References of "Francis, Frédéric"
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See detailEntomofaune du safoutier (Dacryodes edulis (G. Don) H.J. Lam ; Burseraceae) au Gabon : résultat dune première année d’investigation
Poligui, René Noël ULg; Mouaragadja, Isaac; Haubruge, Eric ULg et al

Poster (2010, July)

L’entomofaune du safoutier (Dacryodes edulis (G. Don) H.J. Lam ; Burseraceae) a été étudié au moyen des pièges jaunes et des observations visuelles, pendant seize semaines au Gabon, dans la province du ... [more ▼]

L’entomofaune du safoutier (Dacryodes edulis (G. Don) H.J. Lam ; Burseraceae) a été étudié au moyen des pièges jaunes et des observations visuelles, pendant seize semaines au Gabon, dans la province du Haut-Ogooué. Cinq postes de piégeages ont été installés à Franceville et cinq autres en périphérie de la ville. Les deux méthodes situent l’évolution des insectes en deux vagues dont la première et la plus importante s’étend sur huit semaines, correspond à la période de floraison de l’arbre et de pleine croissance des fruits. La seconde vague va de l’arrêt de croissance des fruits à leur maturation. Le piégeage révèle que les abondances des insectes ainsi que leur diversité biologique par poste sont plus importantes en milieu rural qu’en milieu urbain. Le contrôle visuel présente des abondances relativement similaires, mais avec une diversité sensiblement plus élevée en milieu rural. Les sites à prédominance de savanes permettent des captures d’insectes plus importantes que ceux des forets. L’abondance est globalement moins élevée au niveau des arbres males pour les deux techniques d’étude. Par contre, les observations visuelles enregistrent les pics les plus élevés sur les arbres femelles, mais le piégeage les situe sur les arbres males. La diversité biologique est significativement mieux exprimée par le piégeage, alors que le contrôle visuel spécifie mieux le niveau et l’évolution des ravageurs. Les Aphididae, les Cicadellidae et les psyllidae constituent les familles numériquement les plus importantes des insectes nuisibles. Les Apidae, les coccinellidae et les halticidae forment les familles majeures des insectes utiles. Les Tortricidae constituent la famille ayant la plus grande incidence économique sur le safoutier. [less ▲]

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See detailMorphologie de la mineuse des fruits du safoutier
Poligui, René Noël ULg; Mouaragadja, Isaac; Francis, Frédéric ULg et al

Poster (2010, July)

L’étude de l’entomofaune des associations culturales prenant en compte le safoutier a permis de mettre en évidence des fortes abondances et une diversité des familles entomologiques. Au niveau des ... [more ▼]

L’étude de l’entomofaune des associations culturales prenant en compte le safoutier a permis de mettre en évidence des fortes abondances et une diversité des familles entomologiques. Au niveau des ravageurs majeurs, nous avons caractérisé un lépidoptère (tortricidae) dont les larves minent les noyaux des fruits du safoutier (Dacryodes edulis) et peuvent induire une chute prématurée d’au moins 25% de fruits. Toutes petites, les larves sont blanches et tachetées de points noirs, puis dans leur dernier stade, elles sont roses avec la tête, les plaque anale et prothoracique brunes. La chrysalide se forme dans un cocon de soie blanc. Elle est brune au départ et noir en fin de nymphose, et se caractérise par un crémaster noir proéminent au milieu de deux paires de soie recourbées à leurs extrémités. La nymphose dure au moins 20 jours. L’adulte est un paillon gris terne. Outre le safoutier, ce lépidoptère a été trouvé dans les fruits de Pseudopdondias longifolia. Des investigations ultérieures révéleront certainement d’autres plantes hôtes et permettront d’envisager une lutte biologique efficiente contre cette mineuse des fruits. [less ▲]

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See detailAssociation des approches morphologique et moléculaire pour l’identification des vers à soies endémiques de Madagascar (Lasiocampidae, Borocera cajani)
Rakotondramanana, Alihasina; Nguyen, Bach Kim ULg; Verheggen, François ULg et al

