Worldwide tests of generic attractants, a promising tool for early detection of non-native cerambycid species

A large proportion of the insects which have invaded new regions and countries are emerging species, being found for the first time outside their native range. Being able to detect such species upon arrival at ports of entry before they establish in non-native countries is an urgent challenge. The deployment of traps baited with broad-spectrum semiochemical lures at ports-of-entry and other high-risk sites could be one such early detection tool. Rapid progress in the identification of semiochemicals for cerambycid beetles during the last 15 years has revealed that aggregation-sex pheromones and sex pheromones are often conserved at global levels for genera, tribes or subfamilies of the Cerambycidae. This possibly allows the development of generic attractants which attract multiple species simultaneously, especially when such pheromones are combined into blends. Here, we present the results of a worldwide field trial programme conducted during 2018-2021, using traps baited with a standardised 8-pheromone blend, usually com-plemented with plant volatiles. A total of 1308 traps were deployed at 302 sites covering simultaneously or sequentially 13 European countries, 10 Chinese provinces and some regions of the USA, Canada, Australia, Russia (Siberia) and the Caribbean (Martinique). We intended to test the following hypotheses: 1) if a species is regularly trapped in significant numbers by the blend on a continent, it increases the prob-ability that it can be detected when it arrives in other countries/continents and 2) if the blend exerts an effective, generic attraction to multiple species, it is likely that previously unknown and unexpected spe-cies can be captured due to the high degree of conservation of pheromone structures within related taxa. A total of 78,321 longhorned beetles were trapped, representing 376 species from eight subfamilies, with 84 species captured in numbers greater than 50 individuals. Captures comprised 60 tribes, with 10 tribes including more than nine species trapped on different continents. Some invasive species were captured in both the native and invaded continents. This demonstrates the potential of multipheromone lures as ef-fective tools for the detection of 'unexpected' cerambycid invaders, accidentally translocated outside their native ranges. Adding new pheromones with analogous well-conserved motifs is discussed, as well as the limitations of using such blends, especially for some cerambycid taxa which may be more attracted by the trap colour or other characteristics rather than to the chemical blend

Pair Correlations in a Bidisperse Ferrofluid in an External Magnetic Field:Theory and Computer Simulations

The pair distribution function g(r) for a ferrofluid modeled by a bidisperse system of dipolar hard spheres is calculated. The influence of an external uniform magnetic field and polydispersity on g(r) and the related structure factor is studied. The calculation is performed by diagrammatic expansion methods within the thermodynamic perturbation theory in terms of the particle number density and the interparticle dipole–dipole interaction strength. Analytical expressions are provided for the pair distribution function to within the first order in number density and the second order in dipole–dipole interaction strength. The constructed theory is compared with the results of computer (Monte Carlo) simulations to determine the range of its validity. The scattering structure factor is determined using the Fourier transform of the pair correlation func-tion g(r) – 1. The influence of the granulometric composition and magnetic field strength on the height and position of the first peak of the structure factor that is most amenable to an experimental study is analyzed. The data obtained can serve as a basis for interpreting the experimental small[1]angle neutron scattering results and determining the regularities in the behavior of the structure factor, its dependence on the fractional com-position of a ferrofluid, interparticle correlations, and external magnetic field. © Pleiades Publishing, Inc., 2014

Low frequency complex impedance measurements of Na-montmorillonite suspensions

International audienceThe accurate knowledge of the textural and electrochemical properties of clay suspensions is of great importance for many applications in soil and environmental chemistry involving the use of clay-rich porous media. These applications concern, for example, the understanding of the reactive transport properties of bentonites and argillites for the long-term prediction of the diffusivity of ionic species around radioactive waste repositories1. Na-montmorillonite suspensions are characterized by an anisotropic surface charge distribution: a permanent high surface charge of their basal planes and a pH and salinity dependent surface charge of their edge planes. Current complex impedance measurements of charged suspensions are limited at low frequencies (typically < 1 kHz) by the electrochemical polarization of the current and potential electrodes and by the phase accuracy of the impedancemeter. A new four electrodes sample holder (separate current injection and potential electrodes, Fig. 1a) and a very high accuracy impedancemeter2 are proposed to improve the low-frequency complex impedance measurements of charged Na-montmorillonite suspensions. Low-frequency ([0.1 Hz 45 kHz]) complex impedance measurements, at various clay volume fractions (0.1, 0.2, 0.4, 0.6, and 2%), pH (5, 7, 9) and salinities (NaCl, from 10-4 to 5x10-2 mol L-1), were done to elucidate the textural and electrochemical properties of Na-montmorillonite suspensions. Our results show that the electrochemical polarization of the electrical double layer around the Na-montmorillonite particles can also be observed at low frequency and high salinity (Fig. 2a). Nevertheless, our measurements are also disturbed by the electromagnetic coupling due to the short triaxial cables, which connect the electrodes to the impedancemeter

