A Roques

Publications of A Roques

• Mitochondrial and microsatellite DNA markers reveal a Balkan origin for the highly invasive horse-chestnut leaf miner Cameraria ohridella (Lepidoptera, Gracillariidae).

  Authors: R Valade, M. Kenis, A Hernandez-Lopez, S. Augustin, N Mari Mena, E Magnoux, R Rougerie, F. Lakatos, A Roques, C. Lopez-Vaamonde

  Molecular ecology. 08/2009;

  Abstract Biological invasions usually start with a small number of founder individuals. These founders are likely to represent a small fraction of the total genetic diversity found in the sourceAbstract Biological invasions usually start with a small number of founder individuals. These founders are likely to represent a small fraction of the total genetic diversity found in the source population. Our study set out to trace genetically the geographical origin of the horse-chestnut leafminer, Cameraria ohridella, an invasive microlepidopteran whose area of origin is still unkown. Since its discovery in Macedonia 25 years ago, this insect has experienced an explosive westward range expansion, progressively colonizing all of Central and Western Europe. We used cytochrome oxidase I sequences (DNA barcode fragment) and a set of six polymorphic microsatellites to assess the genetic variability of C. ohridella populations, and to test the hypothesis that C. ohridella derives from the southern Balkans (Albania, Macedonia and Greece). Analysis of mtDNA of 486 individuals from 88 localities allowed us to identify 25 geographically structured haplotypes. In addition, 480 individuals from 16 populations from Europe and the southern Balkans were genotyped for 6 polymorphic microsatellite loci. High haplotype diversity and low measures of nucleotide diversities including a significantly negative Tajima's D indicate that C. ohridella has experienced rapid population expansion during its dispersal across Europe. Both mtDNA and microsatellites show a reduction in genetic diversity of C. ohridella populations sampled from artificial habitats (e.g. planted trees in public parks, gardens, along roads in urban or sub-urban areas) across Europe compared with C. ohridella sampled in natural stands of horse-chestnuts in the southern Balkans. These findings suggest that European populations of C. ohridella may indeed derive from the southern Balkans.

• Alien species in a warmer world - risks and opportunities

  Authors: G.-R. Walther, A. Roques, P. E. Hulme, M. T. Sykes, P. Pyšek, I. Kühn, S. M. Zobel, members of the ALARM Climate Change – Biological Invasions Working Group (Bacher

  Trends in Ecology & Evolution. 01/2009; 23(12):686-693.

• How can alien species inventories and interception data help us prevent insect invasions?

  Authors: M. Kenis, W Rabitsch, M-A Auger-Rozenberg, A Roques

  Bulletin of entomological research. 11/2007; 97(5):489-502.

  Information relevant to invasion processes and invasive alien insect species management in Central Europe was extracted from two databases: a compilation of two inventories of alien insects inInformation relevant to invasion processes and invasive alien insect species management in Central Europe was extracted from two databases: a compilation of two inventories of alien insects in Austria and Switzerland, and a list of interceptions of non-indigenous plant pests in Europe gathered by the European and Mediterranean Plant Protection Organisation (EPPO) for the period 1995-2004. For one-third of the insects established in Switzerland and Austria, the region of origin is unclear. Others come mainly from North America, Asia and the Mediterranean region. Among the intercepted insects, 40% were associated with commodities from Asia, 32% from Europe and only 2% from North America. Sternorrhyncha, Coleoptera and Psocoptera were particularly well represented in the alien fauna compared to the native fauna. In the interception database, Sternorrhyncha were also well represented but Diptera accounted for the highest number of records. Sap feeders and detritivores were the dominant feeding niches in the alien insect fauna. In contrast, external defoliators, stem borers, gall makers, root feeders, predators and parasitoids were underrepresented. Nearly 40% of the alien insects in Switzerland and Austria live only indoors. Another 15% live outdoors but exclusively or predominantly on exotic plants. Less than 20% are found mainly in 'natural' environments. The majority of introductions of alien insects in Europe are associated with the international trade in ornamental plants. An economic impact was found for 40% of the alien insects in Switzerland and Austria, whereas none is known to have an ecological impact. The implications of these observations for further studies and the management of alien species in Europe are discussed.

• Phylogeography of the pine processionary moth Thaumetopoea wilkinsoni in the Near East.

  Authors: M Simonato, Z Mendel, C Kerdelhué, J Rousselet, E Magnoux, P Salvato, A Roques, A. Battisti, L Zane

  Molecular ecology. 07/2007; 16(11):2273-83.

