References of "Verheggen, François"
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See detailField evaluation of survival rates of Harmonia axyridis (Coleoptera: Coccinellidae) and other aphidophagous species
Vandereycken, Axel ULg; Durieux, Delphine ULg; Joie, Emilie ULg et al

Poster (2011, May 24)

The multicoloured Asian ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae), previously introduced as a biological control agent against aphids, is now frequently considered as an intraguild ... [more ▼]

The multicoloured Asian ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae), previously introduced as a biological control agent against aphids, is now frequently considered as an intraguild predator, consuming other aphids natural enemies. Interactions between this exotic ladybird and the other aphidophagous species present in Belgian agro-ecosystems such as Coccinella septempunctata, Episyrphus balteatus, Chrysoperla carnea are asymmetric to the benefit of H. axyridis. Many studies have already shown its predatory behaviour. This study focuses on the survival rate of three aphidophagous species Harmonia axyridis (Ha), Coccinella septempunctata (C7) and Episyrphus balteatus (Eb) in biological fields of potato and sugar beet. During June and July, hermetic cages were disposed on the crops with 10 larvae (second stage) of each aphidophagous. There were 4 combinations of insects placed inside the cages (1) Ha+Eb+C7+ aphids, (2) Ha+Eb+C7, (3) Eb+C7+ aphids and (4) Eb+C7. Each combination was repeated three times. Aphids (Aphis fabae) were added in excess when needed. In sugar beet fields, E. balteatus was the species with the highest mortality rate. The two coccinellid species had a better survival rate than E. balteatus. All aphidophagous species had higher mortality rates in absence of aphids. In potato, the survival rate of all aphidophagous was lower than sugar beet when aphids were present in excess probably because A. fabae reproduced less in potato. Nevertheless, we have observed in potato no mortality of C. 7-punctata during all its development cycle. This suggests that C. 7-punctata could use more efficiently aphids as food sources than H. axyridis. In potato and sugar beet, H. axyridis had the longest development cycle, being still at the larval stage when C. 7-punctata and E. balteatus reached the pupae stage. We can suppose that pupae of E. balteatus and C. 7-punctata were an alternative food (intraguild prey) to H. axyridis when aphids were lacking. Pupae are immobile and therefore more sensitive to the attack of predators. [less ▲]

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See detailAttraction of wireworms to root-emitted volatile organic compounds of barley
Barsics, Fanny ULg; Haubruge, Eric ULg; Verheggen, François ULg

Conference (2011, May 24)

Wireworms, the belowground larvae of click beetles (Coleoptera: Elateridae), represent a threat for various crops, including cereals, potatoes and small fruits, in many countries. In order to promote the ... [more ▼]

Wireworms, the belowground larvae of click beetles (Coleoptera: Elateridae), represent a threat for various crops, including cereals, potatoes and small fruits, in many countries. In order to promote the development of bio-pesticides or the selection of resistant varieties, studies concerning the close relationship between wireworms and the roots they attack have to be conducted. Indeed, lacks of knowledge in the chemical ecology of these small but consequent pests baffle such achievements. Here, we studied the reactions of wireworms (Agriotes sordidus Illiger) facing root-emitted volatile organic compounds (VOCs) of barley. We first tested the ability of wireworms to orientate towards a blend of volatile compounds emitted by seven day’s old mashed roots of barley grown in vermiculite. We used a Y-shaped horizontal olfactometre, which inferior half was filled with compressed and humidified vermiculite. Wireworms were able to detect blends of volatiles emitted by mashed roots, and to orientate their foraging behaviour toward the emission source. Volatile compounds were identified from barley roots using SPME-GC-MS and several chemicals were identified. This study is part of a larger programme which purpose is the identification of VOCs emitted by the roots of barley and different actors of the rhizosphere, and to assess their semiochemical functions. [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 detailThe semiochemically mediated interactions between bacteria and insects
Leroy, Pascal ULg; Sabri, Ahmed ULg; Verheggen, François ULg et al

in Chemoecology (2011), 21

In natural environment, semiochemicals are involved in many interactions between the different trophic levels involving insects, plants and hosts for parasitoids or prey for predators. These volatile ... [more ▼]

In natural environment, semiochemicals are involved in many interactions between the different trophic levels involving insects, plants and hosts for parasitoids or prey for predators. These volatile compounds act as messengers within or between insect species, inducing particular behaviours such as the localisation of a source of food, the orientation to an adequate oviposition site, the selection of a suitable breeding site and the localisation of hosts or prey. In this sense, bacteria have been shown to play an important role in the production of volatile compounds which ones act as semiochemicals. This review, focusing on the semiochemically-mediated interactions between bacteria and insects, highlights that bacterial semiochemicals act as important messengers for insects. Indeed, in most of the studies reported here, insects respond to specific volatiles emitted by specific bacteria hosted by the insect itself (gut, mouthparts, etc.) or present in the natural environment where the insect evolves. Particularly, bacteria from the families Enterobacteriaceae, Pseudomonaceae and Bacillaceae are involved in many interactions with insects. Because semiochemicals naturally produced by bacteria could be a very interesting option for pest management, advances in this field are discussed in the context of biological control against insect pests. [less ▲]

