Iron and nickel complexes with heterocyclic ligands: Stability,synthesis, spectral characterization,antimicrobial activity,acute and subacute toxicity

The synthesis and characterization by elemental analysis, emission atomic spectroscopy, TG measurements, magnetic measurements, FTIR, ¹H NMR, UV–visible spectra and conductivity of a series of iron (II) and nickel (II) complexes with two heterocyclic ligands (L¹(SMX): sulfamethoxazole and L²(MIZ): metronidazole) used in pharmaceutical field and with a new ligand derived benzoxazole (L³(MPBO): 2-(5-methylpyridine-2-yl)benzoxazole), were reported. The formulae obtained for the complexes are: [M(L¹)₂ Cl₂]·nH₂O, [M(L²)₂Cl₂(H₂O)₂]·H₂O and [M(L³)₂(OH)₂]·nH₂O. Stability constants of these complexes have been determined by potentiometric methods in water–ethanol (90:10, v/v) mixture at a 0.2 mol L^?1 ionic strength (NaCl) and at 25.0 ± 0.1 °C. Sirko program was used to determine the protonation constants as well as the binding constants of three species [ML₂H₂]²⁺, [ML₂] and [ML]²⁺. The antimicrobial activity of the ligands and complexes was evaluated in vitro against different human bacteria and fungi using agar diffusion method.Iron sulfamethoxazole complex showed a remarkable inhibition of bacteria growth especially on Staphylococcus aureus and P. aeruginosa. The iron metronidazole complex is active against yeasts especially on Candida tropicalis strain. Nickel complexes presented different antibacterial and antifungal behavior's against bacteria and fungal.The acute toxicity study revealed that the iron complexes are not toxic at 2000 mg/kg dose orally administrated.LD₅₀ for nickel complexes was determined using graphical method.No significant differences in the body weights between the control and the treated groups of both rat sexes in subacute toxicity study using for iron complexes. Hematological and clinical blood chemistry analysis revealed no toxicity effects of the iron complexes. Pathologically, neither gross abnormalities nor histopathological changes were observed for these complexes.     

Estimation of european corn borer egg masses density by sampling of runs

Spatial distributions of individuals may be considered in two ways: Firstly, individuals are situated on a continuum. Secondly, individuals are situated on discrete units, for example, insect eggs on plants. The aim of this paper is to show that sometimes, in the latter case, sampling methods based on infestation runs can be of interest in estimating population density. Analytical results are obtained under complete spatial randomness hypothesis and alternative hypotheses. Sampling procedures with limited cost are discussed and the European corn borer (ECB) case is mainly considered.     

Pyrrolizidine alkaloids in and on the leaf surface of Senecio jacobaea L

This is the first study showing that alkaloids are present on the leaf surface of plants. A concentration of 30-230 pmol/cm2 pyrrolizidine alkaloids (PA's) was detected in 8 different samples taken from Senecio jacobaea. PA concentration on the leaves was marginally correlated with PA concentration of the total leaf tissues. The PA spectrum on the leaf differed from the PA spectrum of the total leaf.     

Electronic tagging of Bluefin Tunas from the Maltese spawning ground suggests size-dependent migration dynamics

Environmental Biology of Fishes - The purse seine fishery in the Mediterranean represents about 60% of the international catch for Atlantic Bluefin Tuna (Thunnus thynnus). Yet, tagging operations...     

Effects of a biocontrol agent of apple powdery mildew (Podosphaera leucotricha) on the host plant and on non-target organisms: an insect pest (Cydia pomonella) and a pathogen (Venturia inaequalis)

A number of studies have focused on the selection and use of new biocontrol agents, but the effects of the introduction of these microorganisms on non-target organisms, including the crop plants themselves, are not well known. Non-target effects of sprayed applications of a potential biocontrol agent of apple powdery mildew (Podosphaera leucotricha Ell. Et Ev.), on scab infections (Venturia inaequalis Cooke Winter), on codling moth [Cydia pomonella L. (Lepidoptera: Tortricidae)] oviposition and damage and apple (Malus x domestica) fruit quality are examined. This biocontrol agent, an epiphytic yeast isolate called Y16, affected neither conidia germination of V. inaequalis nor their penetration of the leaf tissue but suppressed the disease caused by this pathogen. The quantity of eggs laid by the codling moth during its second flight period on yeast treated trees was significantly different to the quantity of eggs laid on the untreated trees. In the first season of the experiments, more eggs were laid on the treated trees, especially on those tree parts closest to the fruit. These results, however, were not confirmed the following season: fewer eggs were laid on the treated trees than on the untreated trees. These conflicting observations are attributed to year-to-year variation in environmental conditions, which may affect yeast survival and activity. A 2-month-long assay was conducted in the orchard during the codling moth's second flight period from mid-July until mid-September. The yeast treatment did not affect the damage caused by the codling moth to the fruits. Finally, the yeast treatment did not affect any of the examined fruit quality parameters.     

