Efficacy of larvicidal and pupicidal activity of Catharanthus roseus aqueous and solvent extracts against Anopheles stephensi Liston and Culex quinquefasciatus Say (Diptera: Culicidae).

OBJECTIVE: To investigate the larvicidal and pupicidal activities of aqueous, ethyl acetate and methanol extracts of Catharanthus roseus (C. roseus) against malaria and filariasis vectors. METHODS: The larvicidal and pupicidal activities of C. roseus leaf extracts were tested against the fourth instar larvae and pupae of Anopheles stephensi (An. stephensi) and Culex quinquefasciatus (Cx. quinquefasciatus). The mortality was observed after 24 and 48 h post the treatment. The data were subjected to probit analysis to determine the lethal concentrations (LC50 and LC90) at which 50% and 90% of the treated larvae or pupae of the tested species were killed. RESULTS: The larval and pupal mortality were observed after 24 and 48 h of exposure of aqueous, ethyl acetate and methanol extracts of C. roseus; no mortality was observed in the control group. The LC50 values against the fourth-instar larvae of An. stephensi were 68.62 and 72.04 mg/mL for the aqueous extract, 82.47 mg/mL for the ethyl acetate extract, and 78.80 and 86.64 mg/mL for the methanol extract, while the aqueous, ethyl acetate and methanol extracts had LC50 values of 85.21, 76.84 and 94.20 mg/mL against the fourth-instar larvae of Cx. quinquefasciatus. The aqueous, ethyl acetate and methanol extracts had LC50 values of 118.08, 182.47 and 143.80 mg/mL against the pupae of An. stephensi and 146.20, 226.84 and 156.62 mg/mL against the pupae of Cx. quinquefasciatus, respectively. CONCLUSIONS: The aqueous and methanol extracts of C. roseus leaves had an excellent potential to control the malarial vector An. stephensi and filariasis vector Cx. quinquefasciatus.

Studies on the impact of biosynthesized silver nanoparticles (AgNPs) in relation to malaria and filariasis vector control against Anopheles stephensi Liston and Culex quinquefasciatus Say (Diptera: Culicidae).

Biosynthesized nanoparticles have been achieved using environmentally acceptable plant extract and eco-friendly reducing and capping agents. The present study was based on assessments of the larvicidal activities to determine the efficacies of synthesized silver nanoparticles (AgNPs) using aqueous leaf extract of Vinca rosea (L.) (Apocynaceae) against the larvae of malaria vector Anopheles stephensi Liston and filariasis vector Culex quinquefasciatus Say (Diptera: Culicidae). Larvae were exposed to varying concentrations of aqueous extract of V. rosea and synthesized AgNPs for 24, 48, and 72 h. AgNPs were rapidly synthesized using the leaf extract of V. rosea, and the formation of nanoparticles was observed within 15 min. The results recorded from UV-Vis spectrum, Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) support the biosynthesis and characterization of AgNPs. The formation of the AgNPs synthesized from the XRD spectrum compared with the Bragg reflections at 2θ = 29.36, 38.26, 44.51, 63.54, and 77.13° which can be indexed to the (121), (111), (200), (220), and (311) orientations, respectively, confirmed the presence of AgNPs. The FTIR spectra of AgNPs exhibited prominent peaks at the spectra showed sharp and strong absorption band at 3,406.71 to 3,431.90 cm(-1) double in case of NH(2) group of a primary amine (N-H stretch). The presence of the sharp peak at 2,926.54 to 2,925.80 cm(-1) very broad often looks like distorted baseline (O-H carboxylic acids). The band 1,633.26 to 1,625.81 cm(-1) was assigned to C = C alkenes, aromatic ring stretching vibration, respectively. SEM analysis of the synthesized AgNPs clearly showed the clustered and irregular shapes, mostly aggregated and having the size of 120 nm. TEM reveals spherical shape of synthesized AgNPs. Particle size analysis revealed that the size of particles ranges from 25 to 47 nm with average size of 34.61 nm. Energy-dispersive X-ray spectroscopy showed the complete chemical composition of the synthesized AgNPs. In larvicidal activity, the results showed that the maximum efficacy was observed in synthesized AgNPs against the fourth instar larvae of A. stephensi (LC(50) = 12.47 and 16.84 mg/mL and LC(90) = 36.33 and 68.62 mg/mL) on 48 and 72 h of exposure and against C. quinquefasciatus (LC(50) = 43.80 mg/mL and LC(90) = 120.54 mg/mL) on 72-h exposure, and aqueous extract showed 100 % mortality against A. stephensi and C. quinquefasciatus (LC(50) = 78.62 and 55.21 mg/mL and LC(90) = 184.85 and 112.72 mg/mL) on 72-h exposure at concentrations of 50 mg/mL, respectively. The AgNPs did not exhibit any noticeable toxicity on Poecilia reticulata after 24, 48, and 72 h of exposure. These results suggest that the synthesized AgNPs have the potential to be used as an ideal eco-friendly approach for the control of the A. stephensi and C. quinquefasciatus. This method is considered as a new approach to control vectors. Therefore, this study provides the first report on the mosquito larvicidal activity of V. rosea synthesized AgNPs against vectors.

