Filariasis Mosquito Vectors Research Articles

Larvicidal potential of Trachyspermum ammi essential oil and Delphinium speciosum extract against malaria, dengue, and filariasis mosquito vectors

Mosquito-borne diseases, such as malaria, dengue, and Zika, pose major public health challenges globally, affecting millions of people. The growing resistance of mosquito populations to synthetic insecticides underscores the critical need for effective and environmentally friendly larvicides. Although chemical pesticides can initially be effective, they often lead to negative environmental consequences and health hazards for non-target species, including humans. This study aimed to evaluate the larvicidal effects of Trachyspermum ammi essential oil and Delphinium speciosum extract on the larvae of three major mosquito species: Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Mosquito larvae of Ae. aegypti, An. stephensi, and Cx. quinquefasciatus were reared under controlled laboratory conditions. The larvicidal activity of T. ammi essential oil and D. speciosum extract was evaluated through standard bioassays, using various concentrations of essential oils (10, 20, 40, 80, and 160 ppm) and extracts (160, 320, 640, 1280, and 2560 ppm) to determine the lethal concentration (LC50) values after 24 h of exposure. Fresh plant materials were collected, with the essential oil extracted via hydro-distillation, and the extract prepared using methanol solvent extraction. The chemical composition of T. ammi essential oil was examined using gas chromatography-mass spectrometry (GC-MS). Additionally, the preliminary analysis of the chemical compounds in D. speciosum extract was carried out using thin layer chromatography (TLC) and nuclear magnetic resonance spectroscopy (NMR) techniques. The results indicated that the essential oil of T. ammi exhibited more effective larvicidal activity compared to the D. speciosum extract. Specifically, the essential oil demonstrated LC50 values of 18 ppm for Cx. quinquefasciatus and 19 ppm for Ae. aegypti. In contrast, the D. speciosum extract showed the strongest larvicidal effect against An. stephensi, with an LC50 of 517 ppm. Concentrations of 40 ppm of the essential oil and 1280 ppm of the extract resulted in 100% mortality across all three species. Both the essential oil of T. ammi and the D. speciosum extract exhibited concentration-dependent larvicidal activity, and these results were statistically significant (p < 0.001) compared to the no-treatment group. GC-MS analysis revealed thymol (88.95%), o-cymen-5-ol (4.11%), and γ-terpinene (2.10%) as the major constituents of the T. ammi essential oil. Additionally, TLC verified the presence of alkaloids in both chloroform and methanolic extracts. Proton NMR identified a diterpene structure for these alkaloids. These findings suggest that T. ammi essential oil is a promising candidate for natural mosquito control strategies. Given its efficacy, further research is warranted to explore its potential in integrated vector management programs.

Nanoliposomes containing limonene and limonene-rich essential oils as novel larvicides against malaria and filariasis mosquito vectors

BackgroundMosquito-borne diseases such as malaria and encephalitis are still the cause of several hundred thousand deaths annually. The excessive use of chemical insecticides for transmission control has led to environmental pollution and widespread resistance in mosquitoes. Botanical insecticides' efficacies improvement has thus received considerable attention recently.MethodsThe larvicidal effects of three essential oils from the Citrus family and limonene (their major ingredient) were first investigated against malaria and filariasis mosquito vectors. An attempt was then made to improve their efficacies by preparing nanoliposomes containing each of them.ResultsThe larvicidal effect of nanoformulated forms was more effective than non-formulated states. Nanoliposomes containing Citrus aurantium essential oil with a particle size of 52 ± 4 nm showed the best larvicidal activity (LC50 and LC90 values) against Anopheles stephensi (6.63 and 12.29 µg/mL) and Culex quinquefasciatus (4.9 and 16.4 µg/mL).ConclusionDue to the green constituents and high efficacy of nanoliposomes containing C. aurantium essential oil, it could be considered for further investigation against other mosquitoes’ populations and field trials.

