The effects of organic amendments on the interactions between a nematophagous fungus Arthrobotrys oligospora and the root-knot nematode Meloidogyne mayaguensis parasitizing tomato plants

The aim of this study was to examine the effects of amendments with leaf biomass on the development of tomato plants in a soil where root-knot nematodes (Meloidogyne mayaguensis) and/or a nematophagous fungus (Arthrobotrys oligospora, strain ORS 18697) had been inoculated. Six origins of leaf biomass were chosen: Acacia mangium, Acacia holosericea, Eucalyptus camaldulensis, Casuarina equisetifolia, Azadirachta indica and Sorghum vulgare. These leaf biomass types inhibited the development of the aerial parts of the tomato plants. This negative effect was not observed when the fungus was inoculated. On the contrary, plant growth was stimulated. Moreover, the antagonistic activity of Arthrobotrys oligospora was strengthened in the presence of ground leaf powder, especially that from Acacia holosericea. The effects of phenolic compounds on fungal growth and predatory activity and on plant growth are discussed.     

A Multivariate Data Analysis of the Clam Ruditapes Decussatus as Sentinel Organism of the Bizerta Lagoon (Tunisia)

Water, Air, & Soil Pollution - From May 1998 to May 1999, the clams Ruditapes decussatus were collected each month at three stations of the Bizerta lagoon. This paper represents a synthesis...     

Degradation pathway of dicyclanil in water in the presence of titanium dioxide. Comparison with photolysis

The solar photolytic behavior of the pesticide 4,6-diamino-2-cyclopropyl-pyrimidine-5-carbonitrile, currently known as dicyclanil, has been mimicked in a photoreactor operating with an artificial light flux. The rate and pathway of degradation were performed. An additional study, using TiO(2) photocatalysis, has been achieved in order to determine the efficiency of photocatalysis to degrade the molecule. The catalyst was titania Degussa P-25. The aim of this article was the identification of the intermediate products formed during the irradiation, to establish the degradation pathway of dicyclanil. The kinetics of the reactions were followed by liquid chromatography with a diode array detector (LC-DAD). Most of the organic compounds occurring during the photodegradation have been identified by means of liquid chromatography and mass spectrometry coupled techniques (HPLC-MS). Additional analyses were carried out to evaluate the mineralization rates into nitrate and ammonium ions.     

Organic Carbon and Total Iron Effect on Soil Vis-SWNIR Spectraand Quantification of Their Contents Using PLS R Models

ABSTRACT

Many factors could influence simultaneously soil spectra. We aimed to study the single effect of organic carbon and total iron in soil visible and short-wave near-infrared spectra and to quantify their contents. Two datasets of soil mixture samples were prepared by mixing, in various fractions, an organic carbon-rich material with a total iron-rich material and then with a total iron-poor material. For these two datasets, contents in organic carbon are quite similar but contents in total iron are significantly different. Results show that samples of the same dataset have the same overall spectral shape. Organic carbon has a decreasing effect that affects the whole spectral range without showing any specific absorption peaks. By contrast, total iron has specific absorption peaks. Spectra of the second dataset characterized by soil mixtures with higher total iron contents were more compact within the spectral bands 400–440 and 920–950 nm. Besides, continuum removal enables to exaggerate absorption peaks of wavelengths linked to total iron content. Partial Least Squares Regression (PLS R) models of both total organic carbon and total iron assign high coefficients to the wavelengths that are considered relevant and conversely low coefficients to those that are considered irrelevant. Both organic carbon content and total iron content were well predicted. For these models, coefficients of determination were superior to 0.9 and RMSE was closed to zero. The global models calibrated on all the samples demonstrated that PLS R was able to integrate sample heterogeneity.     

Interindividual variability in plasma concentrations after systemic exposure of swine to dietary doxycycline supplied with and without paracetamol: a population pharmacokinetic approach

Anorexigenic substances released during infection may hinder the therapeutic efficacy of in-feed antibiotics. Paracetamol (acetaminophen; PARA) inhibits the anorexia of infection and seems to improve the clinical efficacy of doxycycline (DOX) against bacterial respiratory disease in swine herds. In order to verify whether PARA selectively stimulates intake of DOX-medicated feed in diseased pigs, we documented the pharmacokinetics (PK) of DOX when coadministered with PARA and examined the effect of in-feed PARA on the interindividual variability in plasma concentrations after systemic exposure to in-feed DOX in swine herds with respiratory disease. Systemic exposure to DOX was measured with the area under the curve (AUC) of its plasma concentrations over time. First, a rich-sampling PK study of in-feed and i.v. DOX (10 mg/kg of BW) and PARA (30 and 10 mg/kg of BW, respectively) was performed on 5 pigs. The PK profiles of in-feed DOX were used in mathematical simulations to determine 5 optimal sampling times for the farm-based population PK study. A randomized, blind, parallel PK study was performed in 2 herds with bacterial respiratory disease, where liquid feed was fortified with DOX alone (5 mg x kg of BW(-1) x meal(-1)) or combined with PARA (15 mg x kg of BW(-1) x meal(-1)). Medicated meals were given twice, 12 h apart, to group-housed growing pigs (n > 50 pigs x treatment(-1) x herd(-1), totaling 215 pigs). Plasma concentrations of DOX and PARA were measured with HPLC. At variance with our expectations, PARA decreased (P = 0.069) mean AUC of in-feed DOX and did not decrease its variability (P > 0.34). Mean AUC of DOX increased with feed intake and with initial exposure to DOX, and was greater in sick animals. Therefore, symptomatic PARA-induced improvement in bacterial respiratory disease control with DOX is more likely caused by its analgesic/antipyretic effects than by its orexigenic effect. Interindividual variation in the AUC of DOX was large in pigs given group medication, even when sufficient feeding space was allowed and the amount of feed offered was greater than their requirements. Therefore, future studies to improve the efficacy of group antibiotic therapy should focus on feeding behavior characteristics as well as biopharmaceutical properties of medicated feeds.     

Fast variability of tera-electron volt gamma rays from the radio galaxy M87

The detection of fast variations of the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central black hole. We thus can exclude several other sites and processes of the gamma-ray production. The observations confirm that TeV gamma rays are emitted by extragalactic sources other than blazars, where jets are not relativistically beamed toward the observer.     

In vitro susceptibility to antimonials and amphotericin B of Leishmania infantum strains isolated from dogs in a region lacking drug selection pressure

The aim of this study was to evaluate the susceptibility to anti-leishmanial agents of 24 strains isolated from dogs living in the urban area of Alger lacking drug selection pressure. Two different Leishmania infantum zymodemes, MON-1 and MON-281, were identified in these dogs. The in vitro susceptibility to the main forms of antimonial and amphotericin were assessed on promastigote and amastigote life stages in culture. The results obtained for both parasite life stages were concordant whatever the molecule tested. Moreover, our data showed that isolates belonging to the relatively rare zymodeme of L. infantum, MON-281, were less susceptible to antimony than MON-1, when at the same time there was no significant difference for amphotericin B.     

Natural enemies of the South American moth, Tuta absoluta, in Europe, North Africa and Middle East, and their potential use in pest control strategies

The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided.