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See detailDepths and type of substrate influence the ability of Nasonia vitripennis Walker (Hymenoptera: Pteromalidae) to encounter host
Frederickx, Christine ULg; Dekeirsschieter, Jessica ULg; Verheggen, François ULg et al

in Journal of Insect Science [=JIS] (in press)

The foraging behaviour of a parasitoid insect species includes the host’s habitat and subsequent location of the host. Habitats-substrate, substrate moisture and light levels can affect the host location ... [more ▼]

The foraging behaviour of a parasitoid insect species includes the host’s habitat and subsequent location of the host. Habitats-substrate, substrate moisture and light levels can affect the host location made by different species of parasitoids. However, the depth at which parasitoids concentrate their search effort is an another important ecological characteristic and play an important role on the host location. Here, we have investigated the ability of a pupal parasitoid, Nasonia vitripennis Walker, to penetrate and kill fly pupae located at different depth of the substrate. Three different types of substrate were tested: loam soil, compost and vermiculite substrate. In both loam soil and compost, all of the parasitism activity was restricted to pupae placed directly on the surface. Parasitism activity in vermiculite showed that the average number of pupae parasitized was decreased with depth. These results suggest that fly pupae situated deeper in the substrate are less subjected to parasitism by N. vitripennis. [less ▲]

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See detailJatropha curcas L. (Euphorbiaceae): Insectes ravageurs et propriétés biocides
Abdoul Habou, Zakari; Toudou, Adam; Haubruge, Eric ULg et al

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

Jatropha curcas, ou Pourghère, est un arbuste de la famille des Euphorbiacées, largement répandu dans les pays tropicaux. Ses graines sont riches d'une huile pouvant servir de biocarburant dans les ... [more ▼]

Jatropha curcas, ou Pourghère, est un arbuste de la famille des Euphorbiacées, largement répandu dans les pays tropicaux. Ses graines sont riches d'une huile pouvant servir de biocarburant dans les moteurs diesels modifiés. La plante est attaquée par divers insectes ravageurs appartenant principalement aux ordres des Hétéroptères, Coléoptères et Orthoptères. Ils provoquent des dégâts sur les fruits, les inflorescences et les feuilles. Les ravageurs les plus fréquemment observés sur J. curcas sont des punaises du genre Pachycoris (Hétéroptère : Scutelleridae), qui sont largement répandues au Mexique, en Australie, aux États-Unis, au Brésil et au Nicaragua. Ces punaises causent des dégâts importants sur les fruits et provoquent la malformation des graines, et avec elle une réduction de la teneur en huile. Même si les arbustes de Jatropha sont victime d'infestations d'insectes, plusieurs études démontrent l'effet insecticide de son huile contre des ravageurs importants tels que Busseola fusca (Fuller) (Lépidoptère : Noctuidae), Sesamia calamistis Hampson (Lépidoptère : Noctuidae), Aphis gossypii Glover (Homoptère: Aphididae) et Callosobruchus chinensis L. (Coléoptère : Bruchidae). Dans ce document, nous présentons dans une première partie les principaux insectes ravageurs de J. curcas et dans une seconde section les effets insecticides démontrés de son huile. [less ▲]

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See detailEffet du mode de conservation d’huile de Jatropha curcas L. sur son efficacité dans la lutte contre les principaux insectes ravageurs du niébé (Vigna unguiculata (L.) Walp. au Niger
Abdoul Habou, zakari; Toudou, Adam; Haubruge, Eric ULg et al

in Tropicultura (in press)

Jatropha curcas oil has an insecticidal activity harnessed by the farmers in Niger. In this study, we compared the insecticidal activity of two batches of oil conserved during 70 days, one exposed to ... [more ▼]

Jatropha curcas oil has an insecticidal activity harnessed by the farmers in Niger. In this study, we compared the insecticidal activity of two batches of oil conserved during 70 days, one exposed to light and the other kept in the dark. The insecticidal efficacy was evaluated in a field with three concentrations (5, 10 and 15%) trial on the main pests of Cowpea (Vigna unguiculata (L.) Walp) and in a laboratory test on Megalurothrips sjostedti Trybon (Thysanoptera: Thripidae) with different concentrations of crude oil (50; 100; 150 and 200 µl). No difference in insecticidal effect was found between the two modes of oil conservation, both in the laboratory and in the field. In the field, regardless of the mode of conservation, the concentrations of 10% of J. curcas oil enables a reduction of over than 80% of thrips, aphids, and bugs compared to the control. Its increased seeds yield more than 50%. The concentration of 15% gives an insecticidal effect comparable to that of the reference treatment (deltaméthrine) but induces phytotoxicity symptoms on the leaves of Cowpea. [less ▲]

