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See detailOptimisation of a semiochemical slow-release alginate formulation attractive towards Aphidius ervi Haliday parasitoids
Heuskin, Stéphanie ULg; Lorge, Stéphanie; Godin, Bruno et al

in Pest Management Science (2011)

BACKGROUND: Optimisation of alginate formulations is described in order to develop semiochemical (E-β-farnesene and E-β-caryophyllene) slow-release devices in biological control approaches by attracting ... [more ▼]

BACKGROUND: Optimisation of alginate formulations is described in order to develop semiochemical (E-β-farnesene and E-β-caryophyllene) slow-release devices in biological control approaches by attracting predators and parasitoids of aphids. Various formulation criteria were optimised with respect to semiochemical encapsulation capacity. Moreover, the optimised formulation was characterised by texturometry and confocal microscopy. The slow-release rates of semiochemicals were calculated in laboratory controlled conditions. The attractiveness of semiochemical formulations towards Aphidius ervi was demonstrated by olfactometry. RESULTS: Two major parameters were highlighted in encapsulation optimisation: the type of alginate (Sigma L) and the type of crosslinker ion (Ca2+). Other formulation parameters were optimised: ionic strength (0.5M), Ca2+ (0.2 M) and alginate (1.5%) concentrations and the maturation time of beads in CaCl2 solution (48 h). After physical characterisation of beads, semiochemical slow-release measurements showed that alginate formulations were efficient sesquiterpene releasers, with 503 μg of E-β-farnesene and 1791 μg of E-β-caryophyllene totally released in 35 days. The efficiency of semiochemical alginate beads as attractants for female parasitoids was demonstrated, with high percentages of attraction for semiochemical odours (88 and 90% for E-β-farnesene and E-β-caryophyllene respectively) and significant statistical results. CONCLUSION: Semiochemical alginate beads can be considered as efficient slow-release systems in biological control. These formulations could be very useful to attract aphid parasitoids on crop fields. [less ▲]

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See detailDevelopment of natural semiochemical slow-release formulations as biological control devices
Heuskin, Stéphanie ULg; Lorge, Stéphanie ULg; Leroy, Pascal ULg et al

in Ioannou, Efstathia; Roussis, Vassilios (Eds.) Trends in natural products research : a PSE young scientists' meeting, June 12-15, 2011, Kolymvari - Crete. Book of abstracts (2011, June 12)

Semiochemicals – informative molecules used in insect-insect or plant-insect interactions – have been widely considered within various integrated pest management (IPM) strategies. In the present work, two ... [more ▼]

Semiochemicals – informative molecules used in insect-insect or plant-insect interactions – have been widely considered within various integrated pest management (IPM) strategies. In the present work, two sesquiterpenoids, E-β-farnesene and E-β-caryophyllene, were formulated for their properties as aphid enemy attractants. E-β-farnesene, the alarm pheromone of many aphid species, was also identified as a kairomone by attracting aphid predators and parasitoids. E-β-caryophyllene was identified as a potential component of the aggregation pheromone of the Asian ladybird, Harmonia axyridis Pallas, another aphid predator. The two products were purified from essential oils of Matricaria chamomilla L. (Asteraceae) and Nepeta cataria L. (Lamiaceae), respectively. Natural and biodegradable formulations were then investigated in order to deliver these molecules on crop fields for a long period of time as biological control devices. Due to their sensitivity to oxidation, both sesquiterpenes needed to be protected from oxygen degradation. For this purpose, alginate – hydrophilic matrix with low oxygen permeability – was used as polymer for the formulations: the main objective was to deliver semiochemicals in the air in a controlled way. Consequently, a careful selection of alginates was realised. Formulated beads showed different structural and encapsulation properties depending on various formulation factors. Alginate formulations were characterised by texturometry and by confocal microscopy in order to observe the distribution of semiochemicals in alginate network. The last step of alginate bead characterisation consisted in studying release rate of semiochemicals in laboratory-controlled conditions by optimised volatile collection system and validated fast GC analytical procedures Finally, the efficiency of formulations as aphid predator (Syrphidae species) and parasitoid (Aphidius ervi) attractants was demonstrated by field trapping and olfactometry experiments. [less ▲]

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See detailDiallyl disulfides: comparison between classical and microwave assisted synthesis
DETHIER, Bérénice ULg; Richel, Aurore ULg; Laurent, Pascal ULg et al

Poster (2011, June)

