental impacts of AgNPs in integrated vector management programs.

Essential Oils of The Leaves of Syzygium hemilamprum (F. Muell.) Craven & Biffin.: Chemical Analysis, Antimicrobial, Mosquito Larvicidal, Molecular Docking, and ADMET Studies.

The chemical composition of the essential oil and n-hexane extract from Syzygium hemilamprum leaves was first performed. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the essential oil was predominantly composed of monoterpene hydrocarbons (71.5 %) and oxygenated derivatives (20.2 %), with β-pinene (31.5 %), limonene (19.4 %), α-pinene (12.3 %), and α-terpineol (7.4 %) being the principal constituents. The n-hexane extract contained monoterpene hydrocarbons (42.2 %) and non-terpenic compounds (34.0 %), with β-pinene (32.8 %) and n-hexadecane (10.2 %) as the major components. Antimicrobial and mosquito larvicidal assays demonstrated that both samples exhibited antimicrobial activity against Staphylococcus aureus (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Saccharomyces cerevisiae (yeast), with a minimum inhibitory concentration (MIC) of 128 μg/mL for all tested organisms. Both samples also showed significant mosquito larvicidal activity against Aedes aegypti and Culex quinquefasciatus, with LC50 and LC90 values below 20 μg/mL at 24 and 48 hours post-treatment. Molecular docking studies suggested that limonene and α-terpineol could serve as potent inhibitors of mosquito odorant binding proteins. Additionally, an in silico analysis was performed to evaluate the physicochemical and ADMET (absorption, distribution, metabolism, and toxicity) properties of the major constituents of the essential oil.

Combinatorial metabolic engineering strategy of precursor pools for the yield improvement of spinosad in Saccharopolyspora spinosa

Spinosad is an insecticide produced by Saccharopolyspora spinosa, and its larvicidal activity is considered a promising approach to combat crop pests. The aim of this study was to enhance the synthesis of spinosad through increasing the supply of acyl-CoAs precursor by the following steps. (i) Engineering the β-oxidation pathway by overexpressing key genes within the pathway to promote the synthesis of spinosad. The results showed that the overexpression of fadD, fadE, and fadA1 genes, as well as the co-expression of fadA1 and fadE genes, increased the yield of spinosad by 0.36-fold, 0.89-fold, 0.75-fold and 1.25-fold respectively. (ii) Employing combinatorial engineering of the β-oxidation pathway and ACC/PCC pathway to promote the synthesis of spinosad. The results showed that the co-expression of fadE and pccA, as well as accC and fadE, resulted in a 1.77-fold and 1.43-fold increase in spinosad production respectively. (iii) When exogenous triacylglycerol was added to the fermentation medium, the solely engineering of the β-oxidation pathway increased the yield of spinosad by 7.13-fold, reaching 427.23mg/L. While the combinatorial engineering of both the β-oxidation pathway and ACC/PCC pathway increased the yield of spinosad by 9.61-fold, reaching 625.17mg/L, and further optimization of the culture medium resulted in an even higher yield of spinosad, reaching 1293.43mg/L. The results of this study indicate that the above combination strategy can promote the efficient biosynthesis of spinosad.

Isolation of Natural Veratrylidenehydrazide Compound from Wedelia Biflora and Synthesis of Veratrylidenehydrazide Analogue: Investigation of Larvicidal Activity Against Culex Quinquefasciatus and Toxicity Analysis in Nontarget Aquatic Species

AbstractIn this study, veratrylidenehydrazide was isolated from Wedelia biflora, and compounds (1a, 2a, and 3a–j) were synthesised to evaluate their larvicidal and antifeedant activities. Veratrylidenehydrazide 1a was verified using GC‐MS. The veratrylidenehydrazide analogues 2a and 3a–j were synthesised via a condensation method with yield range 71%–92%. The compounds (1a, 2a, and 3a–j) were synthesised and characterised through FT–IR, 1H NMR, 13C NMR, mass spectrometry, and elemental analysis. Veratrylidenehydrazide 1a was verified using GC‐MS analysis. Natural veratrylidenehydrazide compound 1a and the synthesised veratrylidenehydrazide analogues (2a, 3a–j) were screened for larvicidal activity against Culex quinquefasciatus. The larvicidal activity of compound 3g was found to be highly active, while low toxicity was observed against Oreochromis mossambicus nontarget aquatic species compared to natural veratrylidenehydrazide. Compound 3g exhibited a higher binding affinity (−8.8 kcal/mol) compared to standard of temephos (−4.5 kcal/mol), equipotential binding affinity against permethrin (−9.1 kcal/mol), and diflubenzuron (−8.5 kcal/mol). Lead molecules have larvicidal properties, and their use as insecticides makes them important.