Deteksi Antibodi dan Antigen Cacing Filaria dan Indeks Entomologi Vektor Potensial Filariasis di Kota Langsa Provinsi Aceh

Humans can be infected with filariasis through mosquito bites with filaria worms in infective larva stage (L3). This study was conducted to detect the antibody, antigen, and the entomology index of potential mosquito vectors of filariasis in Langsa City. This research was conducted in Matang Seulimeng Village and Sungai Paoh Firdaus in Langsa City on November 2016 with 600 respondents. To determine the level of exposure to the infection source, a finger blood survey was conducted with a quick check using the rapid diagnostic test (RDT). RDT used is Brugia test to measure antibodies and ICT (Immuno Chromatographic Test) to measure filaria worm antigens. The existence of potential vectors is measured by entomology index, which are mosquito density, relative abundance, frequency of mosquitoes caught and species dominance. As the result, there were no respondent have been found positive for antibodies or filarial worms antigens in their blood. For the vector data, the potential mosquito vector of filariasis in Langsa City is Culex quinquifasciatus (23%) with peak biting activity at 01.00 02.00 pm.

Insecticidal efficacy of the essential oil of jambú (Acmella oleracea (L.) R.K. Jansen) cultivated in central Italy against filariasis mosquito vectors, houseflies and moth pests

Ethnopharmacological relevanceAcmella oleracea (L.) R.K. Jansen (Compositae), well-known as jambú, is a medicinal herb of pungent taste, native to Brazil but cultivated in different parts of the world due to its aromatic and pharmacological properties. In folk medicine, the plant has been used against parasites and to combat insects and mites. No data are available on the insecticidal activity of jambú essential oil. Aim of the studyTo test the jambú essential oil obtained from A. oleracea cultivated in central Italy against the filariasis vector, Culex quinquefasciatus, the Egyptian cotton worm, Spodoptera littoralis, and the housefly, Musca domestica. Materials and methodsThe chemical composition of the essential oil was achieved by GC-FID and GC-MS analyses. Acute toxicity experiments were conducted on larvae of the filariasis vector C. quinquefasciatus and S. littoralis and adults of M. domestica to determine the LC50(LD50) and LC90(LD90) values of the oil, along with the positive control, α-cypermethrin. Results(E)-caryophyllene (20.8%), β-pinene (17.3%), myrcene (17.1%) and caryophyllene oxide (10.0%) were the major volatile constituents. Interestingly, the oil contained little amounts (3.9%) of the insecticidal spilanthol. Jambú essential oil exerted relevant effects on C. quinquefasciatus (LC50 = 42.2 mg L−1, LC90 = 73.6 mg L−1) and S. littoralis 3rd instar larvae (LD50 = 68.1 µg larva-1, LD90 = 132.1 µg larva-1). High acute toxicity was also detected testing the jambú oil against adult females of M. domestica, achieving a LD50 value of 44.3 µg adult-1 and a LD90 value of 87.5 µg adult-1. ConclusionsTaken together our data support the traditional use of jambú as an insecticidal agent and represent the scientific basis for the industrial exploitation of the essential oil in the fabrication of green insecticides.

Orchids as Sources of Novel Nanoinsecticides? Efficacy of Bacillus sphaericus and Zeuxine gracilis-Fabricated Silver Nanoparticles Against Dengue, Malaria and Filariasis Mosquito Vectors

