References of "Lognay, Georges"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailThe use of semiochemical slow-release devices in integrated pest management strategies
Heuskin, Stéphanie ULg; Verheggen, François ULg; Haubruge, Eric ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(3), 459-470

The development of integrated pest management (IPM) strategies is increasing since many problems appeared with the use of synthetic pesticides. Semiochemicals – informative molecules used in insect-insect ... [more ▼]

The development of integrated pest management (IPM) strategies is increasing since many problems appeared with the use of synthetic pesticides. Semiochemicals – informative molecules used in insect-insect or plant-insect interaction – are more and more considered within IPM strategies as alternative or complementary approach to insecticide treatments. Indeed, these species-specific compounds do not present any related adversely affectation of beneficial organisms and do not generate any risk of pest insect resistance as observed with insecticides. Because of their complex biological activity, their dispersion in the environment to be protected or monitored needs the elaboration of slow-release devices ensuring a controlled release of the biologically active volatile compounds. These sensitive molecules also need to be protected from degradation by UV light and oxygen. Many studies were conducted on estimation of release-rate from commercialized or experimental slow-release devices. The influence of climatic parameters and dispenser type were estimated by previous authors in order to provide indications about the on-field longevity of lures. The present review outlines a list of slow-release studies conducted by many authors followed by a critical analysis of these studies. [less ▲]

Detailed reference viewed: 94 (28 ULg)
Full Text
Peer Reviewed
See detailEffect of harvest time on seed oil and protein contents and compositions in the oleaginous gourd Lagenaria siceria (Molina) Standl
Loukou, Ahou; Lognay, Georges ULg; Barthelemy, Jean-Paul ULg et al

in Journal of the Science of Food and Agriculture (2011), 91(11), 2073-2080

BACKGROUND: The stage of fruit ripeness at the time of harvest determines the final quality of ripe fruit. In this study, changes in the chemical composition of seed kernels from the oleaginous gourd ... [more ▼]

BACKGROUND: The stage of fruit ripeness at the time of harvest determines the final quality of ripe fruit. In this study, changes in the chemical composition of seed kernels from the oleaginous gourd Lagenaria siceraria (Molina) Standl. during maturation were evaluated to determine the best time to harvest the berries. Two cultivars (round and oval berry) were studied at three maturation stages (30 and 50 days after fruit set (DAFS) and complete plant whiteness (CPW)). [less ▲]

Detailed reference viewed: 126 (34 ULg)
Full Text
Peer Reviewed
See detailMicroorganisms from aphid honeydew attract natural enemies and tending ants
Verheggen, François ULg; Leroy, Pascal; Fischer, Christophe ULg et al

Conference (2011, August)

Aphids are some of the most serious pests of cultivated crops worldwide, causing major yield and economic losses. Previous works have demonstrated ants and natural enemies (including ladybeetles and ... [more ▼]

Aphids are some of the most serious pests of cultivated crops worldwide, causing major yield and economic losses. Previous works have demonstrated ants and natural enemies (including ladybeetles and hoverflies) to be able to use aphid volatile chemicals to locate aphid colonies. Here, we report the first isolation of a bacterium from the pea aphid Acyrthosiphon pisum honeydew, Staphylococcus sciuri, which produces kairomones used by the aphidophagous hoverfly Episyrphus balteatus and the Asian Ladybeetle Harmonia axyridis during their search for prey colonies. Some specific semiochemicals produced by S. sciuri were identified as attractants and ovipositional stimulants. Similarly, we have shown scouts of the aphid tending ant species, Lasius niger, to orientate their foraging behaviour toward an Aphis fabae infested plant and we have demonstrated that the odours released by this aphid honeydew were attractive for ant scouts. Again, bacteria were involved in the production of these honeydew semiochemicals. Interestingly, ant scouts were also able to discriminate honeydew odour from A. fabae (usually attended by L. niger) and A. pisum (unattendedby L. niger). Comparison of the volatile and bacteria composition of both aphid species honeydew were attended. [less ▲]