Biological characterization of marine algae and its potent in vitro antioxidant, antimicrobial and larvicidal activity: a focus on Ulva lactuca Linnaeus 1753: 1163.

This study evaluated the biological characteristics of seaweeds Turbinaria ornata, Ulva lactuca, and Gracilaria crassa. Among the seaweeds tested, ethyl acetate extract of Ulva lactuca exhibited the highest antibacterialactivity against Salmonella enterica, Staphylococcus aureus, and Pseudomonas aeruginosa. The phytochemical analysis of ULME and ULEA showed the presence of most of the tested phytochemicals, whereas only amino acids, tannins, glycosides, and carbohydrates were detected by ULHE. The DPPH scavenging property of U. lactuca exerted the maximum antioxidant property of 62.54% (ULME), 75.64% (ULEA), and 39.55% (ULHE), whereas the alpha amylase inhibitory property (µg/mL) of ULME, ULEA, and ULHE was, respectively, 80.99, 51.15, and 49.23. ULME, ULEA, and ULHE exhibited the greatest alpha-glucosidase inhibition, with IC50 values (g/mL) of 116.12, 45.59, and 170.10 correspondingly. ULEA also showed potent mosquito-larvicidal effects against Aedes aegypti larvae with the maximum lethal concentration values with LC50 and LC90 values (mg/mL) being 11.55 and 65.97, respectively. FTIR analysis of ULME, ULHE, and ULEA were found to have various functional groups, including alkanes, carboxylic acids, alkenes, alkynes, aldehydes, amides and alkanes, ketones, and aromatics, while HPLC revealed a strong peak at 4.760 retention time. In conclusion, Ulva lactuca, particularly its ethyl acetate extract, demonstrates significant antibacterial, antioxidant, and enzyme-inhibitory properties, highlighting its therapeutic and biotechnological potential. Its diverse phytochemicals and effective mosquito-larvicidal activity further support its broad application prospects.

Larvicidal properties of essential oils of three Artemisia species against the chemically insecticide-resistant Nile fever vector Culex pipiens (L.) (Diptera: Culicidae): In vitro and in silico studies

Abstract The objective of this study is to determine the larvicidal activity of essential oils (EOs) extracted from three plants of the genus Artemisia against the mosquito Culex pipiens (C. pipiens) using in vitro and in silico studies. A total number of 20 third- and fourth-instar larvae were exposed to various concentrations of the three plants. The LC50 and LC90 values of the tested Artemisia EOs were determined using Probit analysis. In addition, the sensitivity of C. pipiens to these EOs was determined and compared against a standard insecticide, temephos, under laboratory conditions. Furthermore, in silico assessments were carried out on the major constituents to help understand and explain the acquired in vivo results. Gas chromatography analysis identified the major compounds as d-limonene and β-pinene for Artemisia flahaultii, camphor and borneol for Artemisia. aragonensis, and artemisia ketone and caryophyllene for Artemisia annua. A. flahaultii oil showed the highest efficacy against C. pipiens larvae, followed by A. annua oil with average larvicidal activity. In contrast, A. aragonensis EO, composed of a high percentage of monoterpenes, was the least active. Docking simulation indicated that several studied ligands had promising binding scores within the receptor’s binding site compared to the reference insecticide temephos. The obtained results allow us to conclude that A. flahaultii, a species endemic to Morocco, is an excellent means of controlling C. pipiens.