Mosquitoes are the most critical group of insects in the context of public health, since they transmit key parasites and pathogens, causing millions of deaths annually. Insecticides from natural products may boost the effectiveness of vector control programs. In this study, we tested silver nanoparticles (AgNPs) fabricated using the leaf extract of the orchid Zeuxine gracilis as reducing agent, and the microbial pesticide Bacillus sphaericus, against the mosquitoes Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. The synthesis of AgNP was confirmed analyzing the excitation of surface Plasmon resonance using ultraviolet–visible (UV–Vis) spectrophotometry. SEM and TEM showed the irregular shapes of AgNPs. EDX spectroscopy, FTIR spectroscopy, X-ray diffraction and dynamic light scattering analysis were carried out. AgNPs were highly effective against the larvae of An. stephensi (LC50 = 8.48 µg/mL), Ae. aegypti (LC50 = 10.39 µg/mL) and Cx. quinquefasciatus (LC50 = 13.21 µg/mL), respectively. Combined treatments testing B. sphaericus with AgNPs were also effective against An. stephensi (LC50 = 12.32 µg/mL), Ae. aegypti (LC50 = 14.78 µg/mL) and Cx. quinquefasciatus (LC50 = 19.19 µg/mL). Overall, this study suggests that the orchid-synthesized AgNPs can be a rapid, environmentally safer bio-pesticide to be used in synergy with B. sphaericus to control mosquito vectors.

Acute and sub-lethal toxicity of eight essential oils of commercial interest against the filariasis mosquito Culex quinquefasciatus and the housefly Musca domestica

The massive use of synthetic insecticides led to negative effects on the environment and human health. Therefore, researchers looked at natural products as effective alternatives to conventional pesticides. Here, commercially valuable essential oils (EOs) were selected from mint (Mentha x piperita, Mentha spicata), basil (Ocimum basilicum), helichrysum (Helichrysum italicum), yarrow (Achillea ligustica), geranium (Pelargonium odoratissimum), cinnamon (Cinnamomum verum) and ginger grass (Lippia alba). The chemical composition of these EOs assayed was analyzed by GC–MS. Then, we investigated their insecticidal potential in acute and sub-lethal toxicity assays against mosquito vectors of filariasis (Culex quinquefasciatus) and house flies (Musca domestica). Against C. quinquefasciatus 4th instar larvae, the most toxic EO was C. verum (LC50 = 40.7 μl L−1), followed by L. alba (LC50 = 59.6 μl L−1), while against M. domestica adults, the most toxic EOs were C. verum and H. italicum (LD50 = 42 μg adult−1). The exposure of mosquito larvae to a sub-lethal concentration (LC30 = 25 mg L−1) led to a reduction of adult emergence and fertility. Besides, adult flies that survived after exposure to a sub-lethal dose of C. verum EO (LD20 = 10 μg adult−1) showed a marked decrease in male and female longevity, as well as to a reduction in fecundity, fertility, and natality. Overall, C. verum and H. italicum EOs showed a highly promising insecticidal potential on two key insect vectors and pests. The relatively low prices of the selected EOs, their availability on the market and the noteworthy global production of the bulky materials, make them as ideal candidate ingredients to be used in insecticidal formulations.

Enhanced larvicidal, antibacterial, and photocatalytic efficacy of TiO2 nanohybrids green synthesized using the aqueous leaf extract of Parthenium hysterophorus.

Titanium dioxide nanoparticles are emerging as a biocompatible nanomaterial with multipurpose bioactivities. In this study, titanium dioxide (TiO2) nanoparticles were effectively synthesized using the aqueous leaf extracts of Parthenium hysterophorus prepared by microwave irradiation. TiO2 nanoparticles were fabricated by treating the P. hysterophorus leaf extracts with the TiO4 solution. Biologically active compounds such as alcohols, phenols, alkanes, and fluoroalkanes were involved in bioreduction of TiO4 into TiO2. The formation of green-engineered TiO2 nanoparticles was confirmed by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) spectroscopy and further characterized by X-ray diffraction (XRD) studies. UV-vis spectroscopy analysis showed maximum absorbance at 420nm due to surface plasmon resonance of synthesized TiO2 NPs. FTIR spectrum of the engineered TiO2 NPs showed the presence of bioactive compounds in the leaf extract, which acted as capping and reducing agents. FESEM exhibited an average size of 20-50nm and a spherical shape of TiO2 NPs. EDX analysis indicated the presence of TiO2 NPs by observing the peaks of titanium ions. XRD results pointed out the crystalline nature of engineered TiO2 NPs. The larvicidal activity of TiO2 NPs was studied on fourth instar larvae of dengue, Zika virus, and filariasis mosquito vectors Aedes aegypti and Culex quinquefasciatus. Antimicrobial efficacy of TiO2 NPs was assessed on clinically isolated pathogens Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus vulgaris, and Staphylococcus epidermidis. Besides, we found that TiO2 NPs are able to quickly degrade the industrially harmful pigments methylene blue, methyl orange, crystal violet, and alizarin red dyes under sunlight illumination. Overall, this novel, simple, and eco-friendly approach can be of interest for the control of vector-borne diseases, as well as to formulate new bactericidal agents and to efficiently degrade dye solutions in the polluted areas.

