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In the present investigation, the effective root compound of plumbagin of Plumbago zeylanica (Plumbaginaceae) was evaluated for chemical constituent and antimalarial effect against the fourth instar larvae of Anopheles stephensi Liston (Diptera). In the chromatographic analyses of root compound with Rf value of 0.788 and NMR analyses also revealed that the effective compound contain naphthoquinone plumbagin were identified as the major chemical constituent. Larval mortality was observed after 3 h of exposure period. The plumbagin compound showed remarkable larvicidal activity against A. stephensi (LC 32.65 and LC72.27 ppm). Histopathological effects of compound was observed in the treated larvae. Based on the results, the plumbagin compound of P. zeylanica can be considered as a new source of natural larvicide for the control of malarial vector. [ABSTRACT FROM AUTHOR]

In a search for natural products that could be used to control the vectors of tropical diseases, extracts of medicinal plants Plumbago zeylanica and Cestrum nocturnum have been tested for larvicidal activity against second, third, and fourth instar larvae of Aedes aegypti. The LC values of all the extracts in different solvents of both the plants were less than 50 ppm (15.40-38.50 ppm) against all tested larval instars. Plant extracts also affected the life cycle of A. aegypti by inhibition of pupal development and adult emergence with increasing concentrations. The larvicidal stability of the extracts at five constant temperatures (19°C, 22°C, 25°C, 28°C, and 31°C) evaluated against fourth instar larvae revealed that toxicity of both plant extracts increases with increase in temperature. Toxicity studies carried out against fish species Poecilia reticulata, the most common nontarget organism in the habitats of A. aegypti, showed almost nil to meager toxicity at LC and LC doses of the plant extracts. The qualitative analysis of crude extracts of P. Zeylanica and C. nocturnum revealed the presence of bioactive phytochemicals with predominance of plumbagin in P. zeylanica and saponins in C. nocturnum. Partially purified plumbagin from P. zeylanica and saponins from C. nocturnum were obtained, and their presence was confirmed by thin-layer chromatography and biochemical tests. The bioassay experiment of partially purified secondary metabolites showed potent mosquito larvicidal activity against the fourth instar larval form. Therefore, this study explored the safer and effective potential of plant extracts against vector responsible for diseases of public health importance. [ABSTRACT FROM AUTHOR]

Malaria is one of the world's leading killer infectious diseases with high incidence and morbidity. The problem of multidrug-resistant Plasmodium falciparum has been aggravating particularly in Southeast Asia. Therefore, development of new potential antimalarial drugs is urgently required. The present study aimed to investigate antimalarial activities of a total of 27 medicinal plants and 5 herbal formulations used in Thai traditional medicine against chloroquine-resistant (K1) and chloroquine-sensitive (3D7) P. falciparum clones. Antimalarial activity of the ethanolic extracts of all plants/herbal formulations against K1 and 3D7 P. falciparum clones was assessed using SYBR Green I-based assay. All plants were initially screened at the concentration of 50 μg/ml to select the candidate plants that inhibited malaria growth by ≥50 %. Each candidate plant was further assessed for the IC value (concentration that inhibits malaria growth by 50 %) to select the potential plants. Selectivity index (SI) of each extract was determined from the IC ratio obtained from human renal epithelial cell and K1 or 3D7 P. falciparum clone. The ethanolic extracts from 19 medicinal plants/herbal formulation exhibited promising activity against both K1 and 3D7 clones of P. falciparum with survival of less than 50 % at the concentration of 50 μg/ml. Among these, the extracts from the eight medicinal plants ( Plumbago indica Linn., Garcinia mangostana Linn., Dracaena loureiri Gagnep., Dioscorea membranacea Pierre., Artemisia annua Linn., Piper chaba Hunt., Myristica fragrans Houtt., Kaempferia galanga Linn.) and two herbal formulations (Benjakul Formulation 1 and Pra-Sa-Prao-Yhai Formulation) showed potent antimalarial activity with median range IC values of less than 10 μg/ml against K1 or 3D7 P. falciparum clone or both. All except G. mangostana Linn. and A. annua Linn. showed high selective antimalarial activity against both clones with SI > 10. Further studies on antimalarial activities in an animal model including molecular mechanisms of action of the isolated active moieties are required. [ABSTRACT FROM AUTHOR]