Larvicidal Efficacy of <i>Cassia singueana</i> methanol leaf extract against <i>Aedes aegypti</i> and <i>Culex quinquefasciatus</i>

Despite the persistent control measures, mosquitoes remain abundant and the disease they transmit persists globally posing significant health challenges. There is increasing enthusiasm for exploring botanical solutions as substitutes for conventional chemical insecticides, driven by their broad insecticidal attributes, eco-friendly nature and compatibility with various ecological settings. As such, the study was designed to assess the larvicidal properties of methanol leaf extract of Cassia singueana against Aedes aegypti and Culex quinquefasciatus. The plant was subjected to preliminary and GC-MS phytochemicals screening. Larvicidal bioassay was conducted using six different concentrations (0.10-3.20 mg/ml) and 31.25mg/l temphos and distilled water were used as positive and negative control respectively. The experimental set up was observed after 24 h and the lethal concentrations (LC50 and LC99) were determined using Probit analysis. Preliminary phytochemical screening of C. singueana methanol leaf extract revealed the presence of alkaloids, cardiac glycosides saponins, phenolic compounds, tannins, steroid carbohydrates, flavonoids, and terpenoids. Eighteen (18) bioactive compounds were identified in the methanol leaf extract of C. singueana which includes 1,5-Heptadien-3-yne, 2-Hydroxy-3-methylbenzaldehyde, 2-Butenoic acid, Acetonitrile, 2,2'-iminobis-, 7,11-Hexadecadienal,2-Hexyne, among others. The extract had larvicidal activity against A. aegypti and C. quinquefasciatus with LD99 of 5.44 mg/ml and 15.85 mg/ml respectively at 24 h post-treatment. This study offers valuable perspectives on the possible application and advancement of C. singueana leaf extract as a potential bioinsecticide against A. aegypti and C. quinquefasciatus and consequently control the diseases transmitted by them.

Eco-friendly synthesis of silver nanoparticles using Phyllanthus niruri leaf extract: Assessment of antimicrobial activity, effectiveness on tropical neglected mosquito vector control, and biocompatibility using a fibroblast cell line model

Abstract Mosquitoes are rapidly advancing as vectors of several severe diseases. The increasing resistance of mosquitoes and the environmental harm caused by insecticides pose significant challenges for eradicating mosquito vectors. In this study, 18 plant extracts were tested for larvicidal properties against Aedes aegypti, Culex quinquefasciatus, and Anopheles stephensi larvae. Phyllanthus niruri (Pn) showed enhanced larvicidal activity in both laboratory and field trials. The biosynthesis of silver nanoparticles (AgNPs) using Pn leaf methanol extract (Pn-LME) was confirmed by UV-visible spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Among various concentrations, 3 mM AgNPs exhibited significant LC90 values of 0.83, 1.46, and 9.11 ppm compared to 9.25, 93.48, and 14.60 ppm of Pn-LME against A. stephensi, C. quinquefasciatus, and A. aegypti, respectively. This indicates the high mortality of mosquito vectors at low AgNP concentrations. Additionally, Pn-AgNPs showed enhanced antibacterial activity and no cytotoxicity in normal fibroblast cells (L929). Field trials demonstrated a 98.70% decrease in mosquito larval density at A. stephensi breeding sites, a 96.55% reduction at C. quinquefasciatus sites, and a 97.85% reduction at Ae. aegypti sites. This study presents an eco-friendly and cost-effective AgNP bio-pesticide synthesized from Pn leaves for controlling and preventing the transmission of filarial, dengue, and malaria vectors.

Biological Control of Aedes aegypti Larvae using Sea Shell Powder

Background: The Aedes aegypti mosquito is a primary vector for several arboviral diseases, including dengue, Zika, chikungunya and yellow fever, posing significant public health challenges, especially in tropical and subtropical regions. Traditional chemical insecticides have been the mainstay for controlling Aedes aegypti populations, but their extensive use has led to the development of insecticide resistance, environmental pollution and adverse effects on non-target organisms. This study explores the potential of sea shell powder as a natural larvicide against Aedes aegypti larvae. Methods: Sea shell powder, derived from the calcified exoskeletons of marine mollusks, was tested for its larvicidal activity against fourth instar larvae of Ae. aegypti at concentrations ranging from 100 to 600 ppm. Result: The results demonstrated a concentration and time-dependent increase in larval mortality, with LC50 values of 407.01 ppm at 24 hours and 327.55 ppm at 48 hours. The findings suggest that sea shell powder could serve as an effective, environmentally sustainable alternative to chemical insecticides, offering advantages such as biodegradability, low cost and reduced risk of resistance development. This study supports the potential inclusion of sea shell powder in integrated mosquito management programs, particularly in areas with prevalent insecticide resistance.

