Overexpression of cytochrome P450 and esterase genes involved in permethrin resistance in larvae and adults of Culex quinquefasciatus.

Mosquitoes are important vectors of several arthropod-borne diseases, which remain a priority for epidemiological research. Mosquito vector control strategies have traditionally relied on chemical insecticides such as synthetic pyrethroids. However, the indiscriminate use of pesticides has resulted in the development of resistance in many mosquito species. In insects, resistance evolves primarily through the overexpression of one or more gene products from the cytochrome P450, carboxylesterase, and glutathione superfamilies. The current study examined the expression of cytochrome P450 CYP6M2, CYP6AA7, CYP6Z2, CYP9J34, α-Esterase, Esterase B1, and neuroactin genes in larvae and adults of a permethrin-resistant (PerRes) and susceptible (Sus) Culex quinquefasciatus strains. The results showed that the CYP6AA7 gene was overexpressed (10-fold) in larvae and adults with PerRes (p < 0.01) followed by CYPJ34 (9.0-fold) and CYP6Z2 (5.0-fold) compared to the Sus, whereas fewer changes in CYP6M gene expression were observed in PerRes adults (p < 0.05), and no expression was found in larvae. The esterase gene was overexpressed in PerRes larvae (9.0-fold) followed by adults (2.5-fold) compared to the susceptible strain. Based on data, the present study suggests that cytochrome P450, CYP6AA7, CYP6Z2, CYP9J34, α-Esterase, Esterase B1, and neuroactin genes were involved in permethrin resistance in larval and adult Cx. quinquefasciatus.

Prosopis juliflora hydrothermal synthesis of high fluorescent carbon dots and its antibacterial and bioimaging applications.

Carbon dots have stimulated the curiosity of biomedical researchers due to their unique properties, such as less toxicity and high biocompatibility. The synthesis of carbon dots for biomedical application is a core area in research. In the current research, an eco-friendly hydrothermal technique was employed to synthesize high fluorescent, plant-derived carbon dots from Prosopis juliflora leaves extract (PJ-CDs). The synthesized PJ-CDs were investigated by physicochemical evaluation instruments such as fluorescence spectroscopy, SEM, HR-TEM, EDX, XRD, FTIR, and UV-Vis. The UV-Vis absorption peaks obtained at 270 nm due to carbonyl functional groups shifts of n→π*. In addition, a quantum yield of 7.88 % is achieved. The synthesized PJ-CDs showing the presence of carious functional groups O-H, C-H, C=O, O-H, C-N and the obtained particles in spherical shape with an average size of 8 nm. The fluorescence PJ-CDs showed stability against various environmental factors such as a broad range of ionic strength and pH gradient. The antimicrobial activity of PJ-CDs was tested against a Staphylococcus aureus, and a Escherichia coli. The results suggest that the PJ-CDs could substantially inhibit the growth of Staphylococcus aureus. The findings also indicate that PJ-CDs are effective materials for bio-imaging in Caenorhabditis elegans and they can be also used for pharmaceutical applications.

Biogenic synthesis of ZnO nanoparticles mediated from Borassus flabellifer (Linn): antioxidant, antimicrobial activity against clinical pathogens, and photocatalytic degradation activity with molecular modeling.

Borassus flabellifer leaf extract has been used for rapid biogenic synthesis of zinc oxide nanoparticles (ZnO-NPs) due to rich source of bioactive compounds. The synthesized ZnO-NPs were preliminarily confirmed by UV-visible spectroscopy adsorption peak range at 365 nm. The XRD (X-ray diffraction) confirms purity of ZnO-NPs that were crystalline in nature. The analysis of FT-IR (Fourier-transform infrared spectroscopy) confirms the presence of the following functional group such as alcohol, phenols, carboxylic acids, primary amides, secondary amides, and alkyl halide. The Field Emission Scanning Electron Microscope (FE-SEM) analysis indicated that ZnO-NPs were in spherical shape, followed by EDX analysis which confirmed the presence of Zn-element. Antimicrobial effect of ZnO-NPs was investigated using different clinical pathogens like bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella Pneumonia, and Pseudomonas aeruginosa and fungi Aspergillus flavus, Candida albicans, and Penicillium expansum which confirmed ZnO-NPs efficiency as an antimicrobial agent. ZnO-NP antimicrobial efficiency was observed in higher zone of inhibition at 50 µg/mL concentrations. Antioxidant activity was ascertained to be used for several biomedical applications. The ZnO-NPs efficiently degraded the environmental toxic dyes (methylene blue and crystal violet) under sunlight, and up to 95% higher degradation was achieved in both dyes. In support of photo light degradation, the study was progressed to understand the ZnO-dye interaction stability using molecular mechanism, and it shows efficient bonding features in the NPs environment. Overall, this investigation has great potential for being an effective and eco-friendly material used in environmental applications.

Larvicidal toxicity of Metarhizium anisopliae metabolites against three mosquito species and non-targeting organisms.

