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Clerodendrum chinense–mediated biofabrication of silver nanoparticles: Mosquitocidal potential and acute toxicity against non-target aquatic organisms
Abstract
Mosquito-borne diseases represent a deadly threat for millions of people worldwide. However, the use of synthetic insecticides to control Culicidae may lead to high operational costs and adverse non-target effects. Plant-borne compounds have been proposed for rapid extracellular synthesis of mosquitocidal nanoparticles. Their impact against biological control agents of mosquito larval populations has been poorly studied. In this study, we synthesized silver nanoparticles (Ag NPs) using the Clerodendrum chinense leaf extract as reducing and stabilizing agent. The biosynthesis of AgNP was confirmed analyzing the excitation of surface Plasmon resonance using ultraviolet–visible (UV–vis) spectrophotometry. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the clustered and irregular shapes of Ag NP. The presence of silver was determined by energy dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) spectroscopy analysis investigated the identity of secondary metabolites, which may act as Ag NP capping agents. The acute toxicity of C. chinense leaf extract and biosynthesized Ag NP was evaluated against larvae of Anopheles subpictus, Aedes albopictus and Culex tritaeniorhynchus. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against A. subpictus, A. albopictus, and C. tritaeniorhynchus with LC50 values of 10.23, 11.10 and 12.38 μg/mL, respectively. Biosynthesized Ag NPs were found safer to non-target organisms Diplonychus indicus, Anisops bouvieri and Gambusia affinis, with respective LC50 values ranging from 647.05 to 6877.28 μg/ml. Overall, our results highlight that C. chinense-fabricated Ag NP are a promising and eco-friendly tool against larval populations of mosquito vectors of medical and veterinary importance, with negligible toxicity against non-target aquatic organisms.
... tritaeniorhynchus". Silver NPs were tried at 15, 30, 45, 60, and 75 mg/ml concentrations for 24 h, giving statistically significant higher larval mortality rates in all tested species [111,112] . ...
... An. stephensi 1 st -4 th instar larvae, pupae, adults In vitro [51, 98-102, 103, 105-108, 110, 113, 114] An. subpictus 3 rd , 4 th instar larvae In vitro [97,111,112] C. quinquefasciatus 2 nd , 3 rd , 4 th instar larvae, adults In vitro [97,99,100,[105][106][107][108][109][110] C. tritaeniorhynchus 3 rd instar larvae In vitro [111,112] Ae. aegypti 3 rd , 4 th instar larvae, adults In vitro [103,110] Ae. albopictus 1 st , 3 rd instar larvae, pupae, adults In vitro [111,112,114] Hyalomma marginatum Larvae In vitro [115] ...
... An. stephensi 1 st -4 th instar larvae, pupae, adults In vitro [51, 98-102, 103, 105-108, 110, 113, 114] An. subpictus 3 rd , 4 th instar larvae In vitro [97,111,112] C. quinquefasciatus 2 nd , 3 rd , 4 th instar larvae, adults In vitro [97,99,100,[105][106][107][108][109][110] C. tritaeniorhynchus 3 rd instar larvae In vitro [111,112] Ae. aegypti 3 rd , 4 th instar larvae, adults In vitro [103,110] Ae. albopictus 1 st , 3 rd instar larvae, pupae, adults In vitro [111,112,114] Hyalomma marginatum Larvae In vitro [115] ...
... The use of silver nanoparticles (AgNP) as drug carriers is a promising method for the treatment of a wide variety of diseases (Benelli et al., 2016a. Hence, AgNP have emerged with diverse medical applications, including silver based dressings and silver coated medicinal devices, such as nano-gels and nano-lotions, as well as nanocomposite for mosquitocidal purposes (Singh et al., 2010;Murugan et al., 2015aMurugan et al., , 2015aMurugan et al., , 2015bBenelli, 2016aGovindarajan et al., 2016aGovindarajan et al., , 2016bGovindarajan et al., , 2016c. ...
... Ch-AgNP were highly toxic against A. stephensi young instars, LC 50 values were 3.18 ppm (larva I), 3.58 ppm (II), 4.56 ppm (III), 5.51 ppm (IV) and 6.54 ppm (pupa) ( Table 2). As already showed for other biofabricated AgNP , we found a significant dose-dependent effect (Murugan et al., 2015a(Murugan et al., , 2015bSuresh et al., 2015;Govindarajan et al., 2016aGovindarajan et al., , 2016bGovindarajan et al., , 2016c. Similarly, Roni et al., (2013) reported that AgNP produced using the aqueous leaf extract of Nerium oleander exhibited dose-dependent larval toxicity against A. stephensi. ...
... Penghambatan kutikula mungkin merupakan titik tindakan pertama dan sistem saraf adalah titik akhir Tindakan. Govindarajan et al. (2016) melaporkan efek bioenkapsulasi ekstrak daunClerodendrum cinadengan nanopartikel perak pada nyamuk dan organisme non-target. Mereka menemukan bahwa enkapsulasi tersebut bersifat toksik terhadap aktivitas nyamuk utama penyebab malaria, filariasis limfatik, dan arbovirus. ...
... The authors have not responded to correspondence regarding this retraction. 1 Unit of Vector Control, Phytochemistry and Nanotechnology, ...
... A lethal concentration of 50 % of the silver nanoparticle caused changes in the gut cell layers. Govindarajan et al. [168] reported the effect of bioencapsulation of leaf extract Clerodendrum chinense with silver nanoparticles on mosquitoes and non-target organisms. They found out that the encapsulation was toxic against the activities of the major mosquitoes causing malaria, lymphatic filariasis, and arboviruses. ...
... The insecticidal effect of Ag/ZnO on C. pipiens larvae caused a significantly high rate of larval mortality in short periods of time. These results indicated that the nanocomposite can be developed as mosquito larvicidal agent, since the LC 50 values were usually less than 15 ppm, while the nanoparticles prepared with plant extracts showed LC 50 higher than 20-25 ppm [41,42]. As depicted, a positive relationship between the higher concentration of nanorods and the larval body's absorption of a high quantity of nanoparticles which ultimately caused their death [43]. ...
Background:
Infectious diseases prompted by micro-organisms such as fungi, parasites, or microbes, have influenced many countries' public health causing death. Scientists declared that metal oxide composites have various advantages in the medical field such as the antimicrobial feature has freshly been revealed as well as its role in suppressing mosquito population.
Methods:
In this work silver doped zinc oxide nanorods (Ag/ZnO NRs, 10 wt.%) were prepared by simple chemical route, and their microstructural characteristics were investigated by XRD, EDX, SEM, and TEM techniques. The antimicrobial, larvicidal, and ovicidal of the synthesized nanocomposites were examined.
Results:
The synthesized nanocomposite exhibited binary phase of crystallite size 112 nm was calculated from Williamson-Hall method. EDX spectrum revealed the purity of the composite consists of Zn, O, and Ag elements. The SEM and TEM micrographs showed the particles in nanorods with high density on the surface. The energy gap [Formula: see text] was evaluated from the UV-Vis absorbance in the range from 2.90 [Formula: see text] 3.08 eV inside the visible spectrum. The antimicrobial activity of the nanorods was examined against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) with inhibition zones 10.5 and 14.5 mm, respectively. Whereas gram-negative bacteria (Escherichia coli, Salmonella Typhimurium, and Pseudomonas aeruginosa) were 14 and 17 mm, respectively. Further, Candida albicans was investigated with inhibition zone 7.5 mm. Besides, the insecticidal impact of the nanocomposite against Culex pipiens larvae was performed at 30 mg/l causing 100% larval mortality with LC50 (11.78 mg/l). The micrograph images showed deformations in the larval body as well as egg resulting in zero egg hatchability.
Conclusion:
The findings approved that synthesized nanorods have a significant impact on controlling pathogens that impart different diseases to humans and the environment.
... Based on the Pavela (2015) classification of essential oils' larvicidal potential (Pavela, 2015), NPs were found to be outstandingly efficient (i. e., LC 50 < 10 ppm) against larval instars and pupae in 13 studies (Salunkhe et al., 2011;Patil et al., 2012 a, b;Haldar et al., 2013;Chandramohan et al., 2015;Murugan et al., 2015b, d;Ramanibai and Velayutham, 2015;Govindarajan et al., 2016e;Velayutham and Ramanibai, 2016;Murugan et al., 2017b;Jayaseelan et al., 2018;Gandhi et al., 2018) (see Table 5). The plants tested in these studies belonged to the following 12 families: Pleosporaceae, Asclepiadiaceae, Apocynaceae, Putranjivaceae, Meliaceae, Poaceae, Lamiaceae, Aristolochiaceae, Annonaceae, Moraceae, Menispermaceae, and Cucurbitaceae. ...
Studies capturing the high efficiency of green-synthesized metal nanoparticles (NPs) in targeting mosquito vectors of the world's main infectious diseases suggest the NPs’ possible utilization as bio-insecticides. However, it is necessary to confirm that these potential bio-insecticides are not harmful to non-target organisms that are often sympatric and natural enemies of the vectors of these diseases. In this systematic review, we comprehensively analyse the content of 56 publications focused on the potentially deleterious effects of NPs on these non-target organisms. Current research on biosynthesised NPs, characterization, and impact on mosquito vectors and non-target larvivorous organisms is reviewed and critically discussed. Finally, we pinpoint some major challenges that merit future investigation. Plants (87.5%) were mainly used for synthesizing NPs in the studies. NPs were found to be spherical or mainly spherical in shape with a large distribution size. In most of the included studies, NPs showed interesting mosquitocidal activity (LC50 < 50 ppm). Some plant families (e.g., Meliaceae, Poaceae, Lamiaceae) have produced NPs with a particularly high larvicidal and pupicidal activity (LC50 < 10 ppm). Regarding non-target organisms, most of the studies concluded that NPs were safe to them, with boosted predatory activity in NP-treated milieu. In contrast, some studies reported NP-elicited adverse effects (i.e., genotoxic, nuclear, and enzymatic effects) on these non-target organisms. This review outlines the promising mosquitocidal effects of biosynthesized NPs, recognizing that NPs’ potential usage is currently limited by the harm NPs are thought pose to non-target organism. It is of utmost importance to investigate green NPs to determine whether laboratory findings have applications in the real world.
... Clerodendrum, a genus of the Lamiaceae (Verbenaceae) family, includes approximately 500 species distributed worldwide. Most plants in this genus, such as C. chinense [4], C. indicum [5], C. izuinsulare [6], C. petasites [7], C. phlomidis [8], and C. trichotomum [9], have pharmacological activities. In C. trichotomum, the roots, stems, and leaves have diverse pharmacological activities, including analgesic, anti-inflammatory, and sedative effects [10,11]. ...
Clerodendrum trichotomum, a member of the Lamiaceae (Verbenaceae) family, is an ornamental plant widely distributed in South Asia. Previous studies have focused primarily on its growth characteristics, stress resistance, and pharmacological applications; however, molecular investigations remain limited. Considering germplasm conservation and the extensive applications of this plant, it is necessary to explore transcriptome resources and SSR makers for C. trichotomum. In the present study, RNA sequencing was used to determine the transcriptome of C. trichotomum. Subsequently, unigene annotations and classifications were obtained, and SSRs were mined with MIcroSAtellite. Finally, primer pairs designed with Oligo 6.0 were selected for polymorphism validation. In total, 127,325,666 high-quality reads were obtained, and 58,345 non-redundant unigenes were generated, of which 36,900 (63.24%) were annotated. Among the annotated unigenes, 35,980 (97.51%) had significant similarity to 607 species in Nr databases. In addition, a total of 6,444 SSRs were identified in 5,530 unigenes, and 200 random primer pairs were designed for polymorphism validation. Furthermore, after primary polymorphism identification, 30 polymorphic primer pairs were selected for the further polymorphism screening, and 200 alleles were identified, 197 of which showed polymorphism. In this work, a large number of unigenes were generated, and numerous SSRs were detected. These findings should be beneficial for further investigations into germplasm conservation and various applications of C. trichotomum. These results should also provide a solid foundation for future molecular biology studies in C. trichotomum.
