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See detailAphid honeydew is not only a sugary and amino-acid secretion
Leroy, Pascal ULg; Heuskin, Stéphanie ULg; Sabri, Ahmed ULg et al

Poster (2008)

Aphids, feeding from the phloem sap of plants, are the most common honeydew producing insects. This aphid excretory product consists in an aqueous mixture of different chemical compounds of which the most ... [more ▼]

Aphids, feeding from the phloem sap of plants, are the most common honeydew producing insects. This aphid excretory product consists in an aqueous mixture of different chemical compounds of which the most important are sugars (90-95% of the dry weight) and amino acids. This excretory product, used by parasitoids and predators, plays a crucial role in the tritrophic interactions : (1) honeydew is an important food complement and (2) honeydew acts as a volatile and a contact kairomone. These characteristics could be exploited for enhancing the biological control in fields through the use of an « artificial honeydew ». [less ▲]

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See detailAphid honeydew: An arrestant and a contact kairomone for Episyrphus balteatus (Diptera: Syrphidae) larvae and adults
Leroy, Pascal; Almohamad, Raki; Attia, Sabrine et al

in European Journal of Entomology (2014), 111(2), 237-242

Predator searching efficiency increases in response to a variety of environmental cues associated with its prey. The sugary excretion of aphids (honeydew) has been found to act as a prey-associated cue ... [more ▼]

Predator searching efficiency increases in response to a variety of environmental cues associated with its prey. The sugary excretion of aphids (honeydew) has been found to act as a prey-associated cue for many aphid natural enemies. In the present study, the honeydew excreted by Acyrthosiphon pisum (Harris) was identified as an arrestant and a contact kairomone for young larvae and adults of a common predatory hoverfly, Episyrphus balteatus (De Geer) (Diptera: Syrphidae). First and second instar larvae increased their foraging behaviour in the honeydew-treated area. When plants were sprayed with crude honeydew, the speed of movement of female E. balteatus was significantly higher than in controls, resulting in a longer period of time spent on treated plants and laying eggs. We conclude that the honeydew excreted by A. pisum induces searching behaviour and acts as and arrestant not only for adults but also for young E. balteatus larvae. [less ▲]

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See detailAphid host plant and food suitability for aphidophagous larvae: impact on ladybird reproductive performance.
Francis, Frédéric ULg; Haubruge, Eric ULg; Gaspar, Charles ULg

in The BCPC Conference: Pests and diseases, Volume 3. Proceedings of aninternational conference held at the Brighton Hilton Metropole Hotel,Brighton, UK, 13-16 November 2000 (2000)

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See detailAphid predators sampling in agrosystems in Belgium between 2009 and 2011
Vandereycken, Axel ULg; Durieux, Delphine ULg; Joie, Emilie ULg et al

Poster (2012, February 10)

The Multicolored Asian ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), was imported in 1997 in Belgium to control aphid populations. Few years ago after its introduction, this exotic ... [more ▼]

The Multicolored Asian ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), was imported in 1997 in Belgium to control aphid populations. Few years ago after its introduction, this exotic insect was well adapted to temperate climate conditions and spread out all over ecosystems in Europe causing decline of other aphidophagous species. In arboreal habitats, H. axyridis is the most dominant Coccinellids but we are still lacking information about this occurrence in agrosystems. An aphidophages sampling between 2009 and 2011 was realized in four agrosystems such as broad bean, wheat, corn and potato. Nevertheless H. axyridis populations rise (5 times) from 2009 to 2011 in 2011, H. axyridis is the third most observed aphidophages after Episyrphus balteatus (De Geer) and Coccinella septempunctata (Linné). H. axyridis is the dominating species in corn with 70.83±6.60 individuals per 100m². [less ▲]

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See detailAphid prey suitability as environmental effect on Adalia bipunctata reproduction.
Vanhaelen, Nicolas; Gaspar, Charles ULg; Francis, Frédéric ULg

in Mededelingen van de Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen (Rijksuniversiteit te Gent) (2002), 67(3), 563-8

