Plant chemistry and aphid parasitoids (Hymenoptera : Braconidae): Imprinting and memory

Emerging parasitoids of aphids encounter secondary plant chemistry from cues left by the mother parasitoid at oviposition and from the plant-feeding of the host aphid. In practice, however, it is secondary plant cheinistry oil the Surface of the aphid mummy which influences parasitoid olfactory behaviour. Offspring of Aphidius colemani reared oil Myzus persicae on artificial diet did no distinguish between the odours of bean and cabbage, but showed a clear preference for cabbage odour if sinigrin had been painted oil the back of the mummy. Similarly Aphidius rhopalosiphi reared on Metopolophium dirhodum on wheat preferred the odour of wheat plants grown near tomato plants to odour of wheat alone if the wheat plants oil which they had been reared had been exposed to the volatiles of nearby tomato plants. Aphidius rhopalosiphi reared on M dirhodum, and removed from the mummy before emergence, showed a preference for the odour of a different wheat cultivar if they had contacted a mummy from that cultivar, and similar results were obtained with A. colemani naturally emerged from M. persicae mummies. Aphidius colemani emerged from mummies oil one crucifer were allowed to contact in sequence (for 45 min each) mummies from two different crucifers. The mumber of attacks made in 10 min oil M. persicae was always significantly higher when aphids were feeding oil the same plant as the origin of the last MUMMY offered, or oil the second plant if aphids feeding on the third plant were not included. Chilling emerged A. colemani for 24 h at 5 degrees C appeared to erase the imprint of secondary plant chemistry, and they no longer showed host plant odour preferences in the olfactometer. When the parasitoids were chilled after three Successive mummy experiences, memory of the last experience appeared at least temporarily erased and preference was then shown for the chemistry of the second experience.

Conservation and sustainable use of crop wild relatives

Conservation of crop wild relatives (CWRs) is a complex interdisciplinary process that is being addressed by various national and international initiatives, including two Global Environment Facility projects ('In situ Conservation of Crop Wild Relatives through Enhanced Information Management and Field Application' and 'Design, Testing and Evaluation of Best Practices for in situ Conservation of Economically Important Wild Species'), the European Community-funded project 'European Crop Wild Relative Diversity Assessment and Conservation Forum (PGR Forum)' and the European 'In situ and On Farm Network'. The key issues that have arisen are: (1) the definition of what constitutes a CWR, (2) the need for national and regional information systems and a global system, (3) development and application of priority-determining mechanisms, (4) the incorporation of the conservation of CWRs into existing national, regional and international PGR programmes, (5) assessment of the effectiveness of conservation actions, (6) awareness of the importance of CWRs in agricultural development at local, national and international levels both for the scientific and lay communities and (7) policy development and legal framework. The above issues are illustrated by work on the conservation of a group of legumes known as grasspea chicklings, vetchlings, and horticultural ornamental peas (Lathyrus spp.) in their European and Mediterranean centre of diversity. (c) 2007 Published by Elsevier B.V.

Multivariate relationships between groundwater chemistry and toxicity in an urban aquifer

Multivariate statistical methods were used to investigate file Causes of toxicity and controls on groundwater chemistry from 274 boreholes in an Urban area (London) of the United Kingdom. The groundwater was alkaline to neutral, and chemistry was dominated by calcium, sodium, and Sulfate. Contaminants included fuels, solvents, and organic compounds derived from landfill material. The presence of organic material in the aquifer caused decreases in dissolved oxygen, sulfate and nitrate concentrations. and increases in ferrous iron and ammoniacal nitrogen concentrations. Pearson correlations between toxicity results and the concentration of individual analytes indicated that concentrations of ammoinacal nitrogen, dissolved oxygen, ferrous iron, and hydrocarbons were important where present. However, principal component and regression analysis suggested no significant correlation between toxicity and chemistry over the whole area. Multidimensional Scaling was used to investigate differences in sites caused by historical use, landfill gas status, or position within the sample area. Significant differences were observed between sites with different historical land use and those with different gas status. Examination of the principal component matrix revealed that these differences are related to changes in the importance of reduced chemical species.

Conservation and sustainable use of wild species as sources of new ornamentals

While only about 1-200 species are used intensively in commercial floriculture (e.g. carnations, chrysanthemums, gerbera, narcissus, orchids, tulips, lilies, roses, pansies and violas, saintpaulias, etc.) and 4-500 as house plants, several thousand species of herbs, shrubs and trees are traded commercially by nurseries and garden centres as ornamentals or amenity species. Most of these have been introduced from the wild with little selection or breeding. In Europe alone, 12 000 species are found in cultivation in general garden collections (i.e. excluding specialist collections and botanic gardens). In addition, specialist collections (often very large) of many other species and/or cultivars of groups such as orchids, bromeliads, cacti and succulents, primulas, rhododendrons, conifers and cycads are maintained in several centres such as botanic gardens and specialist nurseries, as are 'national collections' of cultivated species and cultivars in some countries. Specialist growers, both professional and amateur, also maintain collections of plants for cultivation, including, increasingly, native plants. The trade in ornamental and amenity horticulture cannot be fully estimated but runs into many billions of dollars annually and there is considerable potential for further development and the introduction of many new species into the trade. Despite this, most of the collections are ad hoc and no co-ordinated efforts have been made to ensure that adequate germplasm samples of these species are maintained for conservation purposes and few of them are represented at all adequately in seed banks. Few countries have paid much attention to germplasm needs of ornamentals and the Ornamental Plant Germplasm Center in conjunction with the USDA National Plant Germplasm System at The Ohio State University is an exception. Generally there is a serious gap in national and international germplasm strategies, which have tended to focus primarily on food plants and some forage and industrial crops. Adequate arrangements need to be put in place to ensure the long- and medium-term conservation of representative samples of the genetic diversity of ornamental species. The problems of achieving this will be discussed. In addition, a policy for the conservation of old cultivars or 'heritage' varieties of ornamentals needs to be formulated. The considerable potential for introduction of new ornamental species needs to be assessed. Consideration needs to be given to setting up a co-ordinating structure with overall responsibility for the conservation of germplasm of ornamental and amenity plants.