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See detailHost-habitat location by the parasitoid, Nasonia vitripennis Walker (Hymenoptera: Pteromalidae).
Frederickx, Christine ULg; Dekeirsschieter, Jessica ULg; Verheggen, François ULg et al

in Journal of Forensic Sciences (in press)

This study investigated the role of odorant cues used during host-habitat location by the generalist parasitoid, Nasonia vitripennis Walker. N vitripennis is a common parasitoid of Dipteran pupae found in ... [more ▼]

This study investigated the role of odorant cues used during host-habitat location by the generalist parasitoid, Nasonia vitripennis Walker. N vitripennis is a common parasitoid of Dipteran pupae found in association with decaying carrion. Behavioral assays were used to investigate the host-habitat searching behavior under different scenarios. First, we demonstrated N. vitripennis to be significantly attracted toward odorant cues associated with decaying meat. The biological activity of nine of the volatile molecules constituting the odor of decaying meat were tested on the searching behavior of parasitoid females through two complementary chemoecological approaches: electronantennography (EAG) and olfactometry bioassays. Butanoic acid and butan-1-ol elicited high olfactory responses, but no attraction was induced by these two chemicals. Behavioral assays showed that, among the VOCs tested, methyldisulfanylmethane (DMDS) was the only volatile chemical to induce attraction in N. vitripennis. [less ▲]

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See detailFirst evidence of a volatile sex pheromone in the invasive Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)
Fassotte, Bérénice ULg; Fischer, Christophe ULg; Durieux, Delphine ULg et al

Conference (2014, April 02)

Data about sex pheromones, or any semiochemicals that play a role in Coccinellid mating, remain limited. Since years, various studies and behavioral observations have hypothesized that such molecules are ... [more ▼]

Data about sex pheromones, or any semiochemicals that play a role in Coccinellid mating, remain limited. Since years, various studies and behavioral observations have hypothesized that such molecules are involved in sexual communication of ladybeetles. In this study, we collected volatile organic compounds released by virgin females of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), which were either allowed or not allowed to feed on aphids. In the presence of aphids, virgin females exhibited “calling behavior”, which has been associated with the emission of a sex pheromone in several Coleoptera species. Bioassays showed that these females released a blend of volatile compounds that is involved in the attraction of males. Gas Chromatography-Mass Spectrometry analyses highlighted specific volatile cues emanating from females, whereas males did not produce these compounds. Five components were identified: (–)-β-caryophyllene, β elemene, methyl-eugenol, α humulene, and α bulnesene. All compounds were produced after virgin females were fed aphids, and their quantity increased across the experimental period. The results confirm that female H. axyridis produce a volatile sex pheromone. Therefore, this study provides important biological information that could promote the development of efficient pest control management methods to manipulate the movements of this invasive ladybeetle, and to reduce its negative impacts on biodiversity. [less ▲]

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See detailA pheromone-based formulation against phytophagous pests
Fassotte, Bérénice ULg; Vandereycken, Axel ULg; Heuskin, Stéphanie ULg et al

Poster (2014, April 02)

Innovative integrated pest management methods are needed to overcome market withdrawal of synthetic pesticides. Therefore, the identification of environment-friendly bio-products carrying direct or ... [more ▼]

Innovative integrated pest management methods are needed to overcome market withdrawal of synthetic pesticides. Therefore, the identification of environment-friendly bio-products carrying direct or indirect biocide activity is one promising alternative option. Our researches focus on the identification of appropriate formulations releasing volatile organic compounds that are attractive for natural enemies of insect pests. However, the elaboration of slow-release devices that ensure stable and controlled release of active volatile compounds is quite challenging. Here, we developed a formulation based on E-β-farnesene and (–)-β-caryophyllene, these two semiochemicals having strong attractive potential on aphid natural enemies including ladybeetles and hoverflies. Both compounds were encapsulated together in alginate gel beads. The blend efficiency is currently being evaluated through laboratory and field assays. [less ▲]