Garlic contains organosulfur compounds, such as diallyl disulfides (DADS), diallyl monosulfides (DAMS) and diallyl trisulfides (DATS), which have potential health properties. The first objective of this ... [more ▼]

Garlic contains organosulfur compounds, such as diallyl disulfides (DADS), diallyl monosulfides (DAMS) and diallyl trisulfides (DATS), which have potential health properties. The first objective of this work is to conduct the synthesis of these molecules by heating in a classical oil bath or by microwave irradiation with a phase transfer catalyst. We concluded that the synthesis should be cnducted at 40°C in an oil bath, with a phase transfer catalyst. [less ▲]

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See detailStructure-Surface Activity Relationships Of Uronic Acid-Derivative Surfactants From Renewable Resources Applications
Razafindralambo, Hary ULg; Richel, Aurore ULg; Richard, Gaetan ULg et al

Poster (2011, June)

Introduction and Background: Uronic acid-derivative surfactants are amphiphilic compounds with growing interests owing to their potential applications in various areas [1]. This class of carbohydrate ... [more ▼]

Introduction and Background: Uronic acid-derivative surfactants are amphiphilic compounds with growing interests owing to their potential applications in various areas [1]. This class of carbohydrate-based surfactants can be easily prepared from renewable raw materials in a wide range of structure by modular synthesis thanks to the presence of one carboxylic and numerous hydroxyl groups. The polar head group configurations according to the stereochemistry of OH groups, and geometry (cyclic or not), the hydrophobic tail (number and length of alkyl chain), and the type of linker (ester, acetal and amide, etc) are among the main variables in their structural entities. Therefore, the investigation of their structure-surface activity relationships appears valuable for increasing backgrounds, and achieving a rational design for selecting the best structures to be used in different industrial fields [2]. Methodology: A few analogous of glucuronic acid-derivative surfactants have been synthesized by chemical or enzymatic routes. After purification, their structure has been confirmed by various spectroscopic techniques (RMN, MS, IR). Surface tensions of true aqueous solution have been then measured in dynamic and static modes using a series of complementary techniques. Critical micelle concentrations, minimum molecular areas, and maximum surface excesses have also been determined. Results and Discussion: Glucuronic acid derivative surfactants under investigation vary in the polar head group configuration including cyclic or non-cyclic structure and α or β anomeric form, in the hydrophobic tail regarding to the chain length (C8 to C14), the presence of a double bond, as well as an OH group at the terminal carbon, and in the type of linker, ester in C6 or acetal in C1. Results showed that all of these structural attributes affect both dynamic and equilibrium surface properties of glucuronic acid -based surfactants. Conclusion: A set of synthetic glucuronic acid-based surfactants varying in the polar head group, hydrophobic tail, and linker allow us to generate various surface-active properties at the air-water interface, and to increase the knowledge on relationships between their structure and surface-active properties. [1] Laurent, P.; Razafindralambo, H.; Wathelet, B.; Blecker, C.; Wathelet, J.-P.; Paquot, M., Synthesis and Surface-Active Properties of Uronic Amide Derivatives, Surfactants from Renewable Organic Raw Materials. Journal of Surfactants and Detergents 2010, in press. [2] Razafindralambo, H.; Blecker, C.; Mezdour, S.; Deroanne, C.; Crowet, J.; Brasseur, R.; Lins, L.; Paquot, M., Impacts of the Carbonyl Group Location of Ester Bond on Interfacial Properties of Sugar-Based Surfactants: Experimental and Computational Evidences. The Journal of Physical Chemistry B 2009, 113 (26), 8872-8877. Acknowledgment: This work was supported by Belgian Walloon Region within DGTRE research project of excellence (TECHNOSE). [less ▲]

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See detailVolatile organic compounds of the roots of barley and their role in the rhizosphere
Fiers, Marie ULg; Barsics, Fanny ULg; Camerman, Marc ULg et al

Poster (2011, May 24)

Volatile organic compounds emitted by plants are known to intervene with various biotic environmental factors. Up to now, most of the studies have been focused on aerial volatiles and root liquid exudates ... [more ▼]

