Filariasis Vector Culex Quinquefasciatus Research Articles

Prospective of Green waste compounds against Dengue vector Aedes aegypti and Filariasis vector Culex quinquefasciatus

Prospective of Green waste compounds against Dengue vector Aedes aegypti and Filariasis vector Culex quinquefasciatus

Evaluation of pure camphor (C10H16O) against wild-caught Culex quinquefasciatus larvae in East Jakarta, Indonesia: Detoxification enzymes and histopathological midgut

Filariasis, transmitted by the lymphatic filariasis vector Culex quinquefasciatus, is still a global public health issue. Resistance to Cx. quinquefasciatus is caused by the eradication of filariasis with synthetic insecticides. The aim of the study was to evaluate the toxicity of pure camphor on Cx. quinquefasciatus, with a focus on detoxifying enzymes and midgut histopathological abnormalities. Cx. quinquefasciatus larvae are field-collected wild-strain larvae. The WHO protocol was followed for the larval bioassays. Pure camphor concentrations of 0.5, 1.5, 10.5, 25.5, and 50 ppm were applied to larvae for 24, 48, and 72 h, with 5 replications. The biochemical method was used to test detoxification enzymes such as acetylcholinesterase (AChE), glutathione S-transferase (GST), and oxidase. The routine histopathological examination was performed on the larvae's histopathological midguts. At 48 h, pure camphor caused 100% mortality of Cx. quinquefasciatus larvae. LC50 and LC90 values were found to be 2.32 and 12.40 ppm respectively. AChE and oxidase activity were both significantly lower (p

Larvicidal efficacy of the leaf and flower extracts of Tropaeolum majus L. (Tropaeolaceae) against the vector of lymphatic filariasis

Billions of people face consequences throughout the world due to vector-borne diseases. Effective management of vector populations can reduce the burden of vector-borne diseases. The present study was conducted to assess the efficiency of Tropaeolum majus leaf and flower extracts on the Lymphatic Filariasis vector Culex quinquefasciatus. Crude extract of T. majus leaves and flowers was used for larvicidal bioassay against 3rd instar larvae. The effect of both the extracts on non-target organisms was also assessed. Log probit, regression, and ANOVA were carried out to find out the statistical significance. Crude extract of both leaf and flower showed significant larval mortality. 100% and 96% mortality were achieved within 72 h in 2% crude extracts of leaf and flower respectively. After 72 h treatment LC50 value was assessed as 0.56% and 0.78% in the case of leaf and flower extracts respectively, which were quite acceptable. ANOVA analysis established a significant relationship between exposure time and concentration of extracts in imposing mortality to the mosquito larvae. Though, the tests on the non-target organisms showed that those extracts were generally safe. The outcomes suggest that the extracts of T. majus leaves and flowers can be used as an eco-friendly mosquito larvicidal agent. The isolated compounds from this plant may also act as a potent larvicide and are worth further study.

Efficacy of Commonly Used Mosquito Coils Containing Pyrethrin against Lymphatic Filariasis Vector Culex quinquefasciatus (Say) in Gombe

Aims: Mosquito coil is a common insect repellant used in many homes to repel and kill mosquitoes that transmit diseases and another insect pest. The present study was conducted to explore the potency of the commonly used brand of mosquito coil containing pyrethroids against Culex quinquefasciatus in Gombe and its communities.
 Place and Duration of Study: Department of Biological sciences insectary laboratory of Gombe State University, Gombe, Nigeria between August and December 2017.
 Methodology: Four (4) different brands tagged; C1, C2, C3 and C4 containing 0.08% Merperflutrin, 0.2% Pyrethroids, 0.05% Transflutrine + 0.1% Esbiothrin and 0.25% d-Trans-allethrin respectively were investigated. Ten (10) reared adult mosquitoes were transferred separately into various containers using an aspirator. Data on knockdown time and Adult mortality were recorded. All the data collected were analyzed using SPSS version 24.0. Analysis of Variance (ANOVA) was used to determine the significant difference between the treatments at P=.05. 
 Results: Merperflutrin 0.08%, Transflutrine 0.05% + Esbiothrin 0.1% and 0.25% d-Transalletrin recorded highest mortality of 100% each and 0.2% Pyrethroids recorded 96% mortality at 24hours of exposure to the treatment respectively. The mortality is time- dependent and all the treatments show significant mortality at P=.05. Transflutrine 0.05% + Esbiothrin 0.1% recorded the lowest KT50 value of 2.41 min.
 Conclusion: Merperflutrin 0.08%, and Transflutrine 0.05% + Esbiothrin 0.1% have the highest efficacy; faster knockdown rate and could be used as a repellent in minimizing the population of the indoor resting density of mosquitoes’ species in our homes.

