32 research outputs found
Insecticidal, antibacterial and dye adsorbent properties of Sargassum muticum decorated nano-silver particles
No full textMarine algae contain many bioactive constituents. In the current research, the brown seaweed Sargassum muticum was collected from Red Sea and its extract used as a capping agent for the formulation of biocompatible stable silver nanoparticles (AgNPs). The seaweed-fabricated AgNPs were studied through UV–vis, TEM, XRD, EDX, FTIR and Zeta potential analyses. The chemical constituents of S. muticum extract were evaluated by RP-HPLC and 1H NMR. Both seaweed extract and AgNPs had mosquito larvicidal and adulticidal activities. The seaweed-fabricated AgNPs induced high larval mortality against mosquitoes from both Indian and Saudi Arabian strains when compared to the seaweed extract. The LC50 values of AgNPs against the Indian strains of Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi were 43.9, 35.9 and 27.0 μg/ml, respectively; those against the Saudi Arabian strains of Ae. aegypti and Cx. pipiens were 110.4 and 126.2 μg/ml, respectively. In adulticidal experiments, the LC50 values of S. muticum-fabricated AgNPs against Indian strains of Cx. quinquefasciatus, Ae. aegypti and An. stephensi were 42.3, 34.3 and 29.7 μg/ml, respectively, whereas those against the Saudi Arabian strains of Ae. aegypti and Cx. pipiens were 86.4 and 120.0 μg/ml, respectively. Minimal doses of seaweed-fabricated AgNPs were highly effective in inhibiting the growth of Bacillus subtilis (11.25 mm inhibition zone), Escherichia coli (13.35 mm), Klebsiella pneumoniae (14.24 mm) and Salmonella typhi (12.23 mm). Additionally, the seaweed extract was highly efficient to adsorb methylene blue (MB) and methyl orange (MO) dyes. In conclusion, the S. muticum extract revealed to be an effective capping agent to fabricate AgNPs to be industrially used for the control of deadly mosquito vectors and as an antimicrobial and dye adsorbent agent
Insecticide susceptibility in larval population of the West Nile vector Culex pipiens L. (Diptera: Culicidae) in Saudi Arabia
No full textObjective: To investigate the susceptibility to some conventional and non-conventional
insecticides in laboratory and field larval populations of the West Nile vector Culex
pipiens L. (Cx. pipiens), the dominant species in Jeddah Province, Saudi Arabia.
Methods: The tested conventional insecticides were Actikil and Pesgard, while the nonconventional
ones were Bacilod, Dudim and Baycidal. Probit analysis and photomicroscopical
observations were carried out to shed light on acute toxicity in laboratory
and field Cx. pipiens strains.
Results: Cx. pipiens were more susceptible to Pesgard (LC50: 0.045 and 0.032 mg/L)
than Actikil (0.052 and 0.038 mg/L) and Bacilod (0.129 and 0.104 mg/L), for the field
and laboratory strains, respectively. Results showed that treatments with the chitin synthesis
inhibitor Dudim and Baycidal evoked morphological effects similar to those
induced by other insect growth regulators. According to IC50 values obtained (concentration
which to inhibit the emergence of 50% of mosquito adults), the compound Dudim
(0.0003 and 0.0001 mg/L) was more effective against Cx. pipiens L. mosquitoes than
Baycidal (0.0004 and 0.0003 mg/L) for both the field and laboratory strains, respectively.
