Publications of Georges Lognay
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See detailAbout lipid metabolism in Hermetia illucens (L. 1758). On the origin of fatty acids in prepupae.
Hoc, Bertrand ULiege; Genva, Manon ULiege; Fauconnier, Marie-Laure ULiege et al

in Scientific Reports (2020)

Although increasingly targeted in animal nutrition, black soldier fly larvae or prepupae (BSF, Hermetia illucens L. 1758) require the characterization and modulation of their fatty acid profile to become ... [more ▼]

Although increasingly targeted in animal nutrition, black soldier fly larvae or prepupae (BSF, Hermetia illucens L. 1758) require the characterization and modulation of their fatty acid profile to become fully integrated within the feed sector. This improvement will only be possible by the understanding of underlaying biochemical pathways of fatty acid synthesis in BSF. In this study, we hypothesized a labelling of de novo synthesized fatty acids in BSF by the incorporation of deuterated water ( D2O) in their feed. Three batches of fifty larvae were reared on two diets with different polyunsaturated fatty acid profiles moistened with 40% of H2O or D2O: chicken feed or 40% of chicken feed and 60% of flax cake. Although the occurrence of D2O in insect feed increased the larval development time and decreased prepupal weight, it was possible to track the biosynthesis of fatty acids through deuterium labelling. Some fatty acids (decanoic, lauric or myristic acid) were exclusively present in their deuterated form while others (palmitic, palmitoleic or oleic acid) were found in two forms (deuterated or not) indicating that BSF can partially produce these fatty acids via biosynthesis pathways and not only by bioaccumulation from the diet. These results suggest the importance of carbohydrates as a source of acetyl-CoA in the constitution of the BSF fatty acid profile but also the potential importance of specific enzymes (e.g. thioesterase II or Δ12 fat2 desaturase) in BSF fatty acid metabolism. Finally, nearly no deuterated polyunsaturated fatty acids were found in BSF fed with deuterium confirming that BSF is not able to produce these types of fatty acids. Despite the high levels of linolenic acid in flax-enriched diets, BSF will simply bioaccumulate around 13% of this fatty acid and will metabolize approximately two-thirds of it into saturated fatty acids as lauric or myristic acid. [less ▲]

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See detailComposition, Seasonal Variation and Biological Activities of Lantana camara essential oils from Côte d’Ivoire.
Nea, Fatimata ULiege; Kambiré, Didjour Albert; Genva, Manon ULiege et al

in Molecules (2020)

This work aims to study the variations in the composition of Lantana camara leaf, flower and stem essential oils over two years. L. camara organs were harvested in Bregbo (East Côte d'Ivoire) each month ... [more ▼]

This work aims to study the variations in the composition of Lantana camara leaf, flower and stem essential oils over two years. L. camara organs were harvested in Bregbo (East Côte d'Ivoire) each month from June 2015 to June 2017. The essential oils were obtained by hydrodistillation and characterized by GC-MS and 13C NMR. Eighty-four compounds accounting for 84.4 – 99.1% of the essential oils have been identified. The essential oils hydrodistillated from L. camara are dominated by sesquiterpenes such as (E)-β-caryophyllene and α-humulene, which were found in all samples. Some monoterpenes such as thymol, sabinene and α-pinene were also present. Statistical analysis (principal component analysis and clustering) revealed a high variability in essential oil composition between the different organs and also within the studied periods as the thymol proportion was higher during flowering and fruiting months. In addition, the stem, flower, and fruit essential oils were more concentrated in thymol than the leaf essential oils. The proportions of (E)-β-caryophyllene and α-humulene were strictly inverted with the thymol proportion throughout the harvest period or vegetative cycle. The antioxidant, anti-inflammatory and insecticidal activities of leaves and flowers essential oils were also studied. Results showed that L. camara leaf and flower essential oils displayed high antioxidant, anti-inflammatory and insecticidal activities. [less ▲]

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See detailLinking variety‑dependent root volatile organic compounds in maize with diferential infestation by wireworms
La Forgia, Diana ULiege; Thibord, Jean-Baptiste; Larroudé, Philippe et al

in Journal of Pest Science (2020)

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See detailChemical composition and antioxidant activity of Thymus fontanesii essential oil from Algeria
Sidali, Lamia; Brada, Moussa; Fauconnier, Marie-Laure ULiege et al

in Natural Products Journal (2020)

Background: Thymus fontanesii is one of the importance Algerian plant, used traditionally to treat the cough and cold. In addition, it may help to protect the people against lipid peroxidation and ... [more ▼]

