References of "Lognay, Georges"
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See detailElevated carbon dioxide concentration reduces alarm signaling in aphids
Boullis, Antoine ULg; Fassotte, Bérénice ULg; Sarles, Landry ULg et al

in Journal of Chemical Ecology (in press)

Insects often rely on olfaction to communicate with surrounding conspecifics. While the chemical language of insects has been deciphered in recent decades, few studies have assessed how changes in ... [more ▼]

Insects often rely on olfaction to communicate with surrounding conspecifics. While the chemical language of insects has been deciphered in recent decades, few studies have assessed how changes in atmospheric greenhouse gas concentrations will impact pheromonal communication by insects. Here, we hypothesize that changes in the concentration of atmospheric carbon dioxide (CO2) affect the whole dynamics of alarm signaling in aphids, including: (1) the production of the active compound (E)-β-farnesene (Eβf), (2) emission behavior when under attack, (3) perception by the olfactory apparatus, and (4) the escape response. We reared two strains of the pea aphid Acyrthosiphon pisum under ambient and elevated CO2 concentrations for several generations. We found that an increase in CO2 concentration reduced the production (i.e., individual content) and emission of Eβf (released under predation events). While no difference in Eβf neuronal perception was observed, we found that an increase in CO2 strongly reduces the escape behavior expressed by an aphid colony following exposure to natural doses of the alarm pheromone. In conclusion, our results confirm that changes to greenhouse gases do impact chemical communication in insects, and could potentially have a cascade effect on interactions with higher trophic levels. [less ▲]

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See detailInfluence of the secondary endosymbiont Serratia Symbiotica on the resistance to the parasitism in the aphid Acyrthosiphon pisum
Attia, Sabrine; Foray, Vincent; Louâpre, Philippe et al

in Journal of Entomology and Zoology Studies (in press)

Aphids have an obligate association with the primary symbiont Buchnera aphidicola and is known to affect aphid fitness. Aphids commonly harbour other facultative bacterial endosymbionts and may benefit ... [more ▼]

Aphids have an obligate association with the primary symbiont Buchnera aphidicola and is known to affect aphid fitness. Aphids commonly harbour other facultative bacterial endosymbionts and may benefit from their presence through increased resistance to parasitoids [1]. Present results suggest that the ability of hosts to defend against natural enemies depend not only on the presence of symbionts but also on the host genotype. Aphids represent a complex micro-environment for the parasitoid larvae and both the aphid physiology and endosymbiont influence their survival until mummification. [less ▲]

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See detailChemical Composition and Acaricidal Activity of Thymus algeriensis Essential Oil against Varroa destructor
Kouache, Benmoussa; Brada, Moussa; Saadi, Abdelkader et al

in Natural Product Communications (2017), 12(0), 1-4

The aim of the present study was to determine the chemical composition and evaluate the acaricidal activity of Thymus algeriensis essential oil (TAEO) against Varroa destructor. This ectoparasitic mite is ... [more ▼]

The aim of the present study was to determine the chemical composition and evaluate the acaricidal activity of Thymus algeriensis essential oil (TAEO) against Varroa destructor. This ectoparasitic mite is a pest of the honey bee Apis mellifera. The essential oil from the aerial parts of T. algeriensis, obtained by hydrodistillation, was obtained in a yield of 2.8± 0.2%, w/w. The TAEO was analyzed by GC and GC/MS. Thirty-four compounds were identified, representing 99.3% of the oil. The main constituents were carvacrol (48.4%), γ-terpinene (14.9%), p-cymene (14.7%), and thymol (5.6%). Four lots were constituted at the level of an apiary in order to study the dynamics of the Varroa destructor and its host, Apis mellifera. After diagnosis by the biological method "install of diapers", the lots were treated at different doses of TAEO (0.1, 0.3 and 0.5%). TAEO was sprayed on top of the hives. The results show that TAEO at 0.5% resulted in a decrease in the rate of infestation of Varroa destructor, causing a mortality rate of 32.6% without negative effect on the nesting of the queen. The essential oil of T. algeriensis could be used as a bioacaricidal agent. [less ▲]