Conclusions: Our results provide baseline data to enhance control programs and orient
public health decisions on the selection of pesticides againstmosquito vectors inSaudiArabia
Effectiveness of seven mosquito larvicides against the West Nile vector Culex pipiens (L.) in Saudi Arabia
No full textObjective: To explore the effects of different chemical larvicides, bioinsecticides and insect growth regulators against the West Nile vector Culex pipiens (Diptera: Culicidae) (Cx. pipiens) in Saudi Arabia. Methods: We tested seven commercial mosquito larvicides, including classic cyfluthrin, diazinon and propoxur, bioinsecticides Bactilarvae and Tracer 24%, and insect growth regulators Baycidal and Sumilarv. LC50 and LC90 values were calculated in laboratory conditions using probit analysis. Results: Concerning chemical insecticides, the highest larval mortality was observed for diazinon, with LC50 = 0.352 3 mg/L, followed by propoxur and cyfluthrin. The bacterial insecticide Tracer was more effective than Bactilarvae (LC50 = 0.008 7 mg/L and 0.011 7 mg/L, respectively) by 1.37 folds. Furthermore, Cx. pipiens larvae were more susceptible to insect growth regulators Baycidal (IC50 = 0.000 4 mg/L) if compared to Sumilarv (IC50 = 0.002 9 mg/L) by 7.25 folds. Conclusions: Overall, this research added basic knowledge about the effectiveness of seven mosquito larvicides with different mechanisms of action as potential candidates for the control programs of Cx. pipiens mosquito populations in Saudi Arabia
Phytochemical analysis of Rhazya stricta extract and its use in fabrication of silver nanoparticles effective against mosquito vectors and microbial pathogens
No full textWorldwide, billions of people are at risk from viruses, parasites and bacteria transmitted by mosquitoes, ticks, fleas and other vectors. Over exploitation of chemical pesticides to overcome the mosquito borne diseases led to detrimental effects on environment and human health. The present research aims to explore bio-fabrication of metal silver nanomaterials using Rhazya stricta extract against deadly mosquito vectors and microbial pathogens. The phytochemical profile of the R. stricta extracts was studied by HPLC-MS and 1H NMR. Further, confirmation of the bio-fabricated silver nanoparticles (AgNPs) was car- ried out by UV–vis spectroscopy and characterization through FTIR, TEM, EDX, and XRD analyses. The R. stricta-fabricated AgNPs showed acute toxicity on key mosquito vectors from two different country (India and Kingdom of Saudi Arabia, KSA) strains, notably, with LC50 values of 10.57, 11.89 and 12.78 lg/ml on malarial, dengue and filarial key Indian strains of mosquito vectors, respectively, and 30.66 and 38.39 lg/ml on KSA strains of Aedes aegypti and Culex pipiens, respectively. In mosquito adulticidal activity, R. stricta extract alone exhibited LC50 values ranging from 304.34 to 382.45 lg/ml against Indian strains and from 738.733 to 886.886 against Saudi Arabian strains, while AgNPs LC50 boosted from 9.52 to 12.16 lg/ml and from 30.66 to 38.39 lg/ml, respectively. Moreover, it was noticed that at low concentra- tion the tested AgNPs showed high growth retardation of important pathogenic bacteria such as Bacillus subtilis, Klebsiella pneumoniae and Salmonella typhi with inhibition zone diameters from 11.86 to 22.92 mm. In conclusion, the present study highlighted that R. stricta-fabricated AgNPs could be a lead material for the management of mosquito vector and microbial pathogens control
Suaeda maritima-based herbal coils and green nanoparticles as potential biopesticides against the dengue vector Aedes aegypti and the tobacco cutworm Spodoptera litura
No full textThe overuse of synthetic pesticides to control insect pests leads to physiological resistance and adverse environmental effects, in addition to high operational cost. Insecticides of botanical origin have been reported as useful for control of agricultural and public health insect pests. This research proposed a novel method of mangrove-mediated synthesis of insecticidal silver nanoparticles (AgNP) using Suaeda maritima, acting as a reducing and stabilizing agent. AgNP were characterized by UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analysis. S. maritima aqueous extract and mangrove-synthesized AgNP showed larvicidal and pupicidal toxicity against the dengue vector Aedes aegypti and the tobacco cutworm Spodoptera litura. In particular, LC50of AgNP ranged from 8.668 (larva I) to 17.975 ppm (pupa) for A. aegypti, and from 20.937 (larva I) to 46.896 ppm (pupa) for S. litura. In the field, the application of S. maritima extract and AgNP (10 Ã LC50) led to 100% mosquito larval reduction after 72 h. Smoke toxicity experiments conducted on A. aegypti adults showed that S. maritima leaf-, stem- and root-based coils evoked mortality rates comparable or higher if compared to permethrin-based positive control (62%, 52%, 42%, and 50.2 respectively). In ovicidal experiments, egg hatchability was reduced by 100% after treatment with 20 ppm of AgNP and 250 ppm of S. maritima extract. Furthermore, low doses of the AgNP inhibited the growth of Bacillus subtilis, Klebsiella pneumoniae and Salmonella typhi. Overall, our results highlighted the potential of S. maritima-based herbal coils and green nanoparticles as biopesticides in the fight against the dengue vector A. aegypti and the tobacco cutworm S. litura
