References of "Brostaux, Yves"
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See detailDetection of aggregative behaviour in binary choice experiments
Brostaux, Yves ULg

Poster (2011, August 22)

Aggregative behaviour can be defined as a natural tendency for individuals to cluster in space into groups of varying sizes. In entomology, this behaviour can be detected in binary choice experiments ... [more ▼]

Aggregative behaviour can be defined as a natural tendency for individuals to cluster in space into groups of varying sizes. In entomology, this behaviour can be detected in binary choice experiments. Analysis of these experiments reveals specific characteristics (unequal counts between repetitions, dependence of individual choices) that make the traditional adjustment tests fail. We demonstrate that the use of generalized linear models can circumvent these pitfalls and deliver a reliable diagnosis on the social behaviour of the studied invertebrates. The strength of this behaviour can then be evaluated through the use of common correlation models. [less ▲]

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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)

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See detailCarrion beetles visiting pig carcasses during early spring in urban, forest and agricultural biotopes of Western Europe
Dekeirsschieter, Jessica ULg; Verheggen, François ULg; Haubruge, Eric ULg et al

in Journal of Insect Science [=JIS] (2011), 11

Carrion beetles are important in terrestrial ecosystems, consuming dead mammals and promoting the recycling of organic matter into ecosystems. Most forensic studies are focused on succession of Diptera ... [more ▼]

Carrion beetles are important in terrestrial ecosystems, consuming dead mammals and promoting the recycling of organic matter into ecosystems. Most forensic studies are focused on succession of Diptera while neglecting Coleoptera. So far, little information is available on carrion beetles postmortem colonization and decomposition process in temperate biogeoclimatic countries. These beetles are however part of the entomofaunal colonization of a dead body. Forensic entomologists need databases concerning the distribution, ecology and phenology of necrophagous insects, including silphids. Forensic entomology uses pig carcasses to surrogate human decomposition and to investigate entomofaunal succession. However, few studies have been conducted in Europe on large carcasses. The work reported here monitored the presence of the carrion beetles (Coleoptera: Silphidae) on decaying pig carcasses in three selected biotopes (forest, crop field, urban site) at the beginning of spring. Seven species of Silphidae were recorded: Nicrophorus humator (Gleditsch), Nicrophorus vespillo (L.), Nicrophorus vespilloides (Herbst), Necrodes littoralis L., Oiceoptoma thoracica L., Thanatophilus sinuatus (Fabricius), Thanatophilus rugosus (L.). All of these species were caught in the forest biotope, and all but O. thoracica were caught in the agricultural biotope. No silphids were caught in the urban site [less ▲]

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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 ▲]

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

Poster (2011, May 24)

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

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

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See 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 ▲]

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See detailMacros Minitab pour le choix d'une transformation pour la normalisation de variables
Palm, Rodolphe ULg; Brostaux, Yves ULg; Claustriaux, Jean-Jacques ULg

in Notes de Statistique et d'Informatique (2011), (3),

Macros are proposed to Minitab users for transforming data to normality. The following transformations are examined : log transformation, Box et Cox transformation with lambda equal to -2, -1, -0,5, 0,5 ... [more ▼]

Macros are proposed to Minitab users for transforming data to normality. The following transformations are examined : log transformation, Box et Cox transformation with lambda equal to -2, -1, -0,5, 0,5 and 2, Box et Cox transformation with maximum likelihood estimation of lambda and transformations using the Johnson system of distributions. Two examples are given. [less ▲]

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See detailA Regional Inventory and Monitoring Setup to Evaluate Bark Peeling Damage by Red Deer (Cervus Elaphus) in Coniferous Plantations in Southern Belgium
Gheysen, Thibaut; Brostaux, Yves ULg; Hebert, Jacques ULg et al

in Environmental Monitoring & Assessment (2011), 181(1-4), 335-45

Bark peeling by red deer (Cervus elaphus L.) has become a serious issue for productive forests in western Europe. The damage is particularly severe on species such as spruce, as these become vulnerable to ... [more ▼]

