Larvicidal Potential Research Articles

Essential Oils of Five Syzygium Species Growing Wild in Vietnam: Chemical Compositions and Antimicrobial and Mosquito Larvicidal Potentials.

The essential oils of five Vietnamese Syzygium species (Syzygium levinei, S. acuminatissimum, S. vestitum, S. cumini, and S. buxifolium) were first hydro-distilled and analyzed using GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry). Monoterpene hydrocarbons, sesquiterpene hydrocarbons, and oxygenated sesquiterpenoids were the main chemical classes in these oils. All these essential oils showed good-excellent antimicrobial activities against Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus, and the yeast Candida albicans. S. levinei leaf essential oil, rich in bicyclogermacrene (25.3%), (E)-β-elemene (12.2%), (E)-caryophyllene (8.2%), and β-selinene (7.4%), as well as S. acuminatissimum fruit essential oil containing (E)-caryophyllene (14.2%), α-pinene (12.1%), caryophyllene oxide (10.9%), β-selinene (10.8%), α-selinene (8.0%), and α-humulene (5.7%), established the same MIC value of 8 µg/mL against E. faecalis and B. cereus, which were much better than the positive control streptomycin (MIC 128-256 µg/mL). The studied essential oils showed the potential to defend against mosquitoes since they caused the 24 and 48 h LC50 values of less than 50 µg/mL against the growth of Culex quinquefasciatus and Aedes aegypti larvae. Especially, S. buxifolium leaf essential oil strongly inhibited Ae. aegypti larvae with 24 and 48 h LC50 values of 6.73 and 6.73 µg/mL, respectively, and 24 and 48 h LC90 values of 13.37 and 10.83 µg/mL, respectively. These findings imply that Vietnamese Syzygium essential oils might have potential for use as supplemental antibacterial agents or as "green" alternatives for the control of mosquitoes.

Chemical compositions, antioxidant, antimicrobial, and mosquito larvicidal activity of Ocimum americanum L. and Ocimum basilicum L. leaf essential oils

BackgroundOcimum americanum L. (O. americanum) and Ocimum basilicum L. (O. basilicum) are highly valued aromatic medicinal plants. Their leaves are widely used as spices in traditional cuisine. Their essential oils (EOs) are extensively used in food, cosmetic, and pharmaceutical industries. This study aimed to investigate the main chemical profiles of O. americanum and O. basilicum leaf EOs and assess their effects on antibacterial, antioxidant, and larvicidal properties.MethodsEOs were extracted from the leaves of O. basilicum and O. americanum using steam distillation in a Clevenger-type apparatus. The chemical constituents of the EOs were analyzed using gas chromatography–mass spectrometry. 2,2-Diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and metal-chelating techniques were used to assess the free-radical scavenging capability of the oils. The extracted oils were also tested for their antibacterial activities via a disk-diffusion test and the broth microdilution method. Furthermore, the mosquito larvicidal (Aedes aegypti) activity was tested using standard protocols.ResultsCamphor (33.869%), limonene (7.215%), longifolene (6.727%), caryophyllene (5.500%), and isoledene (5.472%) were the major compounds in O. americanum leaf EO. The EO yield was 0.4%, and citral (19.557%), estragole (18.582%) camphor (9.224%) and caryophyllene (3.009%) were the major compounds found among the 37 chemical constituents identified in O. basilicum oil. O. basilicum exhibited a more potent antioxidant activity in DPPH, FRAP, and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid tests than O. americanum. The zones of inhibition and minimum inhibitory concentration of the oils in the microdilution and disk diffusion methods were 8.00 ± 0.19 mm to 26.43 ± 2.19 mm and 3.12–100 µg/mL, respectively. At 400 ppm, O. basilicum and O. americanum EOs demonstrated larvicidal activity, with mortality ratios of 73.60% ± 0.89% and 78.00% ± 1.00%, respectively. Furthermore, after 30 min of exposure to O. americanum and O. basilicum EOs, the larval death rates were 73.60% ± 0.89% and 78.00% ± 1.00%, respectively.ConclusionsThe findings revealed that the EOs extracted from the leaves of O. basilicum and O. americanum exhibited reasonable antioxidant, antibacterial, and mosquito larvicidal potentials, and can be used as alternative medicine for the treatment of human health and larvicidal mosquito control.