Poster (2010, July)

La soie est une matière utilisée par les Malgaches depuis bien avant la colonisation. Cette soie est fabriquée à partir de la collecte de cocons des papillons du genre Borocera spp., ver à soie sauvage ... [more ▼]

La soie est une matière utilisée par les Malgaches depuis bien avant la colonisation. Cette soie est fabriquée à partir de la collecte de cocons des papillons du genre Borocera spp., ver à soie sauvage. On connaît une dizaine d’espèces de vers à soie sauvages endémiques à Madagascar. Ces lépidoptères polyphages se nourrissent surtout des feuilles de Uapaca bojeri et d’autres plantes telles que Dodonea madagascariensis et Psidium guyava. Les critères morphologiques se révèlent insuffisant pour identifier cette diversité d’espèces de vers à soie, surtout au niveau des stades immatures. Afin de pallier à cette incapacité d’identifier les espèces, des méthodes de marqueurs moléculaires, en particulier la RAPD (Random Amplified Polymorphic DNA) et iSSR (inter Simple Sequence Repeat), ont été appliquées. En plus de l’identification des espèces, une étude de la diversité et de la distribution des vers à soie suite à la collecte dans plusieurs forêts éloignées de plusieurs de kilomètres les unes des autres (Arivonimamo, Ambatofinandrahana, Antananarivo). Cette étude a été menée dans le cadre de la conservation de ces espèces de vers à soie endémiques en milieu. Afin d’augmenter durablement les populations de vers à soie endémiques dans les forêts de Uapaca, il est important de déterminer les espèces en présence et les capacités de dispersion de ces dernières. Les techniques d’identification moléculaires développées permettront d’orienter les stratégies de gestion des populations de Borocera et des méthodes de gestion de l’écosystème, appropriables par les gestionnaires et les communautés locales des la forêt à Uapaca bojeri. [less ▲]

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See detailAn introduction device for the aphidophagous hoverfly Episyrphus balteatus (De Geer) (Diptera: Syrphidae)
Leroy, Pascal ULg; Verheggen, François ULg; Capella, Quentin et al

in Biological Control (2010), 54(3), 181-188

Augmentative biocontrol constitutes a safe option to reduce pest populations through the enhancement of natural enemies’ activity. In this context, the aphidophagous syrphid Episyrphus baltetaus (De Geer ... [more ▼]

Augmentative biocontrol constitutes a safe option to reduce pest populations through the enhancement of natural enemies’ activity. In this context, the aphidophagous syrphid Episyrphus baltetaus (De Geer) (Diptera: Syrphidae) is a promising candidate for aphid biological control: larvae of this syrphid attack and consume a wide range of aphid species and are found on many vegetable crops. Because natural populations of beneficial insects are not always sufficient to regulate the pest infestations, this work has focused on the conception of a biological control device containing syrphid eggs which ones can easily be introduced in fields or greenhouses. Using semiochemicals [E-(β)-farnesene, R-(+)-limonene and (Z)-3-hexenol], honeydews and “artificial honeydews” (10% or 30% aqueous solutions of sucrose, fructose and glucose), the syrphid oviposition was artificially induced on an inert surface. Specifically, E-(β)-farnesene and concentrated mono-sugars (30%) were identified as the most efficient ovipositional stimulants. To test and validate the biological control device described above, laboratory and field experiments were performed: a plastic lamella covered with syrphid eggs was suspended on aphid infested plants in order to measure the efficiency of the device. The results obtained were promising since populations of 500 aphids were eliminated in ten days when 15 syrphid eggs were introduced. The use of such a biological control device could certainly contribute to the biological control to reduce the aphid infestations. [less ▲]

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See detailBiological control using Episyrphus balteatus (De Geer) (Diptera: Syrphidae)
Leroy, Pascal ULg; Verheggen, François ULg; Capella, Quentin et al

Poster (2010, May 18)

