Identification of sulcatol, a potential pheromone of the ambrosia beetle Gnathotrichus materiarius (Col., Scolytidae)

We report the identification of a potential pheromone for Gnathotrichus materiarius (Fitch) (Col., Scolytidae). The population sex ratio is close to 1:1, and males initiate attacks on host trees. Headspace and hindgut samples from single males showed the presence of the putative pheromone 6-methyl-5-hepten-2-ol, sulcatol. Unmated males released sulcatol for at least 12 days, and ceased producing the pheromone after 20 days. The peak sulcatol release occurred after 2 days. Males cease production of sulcatol 24 h after being paired with females. Single females were unable to initiate galleries, and no sulcatol was detected from their headspace and hindgut samples. The chiral ratio of the pheromone, observed from headspace samples, was 31% (S)-(+)- and 69% (R)-(-)-sulcatol.

Microspheres of alginate-chitosan containing isoniazid

Isoniazid was encapsulated into microspheres of alginate-chitosan by means of a complex coacervation method in an emulsion system. Since the encapsulation of isoniazid tends to be limited by its hydrophilic characteristics, this study proposes its microencapsulation by adsorption. The particles were prepared in three steps: (1) preparation of a W/O emulsion; (2) phase separation; and (3) adsorption of the drug. The isolated particles were placed in a solution of the drug under stirring to allow adsorption. The morphology and particle size were analysed by scanning electron microscopy (SEM). The isoniazid content was determined by extraction in 1 m phosphate buffer pH 7.5 under stirring for 4 h. Finally, the samples were filtered and analysed in an UV/VIS spectrophotometer at 260 nm. In vitro release tests were carried out in 0.05 m phosphate buffer pH 7.5. The results showed that microspheres of alginate-chitosan obtained were of spherical shape. The emulsion used for microparticle formation allows the preparation of particles with a narrow size distribution. The adsorption observed is probably of chemical nature, i.e. there is an ionic interaction between the drug and the surface of the particles.

Interstitial oxygen mobility in superconducting samples of Bi2Sr2CaCu2O8+y

Since high-temperature superconductors were discovered, several studies have been made on their physical properties, attempting to associate them to the origin of superconductivity. Obviously, the oxygen atoms interstitially dissolved in the matrix have an important role in superconductivity, since they move easily in the lattice. In addition, they contribute to hole creation in the CuO2 planes. Anelastic spectroscopy ( internal friction) measurements are sensitive tools for the study of defects in solids, in particular for oxygen mobility. In this paper, Bi2Sr2CaCu2O8+y samples with several different amounts of interstitial oxygen were analysed by means of anelastic spectroscopy measurements. The measurements were performed by using a torsion pendulum operating at a frequency of about 40 Hz. Complex relaxation structures were observed and attributed to the shift of the oxygen interstitial atoms in BiO chains.

A SIMPLE METHOD FOR DETERMINING LOCATION OF FORAGING ANT NESTS USING LEAF-CUTTING ANTS AS A MODEL

In many situations, it is difficult to evaluate the location of nests of ants, especially in tropical systems, or to determine which trail system corresponds with which nest, as in the case of high-density populations of leaf-cutting ants, Atta spp. Fragments of colored drinking straws coated with an attractant, generally vegetable oil and/or a starchy carbohydrate, are carried by ants and following removal of the attractant are deposited in middens, allowing determination of the origin of foraging workers.

PHEIDOLE ANTS AS POTENTIAL BIOLOGICAL-CONTROL AGENTS OF THE BOLL-WEEVIL, ANTHONOMUS-GRANDIS (COL, CURCULIONIDAE), IN SOUTHEAST BRAZIL

This study evaluates the potential of ants as natural biological control agents of the boil weevil (Anthonomus grandis), during the between-season period, in South-east Brazil. Active adults of Anthonomus were experimentally distributed on the ground of the cotton field. Results show that 20% of the adult Anthonomus are attacked and removed by foraging ants. The native ant Pheidole oliveirai was by far the most efficient predator, accounting for 94% of the predation on Anthonomus. Recruited workers of P. oliveirai were usually very fast at transporting the weevils to their nests. The potential benefit of suppressing overwintering adult Anthonomus during the between-season period is mainly that of reducing the risk of high level infestations during the next cropping cycle.

Effect of boron powder purity on superconducting properties of MgB2

The effect of the properties of starting boron powders on the superconducting properties of MgB2 has been studied. The 92% and 96% pure powders produce lower surface reactivity and larger particle size than the 99% boron powder, as can be seen from Brunauer - Emmett - Teller (BET) and scanning electron microscopy (SEM) results, indicating that the low purity powders cannot be used to archive the same superconducting properties as those of samples made from pure 99% boron powder. However, the purity of 92% and 96% boron powders can be improved by using a simple chemical process, leading to enhanced magnetic critical current densities J(c). From x-ray diffraction (XRD) measurement, oxide impurity has been observed, which might be originated from the B2O3 phase in the boron powders. In order to get high performance MgB2, it is obviously important to control the phase composition and microstructure of amorphous boron starting powders and solid reaction conditions.