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See detailUn regard nouveau sur le mutualisme fourmis-pucerons
Verheggen, François ULg

Scientific conference (2014)

Un regard nouveau sur le mutualisme fourmis-pucerons Nombre d’homoptères producteurs de miellat ont développé des relations de mutualisme avec les fourmis. Depuis des décennies, le cas particulier des ... [more ▼]

Un regard nouveau sur le mutualisme fourmis-pucerons Nombre d’homoptères producteurs de miellat ont développé des relations de mutualisme avec les fourmis. Depuis des décennies, le cas particulier des fourmis et des pucerons est l'un des modèles de mutualisme les plus étudiés, et a captivé des générations d’entomologistes. Sans défense, les pucerons sont des proies faciles pour de nombreux ennemis naturels. Cependant, certaines espèces (dites myrmécophiles) sont observées associés à des fourmis, qui protègent leurs partenaires en échange de leur miellat, riche en sucres et acides aminés. Sédentarisme, absence de réaction agressive, omniprésence et habitudes grégaires, tous ces facteurs contribuent à faciliter leur découverte et leur contrôle par les fourmis. Mais la rencontre entre ces deux partenaires est facilitée par un troisième groupe d’organismes: des bactéries. Se développant dans le miellat, ces dernières guident, par les odeurs qu’elles produisent, les fourmis exploratrices vers la colonie de pucerons. Dans cette conférence nous présenterons les résultats de plusieurs années de recherche démontrant l’importance : (1) du rôle de protection des fourmis, (2) de la composition en sucre du miellat, (3) des phéromones aphidiennes et (4) des bactéries se développant dans le miellat, pour l’établissement et le maintien des relations de mutualisme entre fourmis et pucerons. [less ▲]

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See detailA volatile sex pheromone in the invasive ladybeetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)
Fassotte, Bérénice ULg; Fischer, Christophe ULg; Durieux, Delphine ULg et al

in Communications in Agricultural and Applied Biological Sciences (2014), 79(1), 79-81

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See detailDevelopment of new strategies against the tomato leafminer, Tuta absoluta Meyrick
De Backer, Lara ULg; Francis, Frédéric ULg; Verheggen, François ULg

Conference given outside the academic context (2014)

The tomato leafminer, Tuta absoluta (Meyrick), is a Lepidoptera considered as one of the major pest of Solanaceae. It causes important yield loss in South America, where it is originated, and in the West ... [more ▼]

The tomato leafminer, Tuta absoluta (Meyrick), is a Lepidoptera considered as one of the major pest of Solanaceae. It causes important yield loss in South America, where it is originated, and in the West Palearctic region, where it was introduced in 2006. Insecticide applications and the use of the sexual pheromone have been the main control method used against T. absoluta. Insecticides are inefficient because of the endophytic habit of larvae, which are protected in the leaf mesophyll or inside fruits. Moreover, resistances against various insecticides have been reported. The sexual pheromone based strategies also provide poor results. One explanation has been recently provided by the demonstration of a parthenogenetic reproduction in T. absoluta, from the research group in Gembloux Agro-Bio Tech (ULg). Because there is a real need to improve crop protection against T. absoluta and in the meanwhile reducing the use of synthetic insecticidal compounds, researches aim at providing new perspectives to further biocontrol strategies against T. absoluta. [less ▲]

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See detailAssociative learning of Nasonia vitripennis Walker (Hymenoptera: Pteromalidae) to methyldisulfanylmethane
Frederickx, Christine ULg; Verheggen, François ULg; Brostaux, Yves ULg et al

in Journal of Forensic Sciences (2014)

Traditional methods of volatile detection used by police typically consist of reliance on canine olfaction. However, dogs have some limitations such as cost of training and time of conditioning. The ... [more ▼]

Traditional methods of volatile detection used by police typically consist of reliance on canine olfaction. However, dogs have some limitations such as cost of training and time of conditioning. The possibility of using parasitic wasps for detecting explosives and narcotics has been developed. Moreover, wasps are cheap to produce and can be conditioned with impressive speed for a specific chemical-detection task. We examined the ability of Nasonia vitripennis Walker to learn and respond to methydisulfanylmethane (DMDS), a volatile discriminator of cadaver. The training aimed to form an association between an unconditioned stimulus (pupae) and the conditioned stimulus (odor source). After the training, the time spent of conditioned wasps in the DMDS chamber was measured. Statistical analysis showed that the increasing concentrations involved an increase in the time spent in the chamber containing DMDS. This study indicates that N. vitripennis can respond to DMDS, which provide further support for its development as a biological sensor. [less ▲]