Efficacy of Petiveria Alliacea (Linneaus) leaf and root bark powder in the control of filariasis vector Culex Quinquefasciatus

BackgroundMosquitoes are vectors of parasitic diseases such as malaria, lymphatic filariasis, yellow fever, and dengue fever among others. They are well known as public enemies for their noise nuisance, biting annoyance, sleeplessness, allergic reactions, and diseases transmission during the biting and feeding activities. This then necessitate the search for insecticides of plant origin which are bio-degradable, non-toxic, and readily available for man use.ResultThis study, evaluated the fumigant efficacy of the powder of P. alliacea to control the adult stage of Culex mosquito. Powder of Petiveria alliacea were administered at different dose of (1 g, 2 g, 3 g, 4 g, and 5 g), respectively. Result obtained shows the fumigant effect of the powder were effective with percentage mortality of 18.33–60.00% for the leaf powder and 23.30–71.60% for the root powder within 2 h post-treatment period (P < 0.05). The synergistic effect of the leaf and root powder was also investigated. The lethal dosage (LD50) of the leaf, root, and synergistic effect of leaf and root bark powder required to kill 50% of the adult Culex quinquefasciatus was 3.76 g, 2.86 g, and 2.63 g, respectively. However, 25.06 g, 15.25 g, and 12.94 g of the leaf, root, and leaf and root powder were required to kill 90% (LD90) after a 2-h exposure period.ConclusionThese finding suggested P. alliacea powder could be a good source of insecticide which may be used for the production of biopesticides. The present findings have important implications in the practical control of adult mosquito by using botanical insecticides. These plant powders are easy to prepare, inexpensive, and safe for use in mosquito control.

Coumarin (2H-1-benzopyran-2-one): a novel and eco-friendly aphicide

Coumarin (2H-1-benzopyran-2-one) is a phenolic compound derived from the shikimate pathway and synthesized by various medicinal and aromatic plants as parent molecule of a large group of secondary metabolites, namely coumarins. Its main utilization is as fixative in perfumes and flavour enhancer. Given its role as phytoalexin and phagodepression activity, herein we evaluated for the first time its efficacy against several insect species: the green peach aphid, Myzus persicae, the moth Spodoptera littoralis, the housefly, Musca domestica and the filariasis vector Culex quinquefasciatus. Two non-target species were also included in our toxicity evaluation experiments: the ladybug Harmonia axyridis and the earthworm Eisenia fetida. Results highlighted remarkable selectivity of coumarin, being highly toxic to M. persicae aphids (LC50(90) values of 1.3(1.9) mg L−1) and friendly to natural enemies of aphids as well as soil invertebrates.