Green and facile biosynthesis of silver nanocomposites using the aqueous extract of Rubus ellipticus leaves: Toxicity and oviposition deterrent activity against Zika virus, malaria and filariasis mosquito vectors

Botanical-based nanosynthesis has been recently reported as a cheap alternative for mosquito management. In this study, we investigated the synthesis of silver nanoparticles (AgNPs) using the leaf extract of Rubus ellipticus and AgNPs were characterized using UV–vis spectroscopy, XRD, FTIR, SEM, TEM and EDX analyses. The toxicity of R. ellipticus leaf extract and AgNPs was evaluated against eggs, larvae and adults of Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. Compared to the leaf aqueous extract, biosynthesized AgNPs showed higher toxicity against the mosquito larvae with LC50 values of 12.50, 13.83 and 15.09μg/mL, respectively. AgNPs exerted zero hatchability at 60, 75 and 90μg/mL on A. stephensi, A. aegypti, and C. quinquefasciatus, respectively. Concentrations of 12–60μg/mL reduced egg laying by gravid females from 72.28 to 91.48%. Maximum adulticidal efficacy was observed for AgNPs, with LD50 values were 21.10, 23.04 and 25.06μg/mL, respectively. AgNPs were found safer to non-target organisms Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 values ranging from 896 to 2261μg/mL. Overall, R. ellipticus-fabricated AgNPs acted as effective toxic agents and ovideterrents against three important mosquitoes species, with little harmful effects on non-target aquatic species.

Evaluation of Silver Nanoparticle Toxicity of Coleus aromaticus Leaf Extracts and its Larvicidal Toxicity against Dengue and Filariasis Vectors

Mosquitoes in the larval stage are attractive targets for pesticides as 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, introduces many risks to people and environment. Natural pesticides, especially those derived from plants, are more promising in this aspect. Plants are rich in secondary metabolites which are an efficient source for natural pesticide. Nanoparticle-conjugated plant extracts increase the botanical of plant extracts and are hence attractive sources for mosquito control. The present study investigates the plant-mediated synthesis of silver nanoparticles using the Coleus aromaticus leaf extracts against dengue and filariasis mosquito vectors. Silver nanoparticle-conjugated plant extracts were characterized by Ultraviolet-Visible spectroscopy, scanning electron microscopy, Energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The size of the silver nanoparticles was 262.7 nm. The larvicidal potential of solvent leaf extracts of Coleus aromaticus and synthesized silver nanoparticles using aqueous leaf extract against fourth instar larvae of Aedes aegypti and Culex quinquefasciatus was assessed. Larvae were exposed to varying concentrations of plant extracts and synthesized AgNPs plant extracts post 24 h; mosquito larvae showed maximum mortality in leaf extracts synthesized AgNPs against the fourth instars larvae of Ae. aegypti and Cx. quinquefasciatus. These results suggest that the synthesized AgNPs from leaf extracts have a higher larvicidal potential as compared to crude solvent extracts thus making them an effective combination for controlling dengue and filariasis vectors.

