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Université de Fribourg

Temporal and spatial variations in the parasitoid complex of the horse chestnut leafminer during its invasion of Europe

Grabenweger, Giselher ; Kehrli, Patrik ; Zweimüller, Irene ; Augustin, Sylvie ; Avtzis, Nikolaos ; Bacher, Sven ; Freise, Jona ; Girardoz, Sandrine ; Guichard, Sylvain ; Heitland, Werner ; Lethmayer, Christa ; Stolz, Michaela ; Tomov, Rumen ; Volter, Lubomir ; Kenis, Marc

In: Biological Invasions, 2010, vol. 12, no. 8, p. 2797-2813

The enemy release hypothesis posits that the initial success of invasive species depends on the scarcity and poor adaptation of native natural enemies such as predators and parasitoids. As for parasitoids, invading hosts are first attacked at low rates by a species-poor complex of mainly generalist species. Over the years, however, parasitoid richness may increase either because the invading host...

Université de Fribourg

Disentangling the role of environmental and human pressures on biological invasions across Europe

Pyšek, Petr ; Jarošík, Vojtěch ; Hulme, Philip E. ; Kühn, Ingolf ; Wild, Jan ; Arianoutsou, Margarita ; Bacher, Sven ; Chiron, Francois ; Didžiulis, Viktoras ; Essl, Franz ; Genovesi, Piero ; Gherardi, Francesca ; Hejda, Martin ; Kark, Salit ; Lambdon, Philip W. ; Desprez-Loustau, Marie-Laure ; Nentwig, Wolfgang ; Pergl, Jan ; Poboljšaj, Katja ; Rabitsch, Wolfgang ; Roques, Alain ; Roy, David B. ; Shirley, Susan ; Solarz, Wojciech ; Vilà, Montserrat ; Winter, Marten

In: Proceedings of the National Academy of Sciences of the United States of America, 2010, vol. 107, no. 27, p. 12157-12162

The accelerating rates of international trade, travel, and transport in the latter half of the twentieth century have led to the progressive mixing of biota from across the world and the number of species introduced to new regions continues to increase. The importance of biogeographic, climatic, economic, and demographic factors as drivers of this trend is increasingly being realized but as yet...

Université de Fribourg

Effects of vineyard management on biodiversity at three trophic levels

Bruggisser, Odile T. ; Schmidt-Entling, Martin H. ; Bacher, Sven

In: Biological Conservation, 2010, vol. 143, no. 6, p. 1521-1528

In annual crops, where disturbance intensities are generally high, numerous investigations demonstrated beneficial effects of organic and other extensive farming practices on biodiversity. It is however unclear if organic farming has the same beneficial effect in perennial crops (e.g. vineyards) because of a generally reduced background disturbance level. Moreover, the impact of farming practices...

Université de Fribourg

Water limitation prevails over energy in European diversity gradients of sheetweb spiders (Araneae: Linyphiidae)

Kumschick, Sabrina ; Schmidt-Entling, Martin H. ; Bacher, Sven ; Hickler, Thomas ; Entling, Wiebke ; Nentwig, Wolfgang

In: Basic and Applied Ecology, 2009, vol. 10, no. 8, p. 754-762

Across large spatial scales, species richness in many taxa is mainly determined by climatic variables. However, some of the mechanisms behind large-scale patterns of species richness and abundance are expected to act on the community level, and on a smaller scale than the resolution of the data commonly used for deriving these patterns. We studied the distribution of sheetweb spiders (Araneae:...

Université de Fribourg

Body size–climate relationships of European spiders

Entling, Wiebke ; Schmidt-Entling, Martin H. ; Bacher, Sven ; Brandl, Roland ; Nentwig, Wolfgang

In: Journal of Biogeography, 2009///doi: 10.1111/j.1365-2699.2009.02216.x

Aim: Geographic body size patterns of mammals and birds can be partly understood under the framework of Bergmann's rule. Climatic influences on body size of invertebrates, however, appear highly variable and lack a comparable, generally applicable theoretical framework. We derived predictions for body size–climate relationships for spiders from the literature and tested them using three...