... Despite such exceedingly higher transformation induced by doping, studies focused on biogenic synthesis of Ag doped ZnO nanoparticle are scarce. Ag as well as ZnO nanoparticles have been fabricated with variety of plants [10][11][12][13][14][15] yet none reported the doping of Ag doping into ZnO nanoparticles by biogenic route. Prunus cerasifera, a medicinal plant with reservoir of antioxidant compounds is not only used for pharmacological purposes but also for preparation of wine, jams, marmalades due to its pleasant taste and widespread occurrence in Asian and some European regions, has great potential to be used in biogenic synthesis. ...
Highly stable semiconducting silver doped zinc oxide nanoparticles have been synthesized via facile, biomimetic and sustainable route, through utilization of Zinc acetate dihydrate (C4H6O4Zn · 2H2O) as host, Silver nitrate (AgNO3) as dopant and phytochemicals of angiospermic medicinal plant Prunus cerasifera as the reducing agents. Synthesis of Ag doped ZnO nanoparticles was done in a one pot synthetic mode by varying the amount of dopant from 0.2 – 2.0%. Synthesized photocatalyst nanoparticles were analyzed via UV-vis, FTIR, XRD and SEM. Commendable alleviation in the direct band gap i.e. 2.81 eV was achieved as a result of doping. Silver doped zinc oxide nanoparticles size ranged between 72.11 – 100 nm with rough surface morphology and higher polydispersity degree. The XRD patterns revealed the hexagonal wurtzite geometry of crystals with an average crystallite size of 2.99 nm. Persistent organic dyes Methyl Orange, Safranin O and Rhodamine B were sustainably photodegraded in direct solar irradiance with remarkable degradation percentages up to 81.76, 74.11 and 85.52% in limited time with pseudo first order reaction kinetics (R2 =0.99, 0.99 and 0.97). Furthermore, efficient inhibition against nine microbes of biomedical and agriculturally significance was achieved. Synthesized nanoparticles are potential green remediators of polluted water and perilous pathogens.
... The comparison between the two kinds of AgNPs synthesized by SA and DNS shows that there were slight changes in all recorded bands of IR spectrum for the synthesized AgNPs, with the possible reason of the different functional groups of SA and DNS. Our findings are in agreement with AgNP synthesized using Clerodendrum chinense [43]. ...
Silver nanoparticles have been studied in a wide range of medical and entomological research works due to their eco-friendly aspects. In our study salicylic acid (SA) and its derivative, 3,5-dinitrosalicylic acid (DNS), were used in a one-step synthesis of silver nanoparticles (AgNPs). First, UV–vis absorption spectroscopy was used to detect the formation of AgNPs. Second, the synthesized nanoparticles were characterized using scanning electron microscope, transmission electron microscope; energy-dispersive spectroscopy, X-ray diffraction analysis and Fourier transform infrared spectroscopy. I, II, III and IV Instar larvae and pupae of Ae. Albopictus were exposed to various concentrations of SA, DNS and synthesized AgNPs for 24 h to evaluate the larvicidal and pupicidal effect. In larvicidal bioassay of SA, moderate mortality was observed at 180 ppm against Ae. Albopictus with LC50 values of 86, 108, 135 and 141 ppm for instar larvae I, II, III and IV, respectively. Synthesized AgNPs showed highest mortality rate at 12 ppm and the LC50 values of SAAgNPs were 1.2 ppm (I), 1.4 ppm (II), 1.8 ppm (III), 2.0 ppm (IV) and 1.4 ppm (pupae). Whereas LC50 values of DNSAgNPs were 1.2 ppm (I), 1.5 ppm (II), 1.8 ppm (III) 2.3 ppm (IV) and 1.4 ppm (pupae). Moreover, the investigations toward the systemic effect of the tested substances on the fourth instar larvae of Ae. albopictus was evaluated and the levels of total proteins, esterases, acetylcholine esterase, and phosphatase enzymes were found to be significantly decreased as compared with the control. These results highlight that SA-AgNPs and DNS-AgNPs are potential tools to control larval populations of mosquito.
... Also, C. chinense-fabricated Ag NPs were found safer to non-target organisms Diplonychus indicus, Anisops bouvieri and Gambusia affinis, with respectively LC 50 values ranging from 647.05 to 6877.28 mg/ml. 125 These results indicated that C. chinense-fabricated Ag NPs are a promising and eco-friendly tool against larval populations of mosquito vectors of medical and veterinary importance, with negligible toxicity against non-target aquatic organisms. ...
Clerodendrum is a genus of ca. 500 species in the family Lamiaceae and widely distributed throughout the whole world. Up to now, many species of this genus have been described in various indigenous systems of medicine and are used in preparation of folklore medicines for the treatment of various life-threatening diseases, and more than eleven species of the Clerodendrum genus have been very well studied for their chemical constituents and biological activities, and 283 compounds, including monoterpene and its derivatives, sesquiterpene, diterpenoids, triterpenoids, flavonoid and flavonoid glycosides, phenylethanoid glycosides, steroids and steroid glycosides, cyclohexylethanoids, anthraquinones, cyanogenic glycosides, and others have been isolated and identified. Pharmacological studies have shown that these compounds and extracts from the Clerodendrum genus have extensive activities, such as anti-inflammatory and anti-nociceptive, anti-oxidant, anti-hypertensive, anticancer, antimicrobial, anti-diarrheal, hepatoprotective, hypoglycemic and hypolipidemic, memory enhancing and neuroprotective, and other activities. In this review, we attempt to highlight over phytochemical progress and list the phytoconstituents isolated from the genus Clerodendrum reported so far. The biological activities of this genus are also covered.
... Green biosynthesis of nanoparticles is an ecological approach developing into an important branch of nanotechnology and it is beneficial over chemical and physical methods, since it is inexpensive, eco-friendly and less toxic [13][14][15]. Green synthesis of AgNPs with excellent mosquitocidal activity have been reported using various plants extracts like Avicennia marina, Aloe vera, Phyllanthus niruri, Moringa oleifera, Chomelia asiatica, Zornia diphylla, Clerodendrum chinense, Psychotria nilgiriensis, Manihot esculenta, Bauhinia variegata, Barleria cristata, Hybanthus enneaspermus and Lippia citriodora [16][17][18][19][20][21][22][23][24][25][26][27][28]. Santosh et al. [29] reported that the AgNPs synthesized using Annona muricata leaf extracts showed remarkable larvicidal activity against A. aegypti, A. stephensi and Culex quinquefasciatus. ...
Due to the increased development of resistance of vectors against synthetic insecticides and
chemical drugs, plant based insecticides serve as promising biocontrol agents for effective
vector control. Green approach for the synthesis of nanoparticles has been attained using
environmentally safe, non-toxic plant extracts. The present study was aimed to investigate the
potent larvicidal activity of silver nanoparticles (AgNPs) produced by Derris trifoliata leaf
extract in relation to the various concentrations of methanol and chloroform extracts for 24 h
against 3rd and 4th instar larvae of Aedes aegypti. AgNPs were synthesized using D. trifoliata
leaf extract as reducing and stabilizing agent. Synthesized AgNPs were characterized by UV–
Vis spectroscopy, FTIR spectroscopy, SEM, EDX, XRD and HRTEM. The size of AgNPs as
estimated from the full width at half-maximum of (200) peak of silver was 16.13 nm, the
average crystalline size of the synthesized AgNPs was approximately 20 nm, which was
correlated with the HRTEM results (20 nm). SEM and TEM images have shown the
formation of polydispersed nanoparticles with an average size of 20 nm. The FTIR spectra of
AgNPs exhibited prominent peaks at 2360.7, 1606.2, 1095.6 and 785.9 cm-1. The spectral
peak observed at 1606.2, assigned to stretching vibration (C=O) in carbonyl compounds
characterized by the presence of major constituents of flavonoids and terpenoids. The results
obtained in FTIR spectroscopy correlated with the GC-MS analysis of methanol and
chloroform extracts and indicates the presence of phytosteroids, flavonoids and terpenoids.
The highest larvicidal activity was observed for the synthesized AgNPs against the 3rd instar
larvae with LC50 values of 5.87 mg/l and LC90 of 12.11 mg/l, while against 4th instar larvae
these values were7.00 and17.76 mg/l respectively. The chloroform extracts also showed
increased larvicidal activity than methanol extracts against 3rd instar larvae (LC50=54.42 mg/l,
LC90=140.83 mg/l) and 4th instar larvae (LC50=62.47 mg/l, LC90=145.06 mg/l) of A. aegypti.
Besides, the synthesized AgNPs also exhibited potent antibacterial activity against certain
food borne pathogens. These results infer that the biologically synthesized AgNPs and
organic solvent extracts have the potential to be used as an excellent eco-friendly approach
for vector control against A. aegypti.
... Good examples are Emblica officinalis (Ankamwar et al. 2005), Aloe vera (Chandran et al. 2006), Cinnamomum camphora (Huang et al. 2007), Cinnamon zeylanicum (Sathishkumar et al. 2009a), Azadirachta indica (Tripathi et al. 2009), Glycine max (Vivekanandhan et al. 2009), Camellia sinensis (Begum et al. 2009), Ocimum sanctum (Ahmad et al. 2010), Pongamia pinnata (Raut et al. 2010), Allium sativum (Rastogi and Arunachalam 2011), Tagetes erecta (Krishnamurthy et al. 2012), Cocos nucifera ( R o o p a n e t a l . 2 0 1 3 ) , D e s m o d i u m g a n g e t i c u m (Thirunavokkarasu et al. 2013), Andrographis paniculata (Kotakadi et al. 2014), and Hibiscus sabdariffa (Thovhogi et al. 2015). Effective mosquitocidal activity on Anopheles stephensi, Anopheles subpictus, Aedes aegypti, Aedes albopictus, Culex tritaeniorhynchus, and Culex quinquefasciatus has been reported for Ag NPs fabricated using extracts from Eclipta prostrata (Rajakumar and Abdul Rahuman 2011), Plumeria rubra (Patil et al. 2012a), Pergularia daemia (Patil et al. 2012b), Drypetes roxburghii (Haldar et al. 2013), Sida acuta (Veerakumar et al. 2013), Pongamia pinnata (Naik et al. 2014), Feronia elephantum (Veerakumar et al. 2014a), Leucas aspera (Suganya et al. 2014), Heliotropium indicum (Veerakumar et al. 2014b), Bauhinia variegata (Govindarajan et al. 2016f), Clerodendrum chinense (Govindarajan et al. 2016g), Malva sylvestris (Govindarajan et al. 2016h), Mussaenda glabra (Govindarajan et al. 2016i), and Zornia diphylla ). In addition, the efficacy of green-synthesized Ag NPs has been reported as effective in reducing young instars populations of mosquito vectors even in the field . ...
Mosquito-borne diseases lead to serious public health concerns in tropical and sub-tropical countries worldwide, due to development of mosquito resistance to synthetic pesticides, non-target effects of pesticides, and socioeconomic reasons. Currently, green nanotechnology is a promising research field, showing a wide range of potential applications in vector control programs. The employ of natural products as reducing agents to fabricate insecticidal nanocomposites is gaining research attention worldwide, due to low costs and high effectiveness. Interestingly, biophysical features of green-synthesized nanoparticles strongly differ when different botanicals are employed for nanosynthesis. In this study, a cheap Acacia caesia leaf extract was employed to fabricate silver nanoparticles (Ag NPs) with ovicidal, larvicidal, and adulticidal toxicity against three mosquito vectors, Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. Ag NPs were analyzed by various biophysical methods, including spectroscopy (UV-visible spectrophotometry, XRD, FTIR, EDX) and microscopy (SEM, TEM, AFM) techniques. High acute larvicidal potential was observed against larvae of An. subpictus (LC50 = 10.33 μg/ml), Ae. albopictus (LC50 = 11.32 μg/ml), and Cx. tritaeniorhynchus (LC50 = 12.35 μg/ml). Ag NPs completely inhibited egg hatchability on three vectors at 60, 75, and 90 μg/ml, respectively. In adulticidal assays, LD50 values were 18.66, 20.94, and 22.63 μg/ml. If compared to mosquito larvae, Ag NPs were safer to three non-target aquatic biocontrol agents, with LC50 ranging from 684 to 2245 μg/ml. Overall, our study highlights the potential of A. caesia as an abundant and cheap bioresource to fabricate biogenic Ag NPs effective against mosquito young instars and adults, with moderate impact on non-target aquatic biocontrol agents.
