L’Université de Neuchâtel, au service de la biodiversité urbaine

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«La gestion de la biodiversité autour d’une Faculté des Sciences se doit d’être exemplaire!» Ce cri du coeur d’un professeur de biologie a été le point de départ d’un projet interdisciplinaire, entre la biologie et l’ethnologie, ayant pour but de remettre la biodiversité au goût de tous à (et autour de) l’Université de Neuchâtel. Lire l’article PDF

Châtaigniers: un patrimoine biologique et culturel

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Une brochure née d’un projet pédagogique en biologie ethnologie, durant lequel nous nous sommes penchés sur les châtaigniers et Dryocosmus kuriphilus, le cynips du châtaignier. Ce document est le résultat d’une démarche participative impliquant des biologistes, des ethnologues, des producteurs de châtaignes et des représentants des services cantonaux et fédéraux concernés.  L’objectif de cette brochure est de redessiner le contour d’un problème “simple” à première vue.   PDF / Dessin: Clotide Rigaud

Plant diversity in a nutshell: testing for small-scale effects on trap nesting wild bees and wasps

Declining plant species richness in agro-ecosystems and thus reduced habitat quality can have cascading effects on ecosystem functioning, leading to reduced pollination and biological control. Here we test if plant diversity can affect arthropod diversity and abundance on a very small scale, manipulating plant species richness (2, 6, 12 and 20 sown species) in small adjacent subplots (63 9 m) in 10 wildflower strips in an agricultural landscape. We simultaneously analyzed the effect of plant species richness, vegetation structure, and plant composition on the species richness and abundance of cavity-nesting wild bees, wasps, their prey and natural enemies, and on the structure of their food webs. By separating the trap-nesting species into functional groups according to their prey, we aimed to understand the underlying patterns for the effects of plant diversity. Increasing plant species richness had a significant effect only on spider-predating wasps, the group of wasps trophically most distant from plants. In contrast, bees and food-web structure were unaffected by plant diversity. Spider-predating wasp abundance negatively correlated with the abundance of spiders, suggesting top-down control. Interestingly, the abundance of spiders was the only variable that was strongly affected by plant composition. The hypothesis that the effect of plant diversity decreases with increasing trophic level is not supported by our study, and the mobility of species appears to play a greater role at this small spatial scale.

Fabian, Y., N. Sandau, O. T. Bruggisser, A. Aebi, P. Kehrli, R. P. Rohr, R. E. Naisbit, and L.-F. Bersier. 2014. Plant diversity in a nutshell: testing for small-scale effects on trap nesting wild bees and wasps. Ecosphere 5(2):18. http://dx. doi.org/10.1890/ES13-00375.1 PDF

Quarantine arthropod invasions in Europe: the role of climate, hosts and propagule pressure

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Aim To quantify the relative importance of propagule pressure, climatematching and host availability for the invasion of agricultural pest arthropods in Europe and to forecast newly emerging pest species and European areas with the highest risk of arthropod invasion under current climate and a future climate scenario (A1F1).

Location Europe.

Methods We quantified propagule pressure, climate-matching and host availability by aggregating large global databases for trade, European arthropod interceptions, KoeppenGeiger world climate classification (including the A1F1 climate change scenario until 2100) and host plant distributions for 118 quarantine arthropod species.

Results As expected, all the three factors, propagule pressure, climate suitability and host availability, significantly explained quarantine arthropod invasions in Europe, but the propagule pressure only had a positive effect on invasion success when considered together with climate suitability and host availability. Climate change according to the A1F1 scenario generally increased the climate suitability of north-eastern European countries and reduced the climate suitability of central European countries for pest arthropod invasions.

Main conclusions To our knowledge, this is the first demonstration that propagule pressure interacts with other factors to drive invasions and is not alone sufficient to explain arthropod establishment patterns. European countries with more suitable climate and large agricultural areas of suitable host plants for pest arthropods should thus be more vigilant about introduction pathways. Moreover, efforts to reduce the propagule pressure, such as preventing pests from entering pathways and strengthening border controls, will become more important in north-eastern Europe in the future as the climate becomes more favourable to arthropod invasions.

PDF available here

Outreach (clic on the images!)

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L’antagoniste du cynips du châtaignier est en Suisse!

Torymus sinensis, le parasitoïde exotique lâché en Italie pour lutter contre le cynips du châtaignier a été détecté pour la première fois en Suisse, au Tessin. L’insecte est arrivé naturellement malgré les précautions environnementales prises par la Suisse.

Un article paru dans La Regione Ticino mardi 10 septembre 2013, PDF

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The importance of landscape and spatial structure for hymenopteran-based food-webs in an agro-ecosystem

Capture d’écran 2013-08-26 à 10.55.331. Understanding the environmental factors that structure biodiversity and food webs among communities is central to assess and mitigate the impact of landscape changes.

2. Wildflower strips are ecological compensation areas established in farmland to increase pollination services and biological control of crop pests and to conserve insect diversity. They are arranged in networks in order to favour high species richness and abundance of the fauna.

3. We describe results from experimental wildflower strips in a fragmented agricultural landscape, comparing the importance of landscape, of spatial arrangement and of vegetation on the diversity and abundance of trap-nesting bees, wasps and their enemies, and the structure of their food webs.

4. The proportion of forest cover close to the wildflower strips and the landscape heterogeneity stood out as the most influential landscape elements, resulting in a more complex trap-nest community with higher abundance and richness of hosts, and with more links between species in the food webs and a higher diversity of interactions. We disentangled the underlying mechanisms for variation in these quantitative food web metrics.

5. We conclude that in order to increase the diversity and abundance of pollinators and biological control agents and to favour a potentially stable community of cavity-nesting hymenoptera in wildflower strips, more investment is needed in the conservation and establishment of forest habitats within agro-ecosystems, as a reservoir of beneficial insect populations.

Fabian Y, Sandau N, Bruggisser OT, Aebi A, Kehrli P, RE and Bersier LF (in press) The importance of landscape and spatial structure for hymenopteran-based food webs in an agro-ecosystem. Journal of Applied Ecology The importance of landscape and spatial structure for hymenopteran-based food webs in an agro-ecosystem dpi:10.1111/1365-2656.12103