Numerical analysis of predatory potentiality of Toxorhynchites splendens against larval Aedes albopictus in laboratory and semi-field conditions.

Larvae of the elephant mosquitoes, Toxorhynchites spp. (Diptera: Culicidae) are predacious on larvae of other mosquito species and some small aquatic organisms; this predatory behavior can be applied in (mosquito) vector control. The present study examined the feeding behavior of Toxorhynchites splendens on Aedes albopictus in relation to search area [volume of water (X1)] and prey density (X2), prey instars, predatory preference and larvae's functional response on variable prey densities. Experiments were conducted to determine changes in the feeding activity of T. splendens with different search areas and showed that rate of prey consumption was inversely proportional to the search area as evidenced by a negative value of X1 in the regression equation and positively related to prey density. The non-linear polynomial logistic regression estimated a significant linear parameter (P1 < 0) for the functional response analysis suggesting a Type II functional response. Differences in feeding response related to the different combinations of prey instars were statistically not significant (p > 0.05), expressing that all the instars of prey were equally susceptible to the predator. Toxorhynchites splendens preferred to consume Ae. albopictus larvae rather than Tubifex when supplied together as a food source.

In-vitro Bactericidal Activity of a Novel Plant Source Plumeria pudica against Some Human and Fish Pathogenic Bacteria.

BACKGROUND: The only remedy for up surging problem of antibiotic resistance is the discovery of antibacterial agents of natural origin. OBJECTIVE: The present study was aimed at finding antibacterial potential of crude and solvent extracts of mature leaves of Plumeria pudica. METHODS: Antibacterial activity of three different solvent extracts were evaluated in four human and four fish pathogenic bacteria by measuring the zone of inhibition and determining Minimum Inhibitory Concentration and Minimum Bactericidal Concentration values. Standard antibiotics were used as positive control. Preliminary phytochemical screening of most effective extract i.e., ethyl acetate extract, Fourier Transform Infra Red analysis and GC-MS analysis of the Thin Layer Chromatographic (TLC) fraction of ethyl acetate extract were done meticulously. All experiments were done thrice and analyzed statistically. RESULTS: Crude leaf extracts and solvent extracts caused good inhibition of bacterial growth in all selected bacteria. Ethyl acetate extract showed highest inhibition zones in all tested strains with maximum inhibition (19.50±0.29 mm) in Escherichia coli (MTCC 739). MBC/MIC of the extracts indicated that all three solvent extracts were bactericidal. Preliminary phytochemical tests revealed the presence of tannins, steroids and alkaloids and FT-IR analysis revealed presence of many functional groups namely alcoholic, amide, amine salt and aldehyde groups. From the GC-MS analysis of TLC fraction of ethyl acetate extract, five different bioactive compounds e.g., 2,4-ditert -butylphenyl 5-hydroxypentanoate, Oxalic acid; allyl nonyl ester, 7,9-Ditert-butyl-1-oxaspiro(4,5)deca-6,9-diene- 2,8-dione, Dibutyl phthalate and 2,3,5,8-tetramethyl-decane were identified. CONCLUSION: Leaf extracts of P. pudica contain bioactive compounds that can be used as broad spectrum bactericidal agent.

Antibacterial efficacy of leaf extracts of Combretum album Pers. against some pathogenic bacteria.

BACKGROUND: Plant derived medicines show significant contributions to mankind in treating infections of pathogenic bacteria. Recently plants are used in pharmaceutical industries for novel drug preparations because to ensure efficacy and safety as synthetic antibiotics are threatened for their multidrug resistance. The present study aimed at finding antibacterial potential of aqueous and ethanolic leaf extracts of Combretum album. METHODS: Antibacterial activity was evaluated against seven bacterial strains by determining minimum inhibitory concentration (MIC) and zone of inhibition. Diameters of the zone of inhibition were compared with standard antibiotics. Preliminary phytochemical screening was done according to standard protocol. FTIR analysis was performed to identify the general phytochemical groups of compounds in the extract. All experiments were conducted in triplicate and values were expressed as the mean ± standard deviation. One-way analysis of variance (ANOVA) and Tukey tests were performed for statistical justification. RESULTS: Maximum zones of inhibition were found in case of ethanolic extracts in the following order Bacillus licheniformis (MTCC 530) > Pseudomonas aeruginosa (MTCC 2453) > Bacillus subtilis (MTCC 441) >, Pseudomonas fluorescens (MTCC 103) > Bacillus mycoides (MTCC 7343) > Escherichia coli (MTCC 739) > Pseudomonas putida (MTCC 1654) with zone of inhibition of 27.67 ± 0.33 mm diameter in B. licheniformis (MTCC 530). Qualitatively, the ethanol extract contains flavonoids, tannins and alkaloids. The results of FTIR analysis confirmed the presence of R-CH2-OH groups, aromatics, C-N stretching amine and NH stretching secondary amine. One way ANOVA and Tukey tests statistically justify the data (p ≤ 0.05). CONCLUSIONS: All the tested leaf extracts showed promising antibacterial activity against both gram positive and gram negative bacteria. Phytochemical screening and FTIR analysis revealed the presence of tannins, alkaloids, R-CH2-OH groups, aromatics and flavonoids in ethanolic leaf extract qualitatively and these compounds could be responsible for antibacterial property of leaf extracts of C. album.