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See detailImpact of pollen resources drift on common bumblebees in NW Europe
Roger, N.; Moerman, R.; Carvalheiro, L. G. et al

in Global Change Biology (2017), 23(1), 68-76

Several bee species are experiencing significant population declines. As bees exclusively rely on pollen for development and survival, such declines could be partly related to changes in their host plant ... [more ▼]

Several bee species are experiencing significant population declines. As bees exclusively rely on pollen for development and survival, such declines could be partly related to changes in their host plant abundance and quality. Here, we investigate whether generalist bumblebee species, with stable population trends over the past years, adapted their diets in response to changes in the distribution and chemical quality of their pollen resources. We selected five common species of bumblebee in NW Europe for which we had a precise description of their pollen diet through two time periods (‘prior to 1950’ and ‘2004–2005’). For each species, we assessed whether the shift in their pollen diet was related with the changes in the suitable area of their pollen resources. Concurrently, we evaluated whether the chemical composition of pollen resources changed over time and experimentally tested the impact of new major pollen species on the development of B. terrestris microcolonies. Only one species (i.e. B. lapidarius) significantly included more pollen from resources whose suitable area expanded. This opportunist pattern could partly explain the expansion of B. lapidarius in Europe. Regarding the temporal variation in the chemical composition of the pollen diet, total and essential amino acid contents did not differ significantly between the two time periods while we found significant differences among plant species. This result is driven by the great diversity of resources used by bumblebee species in both periods. Our bioassay revealed that the shift to new major pollen resources allowed microcolonies to develop, bringing new evidence on the opportunist feature of bumblebee in their diets. Overall, this study shows that the response to pollen resource drift varies among closely related pollinators, and a species-rich plant community ensures generalist species to select a nutrient-rich pollen diet. © 2016 John Wiley & Sons Ltd [less ▲]

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See detailOviposition deterring effect of Ocimum basilicum L. (Lamiaceae) on Tuta absoluta Meyrick (Lepidoptera: Gelechiidae)
Yarou, Boni Barthélémy ULg; Bawin, Thomas ULg; Boullis, Antoine ULg et al

Poster (2016, December 02)

Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is one of the most important pests of tomato, reducing crop yield in greenhouses and fields, in several countries around the world. Because synthetic ... [more ▼]

Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is one of the most important pests of tomato, reducing crop yield in greenhouses and fields, in several countries around the world. Because synthetic insecticides lead to resistance and have adverse effects on natural enemies and producers’ health, there is a need for alternatives. In this study, we assess the oviposition deterring effect of O. basilicum using dual-choice behavioral assays performed in flight tunnels. Two modalities were tested, i.e. (1) a tomato plant associated either with an O. basilicum plant versus a tomato plant associated with a plastic pot only filled with potting soil, and (2) a tomato plant with basil essential oil (EO) formulated in paraffin oil (PO) versus a tomato plant with PO only. A 1 ml cylindrical polyethylene plug loaded with 100 µl of solution (formulated EO or PO) was placed on each plant as a diffuser. Forty-eight hours after the release of unsexed adult individuals randomly sampled from the rearing in the central area of the tunnel, we found that plants and EOs reduced T. absoluta oviposition behavior on a nearby located tomato plant. GC-MS analyses showed that the major constituents include estragol (73.8%), linalool (8.6%), β-elemene (2.9%) in O. basilicum essential oils and E-α-bergamotene (38.9%), methyl eugenol (26.1 %), E-β-ocimene (17.7 % ) in O. basilicum VOCs collected with solid-phase micro-extraction method. These results suggest a valuable potential of O. basilicum and associated essential oils as component of an integrated management strategy against the tomato leafminer. [less ▲]

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See detailNutritional Composition and Rearing Potential of the Meadow Grasshopper (Chorthippus parallelus Zetterstedt)
Paul, Aman ULg; Frederich, Michel ULg; Uyttenbroeck, Roel ULg et al

in Journal of Asia-Pacific Entomology (2016), 19(4), 1111-1116

Insects, particularly those belonging to the family Acrididae (grasshoppers), are commonly consumed as human food in many parts of the world. Grasshoppers of the species Chorthippus parallelus are ... [more ▼]