Detailed reference viewed: 83 (8 ULg)
Full Text
Peer Reviewed
See detailChemical and physical factors involved in the aggregation behaviour of Harmonia axyridis Pallas
Durieux, Delphine ULg; Fischer, Christophe ULg; Deneubourg, Jean-Louis et al

Conference (2011, July 27)

Detailed reference viewed: 49 (7 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 95 (42 ULg)
Full Text
Peer Reviewed
See detailMicroorganisms from Aphid Honeydew Attract and Enhance the Efficacy of Natural Enemies
Leroy, Pascal ULg; Sabri, Ahmed ULg; Heuskin, Stéphanie ULg et al

in Nature Communications (2011), 2

Aphids are one of the most serious pests of crops worldwide, causing major yield and economic losses. To control aphids, natural enemies could be an option but their efficacy is sometimes limited by their ... [more ▼]

Aphids are one of the most serious pests of crops worldwide, causing major yield and economic losses. To control aphids, natural enemies could be an option but their efficacy is sometimes limited by their dispersal in natural environment. Here we report the first isolation of a bacterium from the pea aphid Acyrthosiphon pisum honeydew, Staphylococcus sciuri, which acts as a kairomone enhancing the efficiency of aphid natural enemies. Our findings represent the first case of a host-associated bacterium driving prey location and ovipositional preference for the natural enemy. We show that this bacterium has a key role in tritrophic interactions because it is the direct source of volatiles used to locate prey. Some specific semiochemicals produced by S. sciuri were also identified as significant attractants and ovipositional stimulants. The use of this host-associated bacterium could certainly provide a novel approach to control aphids in field and greenhouse systems. [less ▲]

Detailed reference viewed: 147 (68 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 77 (9 ULg)
Full Text
Peer Reviewed
See detailMicro-quantitative method for analysis of sterol levels in honeybees and their pollen loads
Vanderplanck, Maryse; Michez, Denis; Vancraenenbroeck, Sophie ULg et al

in Analytical Letters (2011), 44(10), 1807-1820

A Gas Chromatography-Flame Ionization Detector method for characterization and micro-quantification of sterols was developed. The applicability of this method was evaluated for determining sterolic ... [more ▼]

A Gas Chromatography-Flame Ionization Detector method for characterization and micro-quantification of sterols was developed. The applicability of this method was evaluated for determining sterolic compounds in pollen loads, larvae, and adults of the honeybee. After a multi-step procedure to extract and purify sterols, the compounds were identified on the basis of their retention data and quantified on the basis of peak areas from analyses. Quantifications were feasible with a limited amount of samples, allowing single specimen analyses and estimation of inter-individual variation. The reliability of this microquantitative method for sterol analysis was also investigated. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Peer Reviewed
See detailAnt-aphid mutualism - How do ants locate aphid colonies?
Fischer, Christophe ULg; Sablon, Ludovic ULg; Duriaux, Adrien ULg et al

Poster (2011, June)

That some ant species show mutualistic relationships with some aphid species is well known since several decades. Ants protect aphids against natural enemies and as a reward collect the sugar-rich aphid ... [more ▼]

That some ant species show mutualistic relationships with some aphid species is well known since several decades. Ants protect aphids against natural enemies and as a reward collect the sugar-rich aphid excretion called honeydew. However, very little information is available on possible semiochemicals involved in these interactions. This study aims to identify semiochemicals involved in the establishment of this relation, using both chemical and behavioral approaches. Preliminary choice tests confirmed that ant scouts are able to detect aphid colonies at a distance using volatile organic compounds (VOC). Those VOC influencing ant’s orientation may originate from different sources: the attacked plant, the honeydew produced by the aphids and the aphids themselves. VOC emission profiles of each of those potential sources have been established using gas chromatography. Y-olfactometer assay revealed that honeydew volatile compounds are the key element in this distant attraction. Moreover, based on these VOCs, ant scouts are able to discriminate between the honeydew produced by a myrmecophilous and a non myrmecophilous aphid species. Thus, more than just a sugar source, honeydew is an attractant for ant scouts towards myrmecophilous aphids. [less ▲]