Insecticidal activity of the essential oil from Schizogyne sericea (Asteraceae) on four insect pests and two non-target species

Salado (Schizogyne sericea) is an aromatic shrub occurring very frequently in the coastal areas of Tenerife, Canary Islands. Herein, we investigated whether the essential oil produced by salado under salt stress could be effective as a botanical insecticide against a panel of target insects such as larvae and adults of the filariasis vector Culex quinquefasciatus, the peach-potato aphid Myzus persicae, the housefly Musca domestica and the tobacco cutworm Spodoptera littoralis. The essential oil, which was characterized by p-cymene, isobornyl acetate and thymol esters, as detected by gas chromatographic analysis, was highly effective against larvae of C. quinquefasciatus (LC50 of 49.1 mL.L−1) and adults of M. persicae (LC50 of 2.1 mL.L−1). On the other hand, little toxicity was found on adult females of C. quinquefasciatus and M. domestica, as well as on larvae of S. littoralis. Finally, the S. sericea essential oil was not toxic to selected non-target organisms, 3rd instar larvae and adults of the ladybug Harmonia axyridis or adults of the earthworm Eisenia fetida. Overall, the present research supports a possible use of salado oil in eco-friendly insecticidal formulations useful to manage culicine larval populations as well as M. persicae aphids.

Insecticidal activity of the essential oil and polar extracts from Ocimum gratissimum grown in Ivory Coast: Efficacy on insect pests and vectors and impact on non-target species

Ocimum gratissimum L. (white wild basil) is an aromatic herb cultivated in Western Africa for culinary and pest control purposes. The current research evaluated the insecticidal activity of white wild basil essential oil, ethanolic and water extracts against insect pests and vectors, i.e., the tobacco cutworm Spodoptera littoralis, the housefly Musca domestica, and the filariasis vector Culex quinquefasciatus. Furthermore, the toxicity of the essential oil and polar extracts against the non-target earthworm Eisenia fetida was assessed. The chemical profiles of the essential oil and polar extracts were obtained by GC–MS and HPLC-DAD analyses. Acute toxicity experiments were conducted on larvae of C. quinquefasciatus and S. littoralis and adults of M. domestica and E. fetida, to determine the LC50 and LC90 values of the oil and polar extracts. Chronic toxicity was evaluated on S. littoralis feeding on tomato discs treated with essential oil and polar extracts. The essential oil was dominated by thymol (50.0%) and p-cymene (16.8%), whereas ethanolic and aqueous extracts were characterized by carvacrol (13%) and thymol (11%), and shikimic acid (3%) and rosmarinic acid (2%), respectively. The essential oil was significantly more active on target insects than extracts, showing LC50/LD50 of 39.6 mg L−1 on C. quinquefasciatus, 72.2 μg adult−1 on M. domestica and 30.2 μg larva−1 on S. littoralis. Furthermore, the essential oil and ethanolic extract at sublethal doses (10 and 70 μg cm-2, respectively) affected the survival of S. littoralis larvae from the third day on. White wild basil oil LD50,90 at day 5 were 2.8 and 12.3 μg cm-2. Finally, the essential oil and polar extracts were not toxic to E. fetida over the positive control α-cypermethrin. Overall, our study showed that the essential oil of white wild basil is a potential candidate as a functional ingredient in insecticidal formulations to manage agricultural moth pests and insect vectors of public importance.

Exploring the Insecticidal Potential of Boldo (Peumus boldus) Essential Oil: Toxicity to Pests and Vectors and Non-target Impact on the Microcrustacean Daphnia magna.

Every year Chile exports about 2000 tons of boldo folium (Peumus boldus), which is used around the world as a traditional herbal medicinal product (THMP), mostly to relieve gastrointestinal disorders. This biomass may be a resource for the agrochemical industry to manufacture botanical insecticides. In this regard, the insecticidal potential of boldo has been poorly investigated. In the present work, hydrodistillation of a commercial boldo folium gave 1.5% (w/w) of a yellowish essential oil (boldo essential oil, BEO) containing 1,8-cineole (20.7%), p-cymene (18.5%), limonene (9.1%), ascaridole (9.1%) and β-phellandrene (6.4%) as the main constituents, as determined by gas chromatography-mass spectrometry (GC-MS). NMR analysis allowed us to determine that ascaridole was mainly represented by the cis-isomer. BEO was toxic to larvae of the filariasis vector Culex quinquefasciatus and adults of the housefly Musca domestica, showing LC50/LD50 values of 67.9 mg·L−1 and 98.5 µg·adult−1, respectively. On the other hand, lower insecticidal activity was observed against larvae of the moth pest Spodoptera littoralis (LD50 of 268.9 µg·larva−1). It is worth noting that, when tested at LC90 concentration, BEO was significantly less toxic to aquatic microcrustacean Daphnia magna than the conventional insecticide α-cypermethrin. Finally, in the attempt to explore the BEO mode of action, we tested it for acetylcholinesterase (AChE) inhibitory properties using the Ellman method, obtaining negligible effects (IC50 = 0.45 mg·mL−1). Taken together, these results gave new insights into the potential of BEO as a future ingredient of botanical insecticides.