ANT (HYM, FORMICIDAE) MOSAIC STABILITY IN BAHIAN COCOA PLANTATIONS - IMPLICATIONS FOR MANAGEMENT

Mapping and collection of ants in cocoa trees in a 1 ha plot in the south of Bahia, Brazil, revealed three dominant species of the ant mosaic: Wasmannia auropunctata, Ectatomma tuberculatum and Azteca chartifex spiriti. A. chartifex demonstrated a larger influence in the cocoa plantation due to its spatial and temporal (1 y) stability in the same cocoa trees, and its capacity for territorial expansion. The management of A. chartifex for controlling insect pests of cocoa is strongly recommended. Considerations of temporal permanence of mosaic dominant ants should be a necessary criteria for ant management in tropical tree crops.

EFFECT OF SESAME (SESAMUM-INDICUM L) ON NEST DEVELOPMENT OF ATTA-SEXDENS-RUBROPILOSA FOREL (HYM, FORMICIDAE)

The present study showed a strong deleterious effect on leaf-cutting ant Atta sexdens rubiopilosa nests supplied exclusively with sesame (Sesamum indicum) leaves in the laboratory. Sesame leaves were initially attractive to workers and later became antifeedant. Eucaliptus alba and Hibiscus rosa-sinensis leaves were used as control.

XPS study on water corrosion of fluorzirconate glasses and their protection by a layer of surface modified tin dioxide nanoparticles

The surface corrosion process associated with the hydrolysis of fluorozirconate glass, Z-BLAN (53ZrF(4), 20BaF(2), 20NaF, 4LaF(2), 3AlF(3)), and the corrosion protection efficiency of a nanocrystalline transparent SnO2 layer were investigated by X-ray photoelectron spectroscopy. The tin oxide film was deposited by the sol-gel dip-coating process in the presence of Tiron(R) as particle surface modifier agent. The chemical bonding structure and composition of the surface region of coated and non-coated ZBLAN were studied before water contact and after different immersion periods (5-30 min). In contrast to the effects occurring for non-coated glass, where the surface undergoes a rapid selective dissolution of the most soluble species inducing the formation of a new surface phase consisting of stable zirconium oxyfluoride, barium fluoride and lanthanum fluoride species, the results for the SnO2-coated glass showed that the hydrolytic attack induces a filling of the film nanopores by dissolved glass material and the formation of tin oxylluoride and zirconium oxyfluoride species. This process results in a modified film, which acts as a hermetic diffusion barrier protecting efficiently the glass surface. (C) 2006 Elsevier B.V. All rights reserved.

Population dynamics of Lucilia eximia (Dipt., Calliphoridae)

The theoretical dynamics of experimental populations of Lucilia eximia was investigated as an attempt to understand its population biology. Specifically the population dynamics of L. eximia was analysed by means of a mathematical model that incorporates fecundity and survival as density-dependent demographic parameters in discrete time. The sensitivity of these parameters to changes in the magnitude was also investigated. The mathematical model applied to experimental populations of L. eximia predicts a theoretical one-point equilibrium for immatures. The population dynamics of L. eximia is compared to the dynamics of Chrysomya species and Cochliomyia macellaria.

Boron deficiency inhibits petiole and peduncle cell development and reduces growth of cotton

The effect of boron (B) on cotton growth and fruit shedding may be due not only to physiological or biochemical effects, but also to vascular tissue malformation. This experiment investigated petiole and floral peduncle anatomical alterations and growth of cotton supplied with deficient and sufficient B in nutrient solution. Cotton (Gossypium hirsutum cv. 'Delta Opal') plants were grown in solutions containing 0, 1.5, 3.0, 4.5, and 6.0 mu mol L-1 of B from 22 to 36 d after plant emergence (DAPE). From 36 to 51 DAPE, B was omitted from the nutrient solution. Petioles from young leaves and floral bud peduncles (first position of the first sympodial) were sampled and the cross-section anatomy observed under an optical microscope. The number of vascular bundles of the petiole was decreased in B-deficient plants and the xylem was disorganized. Phloem elements in the peduncle vascular cylinder of B-deficient plants did not show clear differentiation. The few xylem elements that were formed were also disorganized. Modifications caused by B deficiency may have impaired B and photosynthate translocation into new cotton growth. Boron accumulation in the shoot of B-deficient plants suggested that there was some B translocation within the plant. It could be inferred that cotton growth would be impaired by the decrease in carbohydrate translocation rather than by B deficiency in the tissue alone.

Larval dispersal in Chrysomya megacephala, Chrysomya putoria and Cochliomyia macellaria (Dipt., Calliphoridae): Ecological implications of aggregation behaviour

In this study we investigate aggregated patterns as a consequence of post-feeding larval dispersal in three blowfly species, based on the frequency distribution of sampling units in the substrate having 0, 1, 2,..., n pupae. Statistical analysis revealed that aggregated patterns of distribution emerge as a consequence of larval dispersal, and Cochliomyia macellaria has higher levels of aggregation when compared to Chrysomya megacephala and C. putoria. Aggregation during dispersal is associated with a spatial pattern where most larvae in the species tend to pupariate near the food source. The possible consequences for the population ecology of these species are discussed.