Purification and characterization of glutathione S-transferases from two syrphid flies (Syrphus ribesii and Myathropa florea)

in Comparative Biochemistry & Physiology Part B (2003), 137(1), 95-100

Effets de la réduction de doses de formulations d’insecticides et de fongicides sur l’auxiliaire non cible Episyrphus balteatus Degeer

in Phytoprotection (2003), 84

Interactions tritrophiques : étude du modèle Brassicacaeae - pucerons -coccinelle prédatrice

Doctoral thesis (2003)

Pour que le peuple lise : un siècle de lutte inachevée

in Les Cahiers d’Education permanente (2003), 19

Fungal lectin, XCL, is internalized via clathrin-dependent endocytosis and facilitates uptake of other molecules.

in European Journal of Cell Biology (2003), 82(10), 515-22

The lectin isolated from Xerocomus chrysenteron (XCL) displays a toxic activity towards insects. In order to assess its possible mode of action and to gather useful data for its potential use in insect ... [more ▼]

The lectin isolated from Xerocomus chrysenteron (XCL) displays a toxic activity towards insects. In order to assess its possible mode of action and to gather useful data for its potential use in insect-resistant transgenic plants, we investigated the effects of XCL at the cellular level. Immunofluorescence microscopy studies revealed that XCL is rapidly internalized into small endocytic vesicles that further coalesce in the perinuclear region. We show that XCL is endocytosed by the clathrin-dependent pathway, and is delivered to late endosome/lysosome compartments. The internalization of XCL seems to be general since it occurs in different cell types such as insect (SF9) or mammalian (NIH-3T3 and Hela) cell lines. In the presence of XCL, the uptake of GFP and BSA is greatly enhanced, demonstrating that XCL facilitates endocytosis. Thus, XCL could serve as a delivery agent to facilitate the endocytosis of proteins that do not enter the cell alone. [less ▲]

Cultures maraîchères et insectes utiles

in Le Canard déchaîné du Kauwberg (2003), 46

Aphid prey suitability as environmental effect on Adalia bipunctata reproduction.

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 ▲]

Characterisation of aphid myrosinase and degradation studies of glucosinolates

in Archives of Insect Biochemistry and Physiology (2002), 50(4), 173-182

Myrosinase from Brevicoryne brassicae was purified by ammonium sulfate fractionation, dialysis, and chromatography on a DEAE column. The chromatography yielded a single peak and a 115.6-fold purification ... [more ▼]

Myrosinase from Brevicoryne brassicae was purified by ammonium sulfate fractionation, dialysis, and chromatography on a DEAE column. The chromatography yielded a single peak and a 115.6-fold purification. Further FPLC gel filtration gave a single peak at 120 kDa. Denaturing SDS/PAGE of the protein revealed a single band at 60 kDa, indicating that the native B. brassicae myrosinase is a dimer. Kinetic parameters towards 8 glucosinolates were calculated. Strong differences of V-max and Km were observed depending on the substrate. Degradation products of each glucosinolate were identified and quantified by GC-MS and GLC-FID, respectively. Using both crude aphid homogenates and purified myrosinase, two unique hydroxyglucosinolates, 3-butenyl- and benzyl-isothiocyanates were identified from progoitrin ((2S)-2-hydroxybut-3-enyl-glucosinolate) and sinalbin (4-hydroxybenzyl-glucosinolate) degradation respectively. Addition of ascorbic acid to the reaction mixtures containing sinalbin and progoitrin caused the production of hydroxyloted degradation products usually associated with plant myrosinase metabolisation. The occurrence of the myrosinase system in B. brassicae is discussed in terms of similar allelochemical adaptation between the herbivore and its host plant. (C) 2002 Wiley-Liss, Inc. [less ▲]

The use of random amplified polymorphic DNA (RAPD) analysis for studies of genetic variation in populations of Coccinella septempunctata in Belgium.

in Mededelingen van de Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen (Rijksuniversiteit te Gent) (2002), 67(3), 557-61

The movement and dispersion of Coccinella septempunctata and its efficacy as aphid control agent over large areas is not really understood because of the difficulty in identifying the origins of predators ... [more ▼]

The movement and dispersion of Coccinella septempunctata and its efficacy as aphid control agent over large areas is not really understood because of the difficulty in identifying the origins of predators. To quantify the genetic diversity within the species and monitor the spatial foraging, populations were sampled from Belgium and analysed for RAPD DNA variation. Twenty decamer primers generated more than hundred polymorphic RAPD bands and pairwise distances were calculated between populations according to Nei and Li, then used to construct a radial neighbour-joining dendrogram and examine intra- and inter-population variance coefficients, by analysis of molecular variation (AMOVA). This study shows that while a number of factors can complicate the use and interpretation of RAPD fragments as genetic markers, RAPD analysis can be a valuable technique for studies of intra-specific genetic variation in C. septempunctata. [less ▲]

Responses and adaptations of Episyrphus balteatus and Adalia bipunctata to allelochemicals from Brassicaceae plant through their preys

in 8th International Symposium on Ecology of Aphidophaga, Azores 2002. Proceeding abstract 68 (2002)