What can be learnt from the comparison of multiscale brownian dynamics simulations, nuclear magnetic resonance and light scattering experiments on charged micelles?

International audienc

The assessment of non-metallic inclusions in steels and nickel alloys for ultra high vacuum applications

SIGLEAvailable from British Library Document Supply Centre- DSC:4672.2625(JET-R--92/01) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Evaluation et suivi de la biodiversité entomologique forestière au moyen d’indicateurs directs simplifiés – l’exemple des sélections d’espèces (insectes, coléoptères saproxyliques)

National audienceNous avons évalué la biodiversité des Coléoptères saproxyliques au moyen d’indicateurs directs simplifiés fondés sur des sous-groupes d’espèces. Un sous-groupe pertinent devrait bien refléter la variation de richesse totale, ne pas être sensible aux effets environnementaux ou méthodologiques, être stable quelle que soit l’échelle spatiale et être facile à mettre en ½oeuvre. Un large jeu de données a été compilé en France et en Belgique. En dépit d’une forte sensibilité à l’échelle spatiale, le sous-groupe des espèces faciles à identifier s’est avéré le plus performant. Le sous-groupe des espèces indicatrices allemandes s’est révélé performant sur nos données françaises et belges, pointant l’intérêt de listes européennes pour des systèmes de suivi à large échelle

A test for assessment of saproxylic beetle biodiversity using subsets of monitoring species

In European forests, large scale biodiversity monitoring networks need to be implemented - networks which include components such as taxonomical groups that are at risk and that depend directly on forest stand structure. In this context, monitoring the species-rich group of saproxylic beetles is challenging. In the absence of sufficient resources to comprehensively survey a particular group, surrogates of species richness can be meaningful tools in biodiversity evaluations. In search of restricted subsets of species to use as surrogates of saproxylic beetle richness, we led a case study in Western Europe. Beetle data were compiled from 67 biodiversity surveys and ecological studies carried out from 1999 to 2010 with standardized trapping methods in France and Belgium. This large-scale dataset contains 642 forest plots, 1521 traps and 856 species. Twenty-two simplified species subsets were identified as potential surrogates, as well as the number of genera, a higher taxonomic level, taking into account, for each surrogate, the effort required for species identification, the practical monitoring experience necessary, the species conservation potential or the frequency of species occurrence. The performance of each surrogate was analyzed based on the following parameters: overall surrogacy (correlation between subset richness and total species richness), surrogacy vs. identification cost balance, surrogacy variation over a wide range of ecological conditions (forest type, altitude, latitude and bio-geographical area) and consistency with spatial scale. Ecological representativeness and ability to monitor rare species were supplementary criteria used to assess surrogate performance. The subsets consisting of the identifiable (or only easy-to-identify species) could easily be applied in practice and appear to be the best performing subsets, from a global point of view. The number of genera showed good prediction at the trap level and its surrogacy did not vary across wide environmental gradients. However, the subset of easy-to-identify species and the genus number were highly sensitive to spatial scale, which limits their use in large-scale studies. The number of rare species or the species richness of single beetle families (even the best single-family subset, the Cerambycidae) were very weak surrogates for total species richness. Conversely, the German list of monitoring species had high surrogacy, low identification costs and was not strongly influenced by the main geographical parameters, even with our French and Belgian data. In European-wide monitoring networks, such internationally validated subsets could be very useful with regard to the timing and cost-efficiency of field inventories