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See detailIs the multicolored Asian ladybeetle, Harmonia axyridis, the most abundant natural enemy to aphids in agroecosystems?
Vandereycken, Axel ULg; Durieux, Delphine ULg; Joie, Emilie ULg et al

in Journal of Insect Science [=JIS] (2013), 13(158), 1-14

The multicolored Asian ladybeetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), was introduced into Western Europe in the late 1990s. Since the late 2000s, this species has been commonly ... [more ▼]

The multicolored Asian ladybeetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), was introduced into Western Europe in the late 1990s. Since the late 2000s, this species has been commonly considered one of the most abundant aphid predators in most Western European coun- tries. In spite of the large amount of research on H. axyridis, information concerning its relative abundance in agroecosystems is lacking. This study aims to evaluate the abundance of H. axyridis within the aphidophage community in four crops situated in southern Belgium: wheat, Triticum aestivum L. (Poales: Poaceae), corn, Zea mays, potato, Solanum tuberosum (Solanales: Solanaceae), and broad bean Vicia faba (Fabales: Fabaceae). In order to assess the species diver- sity, the collected data were analyzed by considering (1) the species richness and (2) the evenness according to the Shannon diversity index. Eleven aphidophages were observed in every invento- ried agroecosystem, including five abundant species: three coccinellids, the seven-spotted ladybug, Coccinella septempunctata L. (Coleoptera: Coccinellidae), the 14-spotted Ladybird, Propylea quatuordecimpunctata, and H. axyridis; one hoverfly, the marmalade hoverfly, Episyr- phus balteatus De Geer (Diptera: Syrphidae); and one lacewing, the common green lacewing, Chrysoperla carnea Stephens sensu lato (= s.l.) (Neuroptera: Chrysopidae). Harmonia axyridis has been observed to thrive, breed, and reproduce on the four studied crops. Harmonia axyridis is the most abundant predator of aphids in corn followed by C. septempunctata, which is the main aphid predator observed in the three other inventoried crops. In wheat and potato fields, H. axyridis occurs in low numbers compared to other aphidophage. These observations suggest that H. axyridis could be considered an invasive species of agrosystems, and that potato and wheat may intermittently act as refuges for other aphidophages vulnerable to intraguild predation by this invader. Harmonia axyridis is not the most abundant aphid predator in the main Belgian crops. [less ▲]

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See detailA four-year inventory of the invasive ladybeetle Harmonia axyridis in agricultural ecosystems
Vandereycken, Axel ULg; Durieux, Delphine ULg; Joie, Emilie ULg et al

Conference (2013, October 26)

The Multicoloured Asian Ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is known to thrive principally in shrubby and arboreal habitats. Its occurrence in agroecosystems remains poorly ... [more ▼]

The Multicoloured Asian Ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is known to thrive principally in shrubby and arboreal habitats. Its occurrence in agroecosystems remains poorly documented. This study focuses on the occurrence of this exotic species and its seasonal abundance in various field crops. The abundance of adults and larvae of H. axyridis was evaluated over a four-year period, from 2009 to 2012, in four important agronomical crops (wheat, corn, broad bean and potato) in Belgium. A total of 28 aphid predator species were observed including 14 coccinellid species, 13 hoverfly species and one lacewing species. H. axyridis is present and reproduces in all of the four crops studied, with the largest numbers recorded in corn and broad bean crops. In corn, H. axyridis numbers were found to increase over the four inventoried year, reaching 86% of the aphid predators in 2012, while it represented only 15% in 2009. H. axyridis was not always recorded where aphids were abundant, e.g. aphids were abundant on wheat where no H. axyridis were recorded. H. axyridis starts reproducing after the peak in aphid population, suggesting that H. axyridis is able to complete its development by feeding on alternative prey such as larvae and pupae of the same and other species of ladybird and other aphidophagous species. H. axyridis is often considered to be bivoltine but it only completes one generation per year in field crops. The second generation generally develops late in the season in other habitats. Harmonia axyridis is an invasive and an intraguild predator present in high quantities in some specific crops. In these crops, H. axyridis could negatively impact on population of native species due to IGP observed in several other studies. [less ▲]