... Recently, a growing number of plants have been successfully used for efficient and rapid extracellular synthesis of silver, copper and gold nanoparticles (Govindarajan, 2016). Good examples include cheap extracts of neem, Azadirachta indica (Shankar et al., 2004;Murugan et al., 2016), Chomelia asiatica (Muthukumaran et al., 2015a), Sida acuta (Veerekumar et al., 2013), Gmelina asiatica (Muthukumaran et al., 2015b), Barleria cristata , Bauhinia variegata (Govindarajan et al., 2016d) and Clerodendrum chinense (Govindarajan et al., 2016e). Nanoparticles possess peculiar toxicity mechanisms due to surface modification (Oberdorster et al., 2005), and this may actively contribute to their excellent mosquitocidal potential against Culicidae larvae (Saxena et al., 2010;Benelli, 2016;Govindarajan et al., 2016f ). ...
Mosquitoes (Diptera: Culicidae) as as vectors for important diseases and parasites causing millions of deaths every year. The use of synthetic pesticides against Culicidae leads to resistance and environmental concerns. Therefore, eco-friendly control tools are a priority. In this research, Nicandra physalodes-mediated synthesis of silver nanoparticles (Ag NPs) was conducted, in order to control larval populations of three important mosquito vectors, Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. Biofabricated Ag NPs were characterized using UV–vis spectrophotometry, XRD, FTIR spectroscopy, SEM, and TEM analyses. Ag NPs were highly toxic against the three mosquito vectors. Maximum efficacy was detected against A. stephensi (LC50 = 12.39 μg/ml), followed by Ae. aegypti (LC50 = 13.61 μg/ml) and Cx. quinquefasciatus (LC50 = 14.79 μg/ml). Interestingly, Ag NPs were safer for non-target aquatic organism, Diplonychus indicus sharing the same aquatic habitats of mosquito larvae. LC50 and LC90 values were 1032.81 and 19,076.59 μg/ml, respectively. Overall, our results highlight that N. physalodes-fabricated Ag NPs are a promising for development of eco-friendly larvicides against mosquito vectors, with negligible toxicity against non-target aquatic organisms.
Cancer remains a significant global health challenge, necessitating novel therapeutic interventions. Clerodendrum chinense leaf extract (CCL) has gained interest for its potential anticancer properties due to its bioactive composition. This study aims to evaluate the cytotoxic effects of CCL against MCF-7 breast cancer and HeLa cervical cancer cells and elucidate its mechanisms of action. High-performance liquid chromatography identified verbascoside, isoverbascoside, and hispidulin as the major bioactive compounds. CCL exhibited time- and dose-dependent cytotoxicity, with MCF-7 cells showing greater sensitivity (IC50 = 126.8 µg/mL, 72 h) than HeLa cells (216.1 µg/mL, 72 h). Flow cytometry confirmed apoptotic induction, with late apoptosis increasing at moderate concentrations (16.03–23.55%) and necrosis prevailing at higher doses (50.80–63.68%). Reactive oxygen species generation was significantly elevated in MCF-7 (70.2%) and HeLa (60.4%) cells at 250 µg/mL. CCL effectively suppressed colony formation and cell migration in a dose-dependent manner. Molecular docking studies demonstrated that apoptosis induction of CCL bioactive compounds may mediate through the pro-apoptotic BCL2 associated X, apoptosis regulator (BAX) regulator. These findings highlight the potential of CCL as a natural anticancer agent with multiple mechanisms, including reactive oxygen species (ROS)-induced apoptosis, BAX activation, and inhibition of proliferation and metastasis.
Infectious diseases are contagious and have a substantial impact on worldwide public health. They are the world’s most ruthless killers, responsible for the deaths of an estimated 17 million people each year. These diseases have a more significant impact in developing countries. The most vulnerable are people with weakened immune systems and youngsters. Bacteria, viruses, and protozoa can all cause infectious diseases. Malaria is one of the most frequent infectious diseases worldwide, and it has become a significant public health issue. The leading cause of the threat is the ineffectiveness of existing antimalarial treatments. Due to the emergence of medication resistance in Plasmodium falciparum and drug toxicity in humans, conventional therapeutic options have failed. As a result, discovering novel and effective antimalarial medicines is critical. Nanotechnology has a wide range of biomedical uses and could potentially treat malaria. Metallic nanoparticles are effective against the malaria parasite Plasmodium species and the vector female Anopheles mosquito. Metallic nanoparticles are thought to offer a potential answer for malaria control. This chapter focuses on the current scenario of conventional antimalarial medications, as well as a detailed discussion of the use of metallic nanoparticles in the treatment of malaria along with its toxicological concerns.
The silver nitrate was reduced into silver nanoparticles by using the Aristolochia bracteolata plant aqueous extract. The green-synthesized nanoparticles were characterized through UV–Vis spectrophotometry, FTIR, EDAX, XRD, and TEM analysis. Results of TEM analysis clearly show that synthesized AgNP size range is 6 to 20 nm. The average particle size and zeta potential value was determined and found to be 16.7 nm and − 24.2 mV, respectively. The silver nanoparticles showed remarkable antibacterial, DPPH, ABTS, and FRAP activity. Silver nanoparticles exhibited strong antiradical effectiveness with minimal concentration. AgNPs had a dose-dependent effect on Anopheles stephensi larvae, with LC50 values of 21.3, 45.5, 12.7, and 7.9 and LC90 values of 32.4, 65.3, 20.1, and 15.4 µg/mL, respectively. The highest pupal activity was observed at 2.0 µg/mL, with the LC50 being 4.0 and the LC90 being 9.1 µg/mL, respectively. The biotoxicity assay of A. salina shows 6.33–48.33% mortality, which was exhibited by the A. bracteolata-bioconverted AgNPs. The LC50 and LC90 values were 610.381 and 6214 µg/mL. No behavioral variations were observed. The present study provides the first scientific information on the antibacterial, larvicidal, and pupicidal properties of AgNPs produced from a leaf extract of A. bracteolata.
Dengue is a growing mosquito-borne viral disease prevalent in 128 countries, while 3.9 billion people are at high risk of acquiring the infection. With no specific treatment available, the only way to mitigate the risk of dengue infection is through controlling of vector, i.e., Aedes aegypti. Nanotechnology-based prevention strategies like biopesticides with nanoformulation are now getting popular for preventing dengue fever. Metal nanoparticles (NPs) synthesized by an eco-friendly process, through extracts of medicinal plants have indicated potential anti-dengue applications. Green synthesis of metal NPs is simple, cost-effective, and devoid of hazardous wastes. The recent progress in the phyto-synthesized multifunctional metal NPs for anti-dengue applications has encouraged us to review the available literature and mechanistic aspects of the dengue control using green-synthesized NPs. Furthermore, the molecular bases of the viral inhibition through NPs and the nontarget impacts or hazards with reference to the environmental integrity are discussed in depth. Till date, major focus has been on green synthesis of silver and gold NPs, which need further extension to other innovative composite nanomaterials. Further detailed mechanistic studies are required to critically evaluate the mechanistic insights during the synthesis of the biogenic NPs. Likewise, detailed analysis of the toxicological aspects of NPs and their long-term impact in the environment should be critically assessed.
Environmental pollution produced due to direct and untreated release of toxic organic pollutants such as dyes from the textile industries is not only effect the human life but also contaminates the ecosystem through different transferal modes. Green nanomaterials synthesized by using biological reducing agents offer sustainable, economically viable, facile, rapid and eco-friendly approach with photo-catalytic degradation efficiencies >90% for organic dyes over the other traditional technologies. Current review has for the first time comprehensively abridged the suitability of green nanoparticles over chemogenic nanoparticles, the remediative role of these biogenic nanoparticles with major emphasis on the recent progressions in the photocatalysis of different toxic dyes and pollutants. Unlike physicochemi-cally processed nanoparticles, biogenic nanoparticles has profound contribution to the sustainable development goals due to their cleaner and economical synthesis in addition to their detoxifying role. Meticulous review of the publications are strongly suggestive of the adoptability of biogenic nanoparticles at an implementation scale for their auspicious remediative role in addition to facile fabrication, natural reducing agents based synthetic mode, toxicity free and sustainable nature. However, the studies are also indicative of the need for utilization of biogenic synthesis at practical scale to derive maximum sustainability and ecological benefits.
Bio-fabrication of metal nanocrystals can be achieved using eco-friendly and cost-effective routes with plants as reducing and capping mediators. A rapid and simple method for producing silver nanoparticles (AgNPs) using the plant Alstonia venenata (R. Br.) (Family: Apocynaceae) was investigated. The mosquito larvicidal potential and the effect of the A. venenata aqueous leaf extract and AgNPs on non-target fish and insects were evaluated. The AgNPs were studied using UV–Vis spectroscopy, FTIR spectroscopy, SEM, TEM, AFM, and XRD analysis. The larvicidal effectiveness on early third instar larvae was higher for the AgNPs than the plant extract; this was observed by testing on Anopheles stephensi (LC50 = 12.28 µg/mL), Aedes aegypti (LC50 = 13.49 µg/mL), and Culex quinquefasciatus (LC50 = 14.50 µg/mL). Furthermore, the plant extract and AgNPs were found to be safe for the environment-friendly Gambusia affinis fish, and Anisops bouvieri and Diplonychus indicus aquatic insects. This study confirmed that A. venenata is a potential bio-resource for the fabrication of nanocrystals as an effective mosquito control tool with negligible harmful on aquatic fish and insects in the environment.
β-Glucan-binding protein (βGBP) is important for the rational expansion of molecular biology. Here, zinc oxide nanoparticle (ZnONP) was synthesized using βGBP from the crab Scylla serrata (Ss-βGBP-ZnONP). Ss-βGBP-ZnONP was observed as a 100 kDa band on sodium dodecyl sulfate polyacrylamide gel and characterized with UV-vis spectroscopy at 350 nm. X-ray diffraction analysis displayed values consistent with those for zincite. Fourier transform infrared spectroscopy revealed the presence of functional groups, including amide, alcohol, alkane, alkyl halide, and alkene groups. The zeta potential (-5.36 mV) of these particles indicated their stability, and transmission electron microscopy revealed the presence of 50 nm nanocones. Ss-βGBP-ZnONPs were tested at 100 μg/mL against the gram-positive Enterococcus faecalis and gram-negative Pseudomanas aeruginosa using confocal laser scanning microscopy and the bacterial viability assay was also performed. The growth of MCF7 breast cancer cells was inhibited following treatment with 75 μg/mL Ss-βGBP-ZnONPs. Thus, Ss-βGBP-ZnONPs have the ability to control the growth of pathogenic bacteria and inhibit the viability of MCF7 breast cancer cell lines.
In the last decades, major research efforts have been done to investigate the insecticidal activity of plant-based products against mosquitoes. This is a modern and timely challenge in parasitology, aimed to reduce the frequent overuse of synthetic pesticides boosting resistance development in mosquitoes and causing serious threats to human health and environment. This review covers the huge amount of literature available on plant extracts tested as mosquito larvicides, particularly aqueous and alcoholic ones, due to their easy formulation in water without using surfactants. We analysed results obtained on more than 400 plant species, outlining that 29 of them have outstanding larvicidal activity (i.e., LC50 values below 10 ppm) against major vectors belonging to the genera Anopheles, Aedes and Culex, among others. Furthermore, synergistic and antagonistic effects between plant extracts and conventional pesticides, as well as among selected plant extracts are discussed. The efficacy of pure compounds isolated from the most effective plant extracts and – when available – their mechanism of action, as well as their impact on non-target species, is also covered. These belong to the following class of secondary metabolites: alkaloids, alkamides, sesquiterpenes, triterpenes, sterols, flavonoids, coumarins, anthraquinones, xanthones, acetogenonins and aliphatics. Their mode of action on larvae ranges from neurotoxic effects to inhibition of detoxificant enzymes and larval development and midugut damages. In the final section, current drawbacks as well as key challenges for future research, including technologies to synergize efficacy and improve stability - thus field performances - of the selected plant extracts, are outlined. Unfortunately, despite the huge amount of laboratory evidences about their efficacy, only a limited number of studies was aimed to validate their efficacy in the field, nor the epidemiological impact potentially arising from these vector control operations has been assessed. This strongly limits the development of commercial mosquito larvicides of botanical origin, at variance with plant-borne products developed in the latest decades to kill or repel other key arthropod species of medical and veterinary importance, as well as mosquito adults. Further research on these issues is urgently needed.