Rationale for developing novel mosquito larvicides based on isofuranodiene microemulsions

Isofuranodiene is a bioactive furanosesquiterpene occurring as the major volatile compound in the essential oil from Smyrnium olusatrum (Apiaceae). It has a notable potentiality to be used as a botanical insecticide. However, its low solubility together with susceptibility to oxidation and thermal degradation limits its application on a wide scale. To face these challenges, isofuranodiene was encapsulated in stable microemulsions (MEs) at two concentrations (ME 750: 0.75%, ME 375: 0.375%). We assessed the larvicidal activity in the short term and after several days of exposure of pure isofuranodiene and its MEs against the filariasis vector Culex quinquefasciatus. The impact of ME-based larvicide at sublethal concentrations on adult emergence was evaluated. Finally, to shed light on potential ecotoxicology risks for nontarget invertebrates, MEs were tested on the aquatic microcrustacean Daphnia magna and on the earthworm Eisenia fetida. Pure isofuranodiene and S. olusatrum leaf essential oil, used as controls, showed their potential as mosquito larvicidal agents (LC50 of 29.2 and 18.6 μL L−1, respectively). Isofuranodiene formulated in ME 750 was effective against C. quinquefasciatus larvae, leading to significant larval mortality over time and a marked decrease in adult emergence. Both isofuranodiene MEs showed little impact on the nontarget aquatic microcrustacean Daphnia magna (ME 750 and ME 375: mortality < 19% after 48 h of exposure at 32 mL L−1 and 20 mL L−1, respectively) as well as on earthworms (ME 750 and ME 375: no mortality and mortality < 7% after 14 days of exposure to 1000 mg kg−1, respectively), outlining their potential employ in vector control operations.

Determinants of transmission hotspots and filarial infection in households after eight rounds of mass drug administration in India.

Lymphatic filariasis (LF) elimination through mass drug administration (MDA) of DEC and albendazole have resulted in very low levels of infection in most endemic districts in India. But small pockets with residual microfilaraemia in the community and antigeneamia in children ('hotspots') are a cause of concern. We aimed to identify the determinants of such transmission hotspots and filarial infection in households using data from 33 communities. The filariasis vector Culex quinquefasciatus was collected from 627 randomly selected households using gravid traps. Parallel data on environmental, entomological, demographical, socio-economical and behavioural factors were analysed to identify the determinants of hotspots and household-level infection. Hotspots and non-hotspots did not differ significantly in terms of socio-economical and behavioural aspects, but did differ in terms of demographical and environmental factors. Logistic regression revealed that tiled and concrete houses increased the risk of an area being a hotspot by 2.0 and 2.9 times respectively. Presence of Culex breeding habitats was significantly associated with elevated risk of being a hotspot. Proximity of U-drains to a house increased the risk of filarial infection 5.8 times. An environment suitable to Culex breeding influences continued transmission despite eight rounds of MDA, particularly in hotspots. Proximity to U-drains increases the risk of infection in households. Implementing localised vector control measures may help interrupt low-level transmission, thereby reducing the risk of resurgence in the absence of MDA.