Bark peeling by red deer (Cervus elaphus L.) has become a serious issue for productive forests in western Europe. The damage is particularly severe on species such as spruce, as these become vulnerable to fungus attacks that result in considerably depreciated timber. This article presents a monitoring setup for recent bark peeling damage in spruce plantings in Wallonia (southern part of Belgium). This setup implies to collect data annually from a survey involving cluster sampling. It has been employed since 2004 in coniferous stands amounting to 165,000 ha of land, where Norway spruce is the predominant species. The study area was divided into blocks delineated along features preventing deer migrations. A set of indicators was computed either at the whole study area level or at block level. The resulting set of indicators enabled forest managers to follow up debarking intensity in productive forests. Additional analyses were carried out in order to assess the relationship between the social position of trees in the stand and the debarking probability on the one hand, and the relationship between the variation in damage magnitude and seasonality, namely summer versus winter, on the other hand. [less ▲]

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See detailPrincipaux modèles utilisés en régression logistique
Gillet, Adeline; Brostaux, Yves ULg; Palm, Rodolphe ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(3), 425-433

Regression is a commonly used technique for describing the relationship between a response variable and one or more explanatory variables. When the response variable is a categorical variable, usual ... [more ▼]

Regression is a commonly used technique for describing the relationship between a response variable and one or more explanatory variables. When the response variable is a categorical variable, usual regression based on ordinary least squares should be replaced by logistic regression. Binary logistic regression should be used to perform a regression on a dichotomous response. Nominal polytomous logistic regression applies to a categorical response variable that has more than two levels with a natural ordering. And ordinal polytomous logistic regression is used when the response is a categorical variable that has more than two levels with a natural ordering. This note gives an overview of these logistic regression methods and describes three models commonly used when performing ordinal logistic regression. These models are illustrated by an example related to oak decline in the Walloon Region (Belgium). [less ▲]

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See detailEvaluation d’une méthode d’échantillonnage passif pour la mesure des monoterpènes dans l’air intérieur
Marlet, Christelle ULg; Lognay, Georges ULg; Plaisance, Hervé et al

in Pollution Atmosphérique (2011), 210

Monoterpenes are compounds naturally emitted by wooden materials. A preliminary study had demonstrated the occurrence of some monoterpenes in the timber frame constructions. Contrary to the active ... [more ▼]

Monoterpenes are compounds naturally emitted by wooden materials. A preliminary study had demonstrated the occurrence of some monoterpenes in the timber frame constructions. Contrary to the active sampling, the passive sampling with Radiello® device simplifies the sampling step that is an interest in indoor environment. However, the knowledge of the sampling rate is necessary for quantification via the passive samplers Radiello®. Radiello® sampler with Tenax TA cartridge was evaluated for the 4-h concentration measurements of nine monoterpenes (α-pinene, β-pinene, d-limonene, Δ3-carene, camphene, carvone, 1,8-cineole, linalool and p-cymene). The performance parameters of the method (calibration curve, trueness, repeatability, blank level, stability of samples) were estimated. The sampling rates were first evaluated under the standard conditions in an exposure chamber. The influences of three environmental factors (temperature (T), relative humidity (RH) and concentration level (C)) on the sampling rates were also evaluated following a full factorial design at two factor levels (low and high). The monoterpenes concentrations in the exposure chamber were followed by an active sampling on tube Tenax TA. For both sampling devices, analyses were realized by TD-GC-MS. The results of this study demonstrated that the Radiello® device is suitable for the measurement of 5 of 9 studied monoterpenes. The sampling rates were defined by an equation including two factors, temperature and relative humidity. Temperature is found to be the most important factor leading to variability of the all monoterpene sampling rates. An equation allowing to estimate the sampling rate was established for every studied compound. Measurements of monoterpenes with the Radiello® device were then carried out on new wooden houses and compared with measurements obtained by active sampling on Tenax TA tubes. [less ▲]