Background: Thymus fontanesii is one of the importance Algerian plant, used traditionally to treat the cough and cold. In addition, it may help to protect the people against lipid peroxidation and oxidative stress and can be used as an antioxidant agent for the preservation of processed food. Objective: The aim of this study was to determine the chemical composition of Algerian Thymus fontanesii essential oil and to test its antioxidant activity. Method: The oil was extracted by electromagnetic induction (EMI) heating assisted extraction and by hydrodistillation, and was analysed by gas chromatography with flame ionization detector (GC/FID) and gas chromatography/mass spectrometry (GC/MS). The antioxidant activity was evaluated by three assays mainly: DPPH assay, reducing power and β-carotene/linoleic acid. Results: The yield of the essential oil was varied from 2.1 ± 0.3 to 3.1 ± 0.1% (w/w), and from 1.8 ± 0.01 to 2.6 ± 0.02% (w/w), for the electromagnetic induction heating assisted extraction and hydrodistillation, respectively. Twenty seven components were identified representing 95.6 - 99.9% of the oil. Carvacrol (54.7 ± 1.2 - 63.9 ± 1.9%) was the major compound followed by p-cymene (9.2 ± 1.2 - 17.5 ± 1.2%) and γ-terpinene (8.8 ± 0.9 - 14.9 ± 0.8%). The Thymus fontanesii essential oil was found as a significant antioxidant with IC50 values were ranging from 57.3 ± 1.4 to 236.7 ± 1.4 µg/mL, which were higher than that of butylated hydroxyl toluene (BHT) choosing as reference (9.1 ± 1.2 to 67.8 ± 0.1 µg/mL). [less ▲]

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See detailAntimicrobial Activity of the Thio-Cyclized Lippia citriodora Leaf Essential Oil Cultivated in Algeria
Benoua, Fatma Zohra; Brada, Moussa; Boutoumi, Hocine et al

in Journal of Biologically Active Products from Nature (2019), 9(4), 250-259

The essential oil of Lippia citriodora extracted by hydrodistillation from dry leaves with a yield of 0.3 % which characterization by TLC, UV-Vis, and IRTF analyses make it possible to distinguish the ... [more ▼]

The essential oil of Lippia citriodora extracted by hydrodistillation from dry leaves with a yield of 0.3 % which characterization by TLC, UV-Vis, and IRTF analyses make it possible to distinguish the presence of aldehydes functions within the chemical composition. The GC-MS has permitted to confirm and to identify the neral and the geranial in appreciable proportions in the chemical composition of Lippia citriodora essential oil. The thionation of the carbonyl compounds of the essential oil has led to the transformation of the carbonyl compounds into corresponding thiones. The UV-Vis spectroscopy and the FT-IR spectra have shown the disappearance of the aldehyde function and its replacement by thione and thiol functions in solution by tautomery. The GC-MS has permitted to identify the formation of unsaturated cyclic compounds such as the 2-Isopropyl-5-methyl-cyclohexa-2,5-dienethione, the 6-Isopropyl-3-methyl-cyclohexa-2,4-dienethione and the 5-Isopropenyl-2-methyl-cyclohex-2-enethione, as well as an aromatic compound namely the thiothymol (2-Isopropyl-5-methyl-benzenethiol).The antibacterial and especially antifungal activity of the essential oil of Lippia citriodora has been greatly improved with the replacement of the oxygen by the sulphur and therefore the increase of the hydrophobic character and the volatility of the chemical composition of the oil. [less ▲]

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See detailToday and tomorrow: impact of climate change on aphid biology and potential consequences on their mutualism with ants
Blanchard, Solène ULiege; Lognay, Georges ULiege; Verheggen, François ULiege et al

in Physiological Entomology (2019)

Recent studies about mutualism are considering the complexity and versatility of the relation as well as highlighting the importance of the cost/benefit balance between the two protagonists. As species ... [more ▼]

Recent studies about mutualism are considering the complexity and versatility of the relation as well as highlighting the importance of the cost/benefit balance between the two protagonists. As species interactions are highly dependent on the environment, the climate changes that are foreseen for the coming years, are expected to have significant impacts on the evolution of mutualistic interactions. Among mutualisms, the aphid-ant interaction is well documented, partly explained by the pest status of aphids. This literature review focuses on the impact of climate change (particularly atmospheric carbon dioxide concentration and temperature) on aphids’ biology and the potential consequences on their mutualistic interactions with ants. We provide an overview of the published reports that deal with the effects of temperature and carbon dioxide on aphids, for which a positive, a negative or a no-effect was highlighted. A discussion is then provided on how climatic changes can alter four major components of aphid biology that are shaping their interaction with ants: (1) aphid population growth, (2) aphid behavior and mobility, (3) honeydew production and composition, and (4) semiochemistry. At the end of the review, we discuss limits to such studies on aphid-ant mutualism as well as the information still needed to predict how climate change might impact this kind of relationship. [less ▲]