Augmentative biocontrol constitutes a safe way to reduce pest populations through the enhancement of natural enemies’ activity. In this context, the aphidophagous syrphid Episyrphus baltetaus (De Geer ... [more ▼]

Augmentative biocontrol constitutes a safe way to reduce pest populations through the enhancement of natural enemies’ activity. In this context, the aphidophagous syrphid Episyrphus baltetaus (De Geer) (Diptera: Syrphidae) is a promising candidate for aphid biological control: larvae of this syrphid attack and consume a wide range of aphid species and are found on many vegetable crops. Because natural populations of beneficials are not always sufficient to regulate the pest infestations, this work has focused on the conception of a biological control device containing syrphid eggs which can easily be introduced in fields or greenhouses. Using semiochemicals [E-(β)-farnesene, R-(+)-limonene and (Z)-3-hexenol], honeydews and “artificial honeydews” (10% or 30% aqueous solutions of sucrose, fructose and glucose), the syrphid oviposition was artificially induced on an inert surface. To test and validate the biological control device described above, laboratory and field experiments were performed: a plastic lamella covered with syrphid eggs was suspended on aphid infested plants in order to measure the efficiency of the device. The results obtained were promising since populations of 500 aphids were eliminated in ten days when 15 syrphid eggs were introduced. The use of such a biological control device could certainly contribute to aphid biological control strategies. [less ▲]

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See detailEffect of host plants on the abundance of Aphis craccivora Koch (Homoptera : Aphididae) and it parasitism by three parasitoids (Hymenoptera: Braconidae, Pteromalidae, Encyrtidae, ) in green space of Université des Sciences et Techniques de Masuku(USTM, Franceville), Gabon
Poligui, René Noël ULg; Francis, Frédéric ULg; Haubruge, Eric ULg et al

Poster (2010, May 05)

The cow pea aphid, Aphis craccivora Koch were studied on tree wield weeds of lawn (Paspalum sp, Poaceae), Chrysopogon aciculatus (Retz.) Trin. (Poaceae), Sporobolus indicus (L.) R.Br. (Poaceae) and ... [more ▼]

The cow pea aphid, Aphis craccivora Koch were studied on tree wield weeds of lawn (Paspalum sp, Poaceae), Chrysopogon aciculatus (Retz.) Trin. (Poaceae), Sporobolus indicus (L.) R.Br. (Poaceae) and Brachiara decumbens Stapf (Poaceae). 120 infloscences of each host plant specie were examined. The hymenopteran parasitism was based on mummified aphids. In the ascending order of infestation, A.craccivora colonies were less abundant on S.indicus (192 aphids), abundant on C.aciculatus (1546) and highly abundant on B.decumbens (2986). Parasitism on aphids is very low on B.decumbens (7,57%), high on C.aciculatus(57,12%) and very high on S.indicus (82,05%). 410 hymenopteran parasitoids hatch from 500 mummufied aphids taken on S.indicus, for 153 Aphidius sp(Braconidae) individuals ,160 (39,02%) Ceroplastes sp (Pteromalidae) and 97(23, 66%) non identified encyrtid(encyrtidae). Aphidophagous larva of Cheilomenes sulfurea (Coccinelidae) and Platynaspsis capicola Crotch (Coccinellidae) were observed predatoring aphids respectively on C.aciculatus and S.indicus.This study highlight the presence of native beneficials that can be used as biological control agents. [less ▲]

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See detailIntegrated “omics” approaches to investigate the chemical aspects of symbiosis in termites and potential application in ligno-cellulosic use.
Bauwens, Julien ULg; Matteotti, Christel ULg; Brognaux, Alison ULg et al

Scientific conference (2010, May 05)

Cellulosic bioethanol could be one of the solutions to satisfy the increasing demand in renewable energy. The most limitative problem is the efficiency of cellulose transformation into fermentable sugars ... [more ▼]