In this present investigation, we used an inexpensive method for the synthesis of silver nanoparticles (AgNPs) using Garcinia mangostana bark. The phyto-assisted AgNPs further characterized using scanning electron microscope for morphology and the elemental composition was detected via energy dispersive X-ray analysis. The domain size was characterized with the help of X-ray diffraction and UV–Vis spectrophotometric analysis for surface plasmon resonance. The possible functional groups were identified with the help of Fourier transform infrared spectroscopy. Antibacterial properties of nanoparticles were evaluated against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Bacillus cereus and Klebsiella pneumoniae, using agar well diffusion method. Ultimately, the mosquitocidal activity of silver nanoparticles was assessed in the laboratory against fourth instar larvae of Aedes aegypti with LC50 of 5.93 mg L⁻¹ which shows the potential larvicidal effect. To find out the mode of action for larvicidal activity, Agarose gel electrophoresis was carried out. We hypothesize that the toxicity of AgNPs against dengue vectors may be attributed to the small size of these AgNPs, which allows passage through the insect cuticle and into individual cells where they interfere with molting and other physiological processes.
The rapid spread of highly aggressive arboviruses, parasites, and bacteria along with the development of resistance in the pathogens and parasites, as well as in their arthropod vectors, represents a huge challenge in modern parasitology and tropical medicine. Eco-friendly vector control programs are crucial to fight, besides malaria, the spread of dengue, West Nile, chikungunya, and Zika virus, as well as other arboviruses such as St. Louis encephalitis and Japanese encephalitis. However, research efforts on the control of mosquito vectors are experiencing a serious lack of eco-friendly and highly effective pesticides, as well as the limited success of most biocontrol tools currently applied. Most importantly, a cooperative interface between the two disciplines is still lacking. To face this challenge, we have reviewed a wide number of promising results in the field of green-fabricated pesticides tested against mosquito vectors, outlining several examples of synergy with classic biological control tools. The non-target effects of green-fabricated nanopesticides, including acute toxicity, genotoxicity, and impact on behavioral traits of mosquito predators, have been critically discussed. In the final section, we have identified several key challenges at the interface between "green" nanotechnology and classic biological control, which deserve further research attention.
Mosquitoes, being a vector for some potentially dreadful diseases, pose a considerable threat to people all around the world. The control over the growth and propagation of mosquitoes comprises conventional pesticides, insect growth regulators and other microbial control agents. However, the usage of these common chemicals and conventional pesticides eventually has a negative impact on human health as well as the environment, which therefore becomes a major concern. The lacuna allows nanotechnology to come into action and exploit nanopesticides. Nanopesticides are majorly divided into two categories---synthetic and biological. Several nanoformulations serve as a promising nanopesticide viz. nanoparticles, e.g. biologically synthesised nanoparticles through plant extracts, nanoemulsions prepared using the essential oils like neem oil and citronella oil and nanoemulsion of conventional pesticides like pyrethroids. These green approaches of synthesising nanopesticides make use of non-toxic and biologically derived compounds and hence are eco-friendly with a better target specificity. Even though there are numerous evidences to show the effectiveness of these nanopesticides, very few efforts have been made to study the possible non-target effects on other organisms prevalent in the aquatic ecosystem. This study focuses on the role of these nanopesticides towards the vector control and its eco-safe property against the other non-target species.
The green synthesis of pesticides and antibiotics is gaining increasing importance nowadays. We fabricated Euphorbia rothiana-capped Ag nanoparticles (Er-AgNPs), testing their antibiofilm and growth inhibition potential on various microbial pathogens. We evaluated the toxicity of E. rothiana-capped Ag nanoparticles on larvae of the Zika virus vector Aedes aegypti, shedding light on histological changes post-exposure to the plant leaf extract and Er-AgNPs. Nanoparticles were characterized by UV–Vis, and FTIR spectroscopy, XRD and TEM. Light microscopy showed the greatest inhibition of biofilm formation in Gram positive and Gram-negative bacteria post-treatment with E. rothiana-capped Ag nanoparticles at 75 μg/ml. Confocal microscopy confirmed the biofilm interruption and disintegration post-treatment with nanoparticles at 75 μg/ml. E. rothiana extract and Er-AgNPs showed 100% larvicidal activity on A.aegypti at 50 and 8 mg/L, respectively. AgNO3 led to 100% mortality of A. aegypti larvae at 40 mg/L after 48 h. Stereomicroscopic and histopathological analysis reported tissue damages and loss of cuticular parts in mosquito larvae.
Malaria is one of the most common infectious diseases, which has become a great public health problem all over the world. Ineffectiveness of available antimalarial treatment is the main reason behind its menace. The failure of current treatment strategies is due to emergence of drug resistance in Plasmodium falciparum and drug toxicity in human beings. Therefore, the development of novel and effective antimalarial drugs is the need of the hour. Considering the huge biomedical applications of nanotechnology, it can be potentially used for the malarial treatment. Silver nanoparticles (AgNPs) have demonstrated significant activity against malarial parasite (P. falciparum) and vector (female Anopheles mosquito). It is believed that AgNPs will be a solution for the control of malaria. This review emphasizes the pros- and cons of existing antimalarial treatments and in depth discussion on application of AgNPs for treatment of malaria. The role of nanoparticles for site specific drug delivery and toxicological issues have also been discussed.
Our understanding of nanoparticle toxicity and fate in the aquatic environment is still patchy. In the present study, the toxicity of silver nanoparticles coated by Camellia sinensis (Cs) leaf extract metabolites (Cs-AgNPs) was investigated in comparison with C. sinensis leaf extract and AgNO3 on a micro-crustacean, Ceriodaphnia cornuta, and a fish Poecilia reticulata. 100% mortality of C. cornuta was observed post-exposure to AgNO3 (40 µg/ml) if compared to the Cs leaf extract and Cs-AgNPs, showing 30 and 56% mortality at the same concentration, respectively. In P. reticulata 100% mortality was observed testing AgNO3 and Cs-AgNPs post-exposure to 1 and 30 µg/ml, respectively. Light microscopy and CLSM images showed the accumulation of nanoparticles in the intestine of C. cornuta treated with Cs-AgNPs at 40 µg/ml. In addition, histological observations confirmed the abnormal tissue texture in nanoparticle-exposed P. reticulata, if compared to control fishes. Furthermore, C. cornuta and P. reticulata treated with Cs-AgNPs showed DNA damages compared to the control. Overall, these findings indicated relevant limits about the employ of silver-based pesticides in the environment, and also pointed out the Cs-AgNPs were less toxic to C. cornuta and P. reticulata if compared to silver ions.
Mosquito-borne diseases represent a major human and animal health problem in all tropical and subtropical countries worldwide. The synthesis of eco-friendly metal nanoparticles is a fast-growing branch of current nanoscience with a number of biomedical and entomological implications. In this study, we investigated the one-pot synthesis of silver nanoparticles (Ag NPs) using a cheap leaf extract of Merremia emarginata (Convolvulaceae). Bio-reduced Ag NPs were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction analysis, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. SEM, TEM and AFM morphological nanocharacterization showed that this synthesis led to the production of size-controlled Ag NPs, ranging from 25 to 65 nm. The acute toxicity of M. emarginata leaf extract and biosynthesized Ag NPs was evaluated against third instar larvae of the malaria vector Anopheles stephensi, the dengue and Zika virus vector Aedes aegypti and the filariasis vector Culex quinquefasciatus. Compared to the leaf aqueous extract, Ag NPs showed higher toxicity against A. stephensi, A. aegypti, and C. quinquefasciatus with LC50 values of 8.36, 9.20 and 10.02 μg/mL, respectively. M. emarginata-fabricated Ag NPs were found safer to non-target aquatic biocontrol agents Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 ranging from 415.61 to 25,153.46 μg/mL. However, although it has been proven the AgNPs fabricated in the present study are more effective if compared to the crude M. emarginata extract, they still exert some toxicity on biocontrol agents, thus further research is required to produce more eco-friendly formulations for field purposes. © 2017 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society
Mosquitoes vector important diseases, including malaria, dengue and Zika virus. The effective control and eradication of the mosquitoes can restrict the spread and severity of these diseases. Here the efficacy of silver nanoparticles (AgNPs) synthesized using the extract of Hedyotis puberula leaves on eggs, larvae and adults of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. AgNPs were subjected to different biophysical analyses, including UV-Vis spectrophotometry, FTIR, XRD, AFM, SEM, TEM, EDX and DLS analysis. AgNPs were effective against the larvae of A. stephensi (LC50 16.58 μg ml⁻¹), A. aegypti (LC50 18.05 μg ml⁻¹) and C. quinquefasciatus (LC50 19.52 μg ml⁻¹). AgNPs exerted complete egg mortality at 80 μg ml⁻¹ against A. stephensi and at 100 and 120 μg ml⁻¹ against A. aegypti and C. quinquefasciatus, respectively. LC50 of AgNPs on adults of A. stephensi, A. aegypti and C. quinquefasciatus were 33.11, 36.34 and 39.56 μg ml⁻¹, respectively. Both the H. puberula leaf extract and AgNPs were tested against three mosquito biocontrol agents, Anisops bouvieri, Diplonychus indicus and Gambusia affinis. LC50 ranged from 1048 to 33 552 μg ml⁻¹. Overall, the H. puberula aqueous leaf extract can be employed to fabricate eco-friendly AgNPs with mean size of 6-16 nm, highly effective on A. stephensi, A. aegypti and C. quinquefasciatus.
Mosquitoes act as a vector for most of the life-threatening diseases. The green synthesis of eco-friendly metal nanoparticles is a fast-growing branch of current nanoscience with a number of biomedical and entomological implications. Here, we have synthesized silver nanoparticles (AgNPs) by using a poorly studied Indian plant, Ventilago maderaspatana. The results recorded from UV–Visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the quick synthesis of AgNPs. The toxic activity of V. maderaspatana leaf extract and biosynthesized AgNPs was evaluated against the malaria vector Anopheles stephensi, the Zika virus vector Aedes aegypti and the filariasis vector Culex quinquefasciatus. Compared to the leaf aqueous extract, AgNPs showed higher toxicity against A. stephensi, A. aegypti, and C. quinquefasciatus with LC50 values of 24.89, 26.92 and 29.24 μg/mL, respectively. A single treatment with AgNPs tested at 120, 150 and 180 μg/mL led to no egg hatchability. In adulticidal experiments, the maximum efficacy was observed on A. stephensi (LD50 = 41.19 μg/mL), followed by A. aegypti (LD50 = 44.85 μg/mL) and C. quinquefasciatus (LD50 = 48.94 μg/mL), respectively. V. maderaspatana extract and green fabricated AgNPs were found safer to non-target aquatic biocontrol organisms Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 ranging from 1673 to 41,854 µg/ml.
Nowadays, silver nanoparticles receive increasing attention in nanomedicine, due to their characteristics which allow numerous biological applications. In this study, a biofabrication protocol was formulated to synthesize silver nanoparticles using a mangrove extract of Aegiceras corniculatum. The bio-physical characterization of mangrove-fabricated silver nanoparticles were carried out using UV–vis spectrophotometry, FTIR spectroscopy, XRD analysis and HRTEM. In vitro cytotoxicity assays of mangrove fabricated silver nanoparticles was made in comparison with chemically synthesized silver nanoparticles on Vero cell lines. MTT assay was applied in order to investigate the cytotoxic nature of the mangrove fabricated and chemically synthesized silver nanoparticles. The concentration which caused 50 % cell death (CC50) was 18.79 ± 0.9 μg/mL in the cells treated with mangroves fabricated silver nanoparticles whereas chemically synthesized silver nanoparticles produced the same effect (i.e. 50 % cell death) at 8.96 ± 0.8 μg/mL. Results showed that the mangrove-fabricated silver nanoparticles was more biocompatible when compared with chemically synthesized silver nanoparticles, highlighting their promising potential as nanocarriers in pharmacology and nanomedicine.