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See detailIrvingia gabonensis seed fat as hard stock to formulate blends for trans free margarines
Yamoneka, J.; Malumba, P.; Lognay, Georges ULiege et al

in LWT - Food Science and Technology (2019), 101

In order to formulate trans-free margarines, Irvingia gabonensis seed fat (IGF) was blended with a liquid oil which was either rapeseed oil (RO), groundnut oil (GNO), palm super olein (PSO) or Dacryodes ... [more ▼]

In order to formulate trans-free margarines, Irvingia gabonensis seed fat (IGF) was blended with a liquid oil which was either rapeseed oil (RO), groundnut oil (GNO), palm super olein (PSO) or Dacryodes edulis pulp oil (DPO). All the binary fat blends were evaluated in terms of melting behavior by Differential Scanning Calorimetry and p-NMR. Based on their melting behaviors by p-NMR, four blends (IGF/RO 30:70, IGF/GNO 30:70, IGF/GNO 20:80 and IGF/RO 20:80) were selected as having melting profiles closed to those of fat extracted from commercial margarines and literature data. Some physical properties of the selected fat blends such as solid fat content, hardness (by penetration) test, microstructure using an optical microscope and polymorphism using X-Ray Diffraction were evaluated. Those four trans-free fat blends showed similar hardness and solid fat content (SFC) than fats extracted from commercial bakery margarine, baking margarine and table margarine during storage experiments. All those four fat blends showed β’ crystals as stable polymorphic form, which is desirable for margarines. Therefore, those four fat blends are suitable to formulate trans-free margarines with desirable textural properties. © 2018 Elsevier Ltd [less ▲]

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See detailMale flowers of Aconitum compensate for toxic pollen with increased floral signals and rewards for pollinators
Jacquemart, Anne-Laure; Buyens, C.; Hérent, M.-F. et al

in Scientific Reports (2019), 9

Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a ... [more ▼]

Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a seeming contradiction, some plants produce toxins such as alkaloids in their pollen and nectar, protecting their resources from ineffective pollinators. We investigated signals and rewards in the toxic, protandrous bee-pollinated plant Aconitum napellus, hypothesizing that male-phase flower reproductive success is pollinator-limited, which should favour higher levels of signals (odours) and rewards (nectar and pollen) compared with female-phase flowers. Furthermore, we expected insect visitors to forage only for nectar, due to the toxicity of pollen. We demonstrated that male-phase flowers emitted more volatile molecules and produced higher volumes of nectar than female-phase flowers. Alkaloids in pollen functioned as chemical defences, and were more diverse and more concentrated compared to the alkaloids in nectar. Visitors actively collected little pollen for larval food but consumed more of the lesstoxic nectar. Toxic pollen remaining on the bee bodies promoted pollen transfer efficiency, facilitating pollination. [less ▲]

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See detailCuticular hydrocarbon composition does not allow Harmonia axyridis males to identify the mating status of sexual partners
Legrand, Pauline ULiege; Vanderplanck, Maryse ULiege; Lorge, Stéphanie ULiege et al

in Entomologia Generalis (2019), 38(3), 211-224

Males of polyandrous species have to overcome sperm competition. They should select their mate based on the reproductive status of the female to increase their own fitness. Because the sexual behavior of ... [more ▼]

Males of polyandrous species have to overcome sperm competition. They should select their mate based on the reproductive status of the female to increase their own fitness. Because the sexual behavior of lady beetles relies on semiochemicals, with cuticular hydrocarbons (CHCs) being used for mate recognition, we developed and tested two hypotheses. First, we hypothesized that the cuticular hydrocarbon profile qualitatively and quantitatively differs between virgin and mated Harmonia axyridis females, regardless of the color morph. Second, we hypothesized that males discriminate virgin and mated females, preferring copulating with virgin females, rather than previously mated ones, to avoid sperm competition and subsequently increase their fitness. CHCs were solvent-extracted before being quantified and identified by gas chromatography. We found no qualitative differences between mated and unmated females irrespective of the morph; however, quantitative differences were detected. Specifically, the CHC profiles of mated females presented higher concentrations of alkenes, including 9-pentacosene, 9-heptacosene, and 9-hentriacontene. During dual-choice behavioral assays, males equally copulated with virgin and mated females. Our results suggest that there is no CHC-based discrimination strategy in virgin males of H. axyridis between virgin and once-mated females. We discuss alternative strategies that might be used in this lady beetle species. [less ▲]