"Synergistic Larvicidal Potential of Neem Leaf Aqueous Extract and Common Salt Against Aedes Aegypti Linnaeus "

"Synergistic Larvicidal Potential of Neem Leaf Aqueous Extract and Common Salt Against Aedes Aegypti Linnaeus "

Unraveling the Interaction Mechanism of the Compounds From Cladophora sp to Recognize Prospective Larvicidal and Bactericidal Activities: In vitro and In Silico Approaches.

The present investigation aims to validate the larvicidal and antibacterial potential of Cladophora sp through in vitro and in silico approaches. The presence of phytoconstituents, functional groups and the compounds responsible for antibacterial and larvicidal activity were assessed through FT-IR and GC-MS analyses which unveiled the existence of active secondary metabolites, hydroxyl, alkane and carbonyl groups. The larvicidal and antibacterial activity of algal extract were examined and revealed complete mortality and substantial zone of inhibition was observed against Culex quinquefasciatus and E. coli. To support the in vitro investigation in silico studies were performed. Molecular docking investigations of the selected compounds from GC-MS which exhibited favorable agreement with drug likeness and ADMET properties indicated robust interactions with the larvicidal and bacterial proteins showcasing considerable binding affinities. Notably, 1,2,4-Oxadiazole, 3-(1,3-benzodioxol-5-yl)-5-[(4-iodo-1H-pyrazol-1-yl) methyl]- exhibited strong interactions with the target proteins. Density Functional Theory revealed that the energy gap of the lead compound was reduced and substantiates the occurrence of intermolecular charge transfer. Molecular Dynamic simulations confirms the stability and flexibility of the lead compound. Hence, this investigation offers computational perspectives on the molecular interactions of Cladophora sp, suggesting its suitability as a promising biocontrol agent.

Green adeptness in synthesis of non-toxic copper and cobalt oxide nanocomposites with multifaceted bioactivities

BackgroundIn the present era, we are facing different health problems mainly concerning with drug resistance in microorganisms as well as in cancer cells. In addition, we are also facing the problems of controlling oxidative stress and insect originated diseases like dengue, malaria, chikungunya, etc. originated from mosquitoes. In this investigation, we unfurled the potential of Achatina fulica mucus in green synthesis of mucus mediated copper oxide bio-nanocomposites (SM-CuONC) and cobalt oxide bio-nanocomposites (SM-Co3O4NC). Herein we carried out the physico-chemical characterization like UV–Vis spectra, X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission electron microscopy (TEM), Energy Dispersive X-ray Analysis (EDAX) and X-ray photoelectron spectroscopy (XPS) of as synthesized bio-nanocomposites. Both the bio-nanocomposites were tested for their potential as antimicrobial activity using well diffusion assay, anticancer activity by MTT assay, antioxidant activity by phosphomolybdenum assay and mosquito larvicidal activity.ResultsThe results of this study revealed that, SM-CuONC and SM-Co3O4NC were synthesized successfully using A. fulica mucus. The FESEM and TEM data reveal the formation of nanoparticles with quasi-spherical morphology and average particle size of ~ 18 nm for both nanocomposites. The EDAX peak confirms the presence of elemental copper and cobalt in the analyzed samples. The X-ray diffraction analysis confirmed the crystalline nature of the CuO and Co3O4. The result of anti microbial study exhibited that, SM-CuONC showed maximum antimicrobial activity against Escherichia coli NCIM 2065 and Aspergillus fumigatus NCIM 902 which were noted as 2.36 ± 0.31 and 2.36 ± 0.59 cm resp. at 60 µg/well concentration. The result of anticancer activity for SM-CuONC was exhibited as, 68.66 ± 3.72, 62.66 ± 3.61 and 71.00 ± 2.36 percent kill, while SM-Co3O4NC exhibited 61.00 ± 3.57, 72.66 ± 4.50 and 71.66 ± 4.22 percent kill against Human colon cancer (HCT-15), Cervical cancer (HeLa), and Breast cancer (MDA-MB-231) cell lines, respectively, at 20 µg/well concentration. Both the nanocomposites also exhibited better antioxidant activity. Total antioxidant activity for SM-CuONC at 50 µg/ml concentration was found to be highest as 55.33 ± 3.72 while that of SM-Co3O4Ns was 52.00 ± 3.22 mM of ascorbic acid/µg respectively. Both bio-nanocomposites also exhibited 100% mosquito larvicidal activity at concentration ranging from 40 to 50 mg/l. During cytotoxicity study it is noted that at 5 µg/well concentration, SM-CuO and SM-Co3O4NCs suspension showed more than 97% viability of normal (L929) cell lines. We also studied phytotoxicity of both bio-nanocomposites on Triticum aestivum. In this study, 100% seed germination was observed when seeds are treated with SM-CuONC and SM-Co3O4NC at 500 mg/l and 250 mg/l concentration respectively.ConclusionsThis study concludes that in future as synthesized SM-CuONC and SM-Co3O4NC can be used in pharmaceutical, health care system for betterment and welfare of human life as both bio-nanocomposites exhibits better antimicrobial, anticancer, antioxidant and mosquito larvicidal potential.