BACKGROUND: The fungal toxin acts as effective, low-cost chemical substances for pest control worldwide and also an alternative to synthetic insecticides. This study assessed the larvicidal potential of Metarhizium anisopliae fungi derived metabolites against Aedes aegypti, Anopheles stephensi, Culex quinquefasciatus and non-targeted organisms at 24hr post treatment. METHOD: Isolation of entomopathogenic fungi M. anisopliae from natural traps confirmed by using 18s rDNA biotechnological tools. Crude extracts from M. anisopliae solvent extraction and their secondary metabolites were bio-assayed following WHO standard procedures against Ae. aegypti, An. stephensi and Cx. quinquefasciatus, Artemia nauplii, Eudrilus eugeniae, and Solanum lycopersicum after 24 hr exposure. Histopathological analysis of E. eugeniae treated with fungi metabolites toxicity compared to those treated with Monocrotophos after 24hrpost-treatment. M. anisopliae metabolites were characterized using GC-MS and FT-IR analysis. RESULTS: The larvicidal activity was recorded in highest concentration of 75µg/ml, with 85%, 97% and 89% mortality in Ae. aegypti, An. stephensi and Cx. quinquefasciatus respectively. M. anisopliae metabolites produced LC50 values in Ae. aegypti, 59.83µg/ml, in An. stephensi, 50.16µg/ml and in Cx. quinquefasciatus, 51.15µg/ml respectively. M. anisopliae metabolites produced lower toxic effects on A. nauplii, LC50 values were, 54.96µg/ml respectively. Bio-indicator toxicity results show 18% and 58% mortality was recorded in E. eugeniae and A. nauplii and also there is no phytotoxicity that was observed on S. lycopersicum L. under semi-field condition. E. eugeniae histopathological studies shows fungal metabolites showed lower sub-lethal effects compared to synthetic chemical pesticide at 24hrs of the treatment. The GC-MS and FT-IR analysis identified five major components of active ingredients. CONCLUSION: Findings of this study indicate that, M. anisopliae ethyl acetate derived secondary metabolites are effective against larvae of Ae. aegypti, An. stephensi and Cx. quinquefasciatus mosquito species, lower toxicity effects were observed on non-target organisms such as, Artemia nauplii, Eudrilus eugeniae as well as, no toxicity effect were observed on Solanum lycopersicum. Further research should be conducted in laboratory for separation of single pure molecule and be tested semifield conditions.

Diet composition has a differential effect on immune tolerance in insect larvae exposed to Mesorhabditis belari, Enterobacter hormaechei and its metabolites.

In insects, diet plays an important role in growth and development. Insects can vary their diet composition based on their physiological needs. In this study we tested the influence of diet composition involving varying concentrations of macronutrients and zinc on the immune-tolerance following parasite and pathogen exposure in Spodoptera litura larvae. We also tested the insecticidal potential of Mesorhabditis belari, Enterobacter hormaechei and its secondary metabolites on Spodoptera litura larvae. The results shows macronutrient composition does not directly affect the larval tolerance to nematode infection. However, Zinc supplemented diet improved the immune tolerance. While larvae exposed to bacterial infection performed better on carbohydrate rich diet. Secondary metabolites from bacteria produced an immune response in dose dependent mortality. The study shows that the larvae maintained on different diet composition show varied immune tolerance which is based on the type of infection.

Toxicity of Beauveria bassiana-28 Mycelial Extracts on Larvae of Culex quinquefasciatus Mosquito (Diptera: Culicidae).

Microbial-based pest control is an attractive alternative to chemical insecticides. The present study sought to evaluate the toxicity of the entomopathogenic fungus Beauveria bassiana-28 ethyl acetate extracts on different larval stages and pupae of Culex quinquefasciatus mosquitoes. B. bassiana-28 ethyl acetate mycelial extracts produced mosquitocidal activity against larvae and pupae which was comparable to that of the commercial insecticide B. bassiana-22 extract. The LC50 (lethal concentration that kills 50% of the exposed larvae) values of B. bassiana-28 extracts for 1st to 4th instar larvae and pupae were 11.538, 6.953, 5.841, 3.581 and 9.041 mg/L respectively. Our results show that B. bassiana-28 ethyl acetate mycelial extract has strong insecticidal activity against larval and pupal stages of Cx. quinquefasciatus. Fourier transform infrared spectrum study of B. bassiana-28 extract shows peaks at 3226.91; 2927.94; 1593.13; 1404.18; 1224.18; 1247.94; 1078.21; 1018.41; 229.69; and 871.82 cm-1. Major spectral peaks were observed at 3226.91 cm-1, assigned to N-H stretching, 2927.94 cm-1 assigned to C-H bonding and 1595.13 cm-1 assigned to C-O stretching. Gas Chromatography-Mass Spectrometry studies of B. bassiana-28 ethyl acetate crude extract showed presence of six major compounds viz. N-hexadecanoic acids (13.6040%); Z,Z-9,12 octadecadienic acid (33.74%); 9-eicosyne (10.832%); heptacosane (5.148%); tetrateracontane (5.801%); and 7 hexyleicosane (5.723%). Histology of mosquito midgut tissue shows tissue lysis as a result of B.bassiana-28 extract exposure. The study shows that bioactive molecules obtained from B. bassiana-28 mycelial extract has insecticidal properties and can be used as alternative for mosquito control.

