Interactions of local habitat type,landscape composition and flower availability moderate wild bee communities

Context

Landscape and local habitat traits moderate wild bee communities. However, whether landscape effects differ between local habitat types is largely unknown.

Objectives

We explored the way that wild bee communities in three distinct habitats are shaped by landscape composition and the availability of flowering plants by evaluating divergences in response patterns between habitats.

Methods

In a large-scale monitoring project across 20 research areas, wild bee data were collected on three habitats: near-natural grassland, established flower plantings and residual habitats (e.g. field margins). Additionally, landscape composition was mapped around the research areas.

Results

Our monitoring produced a dataset of 27,650 bees belonging to 324 species. Bee communities on all three habitats reacted similarly to local flower availability. Intensively managed grassland in the surrounding landscape had an overall negative effect on the studied habitats. Other landscape variables produced diverging response patterns that were particularly pronounced during early and late season. Bee communities in near-natural grassland showed a strong positive response to ruderal areas. Flower plantings and residual habitats such as field margins showed a pronounced positive response to extensively managed grassland and woodland edges. Response patterns regarding bee abundance were consistent with those found for species richness.

Conclusion

We advise the consideration of local habitat type and seasonality when assessing the effect of landscape context on bee communities. A reduction in the intensity of grassland management enhances bee diversity in a broad range of habitats. Moreover, wild bee communities are promoted by habitat types such as ruderal areas or woodland edges.

     

Pesticide contamination of the upper Elbe River and an adjacent floodplain area

Journal of Soils and Sediments - Pesticide contamination of river waters is a global problem, and therefore, authorities regularly monitor the water quality status. Especially, flood events might...     

Versuche über die Empfindlichkeit vonTrichogramma (Hymenoptera,Chalcidoidea) gegenüber Fungiziden

Zusammenfassung Die Wirkung von 12 im Obstbau gebräuchlichen Fungiziden in praxisüblichen Anwendungskonzentrationen aufTrichogramma-Imagines wurde in Laborversuchen geprüft.Alle berücksichtigten Mehltau-Bekämpfungsmittel, Binapacryl, Dinocap, Triamphos und Chinomethionat, erwiesen sich als mehr oder weniger toxisch, desgleichen die Schorf-Bekämpfungsmittel Mancozeb, Dichlofluanid, Metiram und TMTD. Für die Schorf-Bekämpfungsmittel Captan, Dithianon, Dodin und Zineb wurde unter den Versuchsbedingungen keine Giftwirkung nachgewiesen.Die Angaben der Literatur über die Wirkung der genannten Fungizide aufTrichogramma und andere Chalcidoidea werden diskutiert.

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Summary The effects uponTrichogramma adults of 12 fungicides which are commonly in use in orchards, in normal concentrations were examined by laboratory trials.The mildew fungicides, binapacryl, dinocap, triamphos, and oxythioquinox proved to be toxic as well as the apple scab fungicides mancozeb (= coordination product of zinc ion and [ethylenebis(dithiocarbamato)] manganese), dichlofluanid, metiram (= zinc-activated polyethylene thiuram disulfide), and thiram. Under the conditions of the experiments, there was no evidence of a toxic effect exerted by the apple scab fungicides captan, dithianon, dodine, and zineb.The available data from literature on the effects of the fungicides mentioned uponTrichogramma and other chalcidoids are discussed.

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Durchgeführt mit Unterstützung der Deutschen Forschungsgemeinschaft.

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Dem Direktor des Instituts, Herrn Professor Dr. J. M. Franz, danke ich für sein reges Interesse an den Versuchen und die mir jederzeit gewährte Unterstützung.     

The nameless counterpart: a reconstruction of the experiences of private forestry extension officers with their clients

The changes to the forest ownership structure of small private forests in recent times have opened up an intensive field of research throughout Europe. Most of the studies completed to date adhere to the classic survey model and describe the behaviour and attitudes of forest owners. The research presented in this article analyses the changes to small private forests with the aid of data collected from focus groups comprised of forestry extension officers in Germany. Through the reconstruction of the experiences gleaned by the consultants, it was possible to describe the manner in which they characterise their clientele, and the changes they have observed, against the backdrop of changes occurring across rural areas. The consultants’ strategies for describing forest owners are presented. The orientation pattern presented by the extension officers is compared with the urban orientation of forest owners’ model developed by social scientists.     

Temporal trends in the foliar nutritional status of the French, Walloon and Luxembourg broad-leaved plots of forest monitoring

? Two decades after the launching of the monitoring program of forest ecosystems in Europe (ICP forests), a unique data set is now available regarding the foliar nutritional status of the main broad-leaved species growing in much-diversified sites (soil, climate).

? This study focuses on the foliar concentration time series (1993 to 2005) of the French (RENECOFOR), Walloon and Luxemburg broad-leaved plots. The aim is to show long-term trends while taking the inter-plot and inter-annual variability into account.

? Two kinds of statistical processing were used to analyze the data on foliar chemistry: principal component analysis (PCAs) and linear mixed models. In general, the main temporal trends reveal a decrease in the foliar P concentration and a decrease in the foliar Ca concentration, except for European beech on acid soils.

? These temporal patterns confirm the trends previously observed and could be explained by the joint actions of several processes that influence tree nutrition in the long term: tree age, N and S deposition, harvesting and climate.

     

EMS and UV irradiation induce unstable resistance against CAA fungicides in <Emphasis Type="Italic">Bremia lactucae</Emphasis>

Wild type (WT) field isolates of Bremia lactucae failed to germinate in vitro or infect lettuce leaves in the presence of CAA (carboxylic acid amide) fungicides. Minimal inhibitory concentrations (MIC) for mandipropamid, dimethomorph, benthiavalicarb and iprovalicarb were 0.005, 0.5, 0.5 and 5 μg ml⁻¹, respectively. Mutagenesis experiments showed that spores exposed to EMS (ethyl methane sulphonate) or UV irradiation (254 nm) could infect lettuce leaves in the presence of up to 100 μg ml⁻¹ CAA. The proportion of infected leaves relative to the number of spores inoculated (infection frequency) was inversely related to the concentration of CAA used, ranging between 0 and 160 per 1 × 10⁶ spores. Resistant mutants (RM) lost their resistance within 1–14 reproduction cycles on CAA-treated plants. Crosses were made between RMxWT isolates and RMxRM isolates with an attempt to obtain stable homozygous resistant off-springs. Such crosses yielded few resistant but unstable progeny isolates. Mutagenic treatments given to hybrid isolates also failed to produce stable resistance. Previous gene sequencing data showed that stable resistance to CAAs is based on a single SNP in the cellulose synthase 3 (CesA3) gene of Plasmopara viticola. Therefore, we sequenced a 582 bp DNA fragment of Ces3A of WT, RM and hybrid isolates of B.lactucae. No mutation in this gene fragment was found. We conclude that mutagenic agents like EMS or UV may induce resistance to CAA in Bremia lactucae but this resistance is not stable and not linked to mutations in CesA3 gene.