NEWS

:: August 2015

:: New paper published

Here we present a new set of 45 primers designed to target a wide range of invertebrate taxa common to temperate cereal crops: cereal aphids, their natural enemies such as carabid beetles, ladybeetles, lacewings, and spiders, and potential alternative prey groups (earthworms, springtails, and dipterans).

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:: August 2015

:: New paper published

In this paper we present Food Web Designer, a stand-alone, highly flexible and user friendly software tool to quantitatively visualize trophic and other types of bipartite and tripartite interaction networks.

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:: March 2015

:: New paper published

In a field cage experiment, we investigated the effect of increased predator diversity (single species vs. three-species assemblages) and the presence of weeds (providing structural complexity) on the biological control (process speed) of cereal aphids during conditions of high aphid abundances close to crop heading.

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:: October 2014

:: Appeal project extended

The Appeal-project has been granted a cost neutral extension with one year until Dec 2015.

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:: May 2014

:: New paper published

In this paper we examined how the management options of organic farming at the field scale and crop diversification at the landscape level affect the taxonomic and functional structure of generalist predator communities and how these effects vary along a landscape complexity gradient.

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:: May 2014

:: Workshop held in Darmstadt

A workshop hosted by Nico Blüthgen was held in Darmstadt, Germany 12-13 May 2014.

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:: January 2014

:: New paper published

In this paper a conceptual framework is presented for predicting land-use impact on biological control of pests by natural enemies.

READ MORE>>>

NEWS

August 2015
New paper published
Here we present a new set of 45 primers designed to target a wide range of invertebrate taxa common to temperate cereal crops: cereal aphids, their natural enemies such as carabid beetles, ladybeetles, lacewings, and spiders, and potential alternative prey groups (earthworms, springtails, and dipterans). These primers were combined in three ‘ready to use’ multiplex PCR assays for quick and cost-effective analyses of large numbers of predator samples. The assays were tested on 560 carabids collected in barley fields in Sweden. Results from this screening suggest that aphids constitute a major food source for carabids in cereal crops (overall DNA detection rate: 51 %), whereas alternative extraguild and intraguild prey appear to be less frequently preyed upon when aphids are present (11 % for springtails and 12 % for earthworms; 1 % for spiders and 4 % for carabids). In summary, the newly developed molecular assays proved reliable and effective in assessing previously cryptic predator–prey trophic interactions, specifically with focus on biological control of aphids. The diagnostic PCR assays will be applicable manifold as the targeted invertebrates are common to many agricultural systems of the temperate region.

Staudacher, K., Jonsson, M. & Traugott, M. 2015. Easy to use molecular assays to unravel food web interactions in cereal crops with focus on biological control of aphids. Journal of Pest Science, available online in advance of print

[LINK]

August 2015
New paper published
In this paper we present Food Web Designer, a stand-alone, highly flexible and user friendly software tool to quantitatively visualize trophic and other types of bipartite and tripartite interaction networks. It is offered free of charge for use on Microsoft Windows platforms. Food Web Designer is easy to use without the need to learn a specific syntax due to its graphical user interface. Up to three (trophic) levels can be connected using links cascading from or pointing towards the taxa within each level to illustrate top-down and bottom-up connections. Link width/strength and abundance of taxa can be quantified, allowing generating fully quantitative networks. Network datasets can be imported, saved for later adjustment and the interaction webs can be exported as pictures for graphical display in different file formats. We show how Food Web Designer can be used to draw predator–prey and host-parasitoid food webs, demonstrating that this software is a simple and straightforward tool to graphically display interaction networks for assessing pest control or any other type of interaction in both managed and natural ecosystems from an ecological network perspective.

Sint, D. & Traugott, M. 2015. Food Web Designer: a flexible tool to visualize interaction networks. Journal of Pest Science, available online in advance of print

[LINK]

March 2015
New paper published
In a field cage experiment, we investigated the effect of increased predator diversity (single species vs. three-species assemblages) and the presence of weeds (providing structural complexity) on the biological control (process speed) of cereal aphids during conditions of high aphid abundances close to crop heading. We furthermore investigated the mechanisms involved using molecular gut content analysis. The impact of the three-predator species assemblages of aphid populations was found to be similar to those of the single-predator species treatments, and the presence or absence of weeds did not alter the patterns observed. This suggests that both predator facilitation and intraguild predation were absent or weak in this system, or that these interactions had counteracting effects on prey suppression. Molecular gut content analysis of predators provided little evidence for the latter hypothesis: predator facilitation was not detected and intraguild predation occurred at a low frequency. The present study suggests additive effects of predators and, therefore, that predator diversity per se neither strengthens nor weakens the process speed of biological control of aphids when abundances of aphid are high.