Mosquitoes are key vectors of malaria, dengue, yellow fever, chikungunya, West Nile, Japanese encephalitis, lymphatic filariasis, Zika virus and St. Louis encephalitis virus. Eco-friendly control tools of Culicidae vectors are a priority. Green nanotechnologies may help to boost the effectiveness of mosquito vector control. We proposed a facile fabrication of poly-disperse and stable silver nanoparticles (AgNPs) using the Aganosma cymosa leaf extract. Nanoparticles were characterized by UV–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Nanoparticles showed high toxicity on eggs and larvae of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. LC50 values were 12.45, 13.58 and 14.79 μg/mL, respectively. No egg hatchability was noted post-treatment with 40, 50 and 60 μg/mL, respectively. Nanoparticles were found safer to non-target mosquito predators Anisops bouvieri, Diplonychus indicus and Gambusia affinis, LC50 values ranged from 673.36 to 2247.43 µg/mL. Notably, AgNPs showed high oviposition attractiveness towards the three mosquito species. Overall, the oviposition attractiveness of the A. cymosa extract coupled with the ovicidal action of AgNPs can help to develop “lure and kill” tools to be used at mosquito breeding sites.
Mosquito control is facing key challenges, including outbreaks of new arbovirus threats. We proposed an eco-friendly synthesis of silver nanoparticles (AgNPs) employing a low-cost extract of Hugonia mystax. AgNPs were specified by UV, XRD, FTIR and EDX spectroscopy, SEM and TEM. AgNPs were more toxic to Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus larvae (LC50: 14.45, 15.86, and 17.46 μg/mL) if compared to aquatic biocontrol organisms Gambusia affinis, Diplonychus indicus, and Anisops bouvieri (LC50: 2567.15, 1075.16, and 829.63 μg/ml). Overall, we shed light on the mosquito larvicidal efficacy of H. mystax, a possible biological resource for low-cost fabrication of AgNPs.
Botanical-based nanosynthesis has been recently reported as a cheap alternative for mosquito management. Screening different botanicals as reducing and capping agents led to the production of metal nanoparticles with different biophysical and mosquitocidal features. Here, Naregamia alata-mediated biosynthesis of silver nanoparticles (AgNPs) was conducted. AgNPs were tested on egg, larval and adult populations of three important mosquito vectors, Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. AgNPs were characterized using UV–Vis spectrophotometry, FTIR, AFM, SEM, TEM, EDX, and XRD analyses. Maximum larvicidal toxicity was detected against A. stephensi (LC50 = 12.40 µg/ml), followed by A. aegypti (LC50 = 13.57 µg/ml) and C. quinquefasciatus (LC50 = 14.84 µg/ml). A single treatment with AgNPs tested at 60, 75 and 90 μg/ml led to no egg hatchability. In adulticidal experiments, the maximum efficacy was observed on A. stephensi (LD50 = 31.60 μg/ml), followed by A. aegypti (LD50 = 34.31 μg/ml) and C. quinquefasciatus (LD50 = 37.52 μg/ml), respectively. AgNPs were safer for three non-target mosquito natural enemies, Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 ranging from 629 to 2111 µg/ml. Overall, N. alata-fabricated AgNPs are a promising and eco-friendly tool against Anopheles, Aedes and Culex mosquito vectors, with negligible toxicity against non-target aquatic organisms.
Currently, mosquito vector control is facing a number of key challenges, including the rapid development of resistance to synthetic pesticides and the recent spread of aggressive arbovirus outbreaks. The biosynthesis of silver nanoparticles (AgNPs) is currently considered an environmental friendly alternative to the employ of pyrethroids, carbamates and microbial agents (e.g. Bacillus thuringiensis var. israelensis), since AgNPs are easy to produce, effective and stable in the aquatic environment. However, their biophysical features showed wide variations according to the botanical agent using for the green synthesis, outlining the importance of screening local floral resources used as reducing and stabilizing agents. In this study, we focused on the biophysical properties and the mosquitocidal action of Quisqualis indica-fabricated AgNPs. AgNPs were characterized using spectroscopic (UV, FTIR, XRD) and microscopic (AFM, SEM, TEM and EDX) techniques. AFM, SEM and TEM confirmed the synthesis of poly-dispersed AgNPs with spherical shape and size ranging from 1 to 30nm. XRD shed light on the crystalline structure of these AgNPs. The acute toxicity of Quisqualis indica extract and AgNPs was evaluated against malaria, arbovirus, and filariasis vectors, Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus, as well as on three important non-target aquatic organisms. The Q. indica leaf extract showed moderate larvicidal effectiveness on Cx. quinquefasciatus (LC50=220.42), Ae. aegypti (LC50=203.63) and An. stephensi (LC50=185.98). Q. indica-fabricated AgNPs showed high toxicity against Cx. quinquefasciatus (LC50=14.63), Ae. aegypti (LC50=13.55) and An. stephensi (LC50=12.52), respectively. Notably, Q. indica-synthesized AgNPs were moderately toxic to non-target aquatic mosquito predators Anisops bouvieri (LC50=653.05μg/mL), Diplonychus indicus (LC50=860.94μg/mL) and Gambusia affinis (LC50=2183.16μg/mL), if compared to the targeted mosquitoes. Overall, the proposed one-pot biogenic fabrication of AgNPs using Q. indica is a low-cost and eco-friendly tool in the fight against Zika virus, malaria and filariasis vectors, with little impact against non-target aquatic mosquito predators.
Mosquito-borne diseases represent a major human and animal health problem in all tropical and subtropical countries worldwide. In this study, we investigated the one-pot synthesis of silver nanoparticles (AgNPs) using a cheap leaf extract of Carissa
carandas (Apocynaceae). Bio-reduced AgNPs were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction analysis, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The acute toxicity of C. carandas extract and green-synthesized AgNPs was evaluated on eggs and larvae of Anopheles
stephensi, Aedes
aegypti and Culex
quinquefasciatus. AgNPs showed high toxicity against A. stephensi, A. aegypti, and C. quinquefasciatus larvae with LC50 values of 14.33, 15.69 and 16.95 μg/mL, respectively. A single treatment with AgNPs tested at 60 μg/mL led to no egg hatchability. The egg rafts of C. quinquefasciatus were more resistant to the toxic action of AgNPs if compared to A. aegypti and A. stephensi. C. carandas-fabricated AgNPs were found safer to non-target organisms Anisops
bouvieri, Diplonychus
indicus and Gambusia
affinis, with LC50 ranging from 1097.87 to 17249.89 µg/ml. Overall, this research shed light on the mosquitocidal potential of C. carandas, a potential bio-resource for rapid, cheap and effective synthesis of poly-disperse and stable silver nanocrystals.
Mosquitoes (Diptera: Culicidae) are a key threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. Mosquito young instars are usually targeted with organophosphates, insect growth regulators and microbial control agents. Indoors residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have strong negative effects on human health and the environment. Newer and safer tools have been recently implemented to enhance control of mosquitoes. In this review, I focus on characterization, effectiveness, and non-target effects of mosquitocidal nanoparticles synthesized using botanical products (mosquitocidal nanoparticles, MNP). The majority of plant-fabricated MNP are silver ones. The synthesis of MNP is usually confirmed by UV-visualization spectroscopy, followed by scanning electron microscopy or transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction studies. Interestingly, plant-synthesized metal nanoparticles have been reported as effective ovicides, larvicides, pupicides, adulticides, and oviposition deterrents against different mosquito species of medical and veterinary importance. Few parts per million of different MNP are highly toxic against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti, and the filariasis mosquito Culex quiquefasciatus. However, despite the growing number of evidences about the effectiveness of MNP, moderate efforts have been carried out to shed light on their possible non-target effects against mosquito's natural enemies and other aquatic organisms. In the final section, particular attention was dedicated to this issue. A number of hot areas that need further research and cooperation among parasitologists and entomologists are highlighted.
Malaria is a life-threatening disease caused by parasites transmitted to people and animals through the bites of infected mosquitoes. The employ of synthetic insecticides to control Anopheles populations leads to high operational costs, non-target effects, and induced resistance. Recently, plant-borne compounds have been proposed for efficient and rapid extracellular synthesis of mosquitocidal nanoparticles. However, their impact against predators of mosquito larvae has been poorly studied. In this study, we synthesized silver nanoparticles (AgNPs) using the Datura metel leaf extract as reducing and stabilizing agent. The biosynthesis of AgNPs was confirmed analyzing the excitation of surface plasmon resonance using ultraviolet-visible (UV-vis) spectroscopy. Scanning electron microscopy (SEM) showed the clustered and irregular shapes of AgNPs, with a mean size of 40-60 nm. The presence of silver was determined by energy-dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) spectroscopy analysis investigated the identity of secondary metabolites, which may be acting as AgNP capping agents. In laboratory, LC50 of D. metel extract against Anopheles stephensi ranged from 34.693 ppm (I instar larvae) to 81.500 ppm (pupae). LC50 of AgNP ranged from 2.969 ppm (I instar larvae) to 6.755 ppm (pupae). Under standard laboratory conditions, the predation efficiency of Anax immaculifrons nymphs after 24 h was 75.5 % (II instar larvae) and 53.5 % (III instar larvae). In AgNP-contaminated environment, predation rates were boosted to 95.5 and 78 %, respectively. Our results documented that D. metel-synthesized AgNP might be employed at rather low doses to reduce larval populations of malaria vectors, without detrimental effects on behavioral traits of young instars of the dragonfly Anax immaculifrons.
Background & Objectives. The plan of this work was to study the larvicidal activity of Cassia occidentalis (Linn.) against the larvae of
Culex quinquefasciatus. These larvae are the most significant vectors. They transmit the parasites and pathogens which cause a deadly disease like filariasis, dengue,
yellow fever, malaria, Japanese encephalitis, chikungunya, and so forth, which are considered harmful towards the population in tropic and subtropical regions. Methods.
The preliminary laboratory trail was undertaken to determine the efficacy of petroleum ether and N-butanol extract of dried whole plant of Cassia occidentalis (Linn.)
belonging to the family Caesalpiniaceae at various concentrations against the late third instar larvae of Culex quinquefasciatus by following the WHO guidelines.
Results. The results suggest that 100% mortality effect of petroleum ether and N-butanol extract of Cassia occidentalis (Linn.) was observed at
200 and 300 ppm (parts per million). The results obviously showed use of plants in insect control as an alternative method for minimizing the noxious
effect of some pesticide compounds on the environment. Thus the extract of Cassia occidentalis (Linn.) is claimed as more selective and biodegradable agent.
Conclusion. This study justified that plant Cassia occidentalis (Linn.) has a realistic mortality result for larvae of filarial vector. This is safe to individual
and communities against mosquitoes. It is a natural weapon for mosquito control.
In this paper, we have reported on biological synthesis of nano-sized silver and its antibacterial activity
against human pathogens. The nanoparticles of silver were formed by the reduction of silver nitrate to aqueous silver metal ions during exposure to the extract of marine seaweed Sargassum wightii. The optical properties of the obtained silver nanoparticles were characterized using UV–visible absorption and room temperature photoluminescence. The X-ray diffraction results reveal that the synthesized silver nanoparticles are in the cubic phase. The existence of functional groups was identified using Fourier transform infrared spectroscopy. The morphology and size of the synthesized particles were studied with atomic force microscope and high resolution transmission electron microscope measurements. The synthesized nanoparticles have an effective antibacterial activity against S. aureus, K. pneumoniae, and S. typhi.