Volatile organic compounds emitted by plants are known to intervene with various biotic environmental factors. Up to now, most of the studies have been focused on aerial volatiles and root liquid exudates. Very few researches have been completed concerning belowground volatiles released into the rhizosphere despite their potential capacity to carry information between organisms. The Rhizovol project, started in autumn 2010, involves 5 different units of Gembloux Agro-Bio Tech collectively studying the production of belowground volatiles by barley roots underlying various biotic interactions in the rhizosphere. Some preliminary results of each partner of the project will be presented. To achieve this goal, analytical methods allowing the sampling, separation, identification and quantification of belowground volatile compounds have to be developed, taking into account their potential modifications in the rhizosphere once released by the roots. They enable the subsequent characterization and study of the interactions between barley and its rhizospheric partners chosen for this study. These interactions imply three types of organisms: beneficial organisms, pathogenic agents and plant and insect pests. Beneficial organisms can promote the growth of barley by the emission of volatiles; on the other hand barley can support their growth and metabolism. These phenomenons will be assessed by the study of 19 strains of plant growth-promoting bacteria (PGPR). Three pathogenic agents - two fungi (Fusarium culmorum and Cochliobolus sativus) and one virus (Barley yellow dwarf virus) - were chosen as they are known to cause various diseases on barley, especially on roots. The attractive or repellent effects of barley root volatiles on the pathogenic agents or their vectors, as well as the effect of volatiles on the diseases evolution will be evaluated. The project also includes several types of pests such as plants and insects. Plants can compete with barley for space and nutrients through volatile interactions. This will be assessed by the study of autotoxicity by barley itself and allelopathy with 8 weeds and a hemiparasitic plant (Rhinanthus minor). The effects of barley volatiles can also impact the severity of the attacks by insects. This part will be conducted with wireworms as they represent worldwide known pests, and aphids, through their viral vector role. Eventually, as soil characteristics can strongly influence the diffusion of volatile compounds, the diffusion behaviour of the identified volatile biomolecules through the soil will be modelled. Tritrophic interactions (e.g. insect-plant-pathogenic fungi) will be studied based on each bitrophic interaction results. Over-all, the Rhizovol project aims at improving the knowledge of interactions mediated by volatile compounds in the rhizosphere and at establishing new biocontrol methods that could contribute to integrated disease and pest management systems. [less ▲]

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See detailA semiochemical enhancing the attractiveness of aphidophagous predators in potato crops
Leroy, Pascal ULg; Vandereycken, Axel ULg; Sabri, Ahmed ULg et al

Poster (2011, May 24)

Aphids are major pests of crops worldwide and the use of pesticides has led to resistant populations. The integration of aphid natural enemies in integrated management programs could be an option, but ... [more ▼]

Aphids are major pests of crops worldwide and the use of pesticides has led to resistant populations. The integration of aphid natural enemies in integrated management programs could be an option, but their efficacy is often limited by their quick dispersal from the ecosystem where they are released. Here, using wind-tunnel and field experiments, we have demonstrated that 3-Methyl-2-butenal acts as an efficient attractant and ovipositional stimulant for the hoverfly Episyrphus balteatus (De Geer) (Diptera: Syrphidae), enhancing its efficiency as biological control agent in crop fields. Wind-tunnel assays allowed determining that a minimal dose of 250 µg of 3-Methyl-2-butenal is required to attract the hoverflies over a distance of 2.5 m while a minimal dose of 500 µg is needed to induce the oviposition. Both attraction and oviposition increased proportionally to the tested doses showing that hoverflies are able to regulate their oviposition according to the chemical stimuli from their environment. In field experiments, both Syrphidae and Chrysopidae were strongly attracted by the 3-Methyl-2-butenal at a dose of 10 mg which also induces the oviposition of these two aphid predators in potato crops. This study also highlighted that hoverflies are the most abundant aphid predators found in natural environment. Against aphids, the use of this semiochemical could certainly enhance the efficiency of natural enemies. Furthermore, the use of the chemical cue 3-Methyl-2-butenal could provide a novel approach to control aphids in field and greenhouse systems. [less ▲]

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See detailLutte contre les ravageurs des stocks de céréales et de légumineuses au Sénégal et en Afrique occidentale : synthèse bibliographique
Gueye, Momar Talla; Seck, Dogo; Wathelet, Jean-Paul ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(1), 183-194

Post-harvest losses of cereals and legumes are a major problem in Senegal and West Africa. The solutions to eliminate insects, major pests of stored products were mainly chemical. However, due to ... [more ▼]

Post-harvest losses of cereals and legumes are a major problem in Senegal and West Africa. The solutions to eliminate insects, major pests of stored products were mainly chemical. However, due to pollution associated with pesticides use, selection of resistant strains, environmental pollution, poisoning, the search for alternatives is needed. It is reported on different methods of protecting stocks performed alternatively or in combination with pesticides. The major pest species encountered, particularly Prostephanus truncatus (Horn), insect emerging in Senegal, could be controlled by alternative methods including specially the use of insecticide plants. Different aspects related to this alternative way to chemical pesticides are reviewed herein. Keywords. Cereals, pulses, post-harvest, control, pesticides, insecticide plants. [less ▲]