Roubinet, E., Straub, C., Jonsson, T., Staudacher, K., Traugott, M., Ekbom, B. & Jonsson, M. 2015. Additive effects of predator diversity on pest control caused by few interactions among predator species. Ecological Entomology, 40, 362-371.

[LINK]

October 2014
Appeal project extended

The Appeal-project has been granted a cost neutral extension with one year until Dec 2015. This extension will be used to complete food-web analyses, modelling and valuation of biological control, and to continue presenting results to stakeholders and the scientific community.

May 2014
New paper published

In this paper we examined how the management options of organic farming at the field scale and crop diversification at the landscape level affect the taxonomic and functional structure of generalist predator communities and how these effects vary along a landscape complexity gradient. Organic farming as well as landscapes with longer and more diversified crop rotations enhanced the activity-density of spiders and rove beetles, but not the species richness or evenness. Our results indicate that the two management options affected the functional composition of communities, as they primarily enhanced the activity-density of functionally similar species. The two management options increased the functional similarity between spider species in regards to hunting mode and habitat preference. Organic farming enhanced the functional similarity of rove beetles. Management options at field and landscape levels were generally more important predictors of community structure when compared to landscape complexity. Our study highlights the importance of considering the functional composition of generalist predators in order to understand how agroenvironmental measures at various scales shape community assemblages and ecosystem functioning in agricultural landscapes.

Rusch, A., Birkhofer, K., Bommarco, R., Smith, H.G., Ekbom, B. (2014)  Management intensity at field and landscape levels affects the structure of generalist predator communities. Oecologia, 175: 971-983. [LINK]

May 2014
Workshop held in Darmstadt

A workshop hosted by Nico Blüthgen was held in Darmstadt, Germany 12-13 May 2014. The workshop was held jointly between Appeal and a closely related project. The primary aim was to discuss various approaches to analyses of the food-web data collected in these two projects, and to draw up plans for future publications. The valuation work was also discussed and planned.



Participants of the workshop from left: Karin Staudacher (UIBK), Riikka Kaartinen (SLU), Klaus Birkhofer (Lund university), Tomas Jonsson (SLU), Daniela Sint (UIBK), Eve Roubinet (SLU), Oskar Rennstam-Rubbmark (UIBK), Vesna Gagic (SLU), Nico Blüthgen (University of Darmstadt), Michael Traugott (UIBK), Mattias Jonsson (SLU), Riccardo Bommarco (SLU), Missing from the photo are: Joachim Spangenberg, Susanne Mauren and Oliver Schweiger (all UFZ).

January 2014
New paper published

In this paper a conceptual framework is presented for predicting land-use impact on biological control of pests by natural enemies. A mechanistic landscape model is developed for biological control of cereal aphids, explicitly accounting for the influence of landscape composition on natural enemies varying in mobility, feeding rates, and other life history traits. This model is then used to map biological control services across cereal fields in a Swedish agricultural region with varying landscape complexity. The model predicted that biological control would reduce crop damage by 45 – 70% and that the biological control effect would be higher in complex landscapes. In a validation with independent data, the model performed well and predicted a significant proportion of biological control variation in cereal fields. However, much variability remains to be explained, and the model could be improved by refining the mechanistic understanding of predator dynamics and accounting for variation in aphid colonization. If this kind of ecological production function is combined with production functions for other services, the joint model will be a powerful tool for managing ecosystem services and planning for sustainable agriculture at the landscape scale.

Jonsson, M., Bommarco, R., Ekbom, B., Smith, H.G., Bengtsson, J., Caballero-Lopez, B., Winqvist, C. & Olsson, O. (2014) Ecological production functions for biological control services in agricultural landscapes. Methods in Ecology and Evolution, doi/10.1111/2041-210X.12149

The figure shows the predicted biological control effect by the model across the Swedish region of Scania. Red color indicates effective biological control.

December 2013
Interview-work conducted

Joachim Spangenberg carried out interviews in Southern Sweden, with assistance from Juliana Dänhardt in the related SAPES-project. This work will contribute to a qualitative study aiming at identifying mechanisms how ecosystem services are recognised and managed, which efforts are invested, which kind of cost-benefit calculation is undertaken by the farmers, what is the role of external institutions and the information they provide, and the discussion amongst neighbours. The interviews were conducted along a transect of increasing biological control potential, as identified by the APPEAL-supported study by Rusch et al. 2013.

Joachim Spangenberg during a visit to one of the farms.