  Phylogeographic structure of the eastern pine processionary moth Thaumetopoea wilkinsoni was explored in this study by means of nested clade phylogeographic analyses of COI and COII sequences ofPhylogeographic structure of the eastern pine processionary moth Thaumetopoea wilkinsoni was explored in this study by means of nested clade phylogeographic analyses of COI and COII sequences of mitochondrial DNA and Bayesian estimates of divergence times. Intraspecific relationships were inferred and hypotheses tested to understand historical spread patterns and spatial distribution of genetic variation. Analyses revealed that all T. wilkinsoni sequences were structured in three clades, which were associated with two major biogeographic events, the colonization of the island of Cyprus and the separation of southwestern and southeastern Anatolia during the Pleistocene. Genetic variation in populations of T. wilkinsoni was also investigated using amplified fragment length polymorphisms and four microsatellite loci. Contrasting nuclear with mitochondrial data revealed recurrent gene flow between Cyprus and the mainland, related to the long-distance male dispersal. In addition, a reduction in genetic variability was observed at both mitochondrial and nuclear markers at the expanding boundary of the range, consistent with a recent origin of these populations, founded by few individuals expanding from nearby localities. In contrast, several populations fixed for one single mitochondrial haplotype showed no reduction in nuclear variability, a pattern that can be explained by recurrent male gene flow or selective sweeps at the mitochondrial level. The use of both mitochondrial and nuclear markers was essential in understanding the spread patterns and the population genetic structure of T. wilkinsoni, and is recommended to study colonizing species characterized by sex-biased dispersal.

• Comparative population genetic study of two oligophagous insects associated with the same hosts.

  Authors: C Kerdelhué, E Magnoux, F Lieutier, A Roques, J Rousselet

  Heredity. 08/2006; 97(1):38-45.

  A parallel study of the genetic structure of two oligophagous species associated with the same hosts was conducted to determine the main factors shaping the distribution of genetic diversity. TheA parallel study of the genetic structure of two oligophagous species associated with the same hosts was conducted to determine the main factors shaping the distribution of genetic diversity. The bark beetle Tomicus piniperda and the pine processionary moth (PPM) Thaumetopoea pityocampa are both associated with the genus Pinus and belong to different guilds (xylophagous vs defoliating species). The PPM is an ectophagous species that feeds on the needles of living trees, whereas T. piniperda is endophagous and bores galleries in the inner bark of weakened trees. Both species were sampled in the main regions of France, and their genetic structure was assessed after genotyping with five microsatellite markers. Populations of the PPM were significantly structured. A pattern of isolation by distance was found when distances were calculated as bypassing the Massif Central, whereas no such pattern could be found with raw geographic distances. On the contrary, most populations of T. piniperda were not differentiated. No effect of host species could be detected in either of the two species. We conclude that the two taxa have contrasting effective dispersal rates per generation, and we hypothesize that this reflects the different selection pressures acting on individual fitness via different strategies of host use.

• Host tracking or cryptic adaptation? Phylogeography of Pediobius saulius (Hymenoptera, Eulophidae), a parasitoid of the highly invasive horse-chestnut leafminer

  Authors: A. Hernandez-Lopez, R. Rougerie, S. Augustin, D.C. Lees, R. Tomov, M. Kenis, E. Cota, E. Kullaj, G. Grabenweger, A. Roques, C. Lopez-Vaamonde

  Evolutionary Applications. (in press).

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• Microwave FEL experiments at CESTA

  Authors: J. Launspach, Ph. Anthouard, J. Bardy, C. Bonnafond, H. Bottollier-Curtet, Ph. Delsart, A. Devin, Ph. Eyharts, P. Eyl, J. Gardelle, D. Gardent, G. Germain, P. Grua, J. Labrouche, P. Le Taillandier, J. de Mascureau, E. Merle, A. Roques, M. Thevenot, D. Villate

  Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.

  At CESTA the EUPHROSYNE pulsed generator was used for Ondine I, our first FEL experiment at 35 GHz. The work was focused on beam creation and propogation first with an oxide cathode and then with aAt CESTA the EUPHROSYNE pulsed generator was used for Ondine I, our first FEL experiment at 35 GHz. The work was focused on beam creation and propogation first with an oxide cathode and then with a cold cathode. Typically 1 kA at 2.5 MeV was propagated in single shot operation.A lot of calculations have been done on these problems and we have also developed simulation codes on FEL interaction in both Compton and Raman regimes, taking into account 3D wiggler field, guiding field, waveguide modes, and electron beam injection, to obtain trajectories, gain and efficiency. Good agreement with some previous experiments and codes has been found.In the frame of a preliminary superradiant experiment using a bifilar helical wiggler, we obtained an amplification of the spontaneous emission up to 1 MW in the Kα band and 0.2 MW in the 33–36 GHz band.A microwave apparatus has been completed to work in an amplifier configuration: injection magnetron tube (100 kW), amplification line and diagnostics. All these components are compatible of the new Ondine II experiment designed for operation with the LELIA induction linac.This experiment is to start at 0.1 Hz with the induction injector (1.3 MeV, 1 kA, 50 ns) using the same wiggler technology as Ondine 1.In the future we plan to carry out the 35 GHz experiment at 3 MeV by adding an accelerating module to the LELIA injector. An hybrid planar wiggler with parabolic pole faces is being studied for further experiments.

• Quantitative measurement of the stresses induced during polymerisation of bone cement

  Authors: A. Roques, M. Browne, A. Taylor, A. New, D. Baker

  Biomaterials.