Chemical composition, toxicity and non-target effects of Pinus kesiya essential oil: An eco-friendly and novel larvicide against malaria, dengue and lymphatic filariasis mosquito vectors

Mosquitoes (Diptera: Culicidae) are vectors of important parasites and pathogens causing death, poverty and social disability worldwide, with special reference to tropical and subtropical countries. The overuse of synthetic insecticides to control mosquito vectors lead to resistance, adverse environmental effects and high operational costs. Therefore, the development of eco-friendly control tools is an important public health challenge. In this study, the mosquito larvicidal activity of Pinus kesiya leaf essential oil (EO) was evaluated against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti and the lymphatic filariasis vector Culex quinquefasciatus. The chemical composition of the EO was analyzed by gas chromatography–mass spectroscopy. GC–MS revealed that the P. kesiya EO contained 18 compounds. Major constituents were α-pinene, β-pinene, myrcene and germacrene D. In acute toxicity assays, the EO showed significant toxicity against early third-stage larvae of An. stephensi, Ae. aegypti and Cx. quinquefasciatus, with LC50 values of 52, 57, and 62µg/ml, respectively. Notably, the EO was safer towards several aquatic non-target organisms Anisops bouvieri, Diplonychus indicus and Gambusia affinis, with LC50 values ranging from 4135 to 8390µg/ml. Overall, this research adds basic knowledge to develop newer and safer natural larvicides from Pinaceae plants against malaria, dengue and filariasis mosquito vectors.

Larvicidal and repellent potential of Zingiber nimmonii (J. Graham) Dalzell (Zingiberaceae) essential oil: an eco-friendly tool against malaria, dengue, and lymphatic filariasis mosquito vectors?

Mosquitoes (Diptera: Culicidae) are important vectors of terms of public health relevance, especially in tropical and sub-tropical regions. The continuous and indiscriminate use of conventional pesticides for the control of mosquito vectors has resulted in the development of resistance and negative impacts on non-target organisms and the environment. Therefore, there is a need for development of effective mosquito control tools. In this study, the larvicidal and repellent activity of Zingiber nimmonii rhizome essential oil (EO) was evaluated against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti, and the lymphatic filariasis vector Culex quinquefasciatus. The chemical composition of the EO was analyzed by gas chromatography-mass spectroscopy (GC-MS). GC-MS revealed that the Z. nimmonii EO contained at least 33 compounds. Major constituents were myrcene, β-caryophyllene, α-humulene, and α-cadinol. In acute toxicity assays, the EO showed significant toxicity against early third-stage larvae of An. stephensi, Ae. aegypti, and Cx. quinquefasciatus, with LC50 values of 41.19, 44.46, and 48.26μg/ml, respectively. Repellency bioassays at 1.0, 2.0, and 5.0mg/cm(2) of Z. nimmonii EO gave 100% protection up to 120, 150, and 180min. against An. stephensi, followed by Ae. aegypti (90, 120, and 150min) and Cx. quinquefasciatus (60, 90, and 120min). Furthermore, the EO was safer towards two non-target aquatic organisms, Diplonychus indicus and Gambusia affinis, with LC50 values of 3241.53 and 9250.12μg/ml, respectively. Overall, this research adds basic knowledge to develop newer and safer natural larvicides and repellent from Zingiberaceae plants against malaria, dengue, and filariasis mosquito vectors.

Screening Mosquito House Entry Points as a Potential Method for Integrated Control of Endophagic Filariasis, Arbovirus and Malaria Vectors

