The role of the poplar’s volatiles for the butterflies of the forest margin

Pappeln wie die Zitterpappel (Populus tremula) bilden am Waldrand wichtige Habitate für Nachtfalter. Der Pappelschwärmer (Laothoe populi) und das Abendpfauenauge (Smerinthus ocellata) legen ihre Eier auf den Blättern ab. Als Nachtfalter sind sie auf andere Signale als die optischen angewiesen, um den optimalen Ovipositionsplatz zu finden. Je nach Vitalität des Baumes und seiner Exposition sind die entwicklungsbedingungen der Raupe verschieden. Diese Studie soll aufzeigen, welche Duftstoffe durch Änderungen der Vitalität des Baumes beeinflusst und welche durch die Nachtfalter wahrgenommen werden können.Forest margins are environments very rich in species. The softwood communities found there are unique habitats for many butterflies. The studies conducted in the vicinity of Göttingen resulted in 83 Makrolepidoptera taxa found on willow (Salix caprea) and 65 on poplar (Populus tremula). Since different plants emit different volatiles, many insects are able to follow the odour plumes and find their hosts by perceiving various odours. The emission of volatiles can be influenced by different external factors, like surplus of salts, drought, mycorrhiza. A gas-chromatograph with mass-spectrometric and parallel electroantennographic detector (GC-MS/EAD) was employed to measure in what way the volatile pattern changed and which of the associated chemical substances could be detected by the insect antennae. The volatile pattern is very important for butterflies to find their habitat

The hydrodynamic drag of full scale trees

River hydrodynamicsOverbank flows and vegetatio

A multi-scale hierarchical framework for developing understanding of river behaviour to support river management

The work leading to this paper was funded through the European Union’s FP7 programme under Grant Agreement No. 282656 (REFORM). The framework methodology was developed within the context of Deliverable D2.1 of the REFORM programme, and all partners who contributed to the development of the four parts of this deliverable are included in the author list of this paper. More details on the REFORM framework can be obtained from part 1 of Deliverable D2.1 (Gurnell et al. 2014), which is downloadable from http://​www.​reformrivers.​eu/​results/​deliverables

A herbivore tag-and-trace system reveals contact- and density-dependent repellence of a root toxin

Foraging behavior of root feeding organisms strongly affects plant-environment-interactions and ecosystem processes. However, the impact of plant chemistry on root herbivore movement in the soil is poorly understood. Here, we apply a simple technique to trace the movement of soil-dwelling insects in their habitats without disturbing or restricting their interactions with host plants. We tagged the root feeding larvae of Melolontha melolontha with a copper ring and repeatedly located their position in relation to their preferred host plant, Taraxacum officinale, using a commercial metal detector. This method was validated and used to study the influence of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) on the foraging of M. melolontha. TA-G is stored in the latex of T. officinale and protects the roots from herbivory. Using behavioral arenas with TA-G deficient and control plants, we tested the impact of physical root access and plant distance on the effect of TA-G on M. melolontha. The larvae preferred TA-G deficient plants to control plants, but only when physical root contact was possible and the plants were separated by 5 cm. Melolontha melolontha showed no preference for TA-G deficient plants when the plants were grown 15 cm apart, which may indicate a trade-off between the cost of movement and the benefit of consuming less toxic food. We demonstrate that M. melolontha integrates host plant quality and distance into its foraging patterns and suggest that plant chemistry affects root herbivore behavior in a plant-density dependent manner. © 2017, Springer Science+Business Media New York

Policy Issues in NEG Models: Established Results and Open Questions

This paper provides a non-technical overview of NEG models dealing with policy issues. Considered policy measures include alternative categories of public expenditure, international tax competition, unilateral actions of protection/liberalisation, and trade agreements. The implications of public intervention in two-region NEG models are discussed by unfolding the impact of policy measures on agglomeration/dispersion forces. Results are described in contrast with those obtained in standard non-NEG theoretical models. The high degree of abstraction limits the applicability of NEG models to real world policy issues. We discuss in some detail two extensions of NEG models to reduce this applicability gap: the cases of multi-regional frameworks and firm heterogeneity

Root-emitted volatile organic compounds: can they mediate belowground plant-plant interactions?

peer reviewedBackground Aboveground, plants release volatile organic compounds (VOCs) that act as chemical signals between neighbouring plants. It is now well documented that VOCs emitted by the roots in the plant rhizosphere also play important ecological roles in the soil ecosystem, notably in plant defence because they are involved in interactions between plants, phytophagous pests and organisms of the third trophic level. The roles played by root-emitted VOCs in between- and within-plant signalling, however, are still poorly documented in the scientific literature. Scope Given that (1) plants release volatile cues mediating plant-plant interactions aboveground, (2) roots can detect the chemical signals originating from their neighbours, and (3) roots release VOCs involved in biotic interactions belowground, the aim of this paper is to discuss the roles of VOCs in between- and within-plant signalling belowground. We also highlight the technical challenges associated with the analysis of root-emitted VOCs and the design of experiments targeting volatile-mediated root-root interactions. Conclusions We conclude that root-root interactions mediated by volatile cues deserve more research attention and that both the analytical tools and methods developed to study the ecological roles played by VOCs in interplant signalling aboveground can be adapted to focus on the roles played by root-emitted VOCs in between- and within-plant signalling

Longitudinal segmentation and characterization of river features based on Remote Sensing

International audienc