Insects, particularly those belonging to the family Acrididae (grasshoppers), are commonly consumed as human food in many parts of the world. Grasshoppers of the species Chorthippus parallelus are abundantly found throughout Europe. However, these insects were not consumed by Europeans till now, but could possibly be used as human food, which is why we investigated their chemical composition. We found that they contain high level of proteins (69%), with an excellent amino acid profile and protein digestibility (97%). Furthermore, specimens of C. parallelus have an interesting fatty acids profile and minerals composition. Preliminary toxicity assessment indicates that these insects do not exhibit toxicity towards neutrophil cells (white blood cells). These data suggest that C. parallelus could be considered for human consumption. Rearing trials done during the study show that commercial rearing could be developed to produce sufficient biomass for sustaining human consumption. [less ▲]

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See detailImpact of skimming and microfiltration processes on equol concentration in milk
Daems, Frédéric ULg; Ninane, Véronique; Romnee, Jean-Michel et al

Poster (2016, October 19)

Equol is a microbial metabolite of isoflavones that could be used as therapeutic agent against several diseases and cancers. Cow's milk could be a potential source of equol in the human diet, but more ... [more ▼]

Equol is a microbial metabolite of isoflavones that could be used as therapeutic agent against several diseases and cancers. Cow's milk could be a potential source of equol in the human diet, but more studies are needed on the changes in equol concentration during the technological processing of milk and dairy products. This first exploratory study sought to assess the impact of industrial skimming and microfiltration processes on equol concentration in conventional cow's milk. The milk samples used in this study came from bulk cow’s milk collected in Wallonia (Belgium), by a local dairy and processed in a local cheese factory. Six random sampling were conducted during spring and, for each of them, samples from raw, skimmed and microfiltered milk were analyzed. Equol was present in all samples at a concentration of between 3.2 and 10.3 µg.L-1. A Wilcoxon's signed rank test was then performed on the difference of data, having raw milk as reference, irrespective of the collection date. The results showed that the skimming process slightly increased the equol concentration in milk and therefore that equol had no or little affinity with the lipid milk fraction. The results also showed that, with the microfiltration process, a small proportion of equol was retained. Equol concentration has returned to the same level as that found in raw milk. This might be because of a chemical affinity either with bigger molecules that are physically retained or through direct interaction with the membrane. This scoping study paves the way for more extensive studies on the interaction between equol and other components of the milk. [less ▲]

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See detailValorization of Seeds from Some Field Border Flowering Seeds
Paul, Aman ULg; Danthine, Sabine ULg; Mutwale Kapepula, Paulin ULg et al

Poster (2016, September 20)

Flowering strips are now being increasingly cultivated along the fields to improve biodiversity. However after serving for the desired function, these plants have no utilization besides animal feed. It ... [more ▼]

Flowering strips are now being increasingly cultivated along the fields to improve biodiversity. However after serving for the desired function, these plants have no utilization besides animal feed. It could be really interesting to valorize some commonly grown plant in these strips to render food or health promoting compounds. With this objective in mind the seeds of Achillea millefolium, Anthriscus sylvestris and Prunella vulgaris were investigated for lipids, proteins and phenolic content. Further the lipids were analyzed for fatty acid profile using gas chromatography and the phenolic compounds in the methanolic extract of defatted seeds were identified using HPLC-DAD. The antiradical activity of the methanolic extracts obtained from defatted seeds was investigated using DPPH and ABTS assays. The anti-inflammatory potential of these seed extracts was evaluated on the reactive oxygen species (ROS) production by stimulated neutrophils and on the specific activity of myeloperoxidase (MPO), a pro-oxidant enzyme marker of inflammation. Seeds from all three plants were analyzed with interesting levels of lipids, proteins and phenolic content. Linoleic acid, oleic acid and alpha-linolenic acid were the major fatty acids analyzed in A. millefolium, A. sylvestris and P. vulgaris respectively. On the other hand different phenolic acid formed the major phenolic constituents. Seed extracts displayed high ABTS and DPPH radical-scavenging activities in a dose dependent manner. Also a strong dose dependent anti-inflammatory activity of all three extracts was observed against ROS production by neutrophils and MPO activity. Results indicate that these seed show a great potential to render lipids which could be utilized as human food, further the defatted seeds could be directly included in human diet due to interesting levels of proteins and anti-inflammation ability. [less ▲]