Cellulosic bioethanol could be one of the solutions to satisfy the increasing demand in renewable energy. The most limitative problem is the efficiency of cellulose transformation into fermentable sugars. Investigations to select new glycosyl hydrolases are an interesting approach that constitutes a potential opportunity to improve the valorization of lignocellulosic materials. Three major types of glycosyl hydolases are generally produced by organism’s that are able to efficiently use cellulosic compounds: the endoglucanases, the exoglucanases/cellobiohydrolases and the β-glucosidases. In the ability to transform lignocellulosic materials by animals, symbioses are generally observed with a range of micro-organisms including bacteria, protists and/or fungi that largely (or completely) contribute to the production of the needed enzymatic complexes. In termites, such active enzymes are produced in the insect digestive tract, by the termite insect itself or by symbiotic organisms. Within lower termites gut, such as in our model Reticulitermes santonensis (Feytaud), protists and bacteria are associated and involved in a complex symbiotic system. To investigate the respective role of the insect and different groups of symbionts, multidisciplinary “omics” approaches were here developed including proteomics (ESI-LC-MS-MS, 2D-Dige gel coupled with MALDI-TOF mass spectrometry for protein identification), genomics (with a metagenomic approach based on large cDNA bank construction), metabolomics (LC-MS stragety for carbohydrate degradation product characterization). Moreover, microorganism isolation was used to investigate and characterize glycosyl hydrolases diversity and activity in R. santonensis. The integration of this broad range of “omics” techniques allowed characterizing the role of symbionts in insects in a fundamental approach and to invtigate the chemical ecology of xylophagous insects but also corresponding to an efficient way to promote the selection of efficient enzymatic activities to potentially produce biofuels based on the use of existing lignocellulosic materials. [less ▲]

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See detailBiological control device using the aphidophagous hoverfly Episyrphus balteatus (De Geer) (Diptera: Syrphidae)
Leroy, Pascal ULg; Verheggen, François ULg; Francis, Frédéric ULg et al

Poster (2010, May 05)

Augmentative biocontrol constitutes a safe way to reduce pest populations through the enhancement of natural enemies’ activity. In this context, the aphidophagous syrphid Episyrphus baltetaus (De Geer ... [more ▼]

Augmentative biocontrol constitutes a safe way to reduce pest populations through the enhancement of natural enemies’ activity. In this context, the aphidophagous syrphid Episyrphus baltetaus (De Geer) (Diptera: Syrphidae) is a promising candidate for aphid biological control: larvae of this syrphid attack and consume a wide range of aphid species and are found on many vegetable crops. Because natural populations of beneficials are not always sufficient to regulate the pest infestations, this work has focused on the conception of a biological control device containing syrphid eggs which can easily be introduced in fields or greenhouses. To test and validate the biological control device described above, laboratory and field experiments were performed: a plastic lamella covered with syrphid eggs was suspended on aphid infested plants in order to measure the efficiency of the device. The results obtained were promising since populations of 500 aphids were eliminated in ten days when 15 syrphid eggs were introduced. The use of such a biological control device could certainly contribute to aphid biological control strategies. [less ▲]

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See detailIntraguild interactions implicating invasive species: Harmonia axyridis as a model species
Alhmedi, Ammar; Haubruge, Eric ULg; Francis, Frédéric ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14

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See detailMonitoring of the entomological diversity in a pesticide free orchard:Investigation in the Gembloux agricultural University conservatory
Poligui, René Noël ULg; Haubruge, Eric ULg; Francis, Frédéric ULg

in Communication in Agricultural and Applied Biological Sciences Ghent University (2010), 74/2

In orchards, the fruit production is currently oriented to integrated pest management. In order to develop efficient pest control strategy by using entomophagous beneficial and lowering the application of ... [more ▼]