Secondary plant metabolites (allelochemicals) play a major role in plant-insect interactions. Glucosinolates (GLS) and their degradation products from Brassica species are attractants and feeding ... [more ▼]

Secondary plant metabolites (allelochemicals) play a major role in plant-insect interactions. Glucosinolates (GLS) and their degradation products from Brassica species are attractants and feeding stimulants for Brassicaceae specialist insects but are generally repellent and toxic for generalist herbivores. The impact of these compounds on crucifer specialist insects are well known but their effect on generalist predators is still not well documented. Prey host plant influence on reproduction of an aphidophagous beneficial, the two spot ladybird, was determined using the cabbage aphid, Brevicoryne brassicae reared on a crucifer plant, namely Brassica napus containing low GLS levels. As ladybird developmental and reproductive parameters were already shown to be strongly affected by the allelochemical presence in its preys, the unsuitable aphid and host plant combination was only momentary used to feed the A. bipunctata adults. A strong impact of the diet was observed on the beetle fecundity and the emerging offspring. Changing B. brassicae aphid to a suitable prey slowly improved the temporary negative effect of the former diet. These results enhance the food environmental effect and the importance of tritrophic relations in pest management strategies by predators. Indeed, more than the choice of the beneficial species, the prey host plant has a major influence on the potential efficacy of biological agent to control herbivore species such as aphids. [less ▲]

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See detailAphid responses to volatile cues from turnip plants (Brassica rapa) infested with phloem-feeding and chewing herbivores
Verheggen, François ULg; Haubruge, Eric ULg; De Moraes, Consuelo et al

in Arthropod-Plant Interactions (2013), 7(5), 567-577

Herbivore-induced plant volatiles provide foraging cues for herbivores and for herbivores’ natural enemies. Aphids induce plant volatile emissions and also utilize plant-derived olfactory volatile cues ... [more ▼]

Herbivore-induced plant volatiles provide foraging cues for herbivores and for herbivores’ natural enemies. Aphids induce plant volatile emissions and also utilize plant-derived olfactory volatile cues, but the chemical ecology of aphids and other phloem-feeding insects is less extensively documented than that of chewing insects. Here, we characterize the volatile cues emitted by turnip plants (Brassica rapa) under attack by an aphid (Myzus persicae) or by the chewing lepidopteran larva Heliothis virescens. We also tested the behavioral responses of M. persicae individuals to the odors of undamaged and herbivore-damaged plants presented singly or in combination, as well as to the odor of crushed conspecifics (simulating predation). Gas chromatographic analysis of the volatile blend of infested turnips revealed distinct profiles for both aphid- and caterpillar- induced plants, with induced compounds including green-leaf alcohols, esters, and isothiocyanates. In behavioral trials, aphids exhibited increased activity in the presence of plant odors and positive attraction to undamaged turnip plants. However, aphids exhibited a strong preference for the odors of healthy versus plants subjected to herbivore damage, and neither aphid- or caterpillar-damaged plants were attractive compared to clean-air controls. Reduced aphid attraction to herbivore-infested plants may bemediated by changes in the volatile blend constituent composition, including large amounts of isothiocyanates and green-leaf volatiles or, in the case of aphid-infested plants, of the aphid alarm pheromone, (E)-b-farnesene. [less ▲]

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See detailAphid species and associated natural enemies in field crops: what about the invasive ladybird Harmonia axyridis (Coleoptera: Coccinellidae)?
Vandereycken, Axel ULg; Durieux, Delphine ULg; Joie, Emilie ULg et al

in Entomologie Faunistique = Faunistic Entomology (2015), 68

Following the introduction in the 80's of the invasive coccinellid species Harmonia axyridis (Pallas) in Europe, several studies have begun to focus on the interactions with other aphid predator species ... [more ▼]

