Imidacloprid impedes mitochondrial function and induces oxidative stress in cotton bollworm, Helicoverpa armigera larvae (Hubner: Noctuidae)

Neonicotinoids have high agonistic affinity to insect nicotinic acetylcholine receptors (nAChR) and are frequently used as insecticides against most devastating lepidopteran insect pests. Imidacloprid influenced dose-dependent decline in the state III and IV respiration, respiration control index (RCI), and P/O ratios, in vitro and in vivo. The bioassay indicated its LD50 value to be 531.24 μM. The insecticide exhibited a dose-dependent inhibition on F0F1-ATPase and complex IV activity. At 600 μM, the insecticide inhibited 83.62 and 27.13% of F0F1-ATPase and complex IV activity, respectively, and induced the release of 0.26 nmoles/min/mg protein of cytochrome c. A significant dose- and time-dependent increase in oxidative stress was observed; at 600 μM, the insecticide correspondingly induced lipid peroxidation, LDH activity, and accumulation of H2O2 content by 83.33, 31.51 and 223.66%. The stress was the maximum at 48 h of insecticide treatment (91.58, 35.28, and 189.80%, respectively). In contrast, catalase and superoxide dismutase were reduced in a dose- and time-dependent manner in imidacloprid-fed larvae. The results therefore suggest that imidacloprid impedes mitochondrial function and induces oxidative stress in H. armigera, which contributes to reduced growth of the larvae along with its neurotoxic effect

Microbial solubilization of heavy metals from soil using indigenous sulfur oxidizing bacterium: Effects of sulfur/soil ratio

680-683Present study assesses efficiency of bioleaching to decontaminate heavy metal laden soil affected by tannery effluent employing sulfur oxidizing bacterium, Acidithiobacillus thiooxidans. Concentrations of predominant heavy metals were Cd, 9; Cu, 95; Cr, 11800; Pb, 85; and Zn, 238 mg/kg. Irrespective of sulfur/soil ratio (0.14, 0.21, 0.29, 0.43 and 0.57), pH dropped from near neutral to below 1 over a period of 28 days; drop in pH was rapid when the ratio was 0.57 and it took only 6 days for pH to drop from 7.12 to 0.94. Production of sulphate (22-45 g/l) increased with rise in sulfur/soil ratio. Solubilization of heavy metals was: Cd, 44-57; Cu, 60-92; Cr, 72-81; Pb, 39-56; and Zn, 55-94%

Effect of pH on chromium biosorption by chemically treated Saccharomyces

675-679The effect of initial pH on biosorption by Saccharomyces cerevisiae of total chromium present in tannery effluent was investigated. Maximum biosorption efficiency was evident at neutral pH with a metal removal efficiency of 99 %. S. cerevisiae was then pretreated with NaOH and HCHO-HCOOH to study the role of proteins and amino acids, respectively, in biosorption. At pH 7, 9 and 11, biomass pretreated with NaOH exhibited significant biosorption as compared to raw biomass and that treated with HCHO-HCOOH. However, trend reversed at pH 2. At pH 4, untreated biomass exhibited maximum chromium sorption, when compared to that treated with NaOH and HCHO-HCOOH

Antifungal and insecticidal activities of Raphanus sativus mediated AgNPs against mango leafhopper, Amritodus brevistylus and its associated fungus, Aspergillus niger

Mangifera indica is an important commercial fruit of India and primary food source for the mango leafhopper, Amritodus brevistylus further leading to the development of its associated fungus, Aspergillus niger. The present study was done to assess the antifungal and insecticidal activity of biologically synthesized silver nanoparticles using peel extracts of Raphanus sativus (Brassicaceae). Raphanus sativus peel extract is effective in extracellular reduction of Ag ions and capping the synthesized nanoparticles avoiding further agglomeration. The synthesized AgNPs are characterized by UV-vis spectroscopy, X-ray diffraction analysis, fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive x-ray analysis. Biologically synthesized AgNPs exhibited significant toxicity (LC50 − 7.61 ppm/48h) over mango leafhopper, Amritodus brevistylus. Silver nanoparticles synthesized using Raphanus sativus is also effective against the fungal pathogen, Aspergillus niger (developed on the infestations of mango leafhopper, Amritodus brevistylus) showing very strong inhibitory zone (80 mm)