Current treatment guidelines for leishmaniasis is based on chemotherapy with drugs that show a set of limitations such as high cost, toxicity, difficult route of administration, and lack of efficacy in endemic areas. In this context, phytopharmaceutical products and herbal medicines emerge as promising alternatives for developing new treatment against leishmaniasis. This review discusses the perspectives of leishmaniasis treatment based on natural products and phytotherapy highlighting the Piper genus, especially P. aduncun and P. mollicomum Kunth covering the period of 1998 to 2020. Leishmanicidal activity of pure compounds of Piper spp. [3-(3,4,5-trimethoxyphenyl) propanoic acid, 3-chlorosintenpyridone, 2′-hydroxy-3′,4′,6′-trimethoxy-chalcone, cardamonin, conocarpan, cubebin, eupomatenoid, flavokavain B, (+)-(7R,8S)-epoxy-5,6-didehydrokavain, N-[7-(3′,4′-methylenedioxypheny l-2(E),4(E)-heptadienoyl-pyrrolidine, N-[7-(3′,4′-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl-pyrrolidine, piperovatine, pellitorine, and piplartine (piperlongumine)] were proved against the promastigote and amastigote forms of parasite related with cutaneous (L. (L.) amazonensis, L. (V.) braziliensis, and L. (V.) guyanensis) and visceral (L. (L.) donovani, L. (L.) chagasi, and L. (L.) infantum). We also discussed the perspective of leishmaniasis treatment, considering the potential synergism between different promising species of Piper, presenting some interesting interaction possibilities for future studies between plants. Finally, the necessary steps for technological development of phytomedicines and herbal medicines with the desirable quality requirements for medicines are highlighted. The data presented here highlight the use of Piper spp. as source of pharmacological compounds that can lead to effective, safe, and inexpensive treatments for leishmaniasis. [ABSTRACT FROM AUTHOR]

Leishmaniasis are neglected diseases and a public health problem; they are caused by protozoan species belonging to the genus Leishmania and mostly influences the poor populations in many developing countries. The lack of effective medications, and an approved vaccine, high toxicity and life-threatening side effects and many cases of drug resistance reported in different countries have resulted in the necessity to discover new, efficient, inexpensive, and safe antileishmanial compounds with less or no toxicity. This increase in consumer demand of natural herbal-derived plant extracts as alternative medicines continues despite the low scientific information to establish their efficacy and safety profiles. Various studies have been conducted so far concerning the application of herbal medicines for the treatment of leishmaniasis, but research on relatively effective and low toxic substances is still needed. In this review, we have summarized recent developments and reported studies concerning about herbal and naturally derived therapeutics in the treatment of leishmaniasis, conducted by several researchers worldwide. Some of these medical herbs with promising results have undergone prospective clinical researches, but many others have either not yet been explored. Recent articles described these medical herbs and their active and important molecules, including quinones, phenolic derivatives, lignans, tannins, terpenes, and oxylipins. We searched ISI Web of Science, PubMed, SID, Scholar, Scopus, and Science Direct, and articles published up to 2019 were included. The keywords of leishmaniasis and some words associated with herbal medicines and natural products were used in our search. This review can serve as a quick reference database for researchers. [ABSTRACT FROM AUTHOR]