In orchards, the fruit production is currently oriented to integrated pest management. In order to develop efficient pest control strategy by using entomophagous beneficial and lowering the application of pesticides, sufficient knowledge of entomological populations is needed. Here, a systematic monitoring of insect diversity and abundance in a conservatory orchard of Gembloux was performed. Combining yellow traps and visual observations, 19 pest and 34 beneficial families were identified among the 10766 and 3985 insects caught in yellow traps and visual observations respectively. Calculation of diversity indices allowed us to demonstrate the variability according to fruit tree species and insects observation method. Highest insects diversity was registered in apple, then in cherry and finally in the apple-pear association and plum. Pests and beneficials represented 27% and 39% of the insect collections respectively. Aphids represented from 81% to 95%of pests depending on fruit tree species and observation method. The predominant specie was Brachycaudus helychrysi (Kaltenbach). Aphidophagous guild was largely present and mainly constituted by coccinellids and hoverflies. Harmonia axyridis Pallas and Episyrphus balteatus De Geer were the most abundant. Aphididae was found to be the most common orchard pests with a range of related aphidophagous beneficials. These results highlight the need leading to potential reasoning. [less ▲]

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See detailTritrophic interactions among Macrosiphum euphorbiae aphids, their host plants and endosymbionts: investigation by a proteomic approach.
Francis, Frédéric ULg; Guillonneau, F.; Leprince, Pierre ULg et al

in Journal of Insect Physiology (2010), 56(6), 575-85

The Mi-1.2 gene in tomato confers resistance against certain clones of the potato aphid (Macrosiphum euphorbiae). This study used 2D-DIGE coupled with protein identification by MALDI-TOF-MS to compare the ... [more ▼]

The Mi-1.2 gene in tomato confers resistance against certain clones of the potato aphid (Macrosiphum euphorbiae). This study used 2D-DIGE coupled with protein identification by MALDI-TOF-MS to compare the proteome patterns of avirulent and semivirulent potato aphids and their bacterial endosymbionts on resistant (Mi-1.2+) and susceptible (Mi-1.2-) tomato lines. Avirulent aphids had low survival on resistant plants, whereas the semivirulent clone could colonize these plants. Eighty-two protein spots showed significant quantitative differences among the four treatment groups, and of these, 48 could be assigned putative identities. Numerous structural proteins and enzymes associated with primary metabolism were more abundant in the semivirulent than in the avirulent aphid clone. Several proteins were also up-regulated in semivirulent aphids when they were transferred from susceptible to resistant plants. Nearly 25% of the differentially regulated proteins originated from aphid endosymbionts and not the aphid itself. Six were assigned to the primary endosymbiont Buchnera aphidicola, and 5 appeared to be derived from a Rickettsia-like secondary symbiont. These results indicate that symbiont expression patterns differ between aphid clones with differing levels of virulence, and are influenced by the aphids' host plant. Potentially, symbionts may contribute to differential adaptation of aphids to host plant resistance. [less ▲]

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See detailAssessment of oviposition site quality by aphidophagous hoverflies: reaction to conspecific larvae
Almohamad, Raki; Verheggen, François ULg; Francis, Frédéric ULg et al

in Animal Behaviour (2010), 79

Aphidophagous predators adapt their foraging behaviour to the presence of conspecific and heterospecific larvae. We studied the effect of the presence of conspecific larvae and their tracks on the ... [more ▼]

Aphidophagous predators adapt their foraging behaviour to the presence of conspecific and heterospecific larvae. We studied the effect of the presence of conspecific larvae and their tracks on the oviposition site selection of an aphid-specific predator, Episyrphus balteatus DeGeer (Diptera: Syrphidae), in two-choice experiments using a leaf disc bioassay. Gas chromatography – mass spectrometry analysis was used to identify the volatile chemicals released from odour extracts of E. balteatus larval tracks. The behavioural effects of these volatile substances on hoverfly females were also evaluated. Our experiments demonstrated that E. balteatus females were deterred from ovipositing when presented with a Vicia faba leaf with aphids and conspecific larvae. The oviposition-deterring stimulus was also active when females were presented with a leaf that contained conspecific larval tracks. A mixture of chemical compounds was found in the volatile pattern of odour extracts of larval tracks. The main volatile chemicals were 3-methylbutanoic acid, 2-methylbutanoic acid, 2-methylpropanoic acid, 3-hydroxy- 2-butanone, hexanoic acid and phenol. Females also laid significantly fewer eggs in response to odorant volatiles emitted from larval extracts. These results highlight that predatory hoverfly females avoid ovipositing in aphid colonies in which conspecific larvae or their tracks are already present, suggesting that this behaviour constitutes a strategy that enables females to optimize their oviposition site and reduce competition suffered by their offspring. [less ▲]