Green synthesis and biophysical characterization of silver and palladium nanoparticles using Laureliopsis philippiana: A potent eco-friendly larvicide with negligible impact on zebrafish (Danio rerio)

Green nanoparticles represent a sustainable and eco-friendly approach to developing larvicides targeted at controlling mosquito populations. These nanoparticles are synthesized using natural, non-toxic materials and environmentally benign processes, emphasizing their potential to combat mosquito larvae while minimizing adverse effects on the ecosystem. This approach aligns with the growing need for sustainable solutions in vector control, providing an effective alternative to traditional larvicides with reduced environmental impact. The aim of the present investigation we have utilized the leaf from Laureliopsis philippiana (LP) to synthesize silver (Ag) and palladium (Pd) nanoparticles (NPs) and studied toxicity on deadly disease vectors larvae of Aedes aegypti and Anopheles stephensi. Biosynthesized Ag and Pd NPs were extensively characterized through physical and chemical methods. Gas chromatography–mass spectrometry analysis of L. philippiana assisted in identifying the secondary metabolites of the extract's total flavonoid and phenolic compounds, which are in the reactants of the bio-reduction process during the production of NPs. The in-silico analysis was conducted on mosquito sterol carrier protein-2 (1PZ4) and mosquito odorant binding protein (2L2C). The biosynthesized Ag and Pd NPs revealed the UV absorption peak at 417 and 370 nm, and X-ray diffraction results showed the crystalline structure of NPs. At the same time, in transmission electron microscopy representation, the Ag and Pd NPs were spherical, clustered, and exhibited a noticeable average size of Ag NPs: 13.25 ± 2.53 nm and Pd NPs: 4.07 ± 1.64 nm. The biogenic Ag and Pd NPs showed concentration-dependent larvicidal mortality at 12 and 24-hour exposure with LC50 values of 29.596, 17.804, and 23.915, 14.878 µg/mL on Ae. aegypti and 23.946, 13.938, 19.457, and 12.876 µg/mL against An. stephensi, correspondingly. In-silico studies proved that Laureliopsine A and isoterpinolene showed significant docking scores compared to permethrin on mosquito proteins (1PZ4 and 2L2C). Besides, the LP-Ag and Pd NPs non-toxicity analysis was carried out on zebrafish (Danio rerio) embryos at 72 h post-fertilization. Overall, the findings clearly demonstrated the green synthesized Ag and Pd NPs from L. philippiana to develop environmentally secure and safe larvicides.