Following the introduction in the 80's of the invasive coccinellid species Harmonia axyridis (Pallas) in Europe, several studies have begun to focus on the interactions with other aphid predator species. In this study, aphids and associated predators were sampled to determine their relative abundance in four agricultural crops (broad bean, corn, potato, and wheat) in Belgium during 2010 and 2011. The Moericke trap was used to quantify the mean number of aphids and aphid predators from May to September in both years. A total of 28 aphid species and 21 aphidophagous species were observed. In both years, H. axyridis was among the most abundant aphidophagous predators in all four crops, and was the second most abundant coccinellid species after Coccinella septempunctata L. The community of aphidophagous species was similar across all four inventoried crops. However, the highest population densities of this alien species were recorded in broad bean and potato crops, which also hosted the highest aphid population densities. In conclusion, this study demonstrates that the communities of aphid predators are highly diversified in the agroecosystems, despite the high occurrence of H. axyridis, an introduced predator that has become well established in this environment. [less ▲]

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See detailAphid – ant mutualism : How do aphids focus ant foraging ?
Verheggen, François ULg; Diez, Lise; Detrain, Claire et al

Poster (2008)

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See detailAphid-ant mutualism: an outdoor study of the benefits for Aphis fabae
Verheggen, François ULg; Detrain, Claire; Diez, Lise et al

Conference (2008)

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See detailAphid-ant mutualism: How do aphids focus ant foraging?
Verheggen, François ULg; Detrain, Claire; Diez, Lise et al

Conference (2009, August)

The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural ... [more ▼]

The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural enemies. While aphid predators and parasitoids actively forage for oviposition sites by using aphid semiochemicals, scouts of aphid-tending ant species would also benefit from locating honeydew resources by orienting toward aphid pheromone sources. The present study aims to identify the chemical factors that attract ants and that maintain their mutualistic relationships with aphids. The perception and behavioral impact of Aphis fabae alarm pheromone, namely (E)-β-farnesene, on Lasius niger were firstly investigated using electroantennography and a four-arm olfactometer. Aphis fabae honeydew sugar composition was subsequently analyzed while the foraging and recruiting behaviour of L. niger scouts towards each of the identified sugars was studied. Clear electrical depolarisations were observed from L. niger scout antennae to stimulations of A. fabae alarm pheromone. Scouts were significantly attracted toward (E)-β-farnesene in the four-arm olfactometer, suggesting for the first time that the latter compound is a key chemical in the establishment of the mutualism. Aphis fabae honeydew consisted of 9 identified mono-, di- and tri-saccharides and 8 hydrocarbons that could not be identified. The main identified sugars were sucrose, fructose, glucose and melezitose. L. niger scouts showed the following drinking preferences for the tested sugars: melezitose = sucrose = raffinose > glucose = fructose > maltose = trehalose = melibiose = xylose, with a recruitment launched toward the first three sugars. Therefore, ant scouts may use aphid semiochemicals to locate at distance an aphid colony and subsequently estimate honeydew quality by tasting it before recruiting conspecifics and establishing a mutualistic relationship. [less ▲]

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See detailAphid-ant mutualism: How do aphids focus ant foraging?
Verheggen, François ULg; Detrain, Claire; Diez, Lise et al

Conference (2008)

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See detailAphid-ant mutualism: how honeydew sugars influence the behaviour of ant scouts
Detrain, Claire; Verheggen, François ULg; Diez, Lise et al

in Physiological Entomology (2010), 35(2), 168-174

Honeydew is the keystone on which ant-aphid mutualism is built. The present study investigates how each sugar identified in Aphis fabae Scopoli honeydew acts upon the feeding and the laying of a ... [more ▼]

Honeydew is the keystone on which ant-aphid mutualism is built. The present study investigates how each sugar identified in Aphis fabae Scopoli honeydew acts upon the feeding and the laying of a recruitment trail by scouts of the aphid-tending ant Lasius niger Linnaeus, and thus may enhance collective exploitation by the ant mutualists. The feeding preferences shown by L. niger for honeydew sugars are: melezitose = sucrose = raffinose > glucose = fructose > maltose = trehalose = melibiose = xylose. Although feeding is a prerequisite to the launching of trail recruitment, the reverse is not necessarily true: not all ingested sugar solutions elicit a trail-laying behaviour among fed scouts. Trail mark laying is only triggered by raffinose, sucrose or melezitose, with the latter sugar being specific to honeydew. By comparing gustatory and recruitment responses of ant foragers to sugar food sources, the present study clarifies the role of honeydew composition both as a source of energy and as a mediator in ant-aphid interactions. Lasius niger feeding preferences can be related to the physiological suitability of each sugar (i.e. their detection by gustatory receptors as well as their ability to be digested and converted into energy). Regarding recruitment, the aphid-synthesized oligosaccharide (melezitose) could be used by ant scouts as a cue indicative of a long-lasting productive resource that is worthy of collective exploitation and defence against competitors or aphid predators. [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 ▲]

