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 LC50 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 LC50 and LC90 doses of the AgNPs. This is the first report on mosquito larvicidal activity of latex synthesized nanoparticles.

Larvicidal activity of silver nanoparticles synthesized using Plumeria rubra plant latex against Aedes aegypti and Anopheles stephensi

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 LC50 and LC90 values for first, second, third, and fourth instars of synthesized AgNPs-treated first, second, third, and fourth instars of A. aegypti (LC50 = 4.39, 5.12, 5.66, 6.18; LC90 = 9.90, 11.13, 12.40, 12.95 ppm) and A. stephensi (LC50 = 4.41, 5.35, 5.91, 6.47; LC90 = 10.10, 12.04, 13.05, 14.08 ppm) were found many fold lower than crude latex-treated A. aegypti (LC50 = 55.13, 58.81, 75.66, 94.31; LC90 = 113.00, 118.25, 156.95, 175.71 ppm) and A. stephensi (LC50 = 81.47, 92.09, 96.07, 101.31; LC90 = 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 LC50 and LC90 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.

Larvicidal activity of silver nanoparticles synthesized using Pergularia daemia plant latex against Aedes aegypti and Anopheles stephensi and nontarget fish Poecillia reticulata

The present study explored the effects of crude leaf acetone, chloroform, hot water, methanol, petroleum ether (60–80°C), and water extracts of Calotropis procera (Ait) R. Br., Canna indica L., Hibiscus rosa-sinensis Linn., Ipomoea carnea Jacq. spp. fistulosa Choisy, and Sarcostemma brevistigma Wight that were selected for investigating larvicidal potential against second and fourth instar larvae of the laboratory-reared mosquito species, Culex quinquefasciatus Say, in which the major lymphatic filariasis was used. All plant extracts showed moderate larvicidal effects after 24 h of exposure at 1,000 ppm; however, the highest larval mortality was found in leaf acetone, chloroform, methanol, and petroleum ether of C. indica (LC50 = 29.62, 59.18, 40.77, and 44.38 ppm; LC90 = 148.55, 267.87, 165.00, and 171.91 ppm) against second instar larvae (LC50 = 121.88, 118.25, 69.76, and 56.31 ppm; LC90 = 624.35, 573.93, 304.27, and 248.24 ppm) and against fourth instar larvae and acetone, hot water, methanol, and petroleum ether extracts of I. carnea (LC50 = 61.17, 41.07, 41.82, and 39.32 ppm; LC90 = 252.91, 142.67, 423.76, and 176.39 ppm) against second instar larvae (LC50 = 145.37, 58.00, 163.81, and 41.75 ppm; LC90 = 573.30, 181.10, 627.38, and 162.63 ppm) and against fourth instar larvae of C. quinquefasciatus, respectively. These results suggest that the acetone, methanol extracts of C. indica and hot water, petroleum ether extracts of I. carnea have the potential to be used as an ideal eco-friendly approach for the control of the major lymphatic filariasis vector, C. quinquefasciatus.

Efficacy of larvicidal botanical extracts against Culex quinquefasciatus Say (Diptera: Culicidae).

Mosquitoes are responsible for transmission of many diseases to human. They not only can carry diseases that afflict humans, but also transmit several diseases and parasites to birds, dogs, horses, etc. Anopheles stephensi and Culex quinquefasciatus (Diptera: Culicidae) are urban and rural mosquito pests in Iran. Hormozgan province, southern Iran, has a favourable climate for mosquito breeding and development, with active foci of malaria transmission. Extensive application of chemical insecticides for many years in this area caused irrepairable damages to environment and resulted in resistance in An. stephensi to some insecticides/larvicides 1,2 . Several botanicals offer great promise as sources of phytochemicals for the control of mosquitoes. One of the earliest reports of the use of plant extracts against mosquito larvae is extraction of plant alkaloids like nicotine, anabasine, methyl anabasine and lupinine from the Russian weed in 1933. Anabasis aphylla killed larvae of Culex pipiens Linn., Cx.

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Larvicidal efficacy of latex and extract of Calotropis procera (Gentianales: Asclepiadaceae) against Culex quinquefasciatus and Anopheles stephensi (Diptera: Culicidae).

Aedes aegypti transmits etiologic agents of yellow fever and dengue. Vaccine for dengue virus is not available and vector control is essential to minimize dengue incidence. This report deals with the larvicidal activity of lectins isolated from Myracrodruon urundeuva bark (MuBL) and heartwood (MuHL). The lectins were isolated by ammonium sulphate treatment of crude extracts followed by chromatography on chitin. MuBL and MuHL were evaluated by electrophoresis under native (PAGE) and denaturing conditions (SDS-PAGE). Carbohydrate specificity of lectins was evaluated by hemagglutinating activity (HA) inhibition assay using N -acetyl- d -glucosamine and by affinity chromatography on N -acetyl- d -glucosamine immobilized in agarose gel. Larvicidal activity against A. aegypti was investigated with the extracts, salt fractions and isolated lectins. MuBL and MuHL were characterized by PAGE as basic proteins of molecular masses of 14.0 and 14.4 kDa, respectively. The interaction of lectins with N -acetylglucosamine was detected by inhibition of HA by monosaccharide and lectin adsorptions on N -acetyl- d -glucosamine matrix. All M. urundeuva preparations promoted larvae mortality. LC 16 , LC 50 and LC 84 values of 0.077, 0.125, 0.173 for MuBL and 0.03, 0.04 and 0.05 mg/mL for MuHL were obtained. To our knowledge this is the first report of larvicidal activity of lectins against A. aegypti.

Larvicidal activity of lectins from Myracrodruon urundeuva on Aedes aegypti.

Calotropis procera R. Br. (Asclepiadaceae) is a well-known medicinal plant with leaves, roots, and bark being exploited by popular medicine to fight many human and animal diseases. This work deals with the fractionation of the crude latex produced by the green parts of the plant and aims to evaluate its toxic effects upon egg hatching and larval development of Aedes aegypti. The whole latex was shown to cause 100% mortality of 3rd instars within 5 min. It was fractionated into water-soluble dialyzable (DF) and non-dialyzable (NDF) rubber-free materials. Both fractions were partially effective to prevent egg hatching and most of individuals growing under experimental conditions died before reaching 2nd instars or stayed in 1st instars. Besides, the fractions were very toxic to 3rd instars causing 100% mortality within 24 h. When both fractions were submitted to heat-treatment the toxic effects were diminished considerably suggesting low thermostability of the toxic compounds. Polyacrylamide gel electrophoresis of both fractions and their newly fractionated peaks obtained through ion exchange chromatography or desalting attested the presence of proteins in both materials. When submitted to protease digestion prior to larvicidal assays NDF lost most of its toxicity but DF was still strongly active. It may be possible that the highly toxic effects of the whole latex from C. procera upon egg hatching and larvae development should be at least in part due to its protein content found in NDF. However the toxicity seems also to involve non protein molecules present in DF.

Latex constituents from Calotropis procera (R. Br.) display toxicity upon egg hatching and larvae of Aedes aegypti (Linn.) Márcio Viana Ramos/ + , Glaís de Paiva Bandeira, Cléverson Diniz Teixeira de Freitas,

Petrônio Augusto

Papers

Latex constituents from Calotropis procera (R. Br.) display toxicity upon egg hatching and larvae of Aedes aegypti (Linn.) Márcio Viana Ramos/ + , Glaís de Paiva Bandeira, Cléverson Diniz Teixeira de Freitas,