Evaluation of the pathogenicity of multiple isolates of Beauveria bassiana (Hypocreales: Clavicipitaceae) on Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) for the assessment of a solid formulation under simulated field conditions

A solid state formulation of Beauveria bassiana (Balsamo) Vuillemin has been developed for biological control of the Red Palm Weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790). Two kinds of bioassays (dry conidia and dipping) using 10 isolates from several coleopterans in Mediterranean environments, identified 2 RPW derived isolates (193 and 203) as most pathogenic to RPW larvae and adults (zero survival within first 4–5 d for dry conidia, and 14 and 23 d for dipping bioassays). Isolate 203 (5.1 × 108 ± 1.9 × 108 conidia g-1) was formulated with fragmented date seed into solid granules and tested in palms infested with RPW under semi-field conditions in Feb, Apr/May and Jun of both 2007 and 2008. Beauveria bassiana significantly reduced RPW adult survival with respect to controls in May 2007 and in the Apr/Jun 2008 experiments. Total RPW adult mortality was achieved within 30 days for all B. bassiana treatments, and was associated with increasing numbers of insects with signs of mycosis in 2008 experiments. Beauveria bassiana formulation reduced RPW multiplication in artificially infested palms compared to controls, and a positive correlation between numbers of larvae and time post-infestation was recorded. The suppression of RPW adult populations by B. bassiana persisted for at least 3 months under semi-field conditions. The Beauveria bassiana solid formulation, which induces great adult mortality and persistence in the field, could be applied as a preventive as well as a curative treatment for the integrated management of RPW.

Polarimetric Response of Rice Fields at C-Band: Analysis and Phenology Retrieval

A set of ten RADARSAT-2 images acquired in fully polarimetric mode over a test site with rice fields in Seville, Spain, has been analyzed to extract the main features of the C-band radar backscatter as a function of rice phenology. After observing the evolutions versus phenology of different polarimetric observables and explaining their behavior in terms of scattering mechanisms present in the scene, a simple retrieval approach has been proposed. This algorithm is based on three polarimetric observables and provides estimates from a set of four relevant intervals of phenological stages. The validation against ground data, carried out at parcel level for a set of six stands and up to nine dates per stand, provides a 96% rate of coincidence. Moreover, an equivalent compact-pol retrieval algorithm has been also proposed and validated, providing the same performance at parcel level. In all cases, the inversion is carried out by exploiting a single satellite acquisition, without any other auxiliary information.

Some isolates of the nematophagous fungus Pochonia chlamydosporia promote root growth and reduce flowering time of tomato

The fungal parasite of nematode eggs Pochonia chlamydosporia is also a root endophyte known to promote growth of some plants. In this study, we analysed the effect of nine P. chlamydosporia isolates from worldwide origin on tomato growth. Experiments were performed at different scales (Petri dish, growth chamber and greenhouse conditions) and developmental stages (seedlings, plantlets and plants). Seven P. chlamydosporia isolates significantly (P < 0.05) increased the number of secondary roots and six of those increased total weight of tomato seedlings. Six P. chlamydosporia isolates also increased root weight of tomato plantlets. Root colonisation varied between different isolates of this fungus. Again P. chlamydosporia significantly increased root growth of tomato plants under greenhouse conditions and reduced flowering and fruiting times (up to 5 and 12 days, respectively) versus uninoculated tomato plants. P. chlamydosporia increased mature fruit weight in tomato plants. The basis of the mechanisms for growth, flowering and yield promotion in tomato by the fungus are unknown. However, we found that P. chlamydosporia can produce Indole-3-acetic acid and solubilise mineral phosphate. These results suggest that plant hormones or nutrient ability could play an important role. Our results put forward the agronomic importance of P. chlamydosporia as biocontrol agent of plant parasitic nematodes with tomato growth promoting capabilities.

Influence of Incidence Angle on the Coherent Copolar Polarimetric Response of Rice at X-Band

The coherent nature of the acquisition by TerraSAR-X of both copolar channels (HH and VV) enables the generation of many different polarimetric observables with physical interpretation, as have recently been used for monitoring rice fields. In this letter, the influence of incidence angle upon these polarimetric observables is analyzed by comparing three stacks of images that were acquired simultaneously at different incidence angles (22°, 30°, and 40°) during a whole cultivation campaign. We show that the response of observables related to dominance (entropy, ratios of components) and type of scattering mechanisms (alpha angles) is not greatly influenced by incidence angle at some stages: early and advanced vegetative phases, and maturation. Moreover, the acquisition geometry drives the sensitivity to the presence of the initial stems and tillers, being detected earlier at shallower angles. This analysis is a necessary step before studying potential methodologies for combining different orbits and beams for reducing the time between acquisitions for monitoring purposes.

Chiral gold(I) vs chiral silver complexes as catalysts for the enantioselective synthesis of the second generation GSK-hepatitis C virus inhibitor

The synthesis of a GSK 2nd generation inhibitor of the hepatitis C virus, by enantioselective 1,3-dipolar cycloaddition between a leucine derived iminoester and tert-butyl acrylate, was studied. The comparison between silver(I) and gold(I) catalysts in this reaction was established by working with chiral phosphoramidites or with chiral BINAP. The best reaction conditions were used for the total synthesis of the hepatitis C virus inhibitor by a four step procedure affording this product in 99% ee and in 63% overall yield. The origin of the enantioselectivity of the chiral gold(I) catalyst was justified according to DFT calculations, the stabilizing coulombic interaction between the nitrogen atom of the thiazole moiety and one of the gold atoms being crucial.