October 2013
Result presented at Symposium on Ecological Networks in Coimbra, Portugal

Preliminary results from the empirical work in Appeal were presented at the Symposium on Ecological Networks by the postdocs Karin Staudacher and Riikka Kaartinen. Karins talk was titled “How weeds affect aphid-predator food web interactions in cereal fields”. In her talk Karin presented her work on food-web interactions and biological control of aphids using molecular techniques. Riikkas talk concerned her combined experimental and modelling work on “Predicting food web interactions: how much body size counts?”. Nico Blüthgen, Mattias Jonsson and Daniela Sint also participated in the symposium and all contributed with oral presentations.

Karin Staudacher during her talk in Coimbra.

August 2013
New paper published

The second APPEAL-funded paper has been published. This paper explores how the ground beetle fauna has changed over time in a Swedish region by comparing two datasets collected with an interval of 24 years. During this time period there was a change in agricultural policy through the introduction of a national pesticide risk reduction program which is likely to have influenced the predator fauna. Although the study found no changes in ground beetle species richness and community evenness over time, there were differences in dominance distribution and functional composition. Ground beetles collected in the 1980s had higher proportions of carnivorous, cursorial, and small and intermediate size beetles than those collected in 2003. Communities sampled in 2003 had increased proportions of omnivorous, mobile, spring breeding, and large beetle species. These shifts in functional characteristics of ground beetle communities may improve biological control of cereal aphids and reduce variability in this ecosystem service overtime.

Read more:
Rusch A, R Bommarco, P Chiverton, S Öberg, H Wallin, S Wiktelius & B Ekbom (2013) Response of ground beetle (Coleoptera, Carabidae) communities to changes in agricultural policies in Sweden over two decades. Agriculture, Ecosystems and Environment, 176, 63-69.
[LINK]

June-July 2013
Green-house experiment in progress

A mesocosm experiment led by Postdoc Riikka Kaartinen is conducted in Uppsala during the summer 2013. Riikka is investigating how body size and guild identity of different predator species will affect the suppression of aphids and the level of intra-guild predation among the predators. During the coming months molecular gut content analysis will be conducted to estimate the strength of different trophic interactions and the results of the experiment will be compared with results of simulations. This work is expected to provide us with a better ability to predict which traits a predator should have to be an effective biological control agent.

April 2013
First paper published

The first APPEAL-funded paper has been published. It explores how landscape complexity and crop rotation in the landscape affects biological control of cereal aphids. Predator exclusion cages (see photo) were used to assess the impact of natural enemies on aphid population growth rates in fields located in different landscape context. We found that the overall level of pest control increased with landscape complexity and that this effect was independent of crop rotation intensity. In addition, the within-field stability in pest control services increased with crop rotation intensity in the landscape, although stability in parasitism rates decreased.

Read more:
Rusch A, R Bommarco, M Jonsson, HG Smith & B Ekbom (2013) Flow and stability of natural pest control services depend on complexity and crop rotation at the landscape scale. Journal of Applied Ecology, 50, 345-354.

28 February 2013
Workshop on network-analysis organized

A workshop was held in Uppsala on the application of network-analysis. The workshop was attended by representatives of the Uppsala and Innsbruck-teams and by associated researchers from Lund University. Tomas Jonsson and Riikka Kaartinen held general lectures on the history, theory and practical applications of network analyses, and several projects with bearing on network analysis were presented and discussed. In particular we discussed how molecular-gut content data may be used to parameterize food webs, and how available statistical packages may need to be further developed to handle complex, multiple-trophic level networks.

8-10 January 2013
Annual project meeting held in Obergurgl, Austria

The annual APPEAL meeting this year was held in Obergurgl, Austria. Apart from the three project partners, the meeting was attended by a representative of the advisory board, Dr. Sylvia Bluemel, AGES, Austria. During the meeting, progress and plans for the different work packages were presented, and Dr. Bluemel gave input on the project. Two major points of discussion were how to link empirical work with food-web analyses in WP2, and how to connect biocontrol modeling in WP3 with the valuation work in WP4. An excursion was also made to enjoy the mountain views at the top of Hohe Mut and to learn about the research on arthropod food-webs at the receding glacier front conducted by the Innsbruck-team.

Fieldwork 2012 finished

A major field experiment was conducted in the APPEAL project during the summer 2012. The aim was to compare how the aphid-predatoralternative prey foodwebs and biocontrol services differ between barley fields located in different landscape context and in plots with and without herbicide application.

The experiment was conducted in Scania, Southern Sweden and was led by Dr. Karin Staudacher with support from a number of enthusiastic field assistants. Now follows a period of intensive work to determine and count predator and prey taxa from all the samples taken and to develop multiplex PCRassays for analysis of food choice and feeding rates of the different predators. The development of the
PCR-assays will be conducted at University of Innsbruck and species determination is done at SLU.


This research was funded by the ERA-Net BiodivERsA, with the national funders FORMAS, Sweden, BMBF, Germany, and FWF, Austria, part of the 2010 BiodivERsA call for research proposals.