Rational design and synthesis of new pyrrolone candidates as prospective insecticidal agents against Culex pipiens L. Larvae.

As a result of its high reactivity, furan-2(3H)-one derivative 2 can be selected as a versatile and suitable candidate for building of novel nitrogen heterocyclic compounds. Consequently, furan-2(3H)-one derivative 2 and some nitrogen nucleophiles were utilized as starting materials for the formation of new pyridazinone and pyrrolone derivatives bearing naphthalene moiety. The continuous buildup of insecticide resistance is the main obstacle facing pest control measures. Pyrrole-based insecticides are a favourable choice due to their unique mode of action and no cross-resistance with traditional neurotoxic insecticides. The larvicidal activities of pyrrolone derivatives were assessed against field and laboratory strains of Culex pipiens larvae in comparison with chlorfenapyr (pyrrole insecticide). Compounds 17 (21.05µg/mL) > 9 (22.81µg/mL) > 15 (24.39µg/mL) > 10 (26.76µg/mL) > 16 (32.09µg/mL) were most effective against lab strain of C. pipiens larvae relative to chlorfenapyr (25.43µg/mL). While in field strain, 17 and 15 were the most toxic compounds followed by 9 > 10 > 16 > 2 with LC50 of 9.87, 10.76, 11.52, 12.68, 15.32 and 18.37µg/mL, respectively, compared with chlorfenapyr with 14.03µg/mL. The cytochrome P-450 monooxygenase activities were significantly increased in treated larvae of lab and field strains relative to untreated. The great variations in toxicity of the synthesized compounds were interpreted by structure-activity relationship study. The pyrrolone derivatives are effective against field and insecticide-resistant strains. Therefore, they are considered promising compounds to be integrated into pest management programs.

Chemical characterization, antimicrobial and mosquito larvicidal activities of the essential oil of Camellia pleurocarpa (Gagnep.) Sealy from Vietnam

Camellia pleurocarpa (Gagnep.) Sealy, a species of yellow camellia indigenous to Vietnam, was investigated for its essential oil properties in this study. Hydrodistillation of its leaves yielded a complex mixture rich in sesquiterpenes and diterpenes. Chemical analysis identified 50 constituents, with notable compounds including spathulenol (13.26%), phytol (9.94%), and α-selinene (5.34%). The essential oil exhibited significant antimicrobial activity against three Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus; one Gram-negative bacterium Pseudomonas aeruginosa; and one yeast Candida albicans, with minimum inhibitory concentration (MIC) values ranging from 16 to 32 μg/mL and half-maximal inhibitory concentration (IC50) values ranging from 7.26 to 16.23 μg/mL. Furthermore, it demonstrated larvicidal potential against Aedes aegypti and Culex quinquefasciatus mosquitoes, with LC50 values ranging from 13.49 to 28.95 μg/mL and LC90 values ranging from 28.29 to 53.24 μg/mL. These findings underscore the promising antimicrobial and mosquito larvicidal properties of C. pleurocarpa essential oil, suggesting its potential as a natural alternative in combating microbial infections and controlling mosquito-borne diseases. This study represents the first comprehensive report on the chemical compositions and bioactivities of C. pleurocarpa essential oil.

Friedericia chica, a medicinal plant from the Amazon region, is repellent against Aedes aegypti: in vivo andmolecular dockingevidence.