Larvicidal potential, toxicological assessment, and molecular docking studies of four Egyptian bacterial strains against Culex pipiens L. (Diptera: Culicidae)

Mosquito control in Egypt depends on applying chemical synthetic pesticides that impact negatively on human health and the environment as well as the development of antibiotic and chemical resistance. This study aims to control the 3rd and 4th instars of Culex pipiens larvae using four bacterial strains. According to Phenotypic and molecular identification, the four isolates were identified as Bacillus subtilis MICUL D2023, Serratia marcescens MICUL A2023, Streptomyces albus LARVICID, and Pseudomonas fluorescens MICUL B2023. All strains were deposited in GenBank under accession numbers OQ764791, OQ729954, OQ726575, and OQ891356, respectively. Larvicidal activity of all microbial strain metabolites against a field strain of C. pipiens explored low LC50 results and reached its lowest values on the 3rd day with values of 6.40%, 38.4%, and 46.33% for P. fluorescens, S. albus, and S. marcescens, respectively. In addition, metabolites of P. fluorescence were more toxic than those of S. albus, followed by S. marcescens. B. subtilis shows no larvicidal effect on both field and lab mosquito strains. Microscopic alterations of 3rd and 4th instars showed toxic effects on different body parts (thorax, midgut, and anal gills), including losing external hairs, abdominal breakage, and larvae shrinkage, as well as different histological malformations in the digestive tract, midgut, and cortex. GC–MS analysis detected 51, 30, and 32 different active compounds from S. albus, S. marcescens, and P. fluorescens, respectively. GC detected 1, 2-BENZEA2:A52NEDICARBOXYLIC ACID, 2-Cyclohexene-1-carboxylic-acid-5-2-butenyl-methyl ester, and 3 octadecahydro2R3S4Z9Z-11R-12S from S. albus, S. marcesens, and P. fluorescens, respectively. Total protein, Total carbohydrate, and Acetylcholine esterase activity indicated significantly low levels on the 3rd day. All strain metabolites were safe against HSF cell lines. The docking results confirmed the role of the produced metabolites as larvicidal agents and Acetylcholine esterase inhibition. Such a problem need more studies on applying more and more natural pesticides.

First report on evaluation of commercial eugenol and piperine against Aedes aegypti L (Diptera: Culicidae) larvae: Mortality, detoxifying enzyme, and histopathological changes in the midgut

Dengue fever is a worldwide public health problem, and efforts to eradicate it have focused on controlling the dengue vector, Aedes aegypti. This study aims to assess the toxicity and effect of commercial eugenol and piperine on Ae. aegypti larvae through enzyme detoxification and histopathological changes in the midgut. Laboratory-reared Ae. aegypti larvae were treated with various concentrations of commercial eugenol and piperine and observed after 24, 48, and 72 h. Biochemical methods were used to assess detoxification enzyme activity for acetylcholinesterase, glutathione S-transferase, and oxidase, and changes in the midgut were examined using routine histological examination. In terms of larvicidal activity, piperine exceeded eugenol. Piperine and eugenol had LC50 and LC90 values of 3.057 and 5.543 μM, respectively, and 6.421 and 44.722 μM at 24 h. Piperine and eugenol reduced oxidase activity significantly (p < 0.05), but increased acetylcholinesterase and glutathione S-transferase activity significantly (p < 0.05). After being exposed to piperine and eugenol, the food bolus and peritrophic membrane ruptured, the epithelial layer was interrupted and irregular, the epithelial cells shrank and formed irregularly, and the microvilli became irregular in shape. Commercial piperine and eugenol behave as potential larvicides, with processes involving altered detoxifying enzymes, specifically decreased oxidase function and increased GST activity, as well as midgut histological abnormalities.