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See detailCalculating and Reporting Managed Honey Bee Colony Losses
vanEngelsdorp, Dennis; Brodschneider, Robert; Brostaux, Yves ULg et al

in Yoder, Jay (Ed.) Honey Bee Colony Health (2011)

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See detailPossible Influence of Surfactants and Proteins on the Efficiency of Contact Agar Microbiological Surface Sampling
Deckers, Sylvie M.; Sindic, Marianne ULg; Anceau, Christine ULg et al

in Journal of Food Protection (2010), 73(11), 2116-2122

Agar contact microbiological sampling techniques, based on a transfer of the microorganisms present on a surface to a culture medium, are widely used to assess and control surface cleanliness and to ... [more ▼]

Agar contact microbiological sampling techniques, based on a transfer of the microorganisms present on a surface to a culture medium, are widely used to assess and control surface cleanliness and to evaluate microbial contamination levels. The effectiveness of these techniques depends on many environmental parameters that influence the strength of attachment of the bacteria to the surface. In the present study, stainless steel and high density polyethylene surfaces were inoculated with known concentrations of Staphylococcus epidermidis. Following an experimental design, the surfaces were sampled with different types of replicate organism direct agar contact plates and Petrifilm; results indicated that recovery rates were influenced by the presence of egg white albumin or Tween 80 in the inoculum solutions or by the introduction of surfactants into the contact agar of the microbiological sampling techniques. The techniques yielded significantly different results, depending on sampling conditions, underlining the need for a standardization of laboratory experiments to allow relevant comparisons of such techniques. [less ▲]

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See detailHoney bee colony losses in Belgium during the 2008-9 winter
Nguyen, Bach Kim ULg; Mignon, Jacques ULg; Laget, Dries et al

in Journal of Apicultural Research (2010), 49(4), 337-339

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See detailStudy of the life cycle of two species of forensic interest carrion beetles (Coleoptera, Silphidae): Thanatophilus sinuatus F. & Necrodes littoralis L.
Dekeirsschieter, Jessica ULg; Verheggen, François ULg; Brostaux, Yves ULg et al

in 17 th Benelux Congress of Zoology: Classic Biology in Modern Times: Programme and Abstracts (2010, October)

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See detailPretreatment And Enzymatic Hydrolysis Of Miscanthus x giganteus: Influence Of Process Parameters
Vanderghem, Caroline ULg; Brostaux, Yves ULg; Jacquet, Nicolas ULg et al

Poster (2010, September 21)

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and ... [more ▼]

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and hemicellulose content, it has attracted considerable attention as a possible energy crop to produce bioethanol. Pretreatment of lignocellulosic biomass is a key step to unlocking the protective structures so that the enzymatic hydrolysis of the carbohydrate fraction to monosugars can be achieved more easily and with greater yield. In this study, Miscanthus x giganteus was delignified by a chemical pre-treatment process using a mixture of formic acid/acetic acid (1). The treated material was then hydrolyzed. By means of Box-Behnken experimental design and response surface methodology we investigated the effect of cooking time (60, 120 and 180 min), formic acid/acetic acid/water concentration (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107°C) on the residual Klason lignin content and the % of digestibility. The optimal pretreatment process parameters were identified. [less ▲]

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See detailTypologie des chênaies de la Région wallonne
Perin, Jérôme ULg; Brostaux, Yves ULg; Claessens, Hugues ULg

Poster (2010, May 12)

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See detailBeneficial effects of Bacillus subtilis on field-grown tomato in Burundi : reduction of local Fusarium disease and growth promotion.
Nihorimbere, V.; Ongena, Marc ULg; Cawoy, Hélène ULg et al

in African Journal of Microbiology Research [=AJMR] (2010), 4

Detailed reference viewed: 45 (14 ULg)