  When bone cement cures, residual stresses due to bulk and thermal shrinkage will result. Present finite element (FE) simulations of implanted constructs often do not account for these stresses as anWhen bone cement cures, residual stresses due to bulk and thermal shrinkage will result. Present finite element (FE) simulations of implanted constructs often do not account for these stresses as an initial condition; this may lead to overestimations of the fatigue life of the cement. In the present study, an instrumented stem equipped with strain gauges and a thermocouple was employed to experimentally quantify the residual stresses induced as a result of bone cement curing within a simulated bone/cement/stem construct. Residual stresses as high as 10 MPa were observed in the cement mantle. Residual stresses of this magnitude are potentially high enough to initiate damage within the cement mantle or at the stem/cement interface immediately post-implantation. The acoustic emission technique has demonstrated that cracking and sliding mechanisms are occurring during curing, resulting in partial relaxation of these stresses. The implications for FE simulations of the implanted construct are discussed.

• Contrasting patterns in the invasions of European terrestrial and freshwater habitats by alien plants, insects and vertebrates

  Authors: P Pysek, S Bacher, M Chytry, V Jarosik, J Wild, L Celesti-Grapow, N Gasso, M Kenis, PW Lambdon, W Nentwig, J Pergl, A Roques, J Sadlo, W Solarz, M Vila, PE Hulme

  Global Ecology and Biogeography. 19(3):317-331.

• Host tracking or cryptic adaptation? Phylogeography of Pediobius saulius (Hymenoptera, Eulophidae), a parasitoid of the highly invasive horse-chestnut leafminer

  Authors: A. Hernandez-Lopez, R. Rougerie, S. Augustin, D.C. Lees, R. Tomov, M. Kenis, E. Cota, E. Kullaj, G. Grabenweger, A. Roques, C. Lopez-Vaamonde

  Evolutionary Applications. (in press).

• Grasping at the routes of biological invasions: a framework for integrating pathways into policy

  Authors: P. E. Hulme, S. Bacher, M. Kenis, S. Klotz, I. Kühn, D. Minchin, W. Nentwig, S. Olenin, V. Panov, J. Pergl, P. Pyšek, A. Roques, D. Sol, W. Solarz, M. Vilá

  Journal of Applied Ecology. 45(2):403-414.

  1. Pathways describe the processes that result in the introduction of alien species from one location to another. A framework is proposed to facilitate the comparative analysis of invasion pathways1. Pathways describe the processes that result in the introduction of alien species from one location to another. A framework is proposed to facilitate the comparative analysis of invasion pathways by a wide range of taxa in both terrestrial and aquatic ecosystems. Comparisons with a range of data helped identify existing gaps in current knowledge of pathways and highlight the limitations of existing legislation to manage introductions of alien species. The scheme aims for universality but uses the European Union as a case study for the regulatory perspectives. 2. Alien species may arrive and enter a new region through three broad mechanisms: importation of a commodity, arrival of a transport vector, and/or natural spread from a neighbouring region where the species is itself alien. These three mechanisms result in six principal pathways: release, escape, contaminant, stowaway, corridor and unaided. 3. Alien species transported as commodities may be introduced as a deliberate release or as an escape from captivity. Many species are not intentionally transported but arrive as a contaminant of a commodity, for example pathogens and pests. Stowaways are directly associated with human transport but arrive independently of a specific commodity, for example organisms transported in ballast water, cargo and airfreight. The corridor pathway highlights the role transport infrastructures play in the introduction of alien species. The unaided pathway describes situations where natural spread results in alien species arriving into a new region from a donor region where it is also alien. 4. Vertebrate pathways tend to be characterized as deliberate releases, invertebrates as contaminants and plants as escapes. Pathogenic micro-organisms and fungi are generally introduced as contaminants of their hosts. The corridor and unaided pathways are often ignored in pathway assessments but warrant further detailed consideration. 5. Synthesis and applications. Intentional releases and escapes should be straightforward to monitor and regulate but, in practice, developing legislation has proved difficult. New introductions continue to occur through contaminant, stowaway, corridor and unaided pathways. These pathways represent special challenges for management and legislation. The present framework should enable these trends to be monitored more clearly and hopefully lead to the development of appropriate regulations or codes of practice to stem the number of future introductions.

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

  Authors: R.H.A. Baker, A. Battisti, J. Bremmer, M. Kenis, J. Mumford, F. Petter, G. Schrader, S. Bacher, P. DeBarro, P.E. Hulme, O. Karadjova, A. Oude Lansink, O. Pruvost, P. Pysek, A Roques, Y. Baranchikov, J.H. Sun

  EPPO Bulletin 39 (2009) 1.

  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 thePRATIQUE 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 that is efficient and user-friendly. The research will be undertaken by scientists from 13 institutes in the EU and one each from Australia and New Zealand with subcontractors from institutes in China and Russia. They will produce a structured inventory of PRA datasets for the EU and undertake targeted research to improve existing procedures and develop new methods for (a) the assessment of economic, environmental and social impacts, (b) summarising risk while taking account of uncertainty, (c) mapping endangered areas (d) pathway risk analysis and systems approaches and (e) guiding actions during emergencies caused by outbreaks of harmful organisms. The results will be tested and provided as protocols, decision support systems and computer programs with examples of best practice linked to a computerised European and Mediterranean Plant Protection Organization (EPPO) PRA scheme