Fridericia chica is widely distributed in Brazil, where it is commonly known as crajiru or pariri in several regions. Despite its popular use for treating inflammations and as an insect repellent, there has been limited assessment of its chemical and biological properties, including its bioinsecticide activities. In this study, we conducted phytochemical analyses and investigated the larvicidal and repellent effects of F. chica against the mosquito Aedes aegypti. The F. chica (HEFc) hydroalcoholic extract was partitioned using column chromatography, and subfractions were analyzed using chromatographic and spectroscopic analyses (ESI-IT-MSn and NMR). In addition, HEFc was evaluated for its larvicidal and repellent activities. Phytochemical analyses revealed the presence of 17 constituents, including 2,4-dihydroxybenzoic and p-coumaric acids, along with umbelliferone, acetovanilone, myricetin-3-O-glucuronide, and cis-isorhapontigenin, which are reported for the first time in this species. Although no larvicidal effect was observed at the doses tested, the HEFc exhibited promising repellent effects against A. aegypti, which aligns with its ethnopharmacological potential. In addition, molecular docking studies demonstrated that the compounds of HEFc interacted efficiently with insect odorant binding proteins (OBPs), providing repellent effects. Consistent with the chemical profile and in silico studies, preparations of F. chica have considerable repellent potential.

Olax dissitiflora Oliv. (small-fruited olax): Current status and future prospects as medicinal plant

Olax dissitiflora Oliv. (O. dissitiflora) has several medicinal uses, some of them known since prehistoric times. The present review compiles existing knowledge of the chemical and pharmacological properties, current medicinal uses, and further use potential and applications of O. dissitiflora. Multiple searches on existing literature on the medicinal, phytochemistry and pharmacological properties of O. dissitiflora were conducted in online databases such as Scopus, JSTOR, PubMed, Google Scholar and Science Direct as well as using pre-electronic literature sources obtained from the university library. This study showed that the bark, leaves, roots and twigs of O. dissitiflora are used as aphrodisiac, emetic, mosquito repellent and purgative, and as traditional medicines against dental problems, gonorrhoea, hernia, venereal diseases and wounds. The phytochemical evaluation of the plant revealed that it contains reducing sugars, alkaloids, flavonoids, phenolic compounds, quinones, saponins, steroids, tannins, terpenoids, 21-epimachaerinic acid, oleanolic acid, hederagenin, oleanolic acid 3-O-glucuronide, amphotericin, santalbic acid, exocarpic acid and octadic-9,11-diynoic acid. The pharmacological assessments showed that the crude extracts and phytochemical compounds isolated from the species have antibacterial, antifungal, antiplasmodial, larvicidal and adulticidal activities. The collected ethnomedicinal and ethnopharmacological properties of O. dissitiflora documented in this review will assist to understand the therapeutic relevance and potential of the species as well as providing baseline data required for ethnopharmacological assessments required in the discovery of novel plant-based health products. There is also need for more studies focusing on phytochemistry, pharmacological properties and toxicological evaluations, in vivo and clinical research on O. dissitiflora to compliment and validate the ethnomedicinal properties of the species.

Bioefficacy of Zinc oxide nanoparticle synthesis and their Biological, Environmental applications from Eranthemum roseum

Synthesis of metal oxide nanoparticles using medicinal plants increasing rapidly due to its eco-friendly to environment. In this study Zinc oxide nanoparticle is synthesized using the leaf extract of plant E. roseum. Synthesized NPs was characterized using UV- Vis Spectroscopy analysis where the peak observed at 374 nm with band gap of 2.5 eV, FTIR and XRD analysis validate pure hexagonal structure, Spherical shape of NPs was confirmed by SEM with EDX analysis and main compounds are zinc 75 % and oxygen 22 %. Transmission Electron Microscopy Analysis confirms the oval shaped ZnO NPs Biological activity of E. roseum ZnO NPs such as antioxidant assay DPPH, ABTS, hydroxyl radical activity shows good inhibition against free radicals. The In-vitro Hypoglycemic effects has maximum inhibition of 96 % on α- amylase activity and 87 % on α- Glycosidase activity. Anti-inflammatory activity recorded 93 % maximum inhibition at Albumin denaturation assay and 75 % at Membrane stabilization assay. E. roseum ZnO NPs shows 67.79 % on HepG2 Anti-proliferative cells line. AO/EtBr staining assays confirms the apoptosis effect. Larvicidal activity shows highest mortality of 98.44 % on species C. quinquefasciatus. Photocatalytic dyedegradation of Methylene blue dye shows 65 % of dye degradation.