BackgroundPartial mosquito-proofing of houses with screens and ceilings has the potential to reduce indoor densities of malaria mosquitoes. We wish to measure whether it will also reduce indoor densities of vectors of neglected tropical diseases.MethodologyThe main house entry points preferred by anopheline and culicine vectors were determined through controlled experiments using specially designed experimental huts and village houses in Lupiro village, southern Tanzania. The benefit of screening different entry points (eaves, windows and doors) using PVC-coated fibre glass netting material in terms of reduced indoor densities of mosquitoes was evaluated compared to the control.Findings23,027 mosquitoes were caught with CDC light traps; 77.9% (17,929) were Anopheles gambiae sensu lato, of which 66.2% were An. arabiensis and 33.8% An. gambiae sensu stricto. The remainder comprised 0.2% (50) An. funestus, 10.2% (2359) Culex spp. and 11.6% (2664) Mansonia spp. Screening eaves reduced densities of Anopheles gambiae s. l. (Relative ratio (RR) = 0.91; 95% CI = 0.84, 0.98; P = 0.01); Mansonia africana (RR = 0.43; 95% CI = 0.26, 0.76; P<0.001) and Mansonia uniformis (RR = 0.37; 95% CI = 0.25, 0.56; P<0.001) but not Culex quinquefasciatus, Cx. univittatus or Cx. theileri. Numbers of these species were reduced by screening windows and doors but this was not significant.SignificanceThis study confirms that across Africa, screening eaves protects households against important mosquito vectors of filariasis, Rift Valley Fever and O'Nyong nyong as well as malaria. While full house screening is required to exclude Culex species mosquitoes, screening of eaves alone or fitting ceilings has considerable potential for integrated control of other vectors of filariasis, arbovirus and malaria.

Recombinant bacteria for mosquito control.

Bacterial insecticides have been used for the control of nuisance and vector mosquitoes for more than two decades. Nevertheless, due primarily to their high cost and often only moderate efficacy, these insecticides remain of limited use in tropical countries where mosquito-borne diseases are prevalent. Recently, however, recombinant DNA techniques have been used to improve bacterial insecticide efficacy by markedly increasing the synthesis of mosquitocidal proteins and by enabling new endotoxin combinations from different bacteria to be produced within single strains. These new strains combine mosquitocidal Cry and Cyt proteins of Bacillus thuringiensis with the binary toxin of Bacillus sphaericus, improving efficacy against Culex species by 10-fold and greatly reducing the potential for resistance through the presence of Cyt1A. Moreover, although intensive use of B. sphaericus against Culex populations in the field can result in high levels of resistance, most of this can be suppressed by combining this bacterial species with Cyt1A; the latter enables the binary toxin of this species to enter midgut epithelial cells via the microvillar membrane in the absence of a midgut receptor. The availability of these novel strains and newly discovered mosquitocidal proteins, such as the Mtx toxins of B. sphaericus, offers the potential for constructing a range of recombinant bacterial insecticides for more effective control of the mosquito vectors of filariasis, Dengue fever and malaria.

Non-filarial elephantiasis in the Mt. Elgon area (Kapchorwa District) of Uganda

Following reports of a high frequency of elephantiasis in Kwen County (Kapchorwa District) on the slopes of Mt. Elgon in Uganda, a baseline survey for lymphatic filariasis was carried out in three villages in the affected area. Individuals aged 1 year and above were examined for chronic manifestations of lymphatic filariasis, and for specific circulating filarial antigens and microfilariae of Wuchereria bancrofti. Elephantiasis was observed in all age groups from 10 years and above. The overall prevalence was 4.5%, and the prevalence among individuals aged ≥20 years was 8.2%. Males and females were equally affected. However, there were only few cases of hydrocele (overall prevalence in males of 1.0%) and blood examinations were negative for W. bancrofti circulating antigens and microfilariae. Sampling of potential filariasis mosquito vectors revealed low densities of Anopheles gambiae s.l. and An. funestus, and none of these were infected with filarial larvae. In view of the low hydrocele to elephantiasis ratio, the absence of filarial infection in humans and mosquitoes, the high altitude (1500–2200 m above sea level) and the volcanic soil type, it is concluded that elephantiasis seen in this area is not of filarial origin but most likely is due to podoconiosis (endemic non-filarial elephantiasis).

鹿兒島に於ける「フイラリア」傳播蚊の種類(第 3 回大會講演要旨 I)

鹿兒島に於ける「フイラリア」傳播蚊の種類(第 3 回大會講演要旨 I)