The leaves of Piper nigrum L. ( Piperaceae) were evaluated for chemical constituents and mosquito larvicidal activity against the larvae of Aedes aegypti. GC and GC-MS analyses revealed that the crude extracts contain 16 compounds. Thymol (20.77 %) and ç-elemene (10.42 %) were identified as the major constituents followed by cyclohexene, 4-ethenyl-4-methyl-3-(1-methylethenyl)-1-(1 methylethyl)-, (3R-trans) (7.58 %), 4,6-octadienoic acid, 2-acetyl-2-methyl-, ethyl ester (6.98), 2(3H)-furanone, 3,4-bis(1,3-benzodioxol-5-ylmethyl) dihydro-, (3R-trans) (6.95 %), 1-naphthalenol, 1,2,3,4,4a,7,8,8a-octahydro-1,6-dimethyl-4-(1-methylethyl)-, [1R-(1à,4á,4aá,8aá)]-(Cedreanol) (5.30 %), trans-2-undecen-1-ol (4.48 %), phytol (4.22 %), 1,6-cyclodecadiene, 1-methyl-5-methylene-8-(1-methylethyl)-,[s-(E,E)] (3.78 %) and 2,6-dimethyl-3,5,7-octatriene-2-ol, Z,Z (2.39 %). Larval mortality was observed after 3 h of exposure period. The crude extract showed remarkable larvicidal activity against Ae. aegypti (LC = 34.97). The larvae of Ae. aegypti exposed to the P. nigrum, significantly reduced the activities of α- and β-carboxylesterases and superdioxide. Further, P. nigrum extract was severely affecting the mosquito gut cellular organelles. Based on the results, the chemical constituents of crude extracts of P. nigrum can be considered as a new source of larvicide for the control of Ae. aegypti. [ABSTRACT FROM AUTHOR]

The cytochrome P450 monooxygenases play a major role in insecticide detoxification and become a target for development of insecticide synergists. In this study, a collection of rhinacanthins (rhinacanthin-D, -E, -G, -N, -Q, and -H/I) purified from Rhinacanthus nasutus, in addition to previously purified rhinacanthin-B and -C, were isolated. These compounds displayed various degrees of inhibition against benzyloxyresorufin- O-debenzylation mediated by CYP6AA3 and CYP6P7 which were implicated in pyrethroid resistance in Anopheles minimus malaria vector. Inhibition modes and kinetics were determined for each of rhinacanthins. Cell-based inhibition assays by rhinacanthins employing 3-(4, 5-dimethylthiazol-2-y-l)-2, 5-diphenyltetrazolium bromide (MTT) cytotoxicity test were explored their synergistic effects with cypermethrin toxicity on CYP6AA3- and CYP6P7-expressing Spodoptera frugiperda (Sf9) cells. Rhinacanthin-B, -D, -E, -G, and -N exhibited mechanism-based inhibition against CYP6AA3, an indication of irreversible inhibition, while rhinacanthin-B, -D, -G, and -N were mechanism-based inhibitors of CYP6P7. There was structure-function relationship of these rhinacanthins in inhibition effects against both enzymes. In vitro enzymatic inhibition assays revealed that there were synergistic interactions among rhinacanthins, except rhinacanthin-B and -Q, in inhibition against both enzymes. These rhinacanthins exerted synergism with cypermethrin toxicity on Sf9 cells expressing each of the two P450 enzymes via P450 inhibition and in addition could interact in synergy to further increase cypermethrin toxicity. The inhibition potentials, synergy among rhinacanthins in inhibition against the P450 detoxification enzymes, and synergism with cypermethrin toxicity of the R. nasutus constituents of reported herein could be beneficial to implement effective resistance management of mosquito vector control. [ABSTRACT FROM AUTHOR]

