Bioefficacy of plant-mediated gold nanoparticles and Anthocepholus cadamba on filarial vector, Culex quinquefasciatus (Insecta: Diptera: Culicidae)

Nanoparticle-mediated dsRNA delivery for precision insect pest control: a comprehensive review

Nanoparticle-based delivery systems have emerged as powerful tools in the field of pest management, offering precise and effective means of delivering double-stranded RNA (dsRNA), a potent agent for pest control through RNA interference (RNAi). This comprehensive review aims to evaluate and compare various types of nanoparticles for their suitability in dsRNA delivery for pest management applications. The review begins by examining the unique properties and advantages of different nanoparticle materials, including clay, chitosan, liposomes, carbon, gold and silica. Each material's ability to protect dsRNA from degradation and its potential for targeted delivery to pests are assessed. Furthermore, this review delves into the surface modification strategies employed to enhance dsRNA delivery efficiency. Functionalization with oligonucleotides, lipids, polymers, proteins and peptides is discussed in detail, highlighting their role in improving stability, cellular uptake, and specificity of dsRNA delivery.This review also provides valuable guidance on choosing the most suitable nanoparticle-based system for delivering dsRNA effectively and sustainably in pest management. Moreover, it identifies existing knowledge gaps and proposes potential research directions aimed at enhancing pest control strategies through the utilization of nanoparticles and dsRNA.

Eco-friendly approaches of zinc oxide and silver nitrate nanoparticles along with plant extracts against Spodoptera litura (Fabricius) under laboratory conditions

The tobacco cutworm (Spodoptera litura) is a widespread pest that inflicts severe damage on various crops, including cotton, tobacco, and vegetables, with a particular preference for solanaceous plants. Traditional control methods often rely heavily on synthetic insecticides, leading to adverse effects on the environment, human health, and the development of insecticide resistance. In light of these challenges, this study explores the potential of nanotechnology as an innovative and sustainable approach to combat this notorious pest. Bioassays were conducted using laboratory-reared 3rd instar S. litura larvae. Eight different plant extracts coated with zinc oxide and silver nitrate nanoparticles were tested, with concentrations in both distilled water and ethanol at 3, 5, and 7 ml. Data were collected at 24, 48, and 72-h intervals. The results revealed that the highest larval mortality, reaching 98%, was observed in the group treated with silver nitrate nanoparticles derived from Cymbopogon citratus. In comparison, the group treated with zinc oxide nanoparticles dissolved in ethanol exhibited a larval mortality rate of 90%. Ethanol is a polar solvent that is widely used in the synthesis of nanocomposites. It is capable of forming strong hydrogen bonds with oxygen atoms, making it a good dispersant for zinc oxide nanoparticles. Additionally, ethanol has a low boiling point and a non-toxic nature, which makes it a safe and effective option for the dispersion of nanoparticles. Notably, the study concluded that silver nanoparticles combined with ethanol exhibited prolonged and more potent toxic effects against S. litura when compared to zinc oxide nanoparticles. Overall, this research underscores the potential of nanotechnology as a valuable component of Integrated Pest Management (IPM) strategies. By integrating nanotechnology into pest management practices, we can promote sustainable and environmentally friendly approaches that benefit both farmers and the ecosystem.

Mosquito-Borne Diseases and Their Control Strategies: An Overview Focused on Green Synthesized Plant-Based Metallic Nanoparticles

Mosquitoes act as vectors of pathogens that cause most life-threatening diseases, such as malaria, Dengue, Chikungunya, Yellow fever, Zika, West Nile, Lymphatic filariasis, etc. To reduce the transmission of these mosquito-borne diseases in humans, several chemical, biological, mechanical, and pharmaceutical methods of control are used. However, these different strategies are facing important and timely challenges that include the rapid spread of highly invasive mosquitoes worldwide, the development of resistance in several mosquito species, and the recent outbreaks of novel arthropod-borne viruses (e.g., Dengue, Rift Valley fever, tick-borne encephalitis, West Nile, yellow fever, etc.). Therefore, the development of novel and effective methods of control is urgently needed to manage mosquito vectors. Adapting the principles of nanobiotechnology to mosquito vector control is one of the current approaches. As a single-step, eco-friendly, and biodegradable method that does not require the use of toxic chemicals, the green synthesis of nanoparticles using active toxic agents from plant extracts available since ancient times exhibits antagonistic responses and broad-spectrum target-specific activities against different species of vector mosquitoes. In this article, the current state of knowledge on the different mosquito control strategies in general, and on repellent and mosquitocidal plant-mediated synthesis of nanoparticles in particular, has been reviewed. By doing so, this review may open new doors for research on mosquito-borne diseases.