Synthesis, structure and solution chemistry of mixed-ligand oxovanadium(IV) and oxovanadium(V) complexes incorporating tridentate ONO donor hydrazone ligands

In the title family, the ONO donor ligands are the acetylhydrazones of salicylaidehyde (H2L1) and 2-hydroxyacetophenone (H2L2) (general abbreviation, H2L). The reaction of bis(acetylacetonato)oxovanadium(IV) with a mixture of tridentate H2L and a bidentate NN donor [e.g., 2,2'-bipyridine(bpy) or 1,10-phenanthroline(phen), hereafter B] ligands in equimolar ratio afforded the tetravalent complexes of the type [(VO)-O-IV(L)(B)]; complexes (1)-(4) whereas, if B is replaced by 8-hydroxyquinoline(Hhq) (which is a bidentate ON donor ligand), the above reaction mixture yielded the pentavalent complexes of the type [(VO)-O-V(L)(hq)]; complexes (5) and (6). Aerial oxygen is most likely the oxidant (for the oxidation of V-IV -> V-V) in the synthesis of pentavalent complexes (5) and (6). [(VO)-O-IV(L)(B)] complexes are one electron paramagnetic and display axial EPR spectra, while the [(VO)-O-V(L)(hq)] complexes are diamagnetic. The X-ray structure of [(VO)-O-V(L-2)(hq)] (6) indicates that H2L2 ligand is bonded with the vanadium meridionally in a tridentate dinegative fashion through its phenolic-O, enolic-O and imine-N atoms. The general bond length order is: oxo < phenolato < enolato. The V-O (enolato) bond is longer than V-O (phenolato) bond by similar to 0.07 angstrom and is identical with V-O (carboxylate) bond. H-1 NMR spectrum of (6) in CDCl3 solution indicates that the binding nature in the solid state is also retained in solution. Complexes (1)(4) display two ligand-field transitions in the visible region near 820 and 480 nm in DMF solution and exhibit irreversible oxidation peak near +0.60 V versus SCE in DMSO solution, while complexes (5) and (6) exhibit only LMCT band near 535 nm and display quasi-reversible one electron reduction peak near -0.10 V versus SCE in CH2Cl2 solution. The VO3+-VO2+ E-1/2 values shift considerably to more negative values when neutral NN donor is replaced by anionic ON donor species and it also provides better VO3+ binding via phenolato oxygen. For a given bidentate ligand, E-1/2 increases in the order: (L-2)(2-) < (L-1)(2-). (c) 2004 Elsevier B.V. All rights reserved.

Synthesis, structure, solution chemistry and the electronic effect of para substituents on the vanadium center in a family of mixed-ligand [(VO)-O-V(ONO)(ON)] compexes

Four tridentate dibasic ONO donor hydrazone ligands derived from the condensation of benzoylhydrazine with either 2-hydroxyacetophenone or its para substituted derivatives (H2L1-4, general abbreviation H2L) have been used as primary ligands and 8-hydroxyquinoline (Hhq, a bidentate monobasic ON donor species) has been used as auxiliary ligand. The reaction of [(VO)-O-IV(acac)21 with H2L in methanol followed by the addition of Hhq in equimolar ratio under aerobic condition afforded the mixed-ligand oxovanadium(V) complexes of the type [(VO)-O-V(L)(hq)] (1-4) in excellent yield. The X-ray structure of the compound [(VO)-O-V(L-4)(hq)] (4) indicates that the H2L4 ligand is bonded with vanadium meridionally in a tridentate dinegative fashion through its deprotonated phenolic-O, deprotonated enolic-O and imine-N atoms. The V-O bond length order is: oxo < phenolato < enolato. H-1 NMR spectra of 4 in CDCl3 solution indicates that it's solid-state structure is retained in solution. Complexes are diamagnetic and exhibit only ligand to metal charge transfer (LMCT) transition band near 530 nm in CH2Cl2 solution in addition to intra-ligand pi-pi* transition band near 335 rim and they display quasi-reversible one electron reduction peak near -0.10 V versus SCE in CH2Cl2 solution. lambda(max) (for LMCT transition) and the reduction peak potential (E-p(c)) values of the complexes are found to be linearly related with the Hammett (sigma) constants of the substituents in the aryloxy ring of the hydrazone ligands. lambda(max) and E-p(c) values show large dependence d lambda(max)/d sigma = 32.54 nm and dE(p)(c)/d sigma = 0.19 V, respectively, on the Hammett constant. (c) 2006 Elsevier B.V. All rights reserved.