Dengue fever, currently the most important arbovirus, is transmitted by the bite of the Aedes aegypti mosquito. Given the absence of a prophylactic vaccine, the disease can only be controlled by combating the vector insect. However, increasing reports of resistance and environmental damage caused by insecticides have led to the urgent search for new safer alternatives. In this regard, plants stand out as a source of easy-to-obtain biodegradable insecticide molecules. Twenty (20) plant seed extracts from the Caatinga, an exclusively Brazilian biome, were prepared. Sodium phosphate (50 mM, pH 8.0) was used as extractor. The extracts were used in bioassays and submitted to partial characterisation. A Probit analysis of insecticides was carried out, and intergroup differences were verified by the Student's t test and ANOVA. All the extracts exhibited larvicidal and ovipositional deterrence activity. The extracts of Amburana cearenses, Piptadenia viridiflora, Erythrina velutina, Myracrodruon urundeuva and Schinopsis brasiliensis were also pupicides, while the extracts of P. viridiflora, E. velutina, A. cearenses, Anadenanthera colubrina, Diocleia grandiflora, Bauhinia cheilantha, Senna spectabilis, Caesalpinia pyramidalis, Mimosa regnelli and Genipa americana displayed adulticidal activity. Egg laying was compromised when females were fed extracts of Ricinus communis, Croton sonderianus and S. brasiliensis. At least two proteins with insecticidal activity were found in all the extracts. Phenol compounds were identified in all the extracts and flavonoids, triterpenes or alkaloids in 14 of them. The results show the potential of plant seed extracts from the Caatinga as a source of active molecules against A. aegypti mosquitos. [ABSTRACT FROM AUTHOR]

Seaweeds are one of the most widely studied natural resources for their biological activities. Novel seaweed compounds with unique chemical structures have been reported for their pharmacological properties. The urge to search for novel insecticidal compound with a new mode of action for development of botanical insecticides supports the relevant scientific research on discovering the bioactive compounds in seaweeds. The mosquitocidal potential of seaweed extracts and their isolated compounds are documented in this review paper, along with the discussion on bioactivities of the major components of seaweeds such as polysaccharides, phenolics, proteins, terpenes, lipids, and halogenated compounds. The effects of seaweed extracts and compounds toward different life stages of mosquito (egg, larva, pupa, and adult), its growth, development, and reproduction are elaborated. The structure-activity relationships of mosquitocidal compounds are discussed to extrapolate the possible chemical characteristics of seaweed compounds responsible for insecticidal properties. Furthermore, the possible target sites and mode of actions of the mosquitocidal seaweed compounds are included in this paper. The potential synergistic effects between seaweeds and commercial insecticides as well as the toxic effects of seaweed extracts and compounds toward other insects and non-target organisms in the same habitat are also described. On top of that, various factors that influence the mosquitocidal potential of seaweeds, such as abiotic and biotic variables, sample preparation, test procedures, and considerations for a precise experimental design are discussed. The potential of active seaweed extracts and compounds in the development of effective bioinsecticide are also discussed. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the activity of pacharin isolated from the ethanol extract from roots of Bauhinia acuruana on third-instar larvae of Aedes aegypti Linn. (Diptera: Culicidae). The crude ethanol extract showed larvicidal activity at the concentration of 500 μg/mL. Given this larvicidal activity, this extract was submitted to chromatographic fractionation on a silica gel column eluted with n-hexane, dichloromethane, ethyl ether, ethyl acetate, and methanol in order to isolate the active compound(s). Pacharin, obtained in pure form from fraction eluted with ethyl ether, was evaluated for their larvicidal effects against A. aegypti. In these bioassays, the larvae were exposed at concentrations of 500, 250, 100, 50, and 25 μg/mL of the crude ethanol extract or pacharin. After 24 h, the number of dead larvae was counted and the LC values for larval mortality were calculated. Pacharin showed LC value of 78.9 ± 1.8 μg/mL. The structure of isolated compound was identified on the basis of their spectral data (IR, 1D- and 2D-NMR) and by comparison with literature spectral data. The results indicate pacharin as a potential natural larvicide. [ABSTRACT FROM AUTHOR]