Larvicidal activity, molecular docking, and molecular dynamics studies of 7-(trifluoromethyl)indolizine derivatives against Anopheles arabiensis.

A novel series of 7-(trifluoromethyl)indolizine derivatives (4a-4n) was synthesized using a 1,3-Dipolar cycloaddition reaction. Structure elucidation of the synthesized compounds was done using various spectroscopic techniques. Compounds were assessed for their larvicidal activity against Anopheles arabiensis. Exposure of Anopheles arabiensis larvae to a series of 7-(trifluoromethyl)indolizine at 4µg/mL for 24 and 48h resulted in moderate to high larval mortality rates. Among them, compounds 4b, 4a, 4g, and 4m exhibited the most promising larvicidal activities, with mortality rates of 94.4%, 93.3%, 80.00%, and 85.6%, respectively, compared to controls, Acetone and Temephos. The structural activity relationship analysis of the evaluated compounds revealed that substitution with halogens or electron-withdrawing groups (CN, F, Cl, Br) at the para position of the benzoyl group is crucial for achieving promising larvicidal activity. Molecular docking studies were carried out involving six potential larvicidal target proteins to predict how the tested compounds might work. Compounds 4a and 4b showed strong binding to the Mosquito Juvenile Hormone-Binding Protein (5V13). Molecular dynamics (MD) simulations confirmed the stability of the protein-ligand complexes over the simulation period, reinforcing the reliability of the docking results. Compounds 4a and 4b also exhibited favourable ADMET profiles, showing high oral bioavailability, good permeability, moderate distribution, low plasma protein binding, sufficient metabolic stability, efficient renal clearance and low toxicity. Given the crucial role of Juvenile Hormone in regulating gene expression and developmental pathways through receptor interactions, compounds 4a and 4b show promise as inhibitors of this protein. Inhibiting this process could hinder larval growth and reproduction, presenting a promising approach for early-stage mosquito larvicidal activity. Therefore, compounds 4a and 4b represent lead candidates for further optimization and the development of new larvicidal agents.

Assessment of larvicidal, growth-suppressing, and developmentaltering bioefficacy of Ageratum houstonianum against Aedes aegypti (L.).

Aedes aegypti is a major vector responsible for spreading dengue, chikungunya, yellow fever, and Zika viruses worldwide. These illnesses have increased globally due to climate and environmental changes. Vector control and management are the principal tactics for combating mosquitoes-borne diseases in the absence of an effective vaccine. The study aimed to ascertain bioactivities of Ageratum houstonianum leaf acetone extract (AhLAE) against Aedes aegypti. Bioefficacy of AhLAE was tested against fourth instar larvae (L4) of Ae. aegypti using standard WHO protocol. The mortality, growth, and development of larvae, pupae and adults were recorded after exposure to the extract. The AhLAE showed larvicidal activity against L4 with LC50 and LC90 values of 401.88 and 691.24 mg/L, respectively. The mortality of the larvae further increased on subsequent days. The AhLAE caused a significant reduction in pupae formation and adult emergence. It also increased the larval duration of L4 and development duration of the pupa formed from the treated L4, indicating its growth-suppressing effects. The impact of the AhLAE was dose-dependent; high concentrations caused reduction in survival and growth of L4. Consequently, the L4-pupal and L4-adult growth indexes decreased. Additionally, the AhLAE induced developmental anomalies in the form of larva-pupa (L-P) intermediates. The study found that the AhLAE exhibited larvicidal, growth-suppressing, and development-altering activities against Ae. aegypti. The findings suggest the potential of AhALE as a natural insecticidal agent for controlling mosquitoes.