Octadecadienoate derivatives from Michelia champaca seed extract as potential larvicide and pupicide against Dengue vector Aedes albopictus

The present study was designed aiming at finding novel botanicals for controlling the vector population. Objective was to evaluate the larvicidal and pupicidal efficacies of crude and solvent extracts of Michelia champaca seed against the notorious dengue vector Aedes albopictus. 0.5% concentration of the crude extractive and 40 ppm concentration of ethyl acetate extractive were enough to execute 100% of larval mortality of all the instars after 72 h of exposure and the LC50 and LC90values (95% confidence level) of ethyl acetate extractive were 0.9880 ppm and 36.0491 ppm. In case of pupicidal bioassay, 100% mortality was observed at 200 ppm of ethyl acetate extract. Through TLC techniques, the bioactive compounds were isolated, which caused remarkable larval toxicity at 15 ppm concentration. Three-way factorial ANOVA analysis showed different concentrations, time intervals, and instars revealed a significant difference in larval death. FT-IR analysis revealed the presence several important functional groups. Presence of methyl 5,12-octadecadienoate and ethyl 9cis,11trans-octadecadienoate were ascertained by GC-MS analysis. The said bioactive compounds showed very low toxicity in non-target organisms such as damselfly (Ischnura sp.) and water bug (Diplonychus sp.) Thus, proclaiming the potentialities of Michelia champaca seed extracts as larvicidal and pupicidal agents against Ae. albopictus.

Evaluation of larvicidal activity of Panchagavya, against the teak defoliator (&lt;i&gt;Hyblaea puera&lt;/i&gt; Cramer) and skeletonizer (&lt;i&gt;Eutectona machaeralis&lt;/i&gt; Walker) in a forest plantation

Panchagavya is an organic formulation, formed by merging five cow derivatives, such as dung, urine, milk, ghee, and curd, which promotes the growth of plants. The present investigation was aimed to determine the larvicidal efficacy of Panchagavya with varied concentrations against major pests of teak, Tectona grandis, singly, and combined with leaf extract of members of Meliaceae family, and coupled with extract of seaweed, in experimental research plots. Observations on occurrence of pests was also observed periodically and recorded. Treatments include 5% concentration of panchagavya (T1), which serves as a control and Panchagavya combined with varied dosage of other leaf crude extracts of Melia dubia (T2), Melia azedarach (T3), Azadirachta indica (T4), and a seaweed, Sargassum wightii (T5), with a concentration range of 1000-5000 ppm that were used as foliar application. Among the various pests, Hyblaea puera, and Eutectona machaeralis were found to be dominant, and the III instar larval stage were targeted for the management. Maximum larval mortality was observed with exposure to Panchagavya with crude extract of S. wightii, at an appropriate ratio (T5) against teak defoliator, Hyblaea puera. The per cent pest reduction was found to be 65% and 73% in 48 h and 72 h time interval. Similarly, higher level of larval mortality was recorded against skeletonizer (E. machaeralis) where the reduction per cent was recorded as 62% and 71% at 5000 ppm in (T5) within the interval of 48 h and 72 h. Consequently, a distinct individual lethal effect of Panchagavya (T1, control) against both pests was found to be 8%, 24%, and 46% with similar time frames. However, the efficacy of Panchagavya combined with extract of M. dubia, M. azedarach and A. indica exhibited statistically significant ability in larvicidal potential against H. puera. Whereas, treatments like T2, T3, and T4 showed 59, 67, and 62 % of larval mortality of E. machaeralis larva within the period of 72 h. The results of the study affirmed that the synergistic effects of Panchagavya coupled with seaweed extract at appropriate ratio proved to be effective against major pests of teak plantation.

Nerium oleander Leaf Extract Causes Midgut Damage and Interferes with the Survival of Culex pipiens L. Larvae

Background: Diseases vectored by mosquitoes are one of the major causes of diseases and death worldwide. Insecticide resistance of Cx. pipiens increased the suffering of the people. Plants are a promising source of secondary metabolites to help resolve this problem. Methods: This study investigated the larvicidal potential of N. oleander methanol aqueous extract against Cx. Pipiens. Results: Post 24 h, 48h and 72 h of exposure, the LC50 value was 4.94 mg/mL, and the LC90 value was 8.01 mg/mL. After 72 h of exposure, the values were 2.93 mg/mL and 4.79 mg/mL, respectively. Larvae treated with N. oleander leaf extract displayed degraded microvilli, degenerating peritrophic membrane, and degenerating nuclei with blebbing compared to the control. The GC-MS analysis revealed the presence of eleven phytoconstituents in the leaf extract. 1-Methyl-1H-Tetrazol-5-yl)thio]acetic acid (80.67%), 2-Furancarboxaldehyde, 5-1(hydroxymethyl)- (8.10%), and 9,12-Octadecadienoic acid (Z, Z)- (4.33%) were the main secondary metabolites found in the leaf extract.