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See detailDevelopment of a semiochemical-based control method against the walnut husk fly, Rhagoletis completa Cresson
Sarles, Landry ULg; Lognay, Georges ULg; Verhaeghe, Agnès et al

Poster (2016, September 15)

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See detailCan tropical basil be integrated in vegetable crop pest management?
Yarou, Boni Barthélémy ULg; Verheggen, François ULg; Heuskin, Stéphanie ULg et al

Poster (2016, May 17)

To address human and environmental health issues related to the use of synthetic pesticides, it is important to explore other ecological pest management approaches. Within this context, a study was ... [more ▼]

To address human and environmental health issues related to the use of synthetic pesticides, it is important to explore other ecological pest management approaches. Within this context, a study was conducted to evaluate the toxic and repellent effect of Ocimum gratissimum L. (Lamiaceae) on Myzus persicae S. (Aphididae). The toxicity of O. gratissimum essential oil (EO) was evaluated on M. persicae comparing 3 concentrations (0.001%; 0.01% and 0.1%) to a control (15% sucrose). Mortality rate and fecundity were assessed for each concentration. The observations were made daily, for 4 days, on 12 replicates per treatment. To test the repellent effect of O. gratissimum plants, 2 treatments were compared: a group of 8 Amaranthus cruentus L. (Amaranthaceae) plants with 1 plant of O. gratissimum in the middle and a group of 9 A. cruentus plants (control). The distribution of aphids was analyzed 12 days after the middle plant infestation (20 aphids per plant) for each treatment (6 replicates per treatment). O. gratissimum EO was found toxic from a concentration of 0.01%, with a mortality rate of 34% versus 12% for the control ; The fecundity felt from 30 larvae after 4 days (control) to 15 larvae for the 3 doses of the EO. The analysis with the generalized linear mixed model with Poisson error distribution followed by Turkey test (5 %) showed that EO is significantly more toxic than the control, both for mortality and fecundity (p <0.001). In association test, the population of M. persicae (15 aphids per plant) was significantly (p<0,001) lower when A. cruentus plants was associated with O. gratissimum plant than with the control (22 aphids per plant). Furthermore, the population increases gradually as one moves away from the infestation point in association test whereas it decreases in the control. With regards to these results, it appears that O. gratissimum has biocide effects on M. persicae. This plant may be used in an integrated pest management strategy in the production of vegetable to reduce the use of synthetic pesticides and avoid chemicals residues. [less ▲]

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See detailMechanisms involved in pearlfish resistance to holothuroid toxins
Brasseur, Lola; Parmentier, Eric ULg; Caulier, Guillaume et al

in Marine Biology (2016), 163(129), 1-14

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See detailQuantification of four Isoflavones in Forages with UPLC®-MS/MS, using the Box-Behnken Experimental Design to Optimize Sample Preparation
Daems, Frédéric ULg; Romnee, Jean-Michel; Rasse, Catherine et al

in Chromatographia (2016), 79(11), 711-725

A performant method for the simultaneous quantification of daidzein, genistein, formononetin and biochanin A in forages using an UPLC®-MS/MS was developed and fully validated. The ultrasound-assisted ... [more ▼]