Larvicidal Activity of Bay Leaf (Syzygium polyanthum) Ethanolic Extract in Addition of PEG Diluent on Aedes aegypti Larvae

Larvicidal Activity of Bay Leaf (Syzygium polyanthum) Ethanolic Extract in Addition of PEG Diluent on Aedes aegypti Larvae

Investigation on the mosquitocidal property of cis-13-Octadecenoic acid isolated from Andrographis paniculata against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae)

Mosquitoes are a critical global public health concern, causing millions of deaths each year due to the viral infections and diseases they spread. In recent decades, synthetic insecticides and repellents have been used to control mosquito populations and virus transmission, but they often harm the environment and non-target organisms, including humans. This research investigates the isolation, characterization, and structural elucidation of cis-13-Octadecenoic acid derived from Andrographis paniculata, and its effectiveness against the immature stages of Aedes aegypti and Culex quinquefasciatus. The extracts from A. paniculata underwent fractionation, with the most bioactive fractions being further purified and analyzed. Spectroscopic techniques were employed to confirm the structure of cis-13-Octadecenoic acid. Biological assays were then performed to evaluate its ovicidal, larvicidal, and pupicidal activities. cis-13-Octadecenoic acid exhibited notable ovicidal activity, causing 25 % mortality in Ae. aegypti eggs and 29 % mortality in Cx. quinquefasciatus eggs at a concentration of 2 ppm. Additionally, it showed strong larvicidal and pupicidal activities, with LC50 values of 2.67 ppm and 3.39 ppm for Ae. aegypti larvae and pupae, and 3.10 ppm and 2.93 ppm for Cx. quinquefasciatus larvae and pupae, respectively. These findings demonstrate the potential of cis-13-Octadecenoic acid as an effective natural compound for mosquito control, highlighting the broader importance of natural products as alternatives to synthetic insecticides in the management of vector-borne diseases.

Synthesis and insecticidal assessment of nitrogenous heterocycles derived from 2-pyridone derivative against Culex pipiens L. Larvae

This study reports the synthesis of a novel 1,6-diamino-4-(2,4-dichlorophenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (1) and its subsequent functionalization to yield a library of diverse heterocycles (2-10). The nucleophilicity of compound 1 was exploited to react with various electrophiles to afford a range of structurally enriched derivatives. The structures of all synthesized heterocycles were confirmed by elemental analysis and spectroscopic techniques as (FT-IR, 1H-NMR, 13C-NMR, and mass spectroscopy). Bioassays revealed significant larvicidal activity against mosquito larvae (Culex pipiens L.) for compounds 1-4, 6, 7 and 9. In silico docking studies suggest a potential mode of action through acetylcholinesterase (AChE) inhibition, potentially explaining the observed larvicidal effect. Additionally, interactions with other neuroreceptors were predicted. Finally, analyzing of the structure activity relationship (SAR) of the novel constructed heterocycles gives us a lot of interesting promising results for developing novel and sustainable mosquito control strategies.

Prediction, Design, Synthesis, Insecticidal Activities of Polysubstituted Pyridine Anthranilic Amide Derivatives

Based on the predicted structure, a series of polysubstituted pyridine compounds containing 5-(furan-2-yl)-1H-pyrazole-3-carboxamido were designed and synthesized. These compounds were characterized using 1H NMR, 13C NMR, 19F NMR and HRMS. The results of the bioassays indicated that certain compounds exhibited promising activities against Mythimna separata and Plutella xylostella. It is noteworthy that compound I-6 exhibited 47% insecticidal activity at a concentration of 0.01 μg/mL, which reached the same activity level as chlorantraniliprole (CHL).Moreover, the cytotoxicity experiment showed compound I-26 demonstrated 50% larvicidal activity against M. separata at 10 μg/mL. Moreover, the toxicity of I-26 (IC50 0.007365 μg/mL) was superior to that of CHL (IC50 1.059 μg/mL). Furthermore, molecular docking was employed to predict the binding positions of the compounds, which demonstrated a good correlation between their insecticidal activities and their binding values. Finally, DFT calculations and molecular docking were employed to refine the binding sites of the ryanodine receptors in M. separata with CHL and I-24. The research laid a foundation for the innovation of RyR insecticides in the future.