Detailed reference viewed: 67 (9 ULg)
Full Text
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 ▲]

Detailed reference viewed: 35 (7 ULg)
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 ▲]

Detailed reference viewed: 62 (20 ULg)
Peer Reviewed
See detailAcaricidal activities of Santolina Africana and Hertia Cheirifolia, two endemic plants of north Africa, on the two spotted spider mite (Tetranychus urticae)
Attia, Sabrine; Grissa, Kaouthar Lebdi; Le Goff, Guillaume et al

Poster (2011, May)

The two-spotted spider mite, Tetranychus urticae Koch, is a worldwide pest which feeds on a large variety of plant families. Because its resistance to acaricides is spreading rapidly, the development of ... [more ▼]

The two-spotted spider mite, Tetranychus urticae Koch, is a worldwide pest which feeds on a large variety of plant families. Because its resistance to acaricides is spreading rapidly, the development of new biological control tactics for population management is crucial. Plant extracts, such as Santolina africana and Hertia cheirifolia (Asteraceae), may represent viable alternatives, since they are currently considered to be minimumrisk pesticides. Although these two plants are known for their biocidal properties, the extract concentration that provides the most efficient control has not yet been precisely determined. In this study, we conducted a series of laboratory experiments to determine the susceptibility of adult females to different concentrations of S. africana and H. cheirifolia extract. These plants were steam-distilled and sprayed using a Potter spray tower. Mortality and fecundity were measured upon treatment with extract concentrations ranging from 0.07 to 6.75 mg/L. Female mortality increased with concentration, with LD50 values of 2.35 mg/L for S. africana and 3.43 mg/L for H. cheirifolia, respectively Reduced fecundity was previously observed at concentrations of 0.07, 0.09 and 0.29 mg/L .The chemical composition of the two oils were characterised by GC-MS. The most abundant components of the S. africana oil were terpinen-4-ol (44%), α- terpineol (11.31%) and borneol (6.73%). Camphor (15.11%), terpinen-4-ol (14.2%), α- terpineol (9.3%) were characteristic of the Hertia oil. [less ▲]

Detailed reference viewed: 136 (4 ULg)
See detailMicroorganisms from aphids attract hoverflies and enhance their efficacy
Leroy, Pascal ULg; Sabri, Ahmed ULg; Heuskin, Stéphanie ULg et al

Poster (2011, March 05)

Aphids are some of the most serious pests of crops worldwide, causing major yield and economic losses. They damage plants by feeding on the phloem sap, excreting copious amounts of honeydew and, in some ... [more ▼]

Aphids are some of the most serious pests of crops worldwide, causing major yield and economic losses. They damage plants by feeding on the phloem sap, excreting copious amounts of honeydew and, in some cases, vectoring plant diseases. Here, we report the first isolation of a bacterium from the pea aphid Acyrthosiphon pisum honeydew, Staphylococcus sciuri, which is involved in the release of semiochemicals acting as a kairomone for aphid natural enemies. These semiochemicals were identified by Solid-Phase Microextraction (SPME) and Gas Chromatography-Mass Spectrometry (GC-MS). Our results show that this bacterium plays a key role in the interactions between aphids and natural enemies because it is the direct source of volatiles used by the aphidophagous hoverfly Episyrphus balteatus (De Geer) (Diptera: Syrphidae) to locate its aphid prey. Through wind-tunnel experiments, some specific semiochemicals produced by S. sciuri were identified as significant attractants and ovipositional stimulants. Also, assays under greenhouses and in potato fields have demonstrated that a culture medium containing the bacterium S. sciuri strongly attracts and induces the oviposition of hoverflies, enhancing their efficiency as biological control agents. The use of this no pathogenic bacterium could provide a very novel approach towards enhancing the efficacy of biological control agents to control aphids in field crops and greenhouse systems. [less ▲]

Detailed reference viewed: 98 (5 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 300 (6 ULg)