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See detailThe taste of origin in a lady beetle: do males discriminate between females based on cuticular hydrocarbons?
Legrand, Pauline; Vanderplanck, Maryse ULiege; Marko, Istvan et al

in Physiological Entomology (2019)

The Asian lady beetle Harmonia axyridis originates from Asia and has established invasive populations at a worldwide scale. Recent population genetic studies have traced their invasion routes and ... [more ▼]

The Asian lady beetle Harmonia axyridis originates from Asia and has established invasive populations at a worldwide scale. Recent population genetic studies have traced their invasion routes and demonstrated that bottlenecks in population size have reduced their genetic diversity. As a consequence, phenotypical differences were highlighted between native and invasive populations. Among phenotypical traits, cuticular hydrocarbons (CHCs) might reflect geographical origin of a lady beetle, especially because of their genetic basis. Here, we investigated whether (i) the CHC profiles qualitatively and quantitatively differ between females of H. axyridis from native and invasive populations; and (ii) males discriminate females from native and invasive populations using CHC profiles. CHCs were solvent-extracted before being quantified and identified by gas chromatography and mass spectrometry. We detected a total of 17 CHCs from female elytra including six alkanes, three polyunsaturated and eight monounsaturated alkenes. The total quantity of CHCs differed among the populations with lady beetles from Tai’an (China) displaying a higher CHCs concentration than lady beetles from Gembloux (Belgium) and from Beijing (China) populations. Multivariate analyses detected differences in CHCs qualitative profiles, with females from Tai’an being different from the two other populations. Finally, our behavioural assays showed that females originating from the native Tai’an population were less preferred by males, while females from the invasive population were mounted more often. Our behavioural assays suggest that CHCs are not involved in discrimination of mating partners based on their origin. [less ▲]

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See detailElevated CO2 concentration impact the semiochemistry of aphid honeydew without cascade effect on an aphid predator
Blanchard, Solène ULiege; Boullis, Antoine; Detrain, Claire et al

Conference (2018, July 03)

Honeydew is now considered a cornerstone of the interactions between aphids and their natural enemies. Its composition is impacted by the aphid host plant species and associated phloem sap. Bacteria ... [more ▼]

Honeydew is now considered a cornerstone of the interactions between aphids and their natural enemies. Its composition is impacted by the aphid host plant species and associated phloem sap. Bacteria activity occurring in the aphid honeydew typically results in the release of volatile organic compounds (VOCs) that are used by aphid natural enemies for prey location. Because atmospheric carbon dioxide (CO2) concentration directly impacts plants physiology, we raise the hypothesis that elevated CO2 concentrations impact the quantity of honeydew produced by aphids, as well as the diversity and quantity of honeydew VOCs, with cascade effects on the foraging behavior of aphid natural enemies. Using solid-phase microextraction, we quantified the VOCs emitted by honeydew from pea aphids (Acyrthosiphon pisum Harris) reared either under 450 ± 50 ppm of CO2 (aCO2) or 800 ± 50 ppm of CO2 (eCO2). While the total amount of honeydew (honeydew release by 190 ± 50 individus in both conditions) is not impacted by the CO2 concentration, we found qualitative and quantitative differences in the semiochemistry of aphid honeydew between CO2 conditions. Three VOCs were not found in the honeydew of eCO2 aphids: 3-methyl-2-buten-1-ol, 2-methyl-1-butanol and isobutanol. However, no difference was observed in the searching and oviposition behavior of hoverfly (Episyrphus balteatus De Geer) females exposed to infested plants reared under both CO2 conditions, in a dual choice bioassay. The present work focuses on one particular aspect of atmospheric changes and should be extended to other abiotic parameters, such as temperature. [less ▲]

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See detailImbrasia obscura, an Edible Caterpillar of Tropical Africa: Chemical Composition and Nutritional Value
Mabossy-Mobouna, Germain; Malaisse, François ULiege; Richel, Aurore ULiege et al

in Tropicultura (2018), Vol. 36, N° 4

The consumption of Imbrasia obscura (Butler, 1878) has been quoted in a dozen books and papers in five different countries, namely Cameroon, Central African Republic, Congo Republic, Democratic Republic ... [more ▼]