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See detailLes Ressources Sauvages des Bois de Tapia (Uapaca bojeri) à Madagascar
Barsics, Fanny ULg; Malaisse, François ULg; Razafimanantsoa, Tsiresy et al

Poster (2013, October 19)

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See detailLe taupin : un ravageur souterrain préoccupant
Barsics, Fanny ULg; Haubruge, Eric ULg; Verheggen, François ULg

Poster (2013, October 19)

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See detailLes insectes: Jardiniers du diable, templier de Lucifer
Verheggen, François ULg

Conference given outside the academic context (2013)

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See detailFirst Evidence of a Volatile Sex Pheromone in Harmonia axyridis (Pallas)
Fassotte, Bérénice ULg; Fischer, Christophe ULg; Durieux, Delphine ULg et al

Poster (2013, October)

Until now, no volatile sex pheromone has been highlighted in Coccinellidae but various studies have suggested the existence of such molecules. In the present work, we have sampled volatile organic ... [more ▼]

Until now, no volatile sex pheromone has been highlighted in Coccinellidae but various studies have suggested the existence of such molecules. In the present work, we have sampled volatile organic compounds released in the headspace of virgin females in the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), that were either allowed or not to feed on pea aphids (Acyrthosiphon pisum Harris). When fed on aphids, virgin females showed a stereotypical “calling behavior”, commonly associated with the emission of a sex pheromone in several Coleoptera species. Behavioral assays conducted with calling females in a four-arm olfactometer demonstrated that the blend of released volatile compounds was attractive at a distance for males, but not for other females. The headspace of virgin females that were not previously fed with aphids was not attractive for either sex. GC-MS analyses revealed the presence of five compounds in the volatile blend: (–)-β-caryophyllene, β-elemene, methyl-eugenol, α-humulene and α-bulnesene. Subsequently, we have collected and quantified the constituents from the blend over a period of 9 days after exposure to aphids. All five compounds were produced exclusively after feeding virgin females with aphids, and their quantity significantly increased during the whole period of collection. (–)-β-caryophyllene was found to be the major constituent, representing between 80 and 86 % of the total blend. All these results could promote the development of more specific and efficient management methods to manipulate the movements of this invasive ladybeetle and to reduce its negative impacts on biodiversity. [less ▲]

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See detailThe Multicoloured Asian Ladybird, invasive or not in agroecosystems ?
Vandereycken, Axel ULg; Durieux, Delphine ULg; Fassotte, Bérénice ULg et al

Poster (2013, September 10)

The Multicoloured Asian Ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is known to thrive principally in shrubby and arboreal habitats. Its occurrence in agroecosystems remains poorly ... [more ▼]

The Multicoloured Asian Ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is known to thrive principally in shrubby and arboreal habitats. Its occurrence in agroecosystems remains poorly documented. This study focuses on the occurrence of this exotic species and its seasonal abundance in various field crops. The abundance of adults and larvae of H. axyridis was evaluated over a four-year period, from 2009 to 2012, in four important agronomical crops (wheat, corn, broad bean and potato) in Belgium. A total of 28 aphid predator species were observed including 14 coccinellid species, 13 hoverfly species and one lacewing species. H. axyridis is present and reproduces in all of the four crops studied, with the largest numbers recorded in corn and broad bean crops. In corn, H. axyridis numbers were found to increase over the four inventoried year, reaching 86% of the aphid predators in 2012, while it represented only 15% in 2009. H. axyridis was not always recorded where aphids were abundant, e.g. aphids were abundant on wheat where no H. axyridis were recorded. H. axyridis starts reproducing after the peak in aphid population, suggesting that H. axyridis is able to complete its development by feeding on alternative prey such as larvae and pupae of the same and other species of ladybird and other aphidophagous species. H. axyridis is often considered to be bivoltine but it only completes one generation per year in field crops. The second generation generally develops late in the season in other habitats. Harmonia axyridis is an invasive and an intraguild predator present in high quantities in some specific crops. In these crops, H. axyridis could negatively impact on population of native species due to IGP observed in several other studies. [less ▲]

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