A performant method for the simultaneous quantification of daidzein, genistein, formononetin and biochanin A in forages using an UPLC®-MS/MS was developed and fully validated. The ultrasound-assisted extraction and enzymatic hydrolysis used in the sample preparation step were optimized using the Box-Behnken experimental design. The optimal extraction conditions used for a representative mix of forage plants were 80°C, 10 min and 55% methanol, and for hydrolysis they were 20°C, 18 h and pH=6. The chromatographic separation was achieved using an Acquity® UPLC® HSS T3 column, with a water/methanol linear gradient containing 0.01% of formic acid at a 0.55 mL min-1 flow rate. The four isoflavones were detected by ESI mass spectrometry in positive ion MRM mode. The method allows high throughput analyses of samples and showed an adequate linear regression model for all isoflavones over a range from 5 to 125 ng mL-1. There was good intra- and inter-day precision (≤ 8.2% and ≤ 7.6%) and accuracy (≤ 11.4% and ≤ 7.1%). The recovery rates were in an acceptable range of 70-120%, except for biochanin A, where the rate was about 50%. Good method repeatability was also observed, and there was no matrix effect or carry-over problem. The sample extracts were stable for at least 6 days of storage at -21°C and 6°C. The method proved to be sensitive, precise and accurate for discriminating a wide variety of forages likely to be grazed by ruminants according to their isoflavone content and to observe the impact storage process on isoflavone content in forages. [less ▲]

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See detailFood in a row : urban trees offer valuable floral resources to pollinating insects
Somme, Laurent; Moquet, Laura; Quinet, Muriel et al

in Urban Ecosystems (2016)

Urbanization affects the availability and diversity of floral resources (pollen and/or nectar) for wild pollinating insects. For example, urban green areas are characterized by an abundance of ornamental ... [more ▼]

Urbanization affects the availability and diversity of floral resources (pollen and/or nectar) for wild pollinating insects. For example, urban green areas are characterized by an abundance of ornamental plant species. Increasingly, trees are planted to improve the aesthetics of urban streets and parks. These urban trees might offer important floral resources to pollinating insects. To examine the suitability of urban trees as resources for pollinating insects, we investigated the chemical composition of pollen and nectar as well as the amount of nectar produced by the nine major insect-pollinated tree species planted in cities of Western Europe, namely Acer pseudoplatanus, Aesculus carnea, A. hippocastanum, Robinia pseudoacacia, Tilia cordata, T. x euchlora, T. x europaea, T. platyphyllos and T. tomentosa. The analyses revealed that globally the Tilia trees provide pollen with lower contents of polypeptides, amino acids and phytosterols compared with the other species. Urban tree flowers offer abundant nectar with relatively high sugar contents (0.16–1.28 mg/flower); sucrose was the predominant sugar in all nectars. The investigated tree species could therefore be considered in future city plantings. [less ▲]

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See detailIn vitro evaluation of protein precipitation capacity of temperate browse species
Vandermeulen, Sophie ULg; Leblois, Julie ULg; Ramírez-Restrepo, Carlos Alberto et al

Poster (2016, February 05)

European agri-environmental policies are promoting the establishment of shrubs and trees on grasslands. The use of browse as fodder requires knowledge on their nutritive value since intensive production ... [more ▼]

European agri-environmental policies are promoting the establishment of shrubs and trees on grasslands. The use of browse as fodder requires knowledge on their nutritive value since intensive production systems are still relying on expensive and environment-costing protein sources. However, information on the influence of temperate condensed tannins (CT)-containing browse forage on rumen protein metabolism is elusive. The study aimed to assess the protein precipitation capacity (PPC) of 10 temperate browse species and establish the correlation between PPC values and plants CT content. PPC of foliage of 3 individuals per woody plants was measured using 2 model proteins: bovine serum albumin (BSA) and casein. The N content in protein solutions (4.6g/L; pH=6.8) was determined before and after adding each forage sample. Extractable CT concentration was quantified by spectrophotometry. The PPC varied across plant species (P<0.001). Corylus avellana had the highest ability to precipitate casein (52.4%). In contrast, the BSA precipitation (18.3%) of this plant was similar to Cornus sanguinea (12.7%), Quercus robur (12.1%) and Crataegus monogyna (11.0%). CT content ranged from 1.4 in Fraxinus excelsior to 82.7g/kg of depigmented sample in Corylus avellana (P<0.001) and was correlated to BSA (r=0.70; P<0.001) and casein PC (r=0.51; P<0.01). It was concluded that woody species could play a significant role in modifying protein metabolism, but further in vivo trials are required. [less ▲]

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See detailUse of response surface methodology to optimize samples preparations in laboratory
Daems, Frédéric ULg; Romnee, Jean-Michel; Lognay, Georges ULg

Conference (2016, January 17)

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