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See detailStructural features conferring dual Geranyl/Farnesyl diphosphate synthase activity to an aphid prenyltransferase
Vandermoten, Sophie ULg; Santini, Sébastien; Haubruge, Eric ULg et al

in Insect Biochemistry and Molecular Biology (2009), 39(10), 707-716

In addition to providing lipid chains for protein prenylation, short-chain isoprenyl diphosphate synthases (scIPPSs) play a pivotal role in the biosynthesis of numerous mevalonate pathway end-products ... [more ▼]

In addition to providing lipid chains for protein prenylation, short-chain isoprenyl diphosphate synthases (scIPPSs) play a pivotal role in the biosynthesis of numerous mevalonate pathway end-products, including insect juvenile hormone and terpenoid pheromones. For this reason, they are being considered as targets for pesticide development. Recently, we characterized an aphid scIPPS displaying dual geranyl diphosphate (GPP; C10)/farnesyl diphosphate (FPP; C15) synthase activity in vitro. To identify the mechanism(s) responsible for this dual activity, we assessed the product selectivity of aphid scIPPSs bearing mutations at Gln107 and/or Leu110, the fourth and first residue upstream from the “first aspartate-rich motif” (FARM), respectively. All but one resulted in significant changes in product chain-length selectivity, effectively increasing the production of either GPP (Q107E, L110W) or FPP (Q107F, Q107F–L110A); the other mutation (L110A) abolished activity. Although some of these effects could be attributed to changes in steric hindrance within the catalytic cavity, molecular dynamics simulations identified other contributing factors, including residue-ligand Van der Waals interactions and the formation of hydrogen bonds or salt bridges between Gln107 and other residues across the catalytic cavity, which constitutes a novel product chain-length determination mechanism for scIPPSs. Thus the aphid enzyme apparently evolved to maintain the capacity to produce both GPP and FPP through a balance between these mechanisms. [less ▲]

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See detailMONITORING OF THE ENTOMOLOGICAL DIVERSITY IN A PESTICIDE FREE ORCHARD: INVESTIGATION OF THE GEMBLOUX AGRICULTURAL UNIVERSITY CONSERVATORY
Poligui, René Noël ULg; Haubruge, Eric ULg; Francis, Frédéric ULg

Poster (2009, May 19)

In orchards, the fruit production is currently oriented to integrated pest management. In order to develop efficient pest control strategy by using entomophagous beneficial and lowering the application of ... [more ▼]

In orchards, the fruit production is currently oriented to integrated pest management. In order to develop efficient pest control strategy by using entomophagous beneficial and lowering the application of pesticides, sufficient knowledge of entomological populations is needed. Here, a systematic monitoring of insect diversity and abundance in a conservatory orchard of Gembloux was performed. Combining yellow traps and visual observations, 19 pest and 34 beneficial families were identified among the 10766 and 3985 insects caught in yellow traps and visual observations respectively. Calculation of diversity indices allowed us to demonstrate the variability according to fruit tree species and insects observation method. Highest insects diversity was registered in apple, then in cherry and finally in the apple-pear association and plum. Pests and beneficials represented 27% and 39% of the insect collections respectively. Aphids represented from 81% to 95%of pests depending on fruit tree species and observation method. The predominant specie was Brachycaudus helychrysi (Kaltenbach). Aphidophagous guild was largely present and mainly constituted by coccinellids and hoverflies. Harmonia axyridis Pallas and Episyrphus balteatus De Geer were the most abundant. Aphididae was found to be the most common orchard pests with a range of related aphidophagous beneficials. These results highlight the need leading to potential reasoning . [less ▲]

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