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See detailAphidophagous Guilds On Nettle (Urtica Dioica) Strips Close To Fields Of Green Pea, Rape And Wheat
Alhmedi, A.; Haubruge, Eric ULg; Bodson, Bernard ULg et al

in Insect Science (2007), 14(5), 419-424

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See detailAphids (Myzus persicae) lipoxygenase and oxylipins profiling.
Harmel, N.; Laine, G.; Gosset, V. et al

Conference (2006)

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See detailAphids adapt their alarm pheromone production according to their social environment
Verheggen, François ULg; Haubruge, Eric ULg; Demoraes, Consuelo et al

Poster (2008)

Aphid alarm pheromone—the volatile sesquiterpene (E)-β-farnesene (Eβf) in most species—is released in response to predation and other stresses and typically causes nearby aphids who receive the signal to ... [more ▼]

Aphid alarm pheromone—the volatile sesquiterpene (E)-β-farnesene (Eβf) in most species—is released in response to predation and other stresses and typically causes nearby aphids who receive the signal to cease feeding, drop from their host plant, and disperse. Because aphid alarm pheromone confers apparent fitness benefits on recipients while its production and release likely entail costs for the emitting aphid, it could be adaptive for aphids to regulate their Eβf production in response to variation in the social environment. To explore this possibility we compared the production of Eβf by Acyrthosiphon pisum (Harris) individuals reared from first-instar larvae to the adult stage in isolation to that of individuals reared among conspecifics or among individuals of a different aphid species, Myzus persicae (Sulzer). Levels of EβF produced in each treatment were assayed by GC-FID quantification of EβF in volatiles collected from crushed aphids. Production of EβF by A. pisum reared in isolation (14.4ng/aphid) was significantly lower than that of aphids reared in a colony of conspecifics (49.1ng/aphid), reared in a M. persicae colony (31.5ng/aphid) or reared among conspecifics of another aaphid clone (52.7ng/aphid). Though A. pisum individuals in our experiments produced less EβF when reared among M. persicae than among conspecifics, this difference was not statistically significant. In a separate experiment we reared A. pisum individuals in isolation and exposed them to the odor of conspecifics. Under these conditions, EβF production was similar to that of aphids reared among conspecifics, suggesting that aphids use volatile cues to assess their social environment and regulate their production of alarm pheromone accordingly. [less ▲]

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See detailL'Aphrodite grecque : Contribution à l’étude de ses cultes et de sa personnalité dans le panthéon archaïque et classique
Pirenne-Delforge, Vinciane ULg

Book published by CIERGA (1994)

Survey of the Greek cults of the goddess Aphrodite and analysis of her place within the Greek pantheon.

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See detailAPI design for machine learning software: experiences from the scikit-learn project
Buitinck, Lars; Louppe, Gilles ULg; Blondel, Mathieu et al

Conference (2013, September 23)

scikit-learn is an increasingly popular machine learning library. Written in Python, it is designed to be simple and efficient, accessible to non-experts, and reusable in various contexts. In this paper ... [more ▼]

scikit-learn is an increasingly popular machine learning library. Written in Python, it is designed to be simple and efficient, accessible to non-experts, and reusable in various contexts. In this paper, we present and discuss our design choices for the application programming interface (API) of the project. In particular, we describe the simple and elegant interface shared by all learning and processing units in the library and then discuss its advantages in terms of composition and reusability. The paper also comments on implementation details specific to the Python ecosystem and analyzes obstacles faced by users and developers of the library. [less ▲]

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