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See detailEarthworms smell microorganisms in soil
Zirbes, Lara ULg; Verheggen, François ULg; Mescher, Mark et al

Poster (2011)

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See detailCaractérisation des composés volatils des huiles d’olive produites dans des coopératives de la région orientale du Maroc
Tanouti, K.; Serghini-Caid, H.; Sindic, Marianne ULg et al

Poster (2011)

L'objectif principal de cette étude est de faire progresser nos connaissances sur le profil volatil des huiles d’olive produite dans les régions du Maroc oriental. L’identification des composés volatils des ... [more ▼]

L'objectif principal de cette étude est de faire progresser nos connaissances sur le profil volatil des huiles d’olive produite dans les régions du Maroc oriental. L’identification des composés volatils des échantillons d’huiles d’olive provenant des coopératives de la région orientale du Maroc et la comparaison aux profils de volatils d’huiles européennes a été réalisée on utilisant la méthode de la microextraction en phase solide (SPME) couplée à la GC/MS. [less ▲]

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See detailEssential Oil Composition of Ocimum basilicum L. and Ocimum gratissimum L. from Algeria
Brada, M.; Khelifa, L. H.; Achour, D. et al

in Journal of Essential Oil-Bearing Plants [=JEOBP] (2011), 14(6), 810-814

The constituents of essential oils isolated by hydrodistillation of the overground parts of Ocimum basilicum L. and Ocimum gratissimum L. from Algeria were examined by GC and GC-MS. A total of 46 and 43 ... [more ▼]

The constituents of essential oils isolated by hydrodistillation of the overground parts of Ocimum basilicum L. and Ocimum gratissimum L. from Algeria were examined by GC and GC-MS. A total of 46 and 43 components were identified accounting for 99.4 % and 97.7 % of O. basilicum and O. gratissimum oils, respectively. The oil of O. basilicum contained, as main components, linalool (44.7 %), linalyl acetate (14.0 %), 1,8-cineole (6.7 %), myrcene (5.6 %), α-terpineol (5.1 %), geranyl acetate (4.0 %), alloocimene (2.4 %), neryl acetate (2.4 %), elemol (2.1 %) and β-caryophyllene (1.3 %). Major compounds in the essential oil of O. gratissimum were eugenol (54.8 %), β-elemene (10.9 %), 1,8 cineole (4.1 %), α-humulene (3.8 %) linalool (2.1 %) and α-amorphene (2.1 %). [less ▲]

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See detailTechniques de séchage des starters lactiques et mécanismes affectant la viabilité cellulaire suite à la lyophilisation
Coulibaly, Ibourahema ULg; Dubois Dauphin, Robin ULg; Danthine, Sabine ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(2), 287-299

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See detailComparison of Microwave-Assisted Hydrodistillation and and Traditional Hydrodistillation Methods for the Rosmarinus eriocalyx essential oils from Eastern Morocco
Fadel, O.; Ghazi, K.; Mouni, L. et al

in Journal of materials and environmental science (2011), 2(2),

Volatile compounds of Rosmarinus eriocalyx samples were extracted by steam-hydrodistillation (HD) and microwave-assisted hydrodistillation (MAH). GC-MS and GC-FID analysis of the oils revealed the ... [more ▼]

Volatile compounds of Rosmarinus eriocalyx samples were extracted by steam-hydrodistillation (HD) and microwave-assisted hydrodistillation (MAH). GC-MS and GC-FID analysis of the oils revealed the presence of 22 and 26 compounds in the essential oils obtained through HD and MAH, respectively. The total yield of the volatile fractions obtained through HD and MAH was 1.21% and 1.47%, respectively. The two oils contained the same dominant components: camphor (35.92% HD; 35.33% MAH), camphene (19.74%; 17.07%), a-pinene (14.53%; 12.87%), and 1,8-cineol (6.52%; 6.73%). Higher amounts of oxygenated monoterpenes such as borneol, 1,8-cineol, isobornyl acetate, a-terpeneol, caryophyllene oxide (13.59%) were present in the oil of MAH in comparison with HD (12.36%). However, HD oil contained more monoterpene hydrocarbons such as tricyclene, a-pinene, camphene, o-cymene and limonene (39.04%) than MAH extracted oil (34.45%). [less ▲]

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