Mosquitoes are the carriers of severe and well-known illnesses such as malaria, arboviral encephalitis, dengue fever, chikunguniya fever, West Nile virus and yellow fever. These diseases produce significant morbidity and mortality in humans and livestock around the world. The present study explored the effects of orange peel ethanol extract of Citrus sinensis on larvicidal, pupicidal, repellent and adulticidal activity against Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. The orange peel material was shade dried at room temperature and powdered coarsely. From orange peel, 300 g powdered was macerated with 1 L of ethanol sequentially for a period of 72 h each and filtered. The yields of the orange peel ethanol crude extract of C. sinensis 13.86 g, respectively. The extracts were concentrated at reduced temperature on a rotary vacuum evaporator and stored at a temperature of 4 °C. The larvicidal, pupicidal and adult mortality was observed after 24 h of exposure; no mortality was observed in the control group. For C. sinensis, the median lethal concentration values (LC) observed for the larvicidal and pupicidal activities against mosquito vector species A. stephensi first to fourth larval instars and pupae were 182.24, 227.93, 291.69, 398.00 and 490.84 ppm; A. aegypti values were 92.27, 106.60, 204.87, 264.26, 342.45, 436.93 and 497.41 ppm; and C. quinquefasciatus values were 244.70, 324.04, 385.32, 452.78 and 530.97 ppm, respectively. The results of maximum repellent activity were observed at 450 ppm in ethanol extracts of C. sinensis and the mean complete protection time ranged from 150 to 180 min was tested. The ethanol extract of C. sinensis showed 100 % repellency in 150 min and showed complete protection in 90 min at 350 ppm against A. stephensi, A. aegypti and C. quinquefasciatus, respectively. The adult mortality was found in ethanol extract of C. sinensis with the LC and LC values of 272.19 and 457.14 ppm, A. stephensi; 289.62 and 494.88 ppm, A. aegypti; and 320.38 and 524.57 ppm, respectively. These results suggest that the orange peel extracts of C. sinensis have the potential to be used as an ideal eco-friendly approach for the control of the vector control programmes. [ABSTRACT FROM AUTHOR]

In recent years, uses of environment friendly and biodegradable natural insecticides of plant origin have received renewed attention as agents for vector control. During a screening program for new agrochemicals from Chinese medicinal herbs and local wild plants, the ethanol extract of Evodia rutaecarpa Hook f. et Thomas (Rutaceae) unripe fruits was found to possess larvicidal activity against the mosquitoes. The aim of this research was to determine larvicidal activity of the ethanol extract of E. rutaecarpa unripe fruits and the isolated constituents against the larvae of the Culicidae mosquito Aedes albopictus. The powder, 5 kg of the fruit material, was extracted with 30 l of 95 % ethanol, filtered, and evaporated to dryness in a rotary vacuum evaporator. The crude extract was then partitioned between methanol-water and n-hexane. The n-hexane fraction was evaporated off to given n-hexane extract. The aqueous layer was repartitioned with chloroform to provide chloroform extract after evaporation of the solvent. Further partitioning with ethyl acetate gave a residue after evaporation of the solvent. Bioactivity-directed chromatographic separation of chloroform extract on repeated silica gel columns led to the isolation of three alkaloids (evodiamine, rutaecarpine, and wuchuyuamide I) and two limonoids (evodol and limonin). The structures of the constituent compounds were elucidated based on high-resolution electron impact mass spectrometry and nuclear magnetic resonance. Evodiamine, rutaecarpine, and wuchuyuamide I exhibited strong larvicidal activity against the early fourth instar larvae of A. albopictus with LC values of 12.51, 17.02, and 26.16 μg/ml, respectively. Limonin and evodol also possessed larvicidal activity against the Asian tiger mosquitoes with LC values of 32.43 and 52.22 μg/ml, respectively, while the ethanol extract had a LC value of 43.21 μg/ml. The results indicated that the ethanol extract of E. rutaecarpa and the five isolated constituents have a good potential as a source for natural larvicides. [ABSTRACT FROM AUTHOR]

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 and LC values for first, second, third, and fourth instars of synthesized AgNPs-treated first, second, third, and fourth instars of A. aegypti (LC = 4.39, 5.12, 5.66, 6.18; LC = 9.90, 11.13, 12.40, 12.95 ppm) and A. stephensi (LC = 4.41, 5.35, 5.91, 6.47; LC = 10.10, 12.04, 13.05, 14.08 ppm) were found many fold lower than crude latex-treated A. aegypti (LC = 55.13, 58.81, 75.66, 94.31; LC = 113.00, 118.25, 156.95, 175.71 ppm) and A. stephensi (LC = 81.47, 92.09, 96.07, 101.31; LC = 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 and LC 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. [ABSTRACT FROM AUTHOR]