Docking studies and thiourea-mediated reduced graphene oxide nanosheets' larvicidal efficacy against Culexquinquefasciatus

The larvicidalproperty of graphene oxide (GO) and thiourea-reduced graphene oxide (T-rGO)was assessed against Culexquinquefasciatuslarvae. A simple water-soluble material synthesis method was used. The transformation of graphene into graphene oxide was accomplished in a single step. Under mild conditions, grapheneoxidewasdissolved in water to form a solution. Structure, optical, and microstructural features of the synthesized samples wereevaluatedusing a variety of analytical tools to compare the samples. Both GO and RGO, as well as GO, showed strong larvicidal potential when used against the third instar larvae of the Culexquinquefasciatus mosquito, with LC₅₀and LC₉₀values of 1.71 and 5.17 ppm and 1.89 and 5.00 ppm, respectively. As a result, our study showed that all of the GO and T-rGO under investigation create larvicidal compounds that could be employed to support efforts to control mosquito populations. It also offers an alternative method for producing GO and rGO on a big scale, which may be used in the future for a variety of biomedical applications.The binding efficacy of the active compounds against AChE1 was studied using Auto dock and the results were observed to be highly promising.

Green synthesis of gold nanoparticles using Gracilaria crassa leaf extract and their ecotoxicological potential: Issues to be considered

The use of vegetal species for gold nanoparticles (AuNPs) biosynthesis can constitute an alternative to replacing the extensive use of several hazardous chemicals commonly used during NPs synthesis and, therefore, can reduce biological impacts induced by the release of these products into the natural environment. However, the "green nanoparticles" and/or "eco-friendly nanoparticles" label does not ensure that biosynthesized NPs are harmless to non-target organisms. Thus, we aimed to synthesize AuNPs from seaweed Gracilaria crassa aqueous extract through an eco-friendly, fast, one-pot synthetic route. The formation of spherical, stable, polycrystalline NPs with a diameter of 32.0 nm ± 4.0 nm (mean ±SEM) was demonstrated by UV-vis spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy, energy-dispersive X-ray and X-ray diffraction measurement, and Fourier-transform infrared spectroscopy analysis. In addition, different phytocomponents were identified in the biosynthesized AuNPs, using Gas Chromatography-Mass Spectrometry (GC-MS). However, both G. crassa aqueous extract and the biosynthesized AuNPs showed high ecotoxicity in Anopheles stephensi larvae exposed to different concentrations. Therefore, our study supports the potential of seaweed G. crassa as a raw material source for AuNPs biosynthesis while also shedding light on its ecotoxicological potential, which necessitates consideration of its risk to aquatic biota.

Green Synthesis of Selenium Nanoparticles Mediated by Nilgirianthus ciliates Leaf Extracts for Antimicrobial Activity on Foodborne Pathogenic Microbes and Pesticidal Activity Against Aedes aegypti with Molecular Docking

The present study deals with the synthesis of selenium nanoparticles (SeNPs) using Nilgirianthus ciliatus leaf extracts, characterized by UV-Vis spectrophotometer, XRD, FTIR, FE-SEM, HR-TEM, DLS, and zeta potential analysis. The antimicrobial activity against Staphylococcus aureus (MTCC96), Escherichia coli (MTCC443), and Salmonella typhi (MTCC98) showed the remarkable inhibitory effect at 25 µl/mL concentration level. Furthermore, the characterized SeNPs showed a great insecticidal activity against Aedes aegypti in the early larval stages with the median Lethal Concentration (LC₅₀) of 0.92 mg/L. Histopathological observations of the SeNPs treated midgut and caeca regions of Ae. aegypti 4th instar larvae showed damaged epithelial layer and fragmented peritrophic membrane. In order to provide a mechanistic approach for further studies, molecular docking studies using Auto Dock Vina were performed with compounds of N. ciliatus within the active site of AeSCP2. Overall, the N. ciliates leaf-mediated biogenic SeNPs was promisingly evidenced to have potential larvicidal and food pathogenic bactericidal activity in an eco-friendly approach.

Predators as Control Agents of Mosquito Larvae in Micro-Reservoirs (Review)

The article reviews predators that are able to control populations of mosquito larvae (Culicidae) in phytotelmata and their anthropogenic analogs. The spectrum of mosquito larva consumers in micro-reservoirs is listed. It includes flatworms, crustaceans, arachnids, insects, vertebrates, and carnivorous plants. The biology and practical use of the two most effective biological control agents, predatory mosquitoes Toxorhynchites and copepods, are considered in more detail. Prospects of invertebrate predators as controlling agents for the mosquito larvae in micro-reservoirs in temperate climate zones are briefly discussed.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1134/S1995082922010138.