Université de Fribourg

Alien species in a warmer world: risks and opportunities

Walther, Gian-Reto ; Roques, Alain ; Hulme, Philip E. ; Sykes, Martin T. ; Pyšek, Petr ; Kühn, Ingolf ; Zobel, Martin ; Bacher, Sven ; Botta-Dukát, Zoltán ; Bugmann, Harald ; Czúcz, Bálint ; Dauber, Jens ; Hickler, Thomas ; Jarošík, Vojtěch ; Kenis, Marc ; Klotz, Stefan ; Minchin, Dan ; Moora, Mari ; Nentwig, Wolfgang ; Ott, Jürgen ; Panov, Vadim E. ; Reineking, Björn ; Robinet, Christelle ; Semenchenko, Vitaliy ; Solarz, Wojciech ; Thuiller, Wilfried ; Vilà, Montserrat ; Vohland, Katrin ; Settele, Josef

In: Trends in Ecology & Evolution, 2009, vol. 24, no. 12, p. 686-693

Climate change and biological invasions are key processes affecting global biodiversity, yet their effects have usually been considered separately. Here, we emphasise that global warming has enabled alien species to expand into regions in which they previously could not survive and reproduce. Based on a review of climate-mediated biological invasions of plants, invertebrates, fishes and birds, we...

Université de Fribourg

A generic impact-scoring system applied to alien mammals in Europe

Nentwig, Wolfgang ; Kühnel, Elfi ; Bacher, Sven

In: Conservation Biology, 2009///doi: 10.1111/j.1523-1739.2009.01289.x

We present a generic scoring system that compares the impact of alien species among members of large taxonomic groups. This scoring can be used to identify the most harmful alien species so that conservation measures to ameliorate their negative effects can be prioritized. For all alien mammals in Europe, we assessed impact reports as completely as possible. Impact was classified as either...

Université de Fribourg

PRATIQUE: a research project to enhance pest risk analysis techniques in the European Union

Baker, R. H. A. ; Battisti, A. ; Bremmer, J. ; Kenis, M. ; Mumford, J. ; Petter, F. ; Schrader, G. ; Bacher, Sven ; Barro, P. De ; Hulme, P. E. ; Karadjova, O. ; Lansink, A. O. ; Pruvost, O. ; Pyšek, P. ; Roques, A. ; Baranchikov, Y. ; Sun, J.-H.

In: EPPO Bulletin, 2009, vol. 39, no. 1, p. 87 - 93

PRATIQUE is an EC-funded 7th Framework research project designed to address the major challenges for pest risk analysis (PRA) in Europe. It has three principal objectives: (a) to assemble the datasets required to construct PRAs valid for the whole of the EU, (b) to conduct multi-disciplinary research that enhances the techniques used in PRA and (c) to provide a decision support scheme for PRA...

Université de Fribourg

Establishing systemic rust infections in Cirsium arvense in the field

Wandeler, Heiri ; Nentwig, Wolfgang ; Bacher, Sven

In: Biocontrol Science and Technology, 2008, vol. 18, no. 2, p. 209-214

An existing method to induce systemic rust infections in creeping thistles (Cirsium arvense) using an insect vector, the weevil Ceratapion onopordi, was successfully applied in the field. Urediniospores of Puccinia punctiformis were experimentally transmitted to naturally grown thistles, to our knowledge for the first time resulting in systemically infected shoots in an established thistle...

Université de Fribourg

Functional responses: a question of alternative prey and predator density

Tschanz, Britta ; Bersier, Louis-Félix ; Bacher, Sven

In: Ecology, 2007, vol. 88, no. 5, p. 1300–1308

Throughout the study of ecology, there has been a growing realization that indirect effects among species cause complexity in food webs. Understanding and predicting the behavior of ecosystems consequently depends on our ability to identify indirect effects and their mechanisms. The present study experimentally investigates indirect interactions arising between two prey species that share a...