Comparative Analysis of Major Mosquito Vectors Response to Seed-Derived Essential Oil and Seed Pod-Derived Extract from Acacia nilotica.

Botanical metabolites are increasingly realized as potential replacements to chemical insecticides. In the present study, Acacia nilotica seed essential oil and seed pod solvent extracts were tested for bioefficacy against three important types of mosquitoes. Mortality was recorded 24 h post-treatment, while smoke toxicity of adult mosquitoes was recorded at 10 min intervals for 40 min. Seed pod powder was extracted with different solvents and hydrodistilled seed oil chemical constituents were determined by using Gas chromatography mass spectroscopy (GC-MS) -. Larvicidal and adulticidal efficacy of seed hydrodistilled essential oil and solvent extracts were tested against larval and adult mosquitoes. The seed hydrodistilled oil provided strong larvicidal activity against Anopheles stephensi, (LC50 (lethal concentration that kills 50% of the exposed larvae) = 5.239, LC90 (lethal concentration that kills 90% of the exposed larvae) = 9.713 mg/L); Aedes aegypti, (LC50 = 3.174, LC90 = 11.739 mg/L); and Culex quinquefasciatus, (LC50 = 4.112, LC90 = 12.325 mg/L). Smoke toxicities were 82% in Cx. quinquefasciatus, 90% in Ae. aegypti, and 80% mortality in An. stephensi adults, whereas 100% mortality was recorded for commercial mosquito coil. The GC-MS profile of seed essential oil from A. nilotica showed the presence of hexadecane (18.440%) and heptacosane (15.914%), which are the main and active compounds, and which may be involved in insecticidal activity. Overall findings suggest that the seed oil showed strong mosquitocidal activity against mosquito vectors and therefore may provide an ecofriendly replacement to chemical insecticides.

Insecticidal potential of Ocimum canum plant extracts against Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus larval and adult mosquitoes (Diptera: Culicidae).

Mosquitoes have developed resistance to various synthetic insecticides, making their control increasingly difficult. Insecticides of botanical origin may serve as suitable natural control. This study evaluates the toxic potential of Ocimum canum (Sims) leaf extract and powder against Anopheles stephensi (Liston), Aedes aegypti (Lin) and Culex quinquefasciatus (Say) larval and adult mosquitoes. Larval mortality was observed after 24 h recovery period and adult smoke toxicity observed for 40 min duration at 10 min interval. Methanol extract of O. canum showed highest larval mortality against the larvae of C. quinquefasciatus LC50 = 28.3225, LC90 = 44.1150; Ae. aegypti LC50 = 43.327, LC90 = 61.249; and An. stephensi LC50 = 30.2001, LC90 = 48.2866 ppm. The smoke toxicities were 93% mortality in C. quinquefasciatus, 74% in Ae. aegypti and 79% in An. stephensi adults, respectively, whereas 100% mortality was recorded in the commercial mosquito control. Our results suggest that O. canum leaf extract and powder are natural insecticide, and ideal eco friendly approach for mosquito control.

Chemical composition and larvicidal activity of plant extracts from Clausena dentata (Willd) (Rutaceae) against dengue, malaria, and filariasis vectors.

Mosquitoes in the larval stage are attractive targets for pesticides because mosquitoes breed in water, and thus, it is easy to deal with them in this habitat. The use of conventional pesticides in the water sources, however, introduces many risks to people and/or the environment. Natural pesticides, especially those derived from plants, are more promising in this aspect. Aromatic plants and their essential oils are very important sources of many compounds that are used in different respects. Insecticides of botanical origin may serve as suitable alternative to chemical insecticides. Acetone, chloroform, ethyl acetate, methanol, and petroleum benzine leaf extracts of Clausena dentata were tested against the fourth instar larvae of Anopheles stephensi, Culex quinquefasciatus, and Aedes aegypti (Diptera: Culicidae). Larval mortality was observed after 24 h of exposure. The highest larval mortality was found in acetone leaf extract, C. quinquefasciatus (LC50 = 0.150278 mg/ml; LC90 = 7.302613 mg/ml), A. aegypti (LC50 = 0.169495 mg/ml; LC90 = 1.10034 mg/ml), and A. stephensi (LC50 = 0.045684 mg/ml; LC90 = 0.045684 mg/ml). GC-MS analysis of plant extracts of acetone solvent revealed 16 compounds, of which the major compounds were benzene,1,2,3-trimethoxy-5-(2-propenyl) (14.97%), Z,Z-6,28-heptatriactontadien-2-one (6.81%), 2-allyl-4-methylphenol (28.14%), 2-allyl-4-methylphenol (17.34%), and 2,6,10,14,18,22-tetracosahexaene, 2,6,10,15,19,23-hexamethyl (10.35%). Our result shows acetone leaf extracts of C. dentata have the potential to be used as an ideal eco-friendly approach for mosquito control.