Université de Fribourg

Anthropogenic disturbance as a driver of microspatial and microhabitat segregation of cytotypes of Centaurea stoebe and cytotype interactions in secondary contact zones

Mráz, Patrik ; Španiel, Stanislav ; Keller, Andreas ; Bowmann, Gillianne ; Farkas, Alexandre ; Šingliarová, Barbora ; Rohr, Rudolf P. ; Broennimann, Olivier ; Müller-Schärer, Heinz

In: Annals of Botany, 2012, p. -

Background and Aims: In a mixed-ploidy population, strong frequency-dependent mating will lead to the elimination of the less common cytotype, unless prezygotic barriers enhance assortative mating. However, such barriers favouring cytotype coexistence have only rarely been explored. Here, an assessment is made of the mechanisms involved in formation of mixed-ploidy populations and coexistence of...

Université de Neuchâtel

Selective sequestration and metabolism of plant derived pyrrolizidine alkaloids by chrysomelid leaf beetles

Hartmann, Thomas ; Witte, Ludger ; Ehmke, Adelheid ; Theuring, Claudine ; Rowell-Rahier, Martine ; Pasteels, Jacques M.

In: Phytochemistry, 1997, vol. 45, no. 3, p. 489-497

Pyrrolizidine alkaloids (PAs) are assumed to function as plant defence compounds against herbivory. A number of adapted insects are known to sequester plant derived PAs for their own benefit. Here we summarize the chemical interactions between leaf beetles of the genus Oreina (Coleoptera, Chrysomelidae) and their host plants Adenostyles spp., Senecio nemorensis, and S....

Université de Neuchâtel

Distribution of autogenous and host-derived chemical defenses in Oreina leaf beetles (Coleoptera: Chrysomelidae)

Pasteels, Jacques M. ; Dobler, Susanne ; Rowell-Rahier, Martine ; Ehmke, Adelheid ; Hartmann, Thomas ; Pasteels, Jacques M. ; Dobler, Susanne ; Rowell-Rahier, Martine ; Ehmke, Adelheid ; Hartmann, Thomas

In: Journal of Chemical Ecology, 1995, vol. 21, no. 8, p. 1163-1179

The pronotal and elytral defensive secretions of 10 Oreina species were analyzed. Species feeding on Apiaceae, i.e., O. frigida and O. viridis, or on Cardueae (Asteraceae), i.e., O. bidentata, O. coerulea, and O. virgulata, produce species-specific complex mixtures of autogenous cardenolides. O. melanocephala, which feeds on Doronicum clusii...

Université de Neuchâtel

Sequestration of plant pyrrolizidine alkaloids by chrysomelid beetles and selective transfer into the defensive secretions

Rowell-Rahier, Martine ; Witte, Ludger ; Ehmke, Adelheid ; Hartmann, Thomas ; Pasteels, Jacques M.

In: Chemoecology, 1991, vol. 2, no. 1, p. 41-48

Oreina cacaliae and O. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plants...