Not just popular spices! Essential oils from Cuminum cyminum and Pimpinella anisum are toxic to insect pests and vectors without affecting non-target invertebrates

Each year the flavor and fragrance industry produces more than hundred thousand tons of essential oils. An important portion of this production might be directed to the fabrication of green pesticides relying on the well-documented efficacy of many essential oils against insect pests as well as vectors, besides their safety for human health and the environment. In this regard, two popular spices of economic importance, such as cumin (Cuminum cyminum) and anise (Pimpinella anisum), which are not only cheap, readily available, generally recognized as safe (GRAS), but also produces larger amounts of essential oils, are gaining interest for botanical insecticide development. Herein, we evaluated the efficacy of the essential oils obtained from seeds of these two spices on two agricultural pests, i.e., the peach-potato aphid Myzus persicae and the tobacco cutworm Spodoptera littoralis, and on two insect vectors, i.e., the common housefly Musca domestica and the lymphatic filariasis and Zika virus vector Culex quinquefasciatus. Furthermore, their safety on beneficial organisms such as the earthworm Eisenia fetida and the aphid predator Harmonia axyridis was assessed. The two essential oils, characterized by γ-terpinen-7-al (35.3%), cumin aldehyde (21.8%), and α-terpinen-7-al (15.4%), and (E)-anethole (93.0%), respectively, showed noteworthy effects against all pest targets, with anise more effective on larvae of C. quinquefasciatus (LC50 = 25.4 μl L−1) and S. littoralis (LD50 = 57.3 μg larva−1), whereas cumin was more active on adults of M. persicae (LC50 = 3.2 ml L−1) and M. domestica (LD50 = 31.8 μg adult1). Moreover, when compared at sub-lethal concentrations with the commercial insecticide α-cypermethrin, they were definitely devoid of toxic effects on E. fetida and H. axyridis. These results represent a milestone to manufacture and commercialize green formulations to be used in crop protection and to combat insect vectors of public importance.

The essential oil from industrial hemp (Cannabis sativa L.) by-products as an effective tool for insect pest management in organic crops

The inflorescences of industrial hemp (Cannabis sativa L.) represent a consistent by-product that is underutilized. Moving from the concept that this plant part has evolved as a natural weapon against phytophagous insects, secreting important secondary metabolites such as cannabinoids and volatile terpenes, herein we assayed the potential of its essential oil as a botanical insecticide. For the purpose, the essential oil was obtained by fresh inflorescences of hemp (monoecious cv. Felina 32) by steam-distillation and analysed by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC–MS). The oil was tested against the filariasis vector Culex quinquefasciatus, the peach-potato aphid Myzus persicae, the housefly Musca domestica and the tobacco cutworm Spodoptera littoralis. To prove its harmlessness on non-target invertebrates, it was tested on the multicolored Asian lady beetle, Harmonia axyridis, and Eisenia fetida earthworms, and compared with α-cypermethrin as the positive control. The essential oil composition was dominated by monoterpene and sesquiterpene hydrocarbons, with (E)-caryophyllene (45.4%), myrcene (25.0%) and α-pinene (17.9%) as the most abundant compounds. Results from insecticidal tests showed that the essential oil from inflorescences of industrial hemp cv Felina 32 was highly toxic to M. persicae aphids (LC50 of 3.5 mL L−1) and M. domestica flies (43.3 μg adult−1), while toxicity was moderate towards S. littoralis larvae (152.3 μg larva−1), and scarce against C. quinquefasciatus larvae (LC50 of 252.5 mL L−1) and adults (LC50 > 500 μg cm−2). Contrary to α-cypermethrin, the hemp cv Felina 32 essential oil was not toxic to non-target invertebrate species, including 3rd instar larvae and adults of H. axyridis ladybugs and adults of E. fetida earthworms. Taken together our results shed light on the possible utilization of the crop residue of industrial hemp as a source of environmental-friendly botanical insecticides to be used in Integrated Pest Management and organic agriculture, particularly to manage aphid and housefly populations.