Insecticidal and biological effects of three plant extracts tested against the dengue vector, Stegomyia agyptii (Diptera: Culicidae)

Development of resistant in vectors especially vector mosquitoes are becoming a challenge for the scientific community for management and control mosquito population. Vector mosquitoes are likely to withstand toxicity and develop resistant mechanism to single active compound hence, combining medicinal plants with rich active compounds stops resistant development and proliferation of mosquitoes. In this study we put effort to evaluate the effect of methanol extract of Tagetes patula, Clerodentron phillomedis, and Catharanthus roseus in individual and in combination against the dengue vector, Stegomyia agyptii. Lethal concentrations (LC50 and LC90) were calculated to find out the effect of the test plants in individual and in combination. T. patula extract showed vaguely higher mortality rate when compared to C. phillomedis, and C. roseus but there was no significant variation among the three test plants. The median LC of combined treatment showed a significant difference between the combined (2.25 µg/mL/3rd instar) and individual treatment (6.41 µg/mL/3rd instar for T. patula, 6.85 µg/mL/3rd instar for C. phillomedis and 6.59 µg/mL/3rd instar for C. roseus). The combined efficacy of three test plants was also effective in controlling vector mosquitoes at fields with different agro-climatic conditions. The study proves that the combination of T. patula, C. phillomedis, and C. roseus is effective in different field conditions at lower concentrations

Structural investigation of a dilithiated phosphonate in the solid state

Mitzel NW. Parent substances of inorganic chemistry: Homoleptic pnictogenyl compounds of group 14, E(ZR(2))(4). ANGEWANDTE CHEMIE-INTERNATIONAL EDITION. 1999;38(1-2):86-88

Ligand exchange between arylcopper compounds and bis(hypersilyl)tin or bis(hypersilyl)lead: Synthesis and characterization of hypersilylcopper and a stannanediyl complex with a Cu-Sn bond

Bis(hypersilyl)tin (1) and bis(hypersilyl)lead (2) [hypersilyl= Hyp = tris(trimethylsilyl)silyl] undergo ligand exchange reactions with other carbene homologues to yield heteroleptic distannenes or diplumbenes. Here we report the extension of this reaction principle to coordinatively unsaturated arylcopper(I) compounds. The primary reaction products are probably adducts with the carbene homologues as Lewis base and the arylcopper compounds as Lewis acids. This is followed by rearrangement to the adducts HypCu-E-(Hyp)Ar* (E = Sn (6) and Pb (7); Ar* = C(6)H(3)Mes(2)-2,6,) of hypersilylcopper (9) and the heteroleptic stannanediyl or plumbanediyl. The complex may be the final product or may dissociate into its component parts, free hypersilylcopper (9) and the appropriate heteroleptic carbene homologue. The colorless hypersilylcopper forms a trimer (9), in the solid state with short Cu Cu contacts (238.4-241.5 pm). All observed Cu-Si bonds are relatively long. However, shorter distances (234.9-237.4pm) alternate with longer ones (249.2 pm), such that quasi-monomeric hypersilylcopper units can be identified. The dark green complex 6 exhibits a shorter Cu-Si bond (227.3 pm), The Sn-Cu bond length was determined to be 249.9 pm. The turquoise plumbanediyl Pb(Hyp)Ar* (8) is the first strictly monomeric mixed aryl silyl derivative, even in the solid state. The steric repulsions are obviously less than in the parent homoleptic compounds because the Pb-C bond in 8 is shorter (229.0 pm) and the C-Pb-Si angle (109.2 degrees) is markedly smaller