Highly stable nanoparticles of metallic silver with average dimension of 26.6 nm were synthesized by a simple, cost-effective, reproducible and previously unexploited biogenic source viz. dried green fruits of Drypetes roxburghii (Wall.) (common name putranjiva). The as-synthesized silver nanoparticles (Ag NP) were characterized by their characteristic surface plasmon resonance absorption spectra, X-ray diffraction analysis, energy dispersive X-ray analysis and selected area electron diffraction study. The morphology of the particles was determined by high-resolution transmission electron microscopy. Fourier transform infrared analysis focuses some light on the chemical framework that stabilizes the nanoparticles. The analyses of the phytochemicals present in the fruit extract of the plant were also performed following standard protocol. Mosquito larvicidal bioassay with the Ag NPs was carried out with two mosquitoes, namely Anopheles stephensi Liston and Culex quinquefasciatus Say. The results show impressive mortality rate even at too low concentration of nanoparticle. Toxicity test on non-target organism shows no harmful effect during the study period.
The essential oils of many Apiaceae species have been already studied for their insecticidal and repellent properties against insect pests. In this research, the essential oil (EO) extracted from the fruits of Coriandrum sativum L. (Apiaceae) was evaluated for the first time for its larvicidal and repellent activities against the most invasive mosquito worldwide, Aedes albopictus Skuse (Diptera: Culicidae). The chemical composition of C. sativum EO was investigated by gas chromatography with electron impact mass spectrometry analysis. Coriander EO was mainly composed by monoterpene hydrocarbons and oxygenated monoterpenes, with linalool (83.6 %) as the major constituent. C. sativum EO exerted toxic activity against A. albopictus larvae: LC(50) was 421 ppm, while LC(90) was 531.7 ppm. Repellence trials highlighted that C. sativum EO was a good repellent against A. albopictus, also at lower dosages: RD(50) was 0.0001565 μL/cm(2) of skin, while RD(90) was 0.002004 μL/cm(2). At the highest dosage (0.2 μL/cm(2) of skin), the protection time achieved with C. sativum essential oil was higher than 60 min. This study adds knowledge about the chemical composition of C. sativum EO as well as to the larvicidal and repellent activity exerted by this EO against A. albopictus. On this basis, we believe that our findings could be useful for the development of new and safer products against the Asian tiger mosquito.
Different biological methods are gaining recognition for the production of silver nanoparticles (Ag-NPs) due to their multiple applications. One of the most important applications of Ag-NPs is their use as an anti-bacterial agent. The use of plants in the synthesis of nanoparticles emerges as a cost effective and eco-friendly approach. In this study the biosynthesis of silver nanoparticles using Vitex negundo L. extract and its antimicrobial properties has been reported. The resulting silver particles are characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV–Visible (UV-Vis) spectroscopic techniques. The TEM study showed the formation of silver nanoparticles in the 10–30 nm range and average 18.2 nm in size. The XRD study showed OPEN ACCESS Molecules 2011, 16 6668 that the particles are crystalline in nature, with a face centered cubic (fcc) structure. The silver nanoparticles showed the antimicrobial activity against Gram positive and Gram negative bacteria. Vitex negundo L. was found to display strong potential for the synthesis of silver nanoparticles as antimicrobial agents by rapid reduction of silver ions (Ag + to Ag 0).
Methanolic extracts of the leaves of Atlantia monophylla (Rutaceae) were evaluated for mosquitocidal activity against immature stages of three mosquito species, Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti in the laboratory. Larvae of Cx. quinquefasciatus and pupae of An. stephensi were found more susceptible, with LC50 values of 0.14 mg/l and 0.05 mg/l, respectively. Insect growth regulating activity of this extract was more pronounced against Ae. aegypti, with EI50 value 0.002 mg/l. The extract was found safe to aquatic mosquito predators Gambusia affinis, Poecilia reticulata, and Diplonychus indicus, with the respective LC50 values of 23.4, 21.3, and 5.7 mg/l. The results indicate that the mosquitocidal effects of the extract of this plant were comparable to neem extract and certain synthetic chemical larvicides like fenthion, methoprene, etc.
A new iridoid diglucoside, 5-O-beta-glucopyranosyl-harpagide, has been isolated from the aerial part of Clerodendrum chinense together with three known iridoid glucosides and six known cyclohexylethanoids. Their structures have been determined by analyses of spectroscopic data.
Thirty common insecticides were screened for their toxicity to housefly and honey bee by topical application. Using this toxicity data, the acute oral LD50 values to rats and the insecticide costs, a 'Pesticide Suitability Rating' (PSR) was computed to determine the suitability of these insecticides for use in the household environment taking the housefly as the target insect pest. Based on their PSR values the insecticides were grouped into eight suitability classes. Bioresmethrin, methoxychlor and bromophos appeared as 'very highly acceptable' and permethrin and malathion as 'highly acceptable'. Many insecticides appeared as 'moderately acceptable' and 'fairly acceptable'. Parathionmethyl, monocrotophos and parathion were found to be just above the acceptability limit. Demeton was found 'not acceptable'. None of the screened insecticides was found to meet the requirements of an 'ideal insecticide' (PSR>90). PSR is a new concept and provides a rationale in the use of pesticides under a given set of conditions.
Mosquitoes are blood-feeding insects and serve as the most important vectors for spreading human diseases such as malaria, yellow fever, dengue fever, and filariasis. The continued use of synthetic insecticides has resulted in resistance in mosquitoes. Synthetic insecticides are toxic and affect the environment by contaminating soil, water, and air, and then natural products may be an alternative to synthetic insecticides because they are effective, biodegradable, eco-friendly, and safe to environment. Botanical origin may serve as suitable alternative biocontrol techniques in the future. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, this study was undertaken to assess the larvicidal activity of the synthesized silver nanoparticles (Ag NPs) and aqueous leaf extracts from the medicinal plant Feronia elephantum, Heliotropium indicum and Sida acuta against the medically important mosquito vectors, Anopheles subpictus, Aedes albopictus and Culex tritaeniorhynchus (Diptera: Culicidae). Synthesized Ag NPs were characterized by UV-vis spectroscopy, fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) with EDX, transmission electron microscopy (TEM) and XRD analysis. Range of concentrations of synthesized Ag NPs (8–60 μg/mL) and aqueous leaf extract (30–300 μg/mL) were tested against the larvae of A. subpictus, A. albopictus and C. tritaeniorhynchus. Among the Ag NPs tested, the Ag NPs of F. elephantum were highly effective against third instar larvae of A. subpictus, A. albopictus and C. tritaeniorhynchus with LC50 and LC90 values were 20.01, 21.59, 24.04 μg/mL and 34.76, 37.06, 40.86 μg/mL, respectively. The control showed nil mortality in the concurrent assay. x2 values were significant at p ≤ 0.05 level. From the three plant aqueous leaf extract and Ag NPs tested against late third instar A. subpictus, A. albopictus and C. tritaeniorhynchus, the highest larvicidal activity was observed in F. elephantum, moderate larvicidal activity was observed in H. Indicum and lowest larvicidal activity was observed in S. acuta. Results obtained from this study biosynthesized silver nanoparticles as novel biolarvicidal agent and can be used along with traditional insecticides as approach of Integrated Pest Management (IPM). This is the first report on the mosquito larvicidal activity of the plant aqueous extract and synthesized silver nanoparticles.
Nanotechnology, a promising field of research opens up in the present decade a wide array of opportunities in the present decade and is expected to give major impulses to technical innovations in a variety of industrial sectors in the future. The potential uses and benefits of nanotechnology are enormous. These include agricultural productivity enhancement involving nanoporous zeolites for slow release and efficient dosage of water and fertilizer, nanocapsules for herbicide delivery and vector and pest management and nanosensors for pest detection. The atom by atom arrangement allows the manipulation of nanoparticles thus influencing their size, shape and orientation for reaction with the targeted tissues. It is now known that many insects possess ferromagnetic materials in the head, thorax and abdomen, which act as geomagnetic sensors. In this paper, our discussion is focused on nanoparticles in insects and their potential for use in insect pest management.
Mosquitoes (Diptera: Culicidae) are a huge threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. Culicidae control is of crucial importance. Mosquito eggs, larvae, and pupae are usually targeted using organophosphates, insect growth regulators, and microbial agents. Indoor residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have negative effects on human health and the environment, and induce resistance in a number of species. Eco-friendly tools have been recently implemented against mosquito vectors, including botanical insecticides. The majority of researches focused on larvicides (745 SCOPUS results, July 2015) and adult repellents (434 SCOPUS results), while limited efforts were conducted to identify effective ovicides of botanical origin (59 SCOPUS results). Here, I review current knowledge on the effectiveness of plant-borne ovicides against major mosquito vectors of medical and veterinary importance. The majority of researches focused on the toxicity of crude extracts, their fractions, or essential oils against three important mosquito vectors, Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. As a general trend, C. quinquefasciatus eggs were the most resistant to botanical ovicides. Five studies proposed selected compounds from plant extracts and essential oils as ovicides effective at few parts per million. However, no efforts were conducted to shed light on possible mechanisms underlying the toxicity of plant-borne ovicides. In the final section, a number of hot issues needing further research and cooperation among parasitologists, entomologists, and researchers working in natural product chemistry are outlined.
Mosquitoes (Diptera: Culicidae) are a key threat for millions of people worldwide, since they act as vectors for devastating pathogens and parasites. In this scenario, vector control is crucial. Mosquito larvae are usually targeted using organophosphates, insect growth regulators, and microbial agents. Indoor residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have negative effects on human health and the environment and induce resistance in a number of vectors. Newer and safer tools have been recently implemented to enhance control of mosquitoes. Here, I focus on some crucial challenges about eco-friendly control of mosquito vectors, mainly the improvement of behavior-based control strategies (sterile insect technique ("SIT") and "boosted SIT") and plant-borne mosquitocidals, including green-synthesized nanoparticles. A number of hot areas that need further research and cooperation among parasitologists, entomologists, and behavioral ecologists are highlighted.
Mosquitoes are blood-feeding insects and serve as the most important vectors for spreading human diseases such as malaria, yellow fever, dengue fever, and filariasis. The continued use of synthetic insecticides has resulted in resistance in mosquitoes. Synthetic insecticides are toxic and affect the environment by contaminating soil, water, and air, and then natural products may be an alternative to synthetic insecticides because they are effective, biodegradable, eco-friendly, and safe to environment. Botanical origin may serve as suitable alternative biocontrol techniques in the future. The present study was carried out to establish the larvicidal potential of leaf extracts of Gmelina asiatica and synthesized silver nanoparticles using aqueous leaf extract against late third instar larvae of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. Larvae were exposed to varying concentrations of plant extracts and synthesized AgNPs for 24 h. The results were recorded from UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy analysis support the biosynthesis and characterization of AgNPs. The maximum efficacy was observed in synthesized AgNPs against the larvae of An. stephensi (lethal dose (LC50) = 22.44 μg/mL; LC90 40.65 μg/mL), Ae. aegypti (LC50 = 25.77 μg/mL; LC90 45.98 μg/mL), and C. quinquefasciatus (LC50 = 27.83 μg/mL; LC90 48.92 μg/mL), respectively. No mortality was observed in the control. This is the first report on mosquito larvicidal activity of plant-synthesized nanoparticles. Thus, the use of G. asiatica to synthesize silver nanoparticles is a rapid, eco-friendly, and a single-step approach and the AgNps formed can be potential mosquito larvicidal agents.
Mosquitoes and mosquito-borne diseases are prone to raise health and economic impacts. Synthetic insecticide-based interventions are indeed in situations of epidemic outbreak and sudden increases of adult mosquitoes. Nanoparticles are being used in many commercial applications and were found that aqueous silver ions can be reduced by an aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. Based on this, silver nanoparticles (SNPs) were synthesized using leaf aqueous extract (LAE) of Mukia maderaspatana. Further, the synthesized SNPs were characterized by UV-visible spectrum, which indicated a strong plasmon resonance at 427 nm. X-ray diffraction (XRD) analysis revealed the average crystalline size of the synthesized SNPs was approximately 64 nm by Debye-Scherrer formulae. Fourier transform infrared (FTIR) spectroscopy analysis revealed the presence of different functional groups like amines, halides, alkanes, alkynes, amides, and esters with respective stretches, which are responsible for the bio-reduction of silver ions. Field emission scanning electron microscopy (FESEM) depicted the spherical morphology of SNPs with size range of 13-34 nm. The larvicidal activity of LAE and SNPs exhibited an effective mortality to Aedes aegypti and Culex quinquefasciatus. The lethal concentration (LC50; LC90) of LAE and SNPs were found to be 0.506; 1.082, 0.392; 0.870 ppm and 0.211; 0.703, 0.094; 0.482 ppm, respectively on A. aegypti and C. quinquefasciatus. Thus, the synthesized SNPs have shown preponderant larvicidal activity, but further studies are needed to formulate the potential larvicidal agents.