Larvicidal Activity of Essential Oils of Five Apiaceae Taxa and Some of Their Main Constituents Against Culex quinquefasciatus.

Apiaceae are aromatic herbs producing essential oils which are used on an industrial scale for various purposes. Notably, Apiaceae essential oils may replace synthetic insecticides keeping most of their efficacy and avoiding environmental pollution and human poisoning. In the present work, we explored the insecticidal potential of the essential oils from five Apiaceae taxa, namely Sison amomum, Echinophora spinosa, Heracleum sphondylium subsp. sphondylium, Heracleum sphondylium subsp. ternatum, and Trachyspemum ammi, as well as their major constituents (sabinene, p-cymene, terpinolene, myristicin, and thymol), against the filariasis vector Culex quinquefasciatus. For the purpose, the essential oils were obtained by hydrodistillation and their composition was achieved by gas chromatography/mass spectrometry (GC/MS). Their acute toxicity on third instar larvae of C. quinquefasciatus was determined. The two most active essential oils were those from T. ammi fruits and E. spinosa roots, showing LC50 below 20 μl/l and LD90 below 50 μl/l. These oils were dominated by the monoterpene phenol thymol and the phenylpropanoid myristicin, respectively, which showed the strongest larvicidal activity (LC50 of 15.1 and 16.3 μl/l, respectively) among the pure compounds tested. These results showed that Apiaceae may be useful as source of larvicidal compounds to be used for the development of cheap, effective and eco-friendly insecticidal formulations.

Efficacy of the Volatile Oil from Water Celery (Helosciadium nodiflorum, Apiaceae) against the Filariasis Vector Culex quinquefasciatus, the Housefly Musca domestica, and the African Cotton Leafworm Spodoptera littoralis.

Water celery (Helosciadium nodiflorum, Apiaceae) is a common and invasive hydrophyte occurring in rivers and slow waters of Europe. In the past, it was consumed as a vegetable and spices, but currently it has mostly been abandoned. As a result, this plant produces an unexploited biomass occluding rivers and slow waters. With the aim to valorise water celery as an important biomass source for the development of botanical insecticides, in this work, we investigated the inhibitory effects of the essential oil hydrodistilled from its aerial parts against larvae of the filariasis vector Culex quinquefasciatus, adults of the housefly Musca domestica, and larvae of the African cotton leafworm Spodoptera littoralis. The essential oil, which was characterized by the insecticidal limonene (39.8%) and myristicin (35.3%), exerted important toxic effects on 3rd instar larvae of C. quinquefasciatus and S. littoralis and on adults of M. domestica, with LD50 of 50.4 μl l-1 , 116.7 μg larva-1 , and 45.1 (male) and 70.1 (female) μg adult-1 , respectively. The oil did not show any noticeable inhibitory activity on the acetylcholinesterase enzyme. Our findings add scientific evidences highlighting water celery as an important biomass source to be used for the control of insect pests and vectors of high economic importance.

Chemical composition and insecticidal activity of the essential oil from Helichrysum faradifani endemic to Madagascar

Helichrysum faradifani (Asteraceae) is a perennial shrub growing in rocky and sandy places of Madagascar. The plant is used in the Malagasy traditional medicine as a wound-healing agent, disinfectant and for the treatment of syphilis, diarrhea, cough and headache. In the present work, we analysed the chemical composition of the essential oil distilled from the aerial parts of H. faradifani by GC-MS and evaluated its insecticidal activity against 2nd, 3rd and 4th instar larvae of the lymphatic filariasis vector Culex quinquefasciatus by acute toxicity assays. The most sensitive were 2nd instar (LC50 = 85.7 μL L−1) larvae. For the 3rd and 4th instar larvae, the estimated LC50 were 156.8 and 134.1 μL L−1, respectively. Monoterpene hydrocarbons (51.6%) were the major fraction of the essential oil, with the bicyclic α-fenchene (35.6%) as the predominant component. Sesquiterpene hydrocarbons (34.0%) were the second major group characterising the oil, with γ-curcumene (17.7%) as the most abundant component.