Calotropis gigantea leaf extract and Bacillus thuringiensis were tested first to fourth-instar larvae and pupae of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The medicinal plants were collected from the area around Bharathiar University, Coimbatore, India. Calotropis gigantea leaf was washed with tap water and shade-dried at room temperature. An electrical blender powdered the dried plant materials (leaves). The powder 500 g of the leaf was extracted with 1.5 L of organic solvents of methanol for 8 h using a Soxhlet apparatus and filtered. The crude leaf extracts were evaporated to dryness in a rotary vacuum evaporator. The plant extract showed larvicidal and pupicidal effects after 24 h of exposure; no mortality was observed in the control group. For Calotropis gigantea, the median lethal concentration values (LC) observed for the larvicidal and pupicidal activities against mosquito vector species Anopheles stephensi I to IV larval instars and pupae were 73.77, 89.64, 121.69, 155.49, and 213.79 ppm; Aedes aegypti values were 92.27, 106.60, 136.48, 164.01, and 202.56 ppm; and Culex quinquefasciatus values were 104.66, 127.71, 173.75, 251.65, and 314.70 ppm, respectively. For B. thuringiensis, the LC values of I to IV larval instars and pupae of Anopheles stephensi were 37.24, 45.41, 57.82, 80.09, and 98.34 ppm; Aedes aegypti values were 42.38, 51.90, 71.02, 96.17, and 121.59 ppm; and Culex quinquefasciatus values were 55.85, 68.07, 94.11, 113.35, and 133.87 ppm, respectively. The study proved that the methanol leaf extract of Calotropis gigantea and bacterial insecticide B. thuringiensis has mosquitocidal property and was evaluated as target species of mosquito vectors. This is an ideal ecofriendly approach for the control of vector control programs. [ABSTRACT FROM AUTHOR]

In the present study activity of silver nanoparticles (AgNPs) synthesized using Plumeria rubra plant latex against second and fourth larval instar of Aedes aegypti and Anopheles stephensi was determined. Range of concentrations of synthesized AgNps (10, 5, 2.5, 1.25, 0.625, 0.3125 ppm) and aqueous crude latex (1,000, 500, 250, 125, 62.50, 31.25 ppm) were tested against larvae of A. aegypti and A. Stephensi. The synthesized AgNps from P. rubra latex were highly toxic than crude latex extract in both mosquito species. The LC values for second and fourth larval instars after 24 h of crude latex exposure were 1.49, 1.82 ppm against A. aegypti and 1.10, 1.74 ppm against A. stephensi respectively. These figures were 181.67, 287.49 ppm against A. aegypti and 143.69, 170.58 ppm against A. stephensi respectively for crude latex extract. The mortality rates were positively correlated with the concentration of AgNPs. The characterization studies of synthesized AgNPs by UV-Vis spectrophotometry, transmission electron microscopy (TEM), Particle size analysis (PSA) and zeta potential confirmed the spherical shape and size (32-200 nm) of silver nanoparticles alongwith stability. Toxicity studies carried out against non-target fish species Poecilia reticulata, the most common organism in the habitats of A. aegypti and A. stephensi showed no toxicity at LC and LC doses of the AgNPs. This is the first report on mosquito larvicidal activity of latex synthesized nanoparticles. [ABSTRACT FROM AUTHOR]