Increase of European corn borer (Ostrinia nubilalis) oviposition induced by a treatment of maize plants with maleic hydrazide: Role of leaf carbohydrate content

Earlier experiments seemed to indicate a positive correlation between the choice of the oviposition site of Ostrinia nubilalis Hbn. on maize (Zea mays L.) leaves and their carbohydrate content. In the present study a growth regulator, maleic hydrazide (M.H.), is used to increase the soluble carbohydrate content of the plants. It seems that the insect prefers to oviposit on the treated plants which display higher carbohydrate contents. On the other hand the distribution of the egg-masses on the leaf blade is also modified. Plant height has no influence on these choices.

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Résumé A la suite de nos expérimentations antérieures, qui mettent en évidence l'existence d'une relation entre le choix de site de dépôt des oeufs d'Ostrinia nubilalis et la teneur en sucres du feuillage chez le maïs (Zea mays), la présente étude a été entreprise pour essayer de confirmer cette corrélation positive. A cet égard, nous avons choisi d'augmenter les teneurs en sucres solubles des feuilles de maïs par l'emploi d'un régulateur de croissance: l'hydrazide maléique. Ce composé est en effet connu pour perturber la photosynthèse et ralentir la migration des sucres dans les feuilles, ce qui a pour conséquence d'augmenter leurs teneurs en sucres solubles (glucose, fructose, saccharose). Les femelles montrent alors une préférence pour les plantes ainsi traitées par rapport à des plantes non traitées. Les résultats obtenus ne permettent cependant pas de distinguer les actions respectives de ces trois sucres solubles. En outre, on observe des modifications dans la répartition des oeufs sur les feuilles des plantes traitées par rapport à celles des plantes témoins. La taille des plantes ne semble pas avoir de rôle dans le choix de site d'oviposition.

     

Incidence of apple fruit and leaf surface metabolites on Cydia pomonella oviposition

Water soluble metabolites identified from surfaces of apple tree fruit and leaf stimulate oviposition in Cydia pomonella L. The effects of two artificial blends of primary metabolites representing fruit and leaf surfaces, respectively, and of components within the blends were examined on egg-laying after two time periods: 3 min and 25 min of darkness. An artificial mixture of six metabolites, viz., three sugar alcohols (sorbitol, quebrachitol, and myo-inositol) and three sugars (glucose, fructose, and sucrose) did stimulate egg-laying. Fructose, sorbitol, and myo-inositol are important components of the stimulatory blend. Contact durations may induce variations in egg-laying responses. After 3 min of darkness, there were no differences in numbers of females laying eggs nor in the numbers of eggs laid on cloths treated with the complete blends and the controls. There were, however, clear effects of groups of compounds and of individual compounds. Reduced blends without sugars and sugar alcohols were in many cases significantly less stimulatory than the complete blends and the controls. After 25 min of darkness, the proportions of females laying eggs as well as the numbers of eggs were higher after treatment with the complete blends than on the controls. The proportions of females laying eggs on cloths treated with the reduced blends were rather similar to the controls, whereas there were still significant effects on the numbers of eggs laid after treatment with reduced blends derived from fruits but not from leaves.     

Gender, mediterranean drought, and seasonality: photosystem II photochemistry in Pistacia lentiscus L.

In this work, photosystem II (PSII) photochemistry, leaf water potential, and pigment contents of male and female Pistacia lentiscus L. were investigated during a seasonal cycle at three different, arid locations: superior semiarid, inferior semiarid, and arid. The results showed that the gender, season, and the site conditions interacted to influence the quantum yield and pigment contents in P. lentiscus. Predawn leaf water status was determined only by the site and season. The annual patterns of PSII maximum quantum efficiency (F_v/F_m) were characterized by a suboptimal activity during the winter, especially, populations with the more negative water potential exhibited a lower chlorophyll (Chl) a content and chronic photoinhibition irrespective of a gender. We also demonstrated that both photochemical or nonphotochemical mechanisms were involved to avoid the photoinhibition and both of them depended on the season. This plasticity of photosynthetic machinery was accompanied by changes in carotenoids and Chl balance. In the spring, the female F_v/F_m ratio was significantly higher than in male individuals, when the sexual dimorphism occurred during the fruiting stage, regardless of site conditions. P. lentiscus sex-ratio in Mediterranean areas, where precipitations exceeded 500 mm, was potentially female-biased. Among the fluorescence parameters investigated, nonphotochemical quenching coefficient appeared as the most useful one and a correlation was found between Chl a content and F_v/F_m. These results suggest that functional ecology studies would be possible on a large scale through light reflectance analysis.     