Novel synthesis of gold nanoparticles using Artemisia vulgaris L. leaf extract and their efficacy of larvicidal activity against dengue fever vector Aedes aegypti L

The Aedes aegypti L. mosquito transmits dengue and yellow fever, which cause millions of death every year. Dengue is a mosquito-borne viral disease that has rapidly spread worldwide particularly in countries with tropical and subtropical climates areas. The present study denotes a simple and eco-friendly biosynthesis of gold nanoparticles using Artemisia vulgaris L. leaf extract as reducing agent. The synthesized gold nanoparticles were characterized by UV-Visible Spectroscopy, X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Dynamic Light Scattering (DLS), Zeta Potential (ZP), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDX). Solid state ¹³C NMR was utilized to confirm the presence of larvicidal compound Beta caryophyllene in the synthesized AuNPs. Larvicidal activity of the synthesized AuNPs was measured against A. aegypti over 12 and 24h exposure periods and compared with essential oil in various concentrations (25ppm, 50ppm, 100ppm, 200ppm and 400ppm). After a 12h exposure period, the larvicidal activity of 3^rd instar larva by AuNPs showed LC₅₀=156.55ppm and LC₉₀=2506.21ppm, while and essential oil displayed LC₅₀=128.99ppm and LC₉₀=1477.08ppm. Larvicidal activity of 4^th instar larva by AuNPs showed LC₅₀=97.90ppm and LC₉₀=1677.36ppm, while essential oil displayed LC₅₀=136.15ppm and LC₉₀=2223.55ppm. After a 24h of exposure period, larvicidal activity of 3^rd instar larva by AuNPs showed LC₅₀=62.47ppm and LC₉₀=430.16ppm and essential oil showed LC₅₀=111.15ppm and LC₉₀=1441.51ppm. The larvicidal activity of 4^th instar larva and AuNPs displayed LC₅₀=43.01ppm and LC₉₀=376.70ppm and for essential oil LC₅₀=74.42ppm, LC₉₀=858.36ppm. Histopathology of A. aegypti with AuNPs for 3^rdand 4^th stage larvae after 24h exposure at the highest mortality concentration (400ppm) showed that the area of the midgut, epithelial cells and cortex were highly affected. The present findings demonstrate that the biosynthesis of AuNPs using A. vulgaris leaf extracts could be an eco-friendly, safer nanobiopesticide and treatment against A. aegypti which could be used to combat of dengue fever.

Synthesis of silver and gold nanoparticles using Jasminum nervosum leaf extract and its larvicidal activity against filarial and arboviral vector Culex quinquefasciatus Say (Diptera: Culicidae)

Silver and gold nanoparticles of Jasminum nervosum L. had unique optical properties such as broad absorbance band in the visible region of the electromagnetic spectrum. Characterization of the nanoparticles using UV spectrophotometer, Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy confirmed that the particles were silver (AgNPs) and gold (AuNPs) ranging between 4-22 and 2-20 nm with an average particles size of 9.4 and 10 nm, respectively. AgNPs and AuNPs of J. nervosum had high larvicidal activity on the filarial and arboviral vector, Culex quinquefasciatus, than the leaf aqueous extract. Observed lethal concentrations (LC50 and LC95) against the third instar larvae were 57.40 and 144.36 μg/ml for AgNPs and 82.62 and 254.68 μg/ml for AuNPs after 24 h treatment, respectively. The lethal time to kill 50% of C. quinquefasciatus larvae were 2.24 and 4.51 h at 150 μg/ml of AgNPs and AuNPs, respectively, while in the case of aqueous leaf extract of J. nervosum it was 9.44 h at 500 μg/ml (F 2,14 = 397.51, P < 0.0001). The principal component analysis plot presented differential clustering of the aqueous leaf extract, AgNP and AuNPs in relation to lethal dose and lethal time. It is concluded from the present findings that the biosynthesised AgNPs and AuNPs using leaf aqueous extract of J. nervosum could be an environmentally safer nanobiopesticide, and provided potential larvicidal effect on C. quinquefasciatus larvae which could be used for prevention of several dreadful diseases.

Cadamba: A miraculous tree having enormous pharmacological implications

The Cadamba is one of the important medicinal plants belonging to the Rubiaceae family. It is crucially significant as it has the largest number of phytochemicals and secondary metabolites (viz., cadambagenic acid, cadamine, quinovic acid, β-sitosterol, cadambine, etc.) having pharmacological and biological properties. It can be used as an alternative to various synthetic chemical compounds in the prevention as well as the treatment of several incurable diseases. More than 100 years of research has been done to discover various phytochemicals and their implications. Very few of them, i.e. ≤2% have been commercialized due to the lack of a suitable model system as well as various associated controversial issues. The solubility of phytochemicals is another major concern: Further response that will be generated due to the solvent used is also unpredictable. Moreover, the Cadamba is one of the ornamental plants with religious significance. Here we have made an effort to summarize all the phytochemicals and their significance to render the interest that would help in their commercialization.