In Vitro and Molecular Docking Evaluation of Larvicidal Effects of Essential Oils of Five Aromatic Plants on the Fall Armyworm Spodoptera frugiperda JE. Smith (Lepidoptera: Noctuidae) from Ivory Coast.

Faced with the serious consequences resulting from the abusive and repeated use of synthetic chemicals, today rethinking crop protection is more than necessary. It is in this context that the essential oils of the Lamiaceae Ocimum gratissimum and Ocimum canum, the Poaceae Cymbopogon citratus and nardus and a Rutaceae Citrus sp. of known chemical compositions were experimented. The evaluation of the larvicidal potential of the essential oils was done by the method of topical application of the test solutions, on the L1-L2 stage larvae from the first generation of S. frugiperda obtained after rearing in an air-conditioned room. Lethal concentrations (LC10 , LC50 and LC90 ) were determined after 48 h. After assessing the larvicidal potential of essential oils, molecular docking was carried out to study protein-ligand interactions and their propensity to bind to insect enzyme sites (AChE). The essential oil of O. gratissimum was the most effective with the lowest lethal concentrations (LC10 =0.91 %, LC50 =1.91 % and LC90 =3.92 %). The least toxic oil to larvae was Citrus sp. (LC10 =5.44 %, LC50 =20.50 % and LC90 =77.41 %). Molecular docking revealed that p-cymene and thymol from O. gratissimum essential oil are structurally similar and bind to the AChE active site via predominantly hydrophobic interactions and a H-bond with Tyr374 in the case of thymol. The essential oil of O. gratissimum constitutes a potential candidate for the development of biological insecticides for the fight against insect pests and for the protection of the environment.

Potential for Aedes aegypti Larval Control and Environmental Friendliness of the Compounds Containing 2-Methyl-3,4-dihydroquinazolin-4-one Heterocycle.

2-Methylquinazolin-4(3H)-one was prepared by the reaction of anthranilic acid, acetic anhydride, and ammonium acetate. The reaction of 2-methylquinazolin-4(3H)-one with N-aryl-2-chloroacetamides in acetone in the presence of potassium carbonate gave nine N-aryl-2-(2-methyl-4-oxoquinazolin-3(4H)-yl)acetamide compounds. The structures of these compounds were elucidated on the basis of their IR, 1H nuclear magnetic resonance (NMR), 13C NMR, and high-resolution mass spectrometry (HR-MS) spectral data. These synthesized compounds containing the 2-methyl-3,4-dihydroquinazolin-4-one moiety exhibited activity against Aedes aegypti mosquito larvae with LC50 values of 2.085-4.201 μg/mL after 72 h exposure, which is also confirmed using a quantitative structure-activity relationship (QSAR) model. Interestingly, these compounds did not exhibit toxicity to the nontarget organism Diplonychus rusticus. In silico molecular docking revealed acetylcholine binding protein (AChBP) and acetylcholinesterase (AChE) to be potential molecular targets. These data indicated the larvicidal potential and environmental friendliness of these N-aryl-2-(2-methyl-4-oxoquinazolin-3(4H)-yl)acetamide derivatives.

A study on the larvicidal and adulticidal potential of Cladostepus spongiosus macroalgae and green-fabricated silver nanoparticles against mosquito vectors

