Intraguild predation by <Emphasis Type="Italic">Harmonia axyridis</Emphasis> on coccinellids revealed by exogenous alkaloid sequestration

Summary.  Under laboratory conditions, the multicolored Asian lady beetle, Harmonia axyridis is well known as an intraguild predator of other ladybirds. However the real impact of this exotic species on native species was poorly investigated in the field. Because many ladybird species produce alkaloids as defensive compounds, we propose here a new method of intraguild predation monitoring in coccinellids based on alkaloid quantification by GC-MS. In laboratory experiments, adaline was unambiguously detected in fourth instar larvae of H. axyridis having ingested one egg or one first instar larva of Adalia bipunctata. Although prey alkaloids in the predator decreased with time, traces were still detected in pupae, exuviae and imagines of H. axyridis having ingested one prey when they were fourth instar larvae. Analysis of H. axyridis larvae collected in two potato fields shows for the first time in Europe the presence of exogenous alkaloids in 9 out of 28 individuals tested. This new method of intraguild predation detection could be used more widely to follow the interactions between predators and potential chemically defended insect preys.     

Ecological analysis of disturbed riverbanks in the Montréal area of Québec

In revegetation trials on disturbed riverbank sites in the Montréal region (Québec, Canada), an analysis of their structure by means of their biotic and abiotic components was undertaken. Vegetation sampling and physical surveys, together with soil analyses of 62 stands, grouped in 20 sectors, were carried out in the summer of 1986. The statistical analyses of biotic and abiotic data were executed in parallel by a hierarchical agglomerative cluster analysis (arithmetic average clustering) and by an ordination in reduced space (principal coordinate analysis). The species colonizing these riverbanks are, for the most part, ruderals from the Montréal region, of which more than 50% are introduced species. The pioneering communities characterizing these artificial habitats have had very little impact on the physical conditions of their environment; therefore, the ordination on the plant communities proves to be strongly correlated to the ordination stemming from the abiotic components. The statistical analysis retains the original sectors, underlining the fact that each human intervention generally results in the creation of a particular ecological situation.     

Biological and ecophysiological reactions of white wall rocket (Diplotaxis erucoides L.) grown on sewage sludge compost

We studied the effects of sewage sludge compost on white wall rocket (Diplotaxis erucoides L.) compared with mineral fertilization and control (without any fertilizer) in a greenhouse experiment. The plants grown on the compost-amended soil showed a different growth dynamic: a significant delay in flowering and a bigger root system. Both the compost and the fertilization treatments increased biomass and seed yield. Heavy metal (Cu, Cd, Zn, Ni) distribution within the plant was in the following order: roots > leaves > stems, except for zinc which was homogeneously distributed. The balance of mineral nutrition was not affected by treatments. Zinc was the trace element which was most taken up. Unlike many species of Brassicaceae, white wall rocket is not a hyperaccumulator. Although sewage sludge compost improved plant growth, delay in flowering shows that it is necessary to take precautions when spreading sewage sludge in natural areas.     

Screening of high production volume chemicals for estrogen receptor binding activity (II) by the MultiCASE expert system

A structurally and functionally diverse and cross-validated quantitative structure-activity knowledge database generated by the MultiCASE expert system was used to screen 2526 high production volume chemicals (HPVCs) for their estrogen receptor binding activity. 73 HPVCs were found to contain structural features or biophores that have been documented as having the ability to bind to the estrogen receptor. Potential chemicals were ranked according to their quantitatively predicted ER binding potential and the details of the biophores found in them are discussed.     

PM2.5 source apportionment in a French urban coastal site under steelworks emission influences using constrained non-negative matrix factorization receptor model

The constrained weighted-non-negative matrix factorization(CW-NMF) hybrid receptor model was applied to study the influence of steelmaking activities on PM_(2.5)(particulate matter with equivalent aerodynamic diameter less than 2.5 μm) composition in Dunkerque,Northern France. Semi-diurnal PM_(2.5)samples were collected using a high volume sampler in winter 2010 and spring 2011 and were analyzed for trace metals, water-soluble ions, and total carbon using inductively coupled plasma – atomic emission spectrometry(ICP-AES),ICP- mass spectrometry(ICP-MS), ionic chromatography and micro elemental carbon analyzer. The elemental composition shows that NO_3~-, SO_4~(2-), NH_4~+and total carbon are the main PM_(2.5)constituents. Trace metals data were interpreted using concentration roses and both influences of integrated steelworks and electric steel plant were evidenced. The distinction between the two sources is made possible by the use Zn/Fe and Zn/Mn diagnostic ratios. Moreover Rb/Cr, Pb/Cr and Cu/Cd combination ratio are proposed to distinguish the ISW-sintering stack from the ISW-fugitive emissions. The a priori knowledge on the influencing source was introduced in the CW-NMF to guide the calculation. Eleven source profiles with various contributions were identified: 8 are characteristics of coastal urban background site profiles and 3 are related to the steelmaking activities. Between them,secondary nitrates, secondary sulfates and combustion profiles give the highest contributions and account for 93% of the PM_(2.5)concentration. The steelwork facilities contribute in about 2%of the total PM_(2.5)concentration and appear to be the main source of Cr, Cu, Fe, Mn, Zn.     

Irrigation canals as tools for climate change adaptation and fish biodiversity management in Southern France

This paper is based on the interdisciplinary research conducted in the south of France that analyses the different economic, social and environmental roles played by agricultural irrigation canals. We argue that beyond their productive role, which is to supply farmers with water, they fulfil other environmental services and play an important role in the context of future climate change to face challenges of adaptation. We point up several ecosystem services provided by such canals, e.g. replenishing the groundwater table, the development of riparian vegetation and wet areas in the Mediterranean zone, tools for regulating flooding and drought, the bases for new cultural approaches to nature. Moreover, they play an important role in the maintenance of an ichthyological biodiversity that is indispensable for the persistence of natural ecosystem. Functioning as an ecological corridor, they display interesting capacities as refuges for certain fish species under stress. Indeed, they can potentially connect upstream and downstream zones over a continuum of more than 300 km and thus covering very contrasted climatic zones (alpine versus Mediterranean). For now, most of these services remain largely unknown and underestimated. However, they serve as assets for territorial development since they combine economic, ecological and social factors whose remodelling is becoming increasingly necessary in the face of climate change.