The tremendous worldwide efforts to isolate novel mosquito larvicidal bacteria with improved efficacy present significant promise to control vector-borne diseases of public health importance. In the present study, two native bacterial isolates, Bacillus thuringiensis (Bt SV2) and Serratia species (SV6) were evaluated for mosquito larvicidal potential against the early fourth instar larvae of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus with reference to B. thuringiensis subsp. israelensis (Bti) H 14. The native Gram-positive, spore-forming Bt SV2 isolate showed 100% mortality against early fourth instars of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus, in parallel to Bti H14 strain. After 24 h, Bt SV2 showed 98%, 89%, and 80.67%, and Bti H14 showed 92%, 98.33%, and 60% mortality against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus, respectively. Serratia SV6 showed highest activity against Culex quinquefasciatus (100%) followed by Anopheles stephensi (95%) and Aedes aegypti (91%) after 48 h of exposure. The Gram-negative Serratia SV6 showed delayed toxicity compared to Bti H14 and Bt SV2 against early fourth instars of Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. The relative mortality of all treatments after 12-h exposures showed the varied toxicity with respect to exposure time, bacterial treatment, and mosquito species. Genetic relatedness of the strains was confirmed on the basis of phylogenetic reconstructions based on alignment of 16S rRNA gene sequences which indicated a strong clustering of the strain SV2 with B. thuringiensis and the strain SV6 with Serratia nematodiphila. In conclusion, the native isolate B. thuringiensis SV2 showed significant toxicity while Serratia SV6 showed less and delayed toxicity against several mosquito species compared with BtiH14. They may be used as novel bacterial insecticidal agents in mosquito vector-borne disease control. To our knowledge, this is the first report on mosquito larvicidal potential of Serratia species. [ABSTRACT FROM AUTHOR]

The larvicidal activity of crude petroleum ether, ethyl acetate, and methanol extracts of the whole plants of Phryma leptostachya L. was assayed for its toxicity against the early fourth instar larvae of Culex pipiens pallens. The larval mortality was observed after 24 h of exposure. Among three solvent extracts from Phyrma leptostachya L., the petroleum ether extract exhibited the best larvicidal activity. The corresponding LC values of petroleum ether, ethyl acetate, and methanol extracts were 3.23, 5.23, and 61.86 ppm against the early fourth instar larvae of Culex pipiens pallens. The petroleum ether extract was successively subjected to column chromatography and preparative high performance liquid chromatography, and yielded the three lignans, phrymarolin-I, haedoxane A, and haedoxane E, which were isolated and identified as new mosquito larvicidal compounds. Phrymarolin-I, haedoxane A, and haedoxane E showed high larvicidal activity, for which the lethal doses LC were estimated at 1.21, 0.025, and 0.15 ppm against the early fourth instar larvae of Culex pipiens pallens, respectively. The structures were elucidated by analyses of IR, UV, MS, and NMR spectral data. This is the first report on the mosquito larvicidal activity of the three compounds, phrymarolin-I, haedoxane A, and haedoxane E from Phyrma leptostachya L. [ABSTRACT FROM AUTHOR]

Oils of Carapa guianensis and Copaifera spp. are well known in the Amazonian region as natural insect repellent, and studies have reported their efficiency as larvicide against some laboratory mosquito species. However, in wild populations of mosquitoes, these oils have not yet been evaluated. Thus, the objective of this study was to investigate their efficiency as larvicide in wild populations of Aedes aegypti with a history of exposure to organophosphate. The susceptibility of larvae was determined under three different temperatures, 15°C, 20°C, and 30°C. For each test, 1,000 larvae were used (late third instar and early fourth instar-four replicates of 25 larvae per concentration). Statistical tests were used to identify significant differences. The results demonstrated that as the laboratory A. aegypti, the wild populations of A. aegypti were also susceptible to C. guianensis and Copaifera sp. oils. The lethal concentrations for Copaifera sp. ranged from LC 47 to LC 91 (milligrams per liter), and for C. guianensis, they were LC 136 to LC 551 (milligrams per liter). In relation to different temperature, the effectiveness of the oils on larvae mortality was directly related to the increase of temperature, and better results were observed for temperature at 25°C. The results presented here indicate the potential larvicidal activity of C. guianensis and species of Copaifera, in populations of A. aegypti from the wild. Therefore, the results presented here are very important since such populations are primarily responsible for transmitting the dengue virus in the environment. [ABSTRACT FROM AUTHOR]