Size-controlled biofabrication of silver nanoparticles using the Merremia emarginata leaf extract: Toxicity on Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae) and non-target mosquito predators

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 65nm. 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 10.02μg/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 25,153.46μg/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.

Synergized mixtures of Apiaceae essential oils and related plant-borne compounds: Larvicidal effectiveness on the filariasis vector Culex quinquefasciatus Say

The recent outbreaks of mosquito-borne diseases, such as chikungunya and Zika virus, highlighted the pivotal importance of effective mosquito control programs. Nowadays, Culicidae management is being challenging, due to the rapid development of resistance to synthetic pesticides and the spread of highly invasive mosquito vectors worldwide. This research explored the chemical composition of four Apiaceae essential oils (EOs) from Trachyspermum ammi, Smyrnium olusatrum, Pimpinella anisum and Helosciadium nodiflorum and their potential as sources of synergistic binary mixtures with high effectiveness against larvae of the filariasis vector Culex quinquefasciatus. The essential oils were all highly toxic to the larvae, showing LC50 of 17.6, 17.5, 25.9 and 20.6μlL−1, respectively. GC–MS analysis put in evidence thymol, (E)-anethole, myristicin and (Z)-β-ocimene, and isofuranodiene and germacrone as the main essential oil components, respectively. Three effective EOs were selected to prepare binary mixtures. T. ammi+P. anisum (ratio 1:2) and S. olusatrum+P. anisum (ratio 1:1) were the most toxic larvicidal blends, showing LC50 of 15.2 and 16.9, μlL−1, respectively. LT50 values were 45 and 30min, respectively. Notably, short time exposure to both binary mixtures strongly reduced emergence rates, fertility and natality of C. quinquefasciatus that survived after the treatment at the larval stage. Larvicidal assays assessing the acute toxicity of EO main constituents, i.e. germacrone, isofuranodiene and (E)-anethole, were carried out. LC50 were 18.6mgL−1, 33.7mgL−1 and 24.8μlL−1. Overall, our results pointed out the promising potential of these EOs to develop cheap and effective mosquito larvicides, as well as the importance to consider the synergistic effects among the tested botanicals during the design of novel mosquito larvicides.

One-pot and eco-friendly synthesis of silver nanocrystals using Adiantum raddianum: Toxicity against mosquito vectors of medical and veterinary importance

Mosquitoes (Diptera: Culicidae) represent a key threat for millions of humans and animals worldwide, since they act as vectors for devastating parasites and pathogens. Eco-friendly control tools are a priority. Plant-mediated biosynthesis of nanoparticles is rapid and cost-effective. Here we biosynthesized poly-dispersed silver nanocrystals (AgNPs) using a cheap aqueous leaf extract of Adiantum raddianum. AgNPs were characterized by UV–vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction analysis (XRD). The acute toxicity of A. raddianum extract and biosynthesized AgNPs was evaluated against larvae of the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti and the filariasis vector Culex quinquefasciatus. Compared to the leaf aqueous extract, AgNPs showed higher toxicity against An. stephensi, Ae. aegypti and Cx. quinquefasciatus with LC50 values of 10.33, 11.23 and 12.19μg/ml, respectively. Biosynthesized AgNPs were found safer to non-target organisms Diplonychus indicus, Anisops bouvieri and Gambusia affinis, with respective LC50 values ranging from 517.86 to 635.98μg/ml. Overall, this study firstly shed light on the potential of A. raddianum as a potential bio-resource for rapid, cheap and effective nanosynthesis of novel mosquitocides.

One Pot Green Synthesis of Colloidal Silver Nanocrystals Using the Ventilago maderaspatana Leaf Extract: Acute Toxicity on Malaria, Zika Virus and Filariasis Mosquito Vectors

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.