For the first time, we have successfully synthesized graphene nanosheets in the presence of pomegranate juice. In this approach, pomegranate juice was used not only as reductant but also as capping agent to form graphene nanosheets. At first, the improved Hummer method to oxidize graphite for the synthesis of graphene oxide (GO) was applied, and then the as-produced graphene oxide was reduced by pomegranate juice to form graphene nanosheets. Fourier transformed infrared (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and raman were used to characterize the samples. The results obtained from the characterization techniques proved high purity of the final products.
Mosquitoes transmit serious human diseases, causing millions of deaths every year. Mosquito control is to enhance the health and quality of life of county residents and visitors through the reduction of mosquito populations. Mosquito control is a serious concern in developing countries like India due to the lack of general awareness, development of resistance, and socioeconomic reasons. Today, nanotechnology is a promising research domain which has a wide ranging application in vector control programs. These are nontoxic, easily available at affordable prices, biodegradable, and show broad-spectrum target-specific activities against different species of vector mosquitoes. In the present study, larvicidal activity of aqueous leaf extract and silver nanoparticles (AgNPs) synthesized using C. asiatica plant leaves against late third instar larvae of Anopheles stephensi, Aedes aegypti, and Cx. quinquefasciatus. The range of varying concentrations of synthesized AgNPs (8, 16, 24, 32, and 40 μg/mL) and aqueous leaf extract (40, 80, 120, 160, and 200 μg/mL) were tested against the larvae of An. stephensi, Ae. aegypti, and Cx. quinquefasciatus. The synthesized AgNPs from C. asiatica were highly toxic than crude leaf aqueous extract in three important vector mosquito species. The results were recorded from UV-Vis spectrum, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy analysis (EDX). Considerable mortality was evident after the treatment of C. asiatica for all three important vector mosquitoes. The LC50 and LC90 values of C. asiatica aqueous leaf extract appeared to be effective against An. stephensi (LC50, 90.17 μg/mL; LC90, 165.18 μg/mL) followed by Ae. aegypti (LC50, 96.59 μg/mL; LC90, 173.83 μg/mL) and Cx. quinquefasciatus (LC50, 103.08 μg/mL; LC90, 183.16 μg/mL). Synthesized AgNPs against the vector mosquitoes of An. stephensi, Ae. aegypti, and Cx. quinquefasciatus had the following LC50 and LC90 values: An. stephensi had LC50 and LC90 values of 17.95 and 33.03 μg/mL; Ae. aegypti had LC50 and LC90 values of 19.32 and 34.87 μg/mL; and Cx. quinquefasciatus had LC50 and LC90 values of 20.92 and 37.41 μg/mL. No mortality was observed in the control. These results suggest that the leaf aqueous extracts of C. asiatica and green synthesis of silver nanoparticles have the potential to be used as an ideal eco-friendly approach for the control of An. stephensi, Ae. aegypti, and Cx. quinquefasciatus. This is the first report on the mosquito larvicidal activity of the plant extracts and synthesized AgNPs.
Larvicidal activity of synthesized Ag nanoparticles using 2,7.bis[2-[diethylamino]-ethoxy]fluorence isolate from the Melia azedarach leaves against Aedes aegypti and Culex quinquefasciatus. Six fractions were collected and concentrated, fraction three showed a single spot on TLC which was found to be a pure compound. The structures were elucidated by analyses of UV, MS, and NMR spectral data. The maximum mortality was fluorence against Aedes aegypti and Culex quinquefasciatus (LC50 = 7.94, LC90=23.82 ppm and LC50=13.58 and LC90 = 40.03ppm). The synthesized nanoparticles were characterized and confirmed as Ag nanoparticles by using UV–visible spectroscopy, XRD and HRTEM analysis. The maximum activity was observed in synthesized AgNPs against A. aegypti and C. quinquefasciatus (LC50 = 4.27 and 3.43 µg/ml; LC90 = 12.61 and 10.29 µg/ml). Rephrase test was studied to analyse the toxicological effects Mesocyclops pehpeiensis for 24h at synthesized AgNPs. This method is considered as an innovative alternative approach using to control of mosquitoes.
The economic and health problems related to the Asian tiger mosquito, Aedes albopictus (Diptera: Culicidae), are due to its ectoparasitic behaviour and to the transmission of many diseases, particularly arbovirus and parasites. The difficulty to control the larval instars of A. albopictus, the reduced effectiveness and high environmental impact of adulticide treatments, highlight that the most effective solution to protect against A. albopictus is the use of repellent products for personal use such as DEET (N, N-diethyl-3-methylbenzamide). This compound showed a high repellent power in time but also some disadvantages including toxic effects on humans, especially on children and the elderly. On this purpose, natural substances acting as repellent, such as plant essential oils and extracts, are considered very promising. Here we reported a critical review of our researches on repellence exerted by six different essential oils. The most effective essential oil was C. sativum. Furthermore, we discussed our research work conducted on ten essential oils tested as alternative larvicidal compounds. Following the dedicated WHO method, we proved that R. chalepensis EO was the most effective larvicidal among ten tested essential oils. Moreover, as regards to plant extracts, here we conducted bioassays to verify if the methanolic neem cake extract and its fractions of increasing polarity exhibit good mortality rates against A. albopictus larvae. We believe that the chance to use natural products such as essential oils and neem cake extracts, effective at lower doses when compared to synthetic products currently marketed, could be an advantageous alternative to build newer and safer mosquito control tools.
Silver nanoparticles (AgNPs) that are synthesized by using aqueous extracts of Solanum nigrumL., is a simple, non-toxic and ecofriendly green material. The present study is based on assessments of the larvicidal and antimicrobial activities of the synthesized Ag NPs from fresh leaves, dry leaves and green berries of S. nigrum against larvae of Culex quinquefasciatus and Anopheles stephensi and four human pathogenic and five fish pathogenic bacteria respectively. The synthesized nanoparticles are characterized with UV- Visible Spectroscopy, X- Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscope (TEM) analysis. The nanoparticles are spherical to polyhedral in shape with size of 50-100nm (average size of 56.6nm). In larvicidal bioassay with synthesized Ag NPs, highest mortality are observed at 10ppm against An. stephensi with LC50 values of 1.33, 1.59, 1.56ppm and LC90 values of 3.97, 7.31, 4.76ppm for dry leaves, fresh leaves and berries respectively. Antibacterial activity test reveals better results against fish pathogenic bacteria than human pathogenic bacteria. Non target organism like Toxorhynchites larvae (mosquito predator), Diplonychus annulatum (predatory water-bug) and Chironomus circumdatus larvae (chironomid) are also exposed to respective lethal concentrations (to mosquito larvae) of dry nanoparticles and no abnormality in the non target organisms are recorded. These results suggest that the synthesized Ag NPs of of S. nigrum have the potential to be used as an ideal eco-friendly compound for the control of the mosquito larvae and harmful bacteria.
Mosquitoes act as a vector for most of the life-threatening diseases like malaria, yellow fever, dengue fever, chikungunya fever, filariasis, encephalitis, West Nile Virus infection, etc. Under the Integrated Mosquito Management, emphasis was given on the application of alternative strategies in mosquito control. The continuous application of synthetic insecticides causes development of resistance in vector species, biological magnification of toxic substances through the food chain, and adverse effects on environmental quality and nontarget organisms including human health. Application of active toxic agents from plant extracts as an alternative mosquito control strategy was available from ancient times. These are nontoxic, easily available at affordable prices, biodegradable, and show broad-spectrum target-specific activities against different species of vector mosquitoes. In the present study, the larvicidal activity of silver nanoparticles (AgNPs) synthesized using Sida acuta plant leaf extract against late third instar larvae of Culex quinquefasciatus, Anopheles stephensi, and Aedes aegypti was determined. Range of concentrations of synthesized AgNPs (10, 20, 30, 40, and 50 μg/mL) and aqueous leaf extract (50, 100, 150, 200, and 250 μg/mL) were tested against the larvae of C. quinquefasciatus, A. stephensi and A. aegypti. The synthesized AgNPs from S. acuta leaf were highly toxic than crude leaf aqueous extract in three important vector mosquito species. The results were recorded from UV-Vis spectrum, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy analysis. Larvae were exposed to varying concentrations of aqueous crude extract and synthesized AgNPs for 24 h. Considerable mortality was evident after the treatment of S. acuta for all three important vector mosquitoes. The LC50 and LC90 values of S. acuta aqueous leaf extract appeared to be most effective against A. stephensi (LC50, 109.94 μg/mL and LC90, 202.42 μg/mL) followed by A. aegypti LC50 (119.32 μg/mL and LC90, 213.84 μg/mL) and C. quinquefasciatus (LC50, 130.30 μg/mL and LC90, 228.20 μg/mL). Synthesized AgNPs against the vector mosquitoes of A. stephensi, A. aegypti, and C. quinquefasciatus had the following LC50 and LC90 values: A. stephensi had LC50 and LC90 values of 21.92, and 41.07 μg/mL; A. aegypti had LC50 and LC90 values of 23.96, and 44.05 μg/mL; C. quinquefasciatus had LC50 and LC90 values of 26.13 and 47.52 μg/mL. These results suggest that the use of S. acuta synthesized silver nanoparticles can be a rapid, environmentally safer biopesticide which can form a novel approach to develop effective biocides for controlling the target vector mosquitoes. This is the first report on the mosquito larvicidal activity of the plant aqueous extract and synthesized nanoparticles.
The size and shape dependent electronic and chemical properties of metal nanoparticles has drawn the attention of chemists, physicists, biologists, and engineers who wish to use them for the development of new generation nanodevices. In this article, we report the synthesis of gold nanotriangles using tamarind leaf extract as the reducing agent. On treating aqueous chloroauric acid solution with tamarind leaf extract, rapid reduction of the chloroaurate ions is observed leading to the formation of flat and thin single crystalline gold nanotriangles. Atomic force microscopy analysis of the gold nanotriangles indicated that they ranged in thickness from 20 to 40 nm. These gold nanotriangles with unique and highly anisotropic planer shapes might find application in photonics, optoelectronics, and optical sensing. We investigated the effect of different organic solvent vapors like methanol, benzene and acetone on the conductivity of tamarind leaf extract reduced gold nanotriangles. I‐V characteristics measurement of these nanotriangles was done in presence of these organic solvent vapors. The observed characteristics suggest the application of gold nanotriangles to future chemical sensors.BA thanks the Indian Academy of Sciences, Bangalore for a Summer Fellowship. BA and MC thank the Director, National Chemical Laboratory (NCL), Pune for permission to carry out this research at NCL.
Silver nanoparticles (NPs) were rapidly synthesized by treating silver ions with a Capsicum annuum L. extract. The reaction process was simple and convenient to handle, and was monitored using ultraviolet-visible spectroscopy (UV-vis). The effect of Capsicum annuum L. proteins on the formation of silver NPs was investigated using X-ray photoemission spectroscopy (XPS), electrochemical measurements, Fourier-transform infrared spectroscopy (FTIR) and differential spectrum techniques. The morphology and crystalline phase of the NPs were determined from transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) spectra. The results indicated that the proteins, which have amine groups, played a reducing and controlling role during the formation of silver NPs in the solutions, and that the secondary structure of the proteins changed after reaction with silver ions. The crystalline phase of the NPs changed from polycrystalline to single crystalline and increased in size with increasing reaction time. A recognition–reduction–limited nucleation and growth model was suggested to explain the possible formation mechanism of silver NPs in Capsicum annuum L. extract.