The consumption of Imbrasia obscura (Butler, 1878) has been quoted in a dozen books and papers in five different countries, namely Cameroon, Central African Republic, Congo Republic, Democratic Republic of Congo and Angola. This study presents, for the first time, information concerning two unknown subjects, the chemical composition and the nutritional value of the species. The chemical composition shows that it is a good source of proteins and lipids with the presence of five essential amino-acids (threonine, tyrosine + phenylalanine, histidine and tryptophan) and important amounts of essential fatty acids. The mineral elements such as calcium, phosphorus, magnesium and potassium are also present in good amounts. There is little sodium for which human consumption is frequently excessive. The very high proportion of alpha-linoleic acid contributes very significantly to the low ω-6/ω-3 ratio. Consequently, this caterpillar is a food that may be recommended for human consumption. Farming this species could be encouraged because of its high nutritional value and its good commercial potential especially in areas where malnutrition is common. [less ▲]

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See detailImpact of carbon dioxide concentration on the plant-aphid-natural enemies relationship
Blanchard, Solène ULiege; Detrain, Claire; Lognay, Georges ULiege et al

Conference (2018, May 22)

While the impact of climate change on plant or insect communities has been receiving increasing attention during the last decade, plant-insect interactions under a changing environment remain to be ... [more ▼]

While the impact of climate change on plant or insect communities has been receiving increasing attention during the last decade, plant-insect interactions under a changing environment remain to be studied. These interactions are of importance as regard to the economically dimension of some crop plants and the associated species of insect pests. Insect-plant interactions are mediated by plant secondary metabolites, including volatile organic compounds (VOCs). Modifications in greenhouse gases concentrations, as predicted for 2100, could alter these chemically mediated interactions. Here, we raise the hypothesis that a raise of carbon dioxide concentration (beyond 700 ppm) affects the volatile emission of Broad bean plants, with a cascade impact on insect pests and its natural enemies. For this purpose, an experiment was made to determine the impact of CO2 concentration on aphid choice for their host plant. Choice tests were made on winged aphids between two plants grown under two CO2 concentrations. Differences were found in the choice made by the aphids. We decided then to generate odour samplings on Vicia faba plants reared under the same CO2 concentrations, hypothesizing that differences in plant semiochemicals may induce preferences for aphids. No differences were found when identifying the volatile organic compounds. Because atmospheric carbon dioxide (CO2) concentration directly impacts plants physiology, we raise the hypothesis that elevated CO2 concentrations impact the quantity of honeydew produced by aphids, as well as the diversity and quantity of honeydew VOCs, with cascade effects on the foraging behavior of aphid natural enemies. Using solid-phase microextraction, we quantified the VOCs emitted by honeydew from pea aphids (Acyrthosiphon pisum Harris) reared either under 450 ± 50 ppm of CO2 (aCO2) or 800 ± 50 ppm of CO2 (eCO2). While the total amount of honeydew (honeydew release by 190 ± 50 individus in both conditions) is not impacted by the CO2 concentration, we found qualitative and quantitative differences in the semiochemistry of aphid honeydew between CO2 conditions. Three VOCs were not found in the honeydew of eCO2 aphids: 3-methyl-2-buten-1-ol, 2-methyl-1-butanol and isobutanol. However, no difference was observed in the searching and oviposition behavior of hoverfly (Episyrphus balteatus De Geer) females exposed to infested plants reared under both CO2 conditions, in a dual choice bioassay. [less ▲]

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See detailActivité antimicrobienne des huiles essentielles du juniperus pheonicea
Harhour, Aicha; Brada, Moussa; Fauconnier, Marie-Laure ULiege et al

Scientific conference (2018, May)

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See detailProbiotics as a Sources of Aromas in Functionnal Food: Selected Examples and Analytical Methodology (chap.5)
Kenne Kemene, Thierry ULiege; Lognay, Georges ULiege; Fauconnier, Marie-Laure ULiege

in Razafindralambo, Hary (Ed.) Trends in Probiotic Applications (2018)

Probiotics play an important role in functional foods by generating natural aromas that are fundamental for the acceptability of such products by consumers. Selected strains are added to conventional ... [more ▼]

Probiotics play an important role in functional foods by generating natural aromas that are fundamental for the acceptability of such products by consumers. Selected strains are added to conventional functional foods, not just for health properties but also for their capability to improve flavor and overall taste. Beyond their applications to functional dairy products, the use of microorganisms for the aroma in-situ generation is now expanded to meat and plant-based products. However, aromas produced by probiotics are often complex and all odor compounds are not always suitable to all foodstuff types. Therefore, it is also valuable to overview, in the present chapter, the specific analytical methodology currently used for characterizing and selecting interesting aroma compounds. [less ▲]

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