Quantifying variation in the ability of yeasts to attract Drosophila melanogaster

Yeasts that invade and colonise fruit significantly enhance the volatile chemical diversity of this ecosystem. These modified bouquets are thought to be more attractive to Drosophila flies than the fruit alone, but the variance of attraction in natural yeast populations is uncharacterised. Here we investigate how a range of yeast isolates affect the attraction of female D. melanogaster to fruit in a simple two choice assay comparing yeast to sterile fruit. Of the 43 yeast isolates examined, 33 were attractive and seven repellent to the flies. The results of isolate-versus-isolate comparisons provided the same relative rankings. Attractiveness varied significantly by yeast, with the strongly fermenting Saccharomyces species generally being more attractive than the mostly respiring non-Saccharomyces species (P = 0.0035). Overall the habitat (fruit or other) from which the isolates were directly sampled did not explain attraction (P = 0.2352). However, yeasts isolated from fruit associated niches were more attractive than those from non-fruit associated niches (P = 0.0188) regardless of taxonomic positioning. These data suggest that while attractiveness is primarily correlated with phylogenetic status, the ability to attract Drosophila is a labile trait among yeasts that is potentially associated with those inhabiting fruit ecosystems. Preliminary analysis of the volatiles emitted by four yeast isolates in grape juice show the presence/absence of ethanol and acetic acid were not likely explanations for the observed variation in attraction. These data demonstrate variation among yeasts for their ability to attract Drosophila in a pattern that is consistent with the hypothesis that certain yeasts are manipulating fruit odours to mediate interactions with their Drosophila dispersal agent. © 2013 Palanca et al

Aktive Medienarbeit in einem mediatisierten Umfeld

Aktive Medienarbeit ist eine der zentralen Methoden der Medienpädagogik. Mit der medialen Durchdringung der Gesellschaft und den technischen Entwicklungen des sogenannten „Social Web“ verändern sich die zentralen Bedingungen der Sozialisation und damit einhergehend auch die Rahmenbedingungen aktiver Medienarbeit entscheidend: So ist es heute keine Frage mehr, dass sich Pädagogik mit Medien beschäftigen muss, vielmehr geht es um die Frage, ob diese Beschäftigung die Potenziale von Medien wahrnimmt und nutzt oder ob Medien an sich als problematisch und gefährdend betrachtet werden. Folgt man dem Konzept der aktiven Medienarbeit, steht die Antwort fest: Ziel der aktiven Medienarbeit ist es von jeher, das Interesse Heranwachsender an Medien ernst zu nehmen und sie dabei zu unterstützen, mit Medien ihre Anliegen und Sichtweisen auszudrücken