Morphological changes due to Lead exposure and the influence of DMSA on the gill tissues of the freshwater fish, Catla catla.

Catla catla fingerlings were reared in freshwater and exposed to 15.5 ppm concentration of lead for 60 days. The morphological changes on the gill of the C. catla fingerlings due to lead intoxication and the effect of DMSA (meso 2,3-dimercaptosuccinic acid) on the affected tissues were observed using Scanning Electron Microscope. It has been found that the lead treated gill tissues showed certain marked changes, such as cell hypertrophy, alteration in the lamellar surfaces, epithelial hyperplasia and the fusion of adjacent lamellae. The antidote DMSA treatment reduces the toxic effects and helps the recovery of gill tissue and its return to the level of the control/normal.

Effect of sildenafil citrate (Viagra) and ethanol on the Albino rat testis: a scanning electron microscopic approach.

The effects of sildenafil citrate with ethanol on the rat testis was studied using scanning electron microscopy. Male Albino rats were divided into 8 groups, each being treated for a maximum of 45 days as follows. In the 4 short-term treatment groups, control rats were administered normal saline orally, whereas experimental animals were fed sildenafil citrate (Viagra) 1 microg/g with 18% ethanol (5 g/kg body weight), which was given orally as a single dose. After 1, 2.5, 4 and 24h the rats were killed. In the 4 long-term treatment groups, daily continuous doses of drug and ethanol with a single dosage were given for 15, 30 and 45 days and the animals killed 4h after the last dosage. Changes in the testis were compared with the normal healthy rat testis. The use of a scanning electron microscope for evaluation of the changes in the testis is more suitable for observation of the surface and morphological shapes of the tissue structures.

Influence of pH and water hardness upon nickel accumulation in edible fish Cirrhinus mrigala.

The freshwater fingerlings of Cirrhinus mrigala were exposed to Nickel in acidic medium pH = 6.0 (5.8-6.2), alkaline medium pH = 9.0 (8.8-9.2) and water hardness (40 mg/l) of CaCO3. The study indicates that nickel accumulation was significantly influenced by pH and hardness of water The concentration was found to be significantly higher at pH = 9.0 than at pH = 6.0. Also the presence of hardness in water results in reduced toxicity of nickel.

An assessment of plankton population of Cauvery river with reference to pollution.

Studies on plankton of river Cauvery water, Mettur, Salem District, Tamil Nadu was made to assess the pollution of water from January 2003 to December 2003. The qualitative and quantitative evaluation of the variation in river water showed high quantity of phytoplankton and zooplankton population throughout the study period and rotifers formed dominated group over other groups of organisms. The present study revealed that the water of river Cauvery is highly polluted by direct contamination of sewage and other industrial effluents.