Microbial control agents offer alternatives to chemical pest control as they can be more selective than chemical insecticides. The present study evaluates the mosquito larvicidal potential of microbial pigment prodigiosin produced by Serratia marcescens NMCC46 against Aedes aegypti and Anopheles stephensi. The pigment of S. marcescens NMCC46 was extracted after 24 h from mannitol containing nutrient broth media. The effects of crude extracted pigment on the growth, survival, development, and other life cycle aspects were studied. The LC and LC values of second, third, and fourth instars of A. aegypti (LC = 41.65, 139.51, 103.95; LC = 117.81, 213.68, 367.82) and A. stephensi (LC = 51.12, 105.52, 133.07; LC = 134.81, 204.45, 285.35) were determined. At higher concentration (500 ppm), mortality starts within first 6 h of exposure. More than 50% mortality occurs within the first 24 h. The overall observed effects against A. aegypti and A. stephensi larvae after 48 h were increasing percent survival larvae, survival pupation, adult emergence with decreasing crude pigment extract concentration. These ensure that the resultant mosquito population reduction is substantial even where the larvicidal potential is minimal. The UV ( λ = 536 nm), TLC (Rf = 0.9), HPLC, and FTIR analysis of crude pigment shows the presence of prodigiosin as active compound. Thus, the active compound produced by this species would be more useful against vectors responsible for diseases of public health importance. This is the first report on mosquito larvicidal activity of prodigiosin produced by Serratia species. [ABSTRACT FROM AUTHOR]

Larvicides play a vital role in controlling mosquitoes in their breeding sites. The present study was carried out to establish the larvicidal activities of mycosynthesized silver nanoparticles (AgNPs) against vectors: Aedes aegypti and Anopheles stephensi responsible for diseases of public health importance. The AgNPs synthesized by filamentous fungus Cochliobolus lunatus, characterized by UV-Vis spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The characterization studies confirmed the spherical shape and size (3-21 nm) of silver nanoparticles. The efficacy of mycosynthesized AgNPs at all the tested concentrations (10, 5, 2.5, 1.25, 0.625, and 0.3125 ppm) against second, third, and fourth instar larvae of A. aegypti (LC 1.29, 1.48, and 1.58; LC 3.08, 3.33, and 3.41 ppm) and against A. stephensi (LC 1.17, 1.30, and 1.41; LC 2.99, 3.13, and 3.29 ppm) were observed, respectively. The mortality rates were positively correlated with the concentration of AgNPs. Significant ( P < 0.05) changes in the larval mortality was also recorded between the period of exposure against fourth instar larvae of A. aegypti and A. stephensi. The possible larvicidal activity may be due to penetration of nanoparticles through membrane. Toxicity studies carried out against non-target fish species Poecilia reticulata, the most common organism in the habitats of A. aegypti and A. stephensi showed no toxicity at LC50 and LC90 doses of the AgNPs. This is the first report on mosquito larvicidal activity of mycosynthesized nanoparticles. Thus, the use of fungus C. lunatus to synthesize silver nanoparticles is a rapid, eco-friendly, and a single-step approach and the AgNps formed can be potential mosquito larvicidal agents. [ABSTRACT FROM AUTHOR]

Abstract??Methanolic extracts of 20 medicinal plants were screened at 1?10?mg/ml for in vitro macrofilaricidal activity by worm motility assay against adultSetaria digitata, the cattle filarial worm. Four plant extracts showed macrofilaricidal activity by worm motility at concentrations below 4?mg/ml and an incubation period of 100?min. Complete inhibition of worm motility and subsequent mortality was observed at 3, 2, 1 and 1?mg/ml, respectively, forCentratherum anthelminticum,Cedrus deodara,Sphaeranthus indicusandRicinus communis. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) reduction assay was carried out at 1?mg ml?1and 4-h incubation period, and the results showed thatC. deodara,R. communis,S. indicusandC. anthelminticumexhibited 86.56, 72.39, 61.20 and 43.15% inhibition respectively in formazan formation compared to the control. [ABSTRACT FROM AUTHOR]