Abstract Mosquito vectors in the present universe cause a major problem due to the transmission of pathogens with high morbidity. The present research aimed to explore the larvicidal and adulticidal toxicity of the Cladostepus spongiosus extract and its fabricated AgNPs on key mosquito vectors. The synthesized AgNPs were confirmed by UV-Vis spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrophotometry, and X-ray diffraction analysis. In the mosquitocidal assay, the C. spongiosus extract has shown good larvicidal mortality against Aedes aegypti (88.9%), Anopheles stephensi (84.1%), and Culex. quinquefasciatus (81.6%). Further, adulticidal mortality percentages were 78.8%, 75.4%, and 67.6% against An. stephensi, Ae. Aegypti, and Cx. quinquefasciatus at 1,000 ppm. AgNPs revealed larvicidal mortality percentages of 94.8% against An. stephensi, 92.8% against Ae. Aegypti, and 90.6% against Cx. quinquefasciatus; the adulticidal potential was also revealed to be higher against An. stephensi (89.4%) followed by Ae. aegypti (86.8%) and Cx. quinquefasciatus (83.2%). Comparing the results achieved from the C. spongiosus extract and its derived AgNPs, promising activity was attained against key mosquito vectors at a minimal dose of 70 ppm of AgNPs. Thus, C. spongiosus-mediated AgNPs can be an alternative tool in controlling key mosquito vectors.

Ovicidal and larvicidal potential of Aloe vera Lynn extract on Haemonchosis

Ovicidal and larvicidal potential of Aloe vera Lynn extract on Haemonchosis

Insecticidal activity of ethanolic plant extracts on Aedes aegypti larvae

[Objective] The objective of this study was to determine the larvicidal activity against A. aegypti of ethanolic extracts of plants commonly found in Costa Rica. [Methodology] Larvicidal activity of ethanolic extracts of plants was determined in this study using the WHO/VBC/81.807: WHO/VBC/81. from 1981. An analysis PROBID for dose response was conducted to determine LC50 of the most prominent extracts. [Results] A total of six extracts with the highest toxicity were chosen, with the stem extract of Ipomoea cairica having the lowest LC50 of 0.0341 mg/mL, followed by I. cairica leaf extract with an LC50 of 0.121 mg/mL. The larvicidal activity of ethanolic extracts of plants was determined in this study, with an emphasis on the larvicidal potential of I. cairica as an environmentally friendly alternative for the control of A. aegypti. [Conclusions] The larvicidal activity for ethanolic extracts of different plants, with an emphasis on the larvicidal potential of I. cairica as an environmentally friendly alternative for the control of A. aegypti.

Biosynthesis, mosquito larvicidal potential, and anticancer activities of gold nanoparticles from Acacia sinuata seed extract

Introduction and Aim: Worldwide, mosquitoes are the main vectors of many deadly diseases like malaria, dengue, chikungunya, etc., Anopheles stephensi mosquito which transmits malaria whereas dengue is transmitted mainly by mosquito Aedes aegypti. Current controlling methods such as chemical or microbial pesticides, repellents, biological control agents against mosquito larvae are not so effective. The leading cause of death worldwide is cancer. Nanotechnology can provide alternative effective methods for malaria, dengue and cancer control, diagnosis and treatment. This study investigated the biosynthesis of gold nanoparticles (AuNPs) from Acacia sinuata seed extract and their mosquito larvicidal potential was tested against Aedes aegypti, Anopheles stephensi larvae. The cytotoxic activity of NPs was also analyzed against human cancer cell lines osteosarcoma (MG-63) and colon adenocarcinoma (Caco-2). Materials and Methods: The biosynthesized NPs were confirmed and characterized by conventional techniques UV- visible spectroscopy, FTIR, XRD, HR-TEM, EDX and SAED. Results: The XRD demonstrated the NPs were face-centred, cubic, and crystalline in nature, EDX study confirmed elemental analysis of gold, SAED illustrated the crystalline nature. The HR-TEM studies revealed NPs shape which were mostly spherical and average size of 5.38nm-8.86nm. Third instar larvae of Aedes aegypti, Anopheles stephensi, were susceptible to the larvicidal effects of AuNPs. The synthesized NPs showed a dose-dependent cytotoxic effect against the Caco-2 and MG-63 cell lines, with IC50 (inhibitory concentrations) of 21.31± 0.15 ug/ml and 86.78± 0.23 ug/ml, respectively. Conclusion: These findings reveal that biosynthesized AuNPs have substantial larvicidal and anticancer properties, suggesting they could be used in mosquito control and cancer treatment.