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See detailInsectes et communication chimique - Techniques et méthodes en écologie chimique
Verheggen, François ULg

Conference (2011, March 17)

Les insectes communiquent avec leurs semblables et avec leur environnement par le biais de molécules organiques informatives nommées sémiochimiques. L'écologie chimique est la branche de l'écologie qui s ... [more ▼]

Les insectes communiquent avec leurs semblables et avec leur environnement par le biais de molécules organiques informatives nommées sémiochimiques. L'écologie chimique est la branche de l'écologie qui s'intéresse au décriptage de ce mode de communication, dont le maitre d'œuvre est le système olfactif des insectes, où antennes et sensilles supportent toute la machinerie physiologique nécessaire à la perception des phéromones et coactones. Pour comprendre le language chimique employé par un insecte, de nombreux outils ont été développés, permettant (1) l'échantillonnage des molécules organiques produites par un insecte, (2) la séparation, la quantification et l'identification des différents constituants du mélange phéromonal,(3) l'étude de la perception par le système olfactif de l'insecte et (4) l'étude du comportement d'un individu mis en présence d'un potentiel bouquet phéromonal ou de l'un de ses constituants. De nombreuses phéromones et coactones ont déjà trouvé le chemin de la valorisation dans le domaine de la protection des cultures. Bien que les insectes d'intérêt agronomique soient les plus largement étudiés, les sémiochimiques employés par d'autres groupes d'insectes font l'objet de nouvelles recherches, avec notamment l'émergence de l'entomologie criminelle [less ▲]

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See detailInsectes et communication chimique - Sémiochimiques et olfaction
Verheggen, François ULg

Conference (2011, March 15)

Les insectes communiquent avec leurs semblables et avec leur environnement par le biais de molécules organiques informatives nommées sémiochimiques. L'écologie chimique est la branche de l'écologie qui s ... [more ▼]

Les insectes communiquent avec leurs semblables et avec leur environnement par le biais de molécules organiques informatives nommées sémiochimiques. L'écologie chimique est la branche de l'écologie qui s'intéresse au décriptage de ce mode de communication, dont le maitre d'œuvre est le système olfactif des insectes, où antennes et sensilles supportent toute la machinerie physiologique nécessaire à la perception des phéromones et coactones. Pour comprendre le language chimique employé par un insecte, de nombreux outils ont été développés, permettant (1) l'échantillonnage des molécules organiques produites par un insecte, (2) la séparation, la quantification et l'identification des différents constituants du mélange phéromonal,(3) l'étude de la perception par le système olfactif de l'insecte et (4) l'étude du comportement d'un individu mis en présence d'un potentiel bouquet phéromonal ou de l'un de ses constituants. De nombreuses phéromones et coactones ont déjà trouvé le chemin de la valorisation dans le domaine de la protection des cultures. Bien que les insectes d'intérêt agronomique soient les plus largement étudiés, les sémiochimiques employés par d'autres groupes d'insectes font l'objet de nouvelles recherches, avec notamment l'émergence de l'entomologie criminelle [less ▲]

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See detailOccurrence of aphid predators in Belgian agro-ecosystems
Vandereycken, Axel ULg; Durieux, Delphine ULg; Joie, Emilie ULg et al

Poster (2011, March 06)

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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 detailAphid-host plant interactions: Does aphid honeydew exactly reflect the host plant amino acid composition?
Leroy, Pascal ULg; Wathelet, Bernard ULg; Sabri, Ahmed ULg et al

in Arthropod-Plant Interactions (2011), 5

Plants provide aphids with unbalanced and low concentrations of amino acids. Likely, intracellular symbionts improve the aphid nutrition by participating to the synthesis of essential amino acids. To ... [more ▼]

Plants provide aphids with unbalanced and low concentrations of amino acids. Likely, intracellular symbionts improve the aphid nutrition by participating to the synthesis of essential amino acids. To compare the aphid amino acid uptakes from the host plant and the aphids amino acid excretion into the honeydew, host plant exudates (phloem + xylem) from infested and uninfested Vicia faba L. plants were compared to the honeydew produced by two aphid species (Acyrthosiphon pisum Harris and Megoura viciae Buckton) feeding on V. faba. Our results show that an aphid infestation modifies the amino acid composition of the infested broad bean plant since the global concentration of amino acids significantly increased into the host plant in response to aphid infestations. Specifically, the concentrations of two amino acids glutamine and asparagine were strongly enhanced. The amino acid profiles from honeydews were similar for the two aphid species, but the concentrations found into the honeydews were generally lower than those measured in the exudates of infested plants (aphids uptakes). This work also highlights that aphids take large amounts of amino acids into the host plant, especially glutamine and asparagine which are converted into glutamic and aspartic acids but also into other essential amino acids. The amino acid profiles differed between the host plant exudates and the aphid excretion product. Finally, this study highlights that the pea aphid - a “specialist” for the V. faba host plant - induced more important modifications into the host plant amino acid composition than the “generalist” aphid M. viciae. [less ▲]

Detailed reference viewed: 34 (9 ULg)