Nanofabrication of Graphene Quantum Dots with High Toxicity Against Malaria Mosquitoes, Plasmodium falciparum and MCF-7 Cancer Cells: Impact on Predation of Non-target Tadpoles, Odonate Nymphs and Mosquito Fishes
No full textRecently, it has been highlighted an overlooked connection between the biting activity of Anopheles mosquitoes and the spread of cancer. The excellent physico-chemical properties of graphene quantum dots (GQDs) make them a suitable candidate for biomedical applications. We focused on the toxicity of GQDs against Plasmodium falciparum and its vector Anopheles stephensi, and their impact on predation of non-target mosquito predators. Biophysical methods, including UV–vis, photoluminescence, FTIR and Raman spectroscopy, XRD analysis and TEM, confirmed the effective GQD nanosynthesis. LC50 against A. stephensi ranged from 0.157 (larva I) to 6.323 ppm (pupa). The antiplasmodial activity of GQDs was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of P. falciparum. IC50 were 82.43 (CQ-s) and 85.17 μg/ml (CQ-r). In vivo experiments conducted on Plasmodium berghei infecting albino mice showed moderate activity of GQDs if compared to chloroquine. Concerning non-target effects, the predation efficiency of Gambusia affinis, Anax immaculifrons and Hoplobatrachus tigerinus post-treatment with GQDs was enhanced. Lastly, GQDs were toxic against MCF-7 breast cancer cell lines with an IC50 = 24.81 μg/ml, triggering apoptosis in treated cells. Overall, we highlighted the multipurpose potential of GQDs for the development of newer drugs in the fight against Anopheles vectors, Plasmodium parasites and breast cancer cells
Genetic deviation in geographically close populations of the dengue vector Aedes aegypti (Diptera: Culicidae). Influence of environmental barriers in South India
No full textMosquitoes are vectors of devastating pathogens and parasites, causing millions of deaths every year. Dengue is a mosquito-borne viral infection found in tropical and subtropical regions around the world. Recently, dengue transmission has strongly increased in urban and semiurban areas, becoming a major international public health concern. Aedes aegypti (Diptera: Culicidae) is a primary vector of dengue. Shedding light on genetic deviation in A. aegypti populations is of crucial importance to fully understand their molecular ecology and evolution. In this research, haplotype and genetic analyses were conducted using individuals of A. aegypti from 31 localities in the north, southeast, northeast and central regions of Tamil Nadu (South India). The mitochondrial DNA region of cytochrome c oxidase 1 (CO1) gene was used as marker for the analyses. Thirty-one haplotypes sequences were submitted to GenBank and authenticated. The complete haplotype set included 64 haplotypes from various geographical regions clustered into three groups (lineages) separated by three fixed mutational steps, suggesting that the South Indian Ae. aegypti populations were pooled and are linked with West Africa, Columbian and Southeast Asian lineages. The genetic and haplotype diversity was low, indicating reduced gene flow among close populations of the vector, due to geographical barriers such as water bodies. Lastly, the negative values for neutrality tests indicated a bottle-neck effect and supported for low frequency of polymorphism among the haplotypes. Overall, our results add basic knowledge to molecular ecology of the dengue vector A. aegypti, providing the first evidence for multiple introductions of Ae. aegypti populations from Columbia and West Africa in South India
Seagrasses as sources of mosquito Nano-Larvicides? Toxicity and uptake of Halodule uninervis-biofabricated silver nanoparticles in Dengue and Zika Virus vector Aedes aegypti