Plant growth stages in the interspecific oviposition preference of the european corn borer and relations with chemicals present on the leaf surfaces

The oviposition preference of the European Corn Borer Ostrinia nubilalis Hbn. Lepidoptera pyralidae was studied in relation to phenological stages of different plant species (Zea mays L., Helianthus annuus L., Phaseolus vulgaris L.). The experiments were done in greenhouses in binary choices. The results show that the plant phenological stages were more important than the plant species in the insect oviposition preference. When the choice was given between two plant species throughout their growth, the preference varied in relation to the development of each species. The relative differences in fructose amounts found on the leaf surfaces (phylloplane) were highly correlated with the insect oviposition preference. Amounts of proline, glucose and sucrose may accentuate this previous effect.

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Résumé Cette étude porte sur l'évaluation de l'importance de la phénologie des plantes dans le choix interspécifique de la pyrale du maïs (Ostrinia nubilalis Hbn.) pour pondre. Les expériences ont été poursuivies en serre en choix binaires sur plantes entières. Le choix entre le maïs et le haricot a été donné à l'insecte en différentes combinaisons de stades phénologiques. Les résultats montrent que c'est la phénologie qui gouverne la préférence plus que l'espèce végétale. Au cours de la croissance simultanée du maïs et du haricot d'une part, du maïs et du tournesol d'autre part, l'espèce préférée par la pyrale change. A certaines associations de stades phénologiques il n'y a pas de préférence entre les deux espèces, qui reçoivent alors autant de pontes l'une que l'autre.Des substances biochimiques hydrosolubles telles que les glucides et acides aminés libres présentes en surface des feuilles (phylloplan) ont été étudiées en corrélation avec le comportement de choix de site de ponte de la pyrale. Les différences relatives des quantités de fructose entre les deux espèces composantes du choix sont hautement corrélées avec la préférence de l'insecte. L'effet de cette substance est accentué par les différences relatives des quantités de proline, glucose et saccharose.

     

Resistance of apple trees to Cydia pomonella egg-laying due to leaf surface metabolites

During host plant selection and particularly after alighting on a plant, chemical cues from the plant surface influence an insect's acceptance of the plant and, subsequently, its egg‐laying behaviour. Primary metabolites in the phylloplane may be more important than hitherto known. We have shown that soluble carbohydrates, such as glucose, fructose, and sucrose, and sugar alcohols, such as sorbitol, quebrachitol, and myo‐inositol, can be detected by insects after contacting the plant and that they positively influence egg‐laying of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), on apple trees. We addressed the question whether a lack of these substances could also explain apple tree resistance to C. pomonella in terms of reduced egg‐laying. Leaf surface washings were collected in an apple orchard by spraying water on the resistant cultivar X65‐11 and on the susceptible cultivar P5R50A4. The washings were tested on a nylon cloth on isolated females under no‐choice conditions. The washings were analysed and synthetic blends, each consisting of the six metabolites in the proportions established in the leaf surface washings of both cultivars, were then tested for their effect on egg‐laying of C. pomonella. Dose–response egg‐laying tests were carried out on substrates impregnated with the X65‐11 leaf surface blend at 1, 100, 1 000, and 10 000 times the natural dose. Egg‐laying behaviour in the bioassays with leaf surface washings of both cultivars closely resembled egg‐laying in the orchard. Washings of P5R50A4 stimulated egg‐laying to a greater extent than those of X65‐11 and the water control. Synthetic blends reduced substrate acceptance and egg‐laying, compared to the washings of X65‐11. Ratios between components within the blend are responsible for this resistance. In conclusion, quantities and ratios of the six primary metabolites found on the leaf surface may influence host preference of C. pomonella as well as their egg‐laying behaviour, thus they may play a role in the trees’ resistance to the codling moth.