Abstract The condition called "river disease" (MDR by its acronym in Spanish) is an intoxication in immature stages of honey bees caused by a compound from the genus Sebastiania Spreng and concentrated in the exudates of Epormenis cestri Berg. Our objective was to determine the temporal dynamics of the life cycle of E. cestri, its association with the predominant vegetation components and the influence of the Uruguay river on the size of its populations. With this aim, we selected 5 sites in the vicinity of the Uruguay river where populations of E. cestri were sampled using the Stem-tap technique modified for this purpose. The effect of landscape components on the abundance of E. cestri was evaluated using GLMM. It was determined that the hatching of the E. cestri eggs was in mid-October, finding a staggered distribution of its phenophases. In addition, we found significantly negative effects of the Espinal forest cover and the increase in the distance from the banks of the Uruguay river on the total abundance of E. cestri. This work shows some first clues for the understanding of how the components of the landscape structure the populations of E. cestri, allowing to predict the critical moment of incidence of MDR.

This article is about the life paths of teenagers who obtain their certificate in technical secondary schools and come from low income social sectors, and also about their opinion about this educational model. It results from a qualitative research that tried to find the sense of technical secondary school from the traces the school left in the young people who get their certificate. 32 adolescents from an urban environment were interviewed, connected by the educational institutions themselves. The results of the study show that the techn ical secondary education does not necessarily allow for thepeople who obtain a diploma to keep studyingin higher technical studies (high school or university). The possibility to keep studying is observed only in specific conditions, above all when there is a family anchor (a father or a member of thefamily who has aformaljob). In this sense, the early technological training offered by the technical secondary education does not define necessarily the paths, nor it reduces the subject's freedom to choose it, although it conditions in some way their horizons. The possibility to keep studying at high school or university emerges as a distinguishingfac-tor for the teenagers who obtained their certificate, when taking into account also phenomena as social condition and gender.

El artículo da cuenta de las trayectorias de vida de jóvenes egresados de la secundaria técnica procedentes de sectores sociales de escasos recursos, así como sus valoraciones acerca de esa modalidad educativa. Es resultado de una investigación cualitativa que buscaba inferir el sentido de la secundaria técnica desde las huellas que permanecieron en los egresados. Fueron entrevistados 32 jóvenes urbanos, a los cuales se accedió principalmente desde instituciones educativas. Los resultados del estudio muestran que la secundaria técnica no da lugar necesariamente a que sus egresados logren la continuidad de estudios técnicos de nivel medio o superior. Estas continuidades sólo tienen lugar bajo ciertas condiciones, en particular cuando existe un ancla familiar representada por un padre o un familiar que ejerce un oficio. En el mismo sentido, la formación tecnológica temprana brindada por la secundaria técnica, no determina las trayectorias ni reduce la libertad de elección de los sujetos, aun cuando condiciona horizontes. La continuación de estudios, tanto de educación media como superiores, emerge como un factor diferenciador de los egresados, cruzado con condición social y género.

The effect of odor signals on the locomotor activity of Cycloneda sanguinea and Harmonia axyridis was evaluated using two different actometric devices. The purpose of the analysis was to differentiate between the responses elicited by direct contact with the substrates and the responses that occurred if the coccinellids were exposed only to volátiles and had no direct substrate contact. The odor profile of the environmental volátiles (semiochemicals) in the bioassays was analyzed using an electronic nose (Modular Sensor System Moses II). The treatments used included volatiles emitted by pepper leaves (healthy or infested with Myzus persicae), M. persicae molts and honeydew, and healthy leaves treated with an artificial inducer of the systemic acquired response to herbivory (AISAR). The results suggest that a specific stimulus linked to aphid-host interaction would trigger a distinctive locomotor activity pattern in H. axyridis, with or without any contact with the aphids or the host plant. In contrast, C. sanguinea was not able to differentiate between volatiles from infested or uninfected pepper leaves or to distinguish these volatiles from clean filter paper (control). If C. sanguinea was in contact with aphid-infested pepper leaves (regardless of the previous prey density), it moved slowly and scanned the area exhaustively; H. axyridis showed significantly reduced locomotor activity when it was in contact with aphid-infested pepper leaves or aphid molts and honeydew, all reliable signals of the presence of a food source. In both species, treatment with Actigard (AISAR: Acibenzolar-S-methyl) failed to evoke the behavioral response observed in the treatment with aphid-infested pepper plants. The study also demonstrated that the E-nose can differentiate among blends of volatiles released from cut healthy or aphid-infested pepper leaves.

El efecto de los semioquímicos volátiles en la actividad locomotriz de Cycloneda sanguinea y Harmonia axyridis fue evaluado mediante el empleo de dos actómetros, a fin de estudiar cambios en las respuestas de los coccinélidos en contacto directo con los sustratos y los expuestos solamente a las sustancias volátiles. El perfil de volátiles implícitos en los bioensayos se analizaron mediante una nariz electrónica (Modular Sensor System Moisés II). Los tratamientos incluyeron el uso de los compuestos volátiles emitidos por hojas de pimiento sanas o infestadas conMyzus persicae, excretas de M. persicae, hojas sanas tratadas con Actigard (Acibenzolar-S-methyl). Los resultados del presente estudio sugieren que un estímulo específico vinculado a la interacción áfido-hospedero desencadenó un patrón de actividad locomotriz distintivo en H. axyridis, estando en contacto, o no, con la planta hospedera. En cambio, C. sanguinea no mostró cambios significativos en sus patrones de comportamiento ante la exposición a los volátiles. Una vez que C. sanguinea estuvo en contacto con hojas infestadas (independientemente de la densidad de áfidos), se movió lentamente, examinando exhaustivamente la zona. H. axyridis mostró una reducción significativa de la actividad locomotriz cuando estuvo en contacto con las hojas de pimiento infestadas o excretas de áfidos, actuando éstas como señales de una fuente confiable de alimento. El tratamiento con Actigard no evocó, en ambas especies de Coccinellidae, la misma respuesta comportamental que las plantas de pimiento infestadas con áfidos. Además, se demuestra que la nariz electrónica es capaz de diferenciar entre las mezclas de volátiles liberados de hojas de pimiento sanas o infestadas con áfidos.

Este texto faz parte de uma série de ensaios escritos no âmbito do Projeto Inovações Educacionais na América Latina, desenvolvido pela Unesco com diferentes países da região. Tais ensaios representam um esforço para lançar luz sobre diferentes significados que podem ser atribuídos ao conceito de inovação, de modo que possibilite que os grupos envolvidos com a temática estabeleçam, mediante consenso, um conjunto de referências teóricas capazes de balizar a escolha e a análise das experiências que sinalizam efetivas modificações nas práticas educativas.

This is part of a serie of essays written for the Educational Innovations Project developed by Unesco with different countries of the region. These essays attempt to shed light on the different meanings that can be attributed to the concept of innovation, in order to make possible for the groups involved with the theme to establish a group of theoretical references by consensus to serve as landmarks in the choice and analysis of experiences of effective change in educational practices.