No full textMosquitoes (Diptera: Culicidae) act as vectors for devastating pathogens and parasites. Zika virus, an Aedes mosquito-borne flavivirus, is becoming a worldwide public health concern following its suspected association with over 4000 recent cases of microcephaly in the infants of some women who were pregnant when they contracted the disease. There are no specific treatments for Zika virus, thus the eco-friendly and effective control of mosquito vectors is crucial. This research proposed a novel method of seagrass-mediated synthesis of silver nanoparticles (AgNP) using Halodule uninervis as a reducing and capping agent. UV–Vis spectroscopy, FTIR spectroscopy, SEM, EDX spectroscopy, XRD and Raman analysis confirmed the rapid and cheap synthesis of AgNP. LC50of H. uninervis extract against Aedes aegypti was 295.629 ppm and LC50of H. uninervis-synthesized AgNP was 12.554 ppm. Microscopy analysis pointed out the uptake of H. uninervis-fabricated AgNP in the midgut of mosquito larvae. In MIC assays, low doses of the AgNP inhibited the growth of Bacillus subtilis, Klebsiella pneumoniae and Salmonella typhi. Overall, this research shed light on the mosquitocidal potential of H. uninervis, as a bio-resource for the cheap and effective nanosynthesis of mosquitocidal biopesticides
Characterization and mosquitocidal potential of neem cake-synthesized silver nanoparticles: genotoxicity and impact on predation efficiency of mosquito natural enemies
No full textMosquitoes (Diptera: Culicidae) serve as important vectors for a wide number of parasites and pathogens of huge medical and veterinary importance. Aedes aegypti is a primary dengue vector in tropical and subtropical urban areas. There is an urgent need to develop eco-friendly mosquitocides. In this study, silver nanoparticles (AgNP) were biosynthesized using neem cake, a by-product of the neem oil extraction from the seed kernels of Azadirachta indica. AgNP were characterized using a variety of biophysical methods, including UV–vis spectrophotometry, FTIR, SEM, EDX, and XRD analyses. Furthermore, the neem cake extract and the biosynthesized AgNP were tested for acute toxicity against larvae and pupae of the dengue vector Ae. aegypti. LC50 values achieved by the neem cake extract ranged from 106.53 (larva I) to 235.36 ppm (pupa), while AgNP LC50 ranged from 3.969 (larva I) to 8.308 ppm (pupa). In standard laboratory conditions, the predation efficiency of a Carassius auratus per day was 7.9 (larva II) and 5.5 individuals (larva III). Post-treatment with sub-lethal doses of AgNP, the predation efficiency was boosted to 9.2 (larva II) and 8.1 individuals (larva III). The genotoxic effect of AgNP was studied on C. auratus using the comet assay and micronucleus frequency test. DNA damage was evaluated on peripheral erythrocytes sampled at different time intervals from the treatment; experiments showed no significant damages at doses below 12 ppm. Overall, this research pointed out that neem cake-fabricated AgNP are easy to produce, stable over time, and can be employed at low dosages to reduce populations of dengue vectors, with moderate detrimental effects on non-target mosquito natural enemies
DNA barcoding and molecular evolution of mosquito vectors of medical and veterinary importance
No full textMosquitoes (Diptera: Culicidae) are a key threat for millions of people worldwide, since they act as vectors for devastating pathogens and parasites. The standard method of utilisation of morphological characters becomes challenging due to various factors such as phenotypical variations. We explored the complementary approach of CO1 gene-based identification, analysing ten species of mosquito vectors belonging to three genera, Aedes, Culex and Anopheles from India. Analysed nucleotide sequences were found without pseudo genes and indels; they match with high similarity in nucleotide Basic Local Alignment Search Tool (BLASTn) search. The partial CO1 sequence of Anopheles niligricus was the first time record submitted to National Center for Biotechnology Information (NCBI). Mean intra- and interspecies divergence was found to be 1.30 and 3.83 %, respectively. The congeneric divergence was three times higher than the conspecifics. Deep intraspecific divergence was noted in three of the species, and the reason could be explained more accurately in the future by improving the sample size across different locations. The transitional and transversional substitutions were tested individually. Ts and Tv substitutions in all the 1st, 2nd and 3rd codons were estimated to be (0.44, 99.51), (40.35, 59.66) and (59.16, 40.84), respectively. Saturation of the sequences was resolved, since both the Ts and Tv exhibited a linear relationship suggesting that the sequences were not saturated. NJ and ML tree analysis showed that the individuals of the same species clustered together based on the CO1 sequence similarity, regardless of their collection site and geographic location. Overall, this study adds basic knowledge to molecular evolution of mosquito vectors of medical and veterinary importance and may be useful to improve biotechnological tools employed in Culicidae control programmes