In this paper we have reported the spectrophotometeric and transmission electron microscopic (TEM) data to the shape-directing role of cetyltrimethylammonium bromide (CTAB) on the green extra-cellular synthesis of bio-conjugated Ag-nanoparticles using Ocimum sanctum leaves extract. TEM images revealed that the nanoparticles are mostly spherical (average particle size ranged from 18 to 35nm) with some truncated triangular nanoplates, aggregated in a beautiful manner to yield locket-like silver and capped by a thin layer of biomolecules of O. sanctum, whereas nanoparticles are highly poly-dispersed in presence of CTAB. The shape and position of wavelength maxima strongly depends on the reaction time, [leaves extract] and [CTAB]. The visual observations also suggest that the prefect transparent silver sol becomes turbid in presence of CTAB after some time.
Biosynthesized nanoparticles have been achieved using environmentally acceptable plant extract and eco-friendly reducing and capping agents. The present study was based on assessments of the larvicidal activities to determine the efficacies of synthesized silver nanoparticles (AgNPs) using aqueous leaf extract of Vinca rosea (L.) (Apocynaceae) against the larvae of malaria vector Anopheles stephensi Liston and filariasis vector Culex quinquefasciatus Say (Diptera: Culicidae). Larvae were exposed to varying concentrations of aqueous extract of V. rosea and synthesized AgNPs for 24, 48, and 72 h. AgNPs were rapidly synthesized using the leaf extract of V. rosea, and the formation of nanoparticles was observed within 15 min. The results recorded from UV-Vis spectrum, Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) support the biosynthesis and characterization of AgNPs. The formation of the AgNPs synthesized from the XRD spectrum compared with the Bragg reflections at 2θ = 29.36, 38.26, 44.51, 63.54, and 77.13° which can be indexed to the (121), (111), (200), (220), and (311) orientations, respectively, confirmed the presence of AgNPs. The FTIR spectra of AgNPs exhibited prominent peaks at the spectra showed sharp and strong absorption band at 3,406.71 to 3,431.90 cm(-1) double in case of NH(2) group of a primary amine (N-H stretch). The presence of the sharp peak at 2,926.54 to 2,925.80 cm(-1) very broad often looks like distorted baseline (O-H carboxylic acids). The band 1,633.26 to 1,625.81 cm(-1) was assigned to C = C alkenes, aromatic ring stretching vibration, respectively. SEM analysis of the synthesized AgNPs clearly showed the clustered and irregular shapes, mostly aggregated and having the size of 120 nm. TEM reveals spherical shape of synthesized AgNPs. Particle size analysis revealed that the size of particles ranges from 25 to 47 nm with average size of 34.61 nm. Energy-dispersive X-ray spectroscopy showed the complete chemical composition of the synthesized AgNPs. In larvicidal activity, the results showed that the maximum efficacy was observed in synthesized AgNPs against the fourth instar larvae of A. stephensi (LC(50) = 12.47 and 16.84 mg/mL and LC(90) = 36.33 and 68.62 mg/mL) on 48 and 72 h of exposure and against C. quinquefasciatus (LC(50) = 43.80 mg/mL and LC(90) = 120.54 mg/mL) on 72-h exposure, and aqueous extract showed 100 % mortality against A. stephensi and C. quinquefasciatus (LC(50) = 78.62 and 55.21 mg/mL and LC(90) = 184.85 and 112.72 mg/mL) on 72-h exposure at concentrations of 50 mg/mL, respectively. The AgNPs did not exhibit any noticeable toxicity on Poecilia reticulata after 24, 48, and 72 h of exposure. These results suggest that the synthesized AgNPs have the potential to be used as an ideal eco-friendly approach for the control of the A. stephensi and C. quinquefasciatus. This method is considered as a new approach to control vectors. Therefore, this study provides the first report on the mosquito larvicidal activity of V. rosea synthesized AgNPs against vectors.
The development of reliable, eco-friendly processes for the synthesis of nanomaterials is an important aspect of nanotechnology today. One approach that shows immense potential is based on the biosynthesis of nanoparticles using biological micro-organisms such as bacteria. In this laboratory, we have concentrated on the use of fungi in the intracellular production of metal nanoparticles. As part of our investigation, we have observed that aqueous silver ions when exposed to the fungus Fusarium oxysporum are reduced in solution, thereby leading to the formation of an extremely stable silver hydrosol. The silver nanoparticles are in the range of 5–15 nm in dimensions and are stabilized in solution by proteins secreted by the fungus. It is believed that the reduction of the metal ions occurs by an enzymatic process, thus creating the possibility of developing a rational, fungal-based method for the synthesis of nanomaterials over a range of chemical compositions, which is currently not possible by other microbe-based methods.
In present study, the bioactivity of latex-producing plant Pergularia daemia as well as synthesized silver nanoparticles (AgNPs) against the larval instars of Aedes aegypti and Anopheles stephensi mosquito larvae was determined. The range of concentrations of plant latex (1,000, 500, 250, 125, 62.25, and 31.25 ppm) and AgNPs (10, 5, 2.5, 1.25, 0.625, and 0.3125 ppm) were prepared. The LC(50) and LC(90) values for first, second, third, and fourth instars of synthesized AgNPs-treated first, second, third, and fourth instars of A. aegypti (LC(50) = 4.39, 5.12, 5.66, 6.18; LC(90) = 9.90, 11.13, 12.40, 12.95 ppm) and A. stephensi (LC(50) = 4.41, 5.35, 5.91, 6.47; LC(90) = 10.10, 12.04, 13.05, 14.08 ppm) were found many fold lower than crude latex-treated A. aegypti (LC(50) = 55.13, 58.81, 75.66, 94.31; LC(90) = 113.00, 118.25, 156.95, 175.71 ppm) and A. stephensi (LC(50) = 81.47, 92.09, 96.07, 101.31; LC(90) = 159.51, 175.97, 180.67, 190.42 ppm). The AgNPs did not exhibit any noticeable effects on Poecillia reticulata after either 24 or 48 h of exposure at their LC(50) and LC(90) values against fourth-instar larvae of A. aegypti and A. stephensi. The UV-visible analysis shows absorbance for AgNPs at 520 nm. TEM reveals spherical shape of synthesized AgNPs. Particle size analysis revealed that the size of particles ranges from 44 to 255 nm with average size of 123.50 nm. AgNPs were clearly negatively charged (zeta potential -27.4 mV). This is the first report on mosquito larvicidal activity P. daemia-synthesized AgNPs.
Considering the contents of international journals of parasitology dealing with broader topics inside this field show that rather a few papers appear with studies in the discipline of arachno-entomology. In the journals Journal of Parasitology, Parasitology Research and Trends in Parasitology, the relations of published papers on protozoology, helminthology and arachno-entomology showed that in all three journals, papers on protozoans were the most common, while those on helminths of any kind reached the second place being rather as common as the protozoan papers in Parasitology Research and in the Journal of Parasitology. In Trends of Parasitology, however, the papers on helminths reached only about 25% of the numbers published on protozoan topics. But in all three journals-and this is important-the papers on arachno-entomological themes were scarce reaching less than the half of the protozoan papers in Parasitology Research, and only about 15% in the Journal of Parasitology and in the Trends of Parasitology. These disproportions between the three great subdivisions of targets in the focus of parasitological research are dangerous, since this lack exists already for several decades and thus led to a backlog of unsolved increasing problems that are caused by ticks, mites, insects and/or parasitic crustaceans especially in times of intensive globalization and global warming. Studies on the biology, vectorship, invasion and spreading of wanted vectors and on the control of pests and parasites belonging to the field of arachno-entomology are urgently needed.
The influence of biochar on nitrogen (N) transformation processes in soil is not fully understood. This study assessed the influence of four biochars (wood and poultry manure biochars synthesized at 400 degrees C, nonactivated, and at 550 degrees C, activated, abbreviated as: W400, PM400, W550, PM550, respectively) on nitrous oxide (N2O) emission and N leaching from an Alfisol and a Vertisol. Repacked soil columns were subjected to three wetting-drying (W-D) cycles to achieve a range of water-filled pore space (WFPS) over a 5-mo period. During the first two W-D cycles, W400 and W550 had inconsistent effects on N2O emissions and the soils amended with PM400 produced higher N2O emissions relative to the control. The initially greater N2O emission from the PM400 soils was ascribed to its higher labile intrinsic N content than the other biochars. During the third W-D cycle, all biochar treatments consistently decreased N2O emissions, cumulatively by 14 to 73% from the Alfisol and by 23 to 52% from the Vertisol, relative to their controls. In the first leaching event, higher nitrate leaching occurred from the PM400-amended soils compared with the other treatments. In the second event, the leaching of ammonium was reduced by 55 to 93% from the W550- and PM550-Alfisol and Vertisol, and by 87 to 94% from the W400- and PM400-Vertisol only (cf. control). We propose that the increased effectiveness of biochars in reducing N2O emissions and ammonium leaching over time was due to increased sorption capacity of biochars through oxidative reactions on the biochar surfaces with ageing.
Climate change is expected to have direct and indirect impacts on African livestock. Direct impacts include increased ambient temperature, floods and droughts. Indirect impacts are the result of reduced availability of water and forage and changes in the environment that promote the spread of contagious diseases through increased contact between animals, or increased survival or availability of the agent or its intermediate host. The distribution and prevalence of vector-borne diseases may be the most significant effect of climate change. The potential vulnerability of the livestock industry will depend on its ability to adapt to such changes. Enhancing this adaptive capacity presents a practical way of coping with climate change. Adaptive capacity could be increased by enabling the African livestock owner to cope better with animal health problems through appropriate policy measures and institutional support. Developing an effective and sustainable animal health service, associated surveillance and emergency preparedness systems and sustainable disease control and prevention programmes is perhaps the most important strategy for dealing with climate change in many African countries.
Plant extracts, especially botanical insecticides, are currently studied more and more because of the possibility of their use in plant protection. Many of the natural plant compounds and organic compounds used in the control of insect pests are known to affect digestive enzymes. When fed a diet of rice leaves treated with botanical insecticides and bacterial toxins in bioassays, activities of the digestive enzymes protease, amylase, and lipase in the rice leaffolder larvae are affected. Digestive enzyme activities were affected by botanical insecticides and bacterial toxins individually and in combination. When combined, the effect was more severe at low concentration. There were statistically significant differences (P < or = 0.05) in enzyme activities in combined and individual treatments. The combination of Btk and botanical insecticides caused a two-fold decrease in enzyme activity even at reduced concentration. Clear dose-response relationships were established with respect to enzyme activity. A synergistic effect of botanical insecticides and bacterial toxins was found when combined in low doses. These effects are most pronounced in early instars.
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. In this study, the oils of 41 plants were evaluated for their effects against third-instar larvae of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. At first, the oils were surveyed against A. aegypti using a 50-ppm solution. Thirteen oils from 41 plants (camphor, thyme, amyris, lemon, cedarwood, frankincense, dill, myrtle, juniper, black pepper, verbena, helichrysum and sandalwood) induced 100% mortality after 24 h, or even after shorter periods. The best oils were tested against third-instar larvae of the three mosquito species in concentrations of 1, 10, 50, 100 and 500 ppm. The lethal concentration 50 values of these oils ranged between 1 and 101.3 ppm against A. aegypti, between 9.7 and 101.4 ppm for A. stephensi and between 1 and 50.2 ppm for C. quinquefasciatus.
Since ancient times, plant products were used in various aspects. However, their use against pests decreased when chemical products became developed. Recently, concerns increased with respect to public health and environmental security requiring detection of natural products that may be used against insect pests. In this study, 41 plant extracts and 11 oil mixtures were evaluated against the yellow fever mosquito, Aedes aegypti (Linnaeus), the malaria vector, Anopheles stephensi (Liston), and the filariasis and encephalitis vector, Culex quinquefasciatus (Say) (Diptera: Culicidae) using the skin of human volunteers to find out the protection time and repellency. The five most effective oils were those of Litsea (Litsea cubeba), Cajeput (Melaleuca leucadendron), Niaouli (Melaleuca quinquenervia), Violet (Viola odorata), and Catnip (Nepeta cataria), which induced a protection time of 8 h at the maximum and a 100% repellency against all three species. This effect needs, however, a peculiar formulation to fix them on the human skin.
Biosynthesis of silver nanoparticles from extract of Desmodium gangeticum (L.) DC. and its biomedical potential. Spectrochim
- Thirunavokkarasu