No abstract

and one experimental line (Syn II Pre III), their relationships with H. obscurus populations, and the stimulant or deterrent effects of the root extracts and of individual fatty acids on the weight gain of H. obscurus were investigated. There was an inverse relationship between the insect population size and the palmitic acid content. The Superqueli INIA cultivar contained the highest palmitic acid content and the lowest insect load. When solutions of either palmitic or oleic acids were individually incorporated into an artificial diet, palmitic acid caused a decrease in weight gain, whereas the effect of oleic acid was similar to that of the phagostimulant saccharose. Hence, palmitic acid might be applied directly in H. obscurus control programs to prevent or reduce feeding and oviposition behaviors or might be used as a tool for selecting resistant cultivars.

Red clover (Trifolium pratense L.), a valuable legume in Chile, is important mainly for seed production and as forage for animal production. Although it is considered a perennial, the productivity of this legume declines during the second year of growth primarily because of infestation by the red clover root borer, Hylastinus obscurus (Coleoptera: Curculionidae). Currently, there is no efficient method for controlling this insect, although the use of semiochemicals may provide a new alternative to reduce the damage caused by this curculionid. In this context, E-2-hexenal and limonene, which were previously determined to be an attractant and a repellent, respectively, for H. obscurus, were released from dispensers established in two cultivars (Quiñequeli INIA and Superqueli INIA) and one experimental line (Syn II Pre III) of red clover at the Centro Regional de Investigación Carillanca (INIA-Carillanca) (Vilcún, Chile). H. obscurus was found in significantly higher numbers on plants from areas treated with E-2-hexenal than from areas treated with limonene or in areas that were left untreated as control areas. However, this attractiveness was influenced by the red clover source such that the effect of E-2-hexenal was observed in Superqueli INIA and Syn II Pre III but not in Quiñequeli INIA. Unlike previous studies, limonene had no effect on H. obscurus. Our results provide the first evidence under field conditions for the potential use of E-2-hexenal as an attractant for the red clover root borer H. obscurus.

The insecticidal effects of five ethanolic extracts produced from three species of the genus Maytenus: M. boaria leaf (MBL), M. boaria bark (MBB), M. boaria seed (MBS), M. disticha leaf (MDL) and M. magellanica leaf (MML) were evaluated on the lady beetle Hippodamia convergens (Coleoptera: Coccinellidae) and on the pest of berry Aegorhinus superciliosus (Coleoptera: Curculionidae). The anti-feeding effects of the extracts on the latter were also evaluated. Residual application was used, with five concentrations for each species of insect and ten replications of each assay. To evaluate anti-feeding action in adult A. superciliosus, choice (C) and no-choice (NC) experiments were established to determine the percentage of leaf area consumed. The assays lasted for 120 hours, with the mortality and anti-feeding effect monitored every 24 hours. The highest percentage of mortality in the two insect species was recorded with the MBS ethanolic extract: H. convergens presented 82 %, with LC50: 32 mg/ml; while A. superciliosus presented 85 % in the choice assay and 86 % in the no-choice assay, with LC50: 23 mg/ml. In both assays, the mortality increased with exposure time, reaching its highest at 120 hours. The lowest mortality was obtained with MBB extract in choice (C) and with MML extract in no-choice (NC) assays. In the choice assay, the highest percentage of leaf area consumed was recorded with MBB extract, while in the no-choice assay the highest percentage of consumed was with MML extract, which presented higher values even than the control with no application. The lowest leaf percentage consumed, in both assays, was recorded with MBS extract at the highest concentrations (20 and 30 % w/v).

Even though membrane prices have experienced a notorious decrease during the last years, they still represent an important cost associated with the application of membrane bioreactors (MBR) for wastewater treatment. The operation of MBRs with self-forming dynamic membranes may significantly reduce the associated costs, promoting the application of MBRs. A self-forming dynamic membrane only requires a support material over which a cake layer is formed, that acts as a membrane, which rejects the solids contained in the bioreactor. During the present research 2 sieving meshes of 20 and 100 µm were tested as model materials for the development of self-forming dynamic membranes. Results show that it is possible to support the operation of the reactor in time and to provide a high quality permeate, with turbidity levels below 3 NTU. The employment of a mesh of 100 µm allows to increase the flux but compromises the retention of solids and the removal of organic matter.