Ovicidal, larvicidal and pupicidal potential of neem seed kernel extract against Aedes aegypti L.

Ovicidal, larvicidal and pupicidal potential of neem seed kernel extract against Aedes aegypti L.

Isolation, Genomic, and Proteomic Characterization of a Novel Neotropical Strain of Bacillus thuringiensis with Mosquitocidal Activities

The combination of genomic and proteomic analyses is a useful tool for the study of novel Bacillus thuringiensis (Bt) strains, as these approaches allow the accurate identification of pesticidal proteins and virulence factors produced. Here, we isolated and evaluated the potential of a novel Neotropical Bt strain (TOD651) for controlling larvae of Aedes aegypti and Culex quinquefasciatus mosquitoes. Aiming for the full comprehension of the TOD651 larvicidal potential, we further evaluated the whole TOD651 genome and conducted the proteomic analysis of the TOD651 spore–crystal mixtures. Our results showed that Bt TOD651 similarly killed both A. aegypti (0.011 µg/mL) and C. quinquefasciatus (0.023 µg/mL) larvae, exhibiting similar potency to the commercial Bt strain. The genome sequence revealed that Bt TOD651 harbors cry11Aa3, cry10Aa4, cry4Aa4, cry4Ba5, cyt1Aa5, cyt1Ca1, cyt2Ba13, mpp60Aa3, and mpp60Ba3. The proteomic analysis revealed no expression of Mpp60Aa3, while all the other pesticidal proteins were expressed (Cry4Ba5 was more abundant than Cyt1Aa5). The expression of the Mppe showed the major proportions between proteases. The virulent factor neutral protease B and spore coat proteins were also expressed. The expression of relevant pesticidal proteins (e.g., Cry, Cyt, Mpp, and other pathogenic factors), whose actions can occur in a synergic relation, indicates that the biocontrol using Bt TOD651 may contribute to delaying the selection of resistant individuals.

Sonication and heat-mediated synthesis, characterization and larvicidal activity of sericin-based silver nanoparticles against dengue vector (Aedes aegypti).

Fabrication, characterization and evaluation of the larvicidal potential of novel silk protein (sericin)-based silver nanoparticles (Se-AgNPs) were the prime motives of the designed study. Furthermore, investigation of the sericin as natural reducing or stabilizing agent was another objective behind this study. Se-AgNPs were synthesized using sonication and heat. Fabricated Se-AgNPs were characterized using particle size analyzer, UV spectrophotometry, FTIR and SEM which confirmed the fabrication of the Se-AgNPs. Size of sonication-mediated Se-AgNPs was smaller (7.49 nm) than heat-assisted Se-AgNPs (53.6 nm). Being smallest in size, sonication-assisted Se-AgNPs revealed the significantly highest (F4,10 = 39.20, p = .00) larvicidal activity against fourth instar lab and field larvae (F4,10 = 1864, p = .00) of dengue vector (Aedes aegypti) followed by heat-assisted Se-AgNPs and positive control (temephos). Non-significant larvicidal activity was showed by silver (without sericin) which made the temperature stability of silver, debatable. Furthermore, findings of biochemical assays (glutathione-S transferase, esterase, and acetylcholinesterase) showed the levels of resistance in field strain larvae. Aforementioned findings of the study suggests the sonication as the best method for synthesis of Se-AgNPs while the larvicidal activity is inversely proportional to the size of Se-AgNPs, i.e., smallest the size, highest the larvicidal activity. Conclusively, status of the sericin as a natural reducing/stabilizing agent has been endorsed by the findings of this study. RESEARCH HIGHLIGHTS: Incorporation of biocompatible and inexpensive sericin as a capping/reducing agent for synthesis of Se-AgNPs. A novel sonication method was used for the fabrication of Se-AgNPs which were thoroughly characterized by particle size analyzer, UV-visible spectrophotometry, SEM and FTIR. Analysis of enzymatic (GSTs, ESTs) levels in field and lab strains of Aedes aegypti larvae for evaluation of insecticides resistance.