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

in Med. Fac. Landbouw. Univ. Gent (2002), 67(3), 557-561

Impact of closed habitat on the entomological diversity and abundance in carrot open fields

in Med. Fac. Landbouw. Univ. Gent (2002), 67(3), 481-486

Entomological diversity in agro-ecosystems : not necessarily an ecological desert

in Bulletin de l’Institut Royal des Sciences naturelles de Belgique, Biologie, 72 : 153-154. (2002)

Effet de l’environnement proche sur la biodiversité entomologique en culture maraîchères de plein champ

in Parasitica (2001), 56

Effects of insecticide treatments on insect density and diversity in vegetable open fields.

in Mededelingen van de Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen (Rijksuniversiteit te Gent) (2001), 66(2a), 403-411

Vegetable open field areas increased for 15 years in Wallonia, mainly in Hesbaye. To be in accordance with quality standards, especially in terms of agro-chimical residues (R.M.L.), biological pest ... [more ▼]

Vegetable open field areas increased for 15 years in Wallonia, mainly in Hesbaye. To be in accordance with quality standards, especially in terms of agro-chimical residues (R.M.L.), biological pest control was developed and allowed to reduce the insecticide use, leading to have safer fresh products. Among cultivated species in Wallonia, leguminous crops represent more than 85% of the vegetable production. To assess the impact of insecticide treatment on both pests (mainly aphids) and beneficial insects (predators and parasitoids), broad bean (Vicia faba L.) fields were investigated during all the production duration. Twelve fields between Waremme and Hannut were visited weakly from May to July. In each field, control untreated and treated plots were investigated. Insects were caught using yellow traps and determined until the family level. Approximately 90.000 insects belonging to 59 major families (99% of captures) and 64 minor families were identified. These results showed that biodiversity in terms of family numbers was significantly higher in unsprayed plots. In addition, biodiversity and biomass (insect density) increased gradually during the season. Evaluation of pest and beneficial diversity and density was discussed in relation to aphicid (lambda-cyhalothrin, pirimicarb) treatments and the development of I.P.M. program in vegetable crops. [less ▲]

Oviposition preferences of Episyrphus balteatus.

in Mededelingen van de Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen (Rijksuniversiteit te Gent) (2001), 66(2a), 269-75

A crucial aspect of predator oviposition behaviour is host plant choice, especially in hoverflies where the newly hatched offspring are unable to move a great distance to search for the appropriate prey ... [more ▼]

A crucial aspect of predator oviposition behaviour is host plant choice, especially in hoverflies where the newly hatched offspring are unable to move a great distance to search for the appropriate prey. Such offspring must generally feed on the host plant aphids previously selected by the mother. Some factors involved in the selection of the oviposition site of Episyrphus balteatus De Geer include aphids associated to chemical stimuli, aphid colony size and host plant characteristics. Here we tested the hypothesis that there will not only be a rank order hierarchy of preference for aphid prey species reared on the same host plant but that a similar hierarchy of different host plant of one aphid species could be established. Therefore we compared the number of eggs laid on different combinations of host plant and aphid species. Vicia faba L., secondary metabolites free, Brassica napus L. and Sinapis alba L., containing low and high levels of glucosinolates respectively were used. The latter compounds are well known allelochemicals from Brassicaceae having a strong influence on specialist and generalist insects from both phytophagous and entomophagous levels. These experiments enhance the importance of tritrophic interactions in biological control of pests by underlining the host plant influence on aphidophagous predators, either directly or through the odours emitted by the phytophagous prey. [less ▲]

Glutathione S-transferases of Aulacorthum solani and Acyrthosiphon pisum: partial purification and characterization.

in Comparative Biochemistry & Physiology Part B (2001), 129(1), 165-71

Glutathione S-transferases (GST) play an important role in the detoxification of many substances including allelochemicals from plants. Brassicaceae plants contain glucosinolates and emit volatile ... [more ▼]

Glutathione S-transferases (GST) play an important role in the detoxification of many substances including allelochemicals from plants. Brassicaceae plants contain glucosinolates and emit volatile isothiocyanates which affect the GST system. A comparison of the GST of two aphid species, the generalist Aulacorthum solani found on Brassicaceae and the Fabaceae specialist Acyrthosiphon pisum, was made to try to explain their respective feeding behaviour. Differences of GST were determined among the two aphid species based on purification by affinity chromatography, SDS-PAGE and on kinetic studies. Purification yields using an epoxy-activated Sepharose 6B column were highly different for the two aphid species (18% and 34% for A. solani and A. pisum, respectively). These variations were confirmed by SDS-PAGE. While only a 27-kDa band was observed for A. pisum, two bands of approximately 25-kDa were visualized for the generalist aphid, A. solani. Considering the kinetic results, differences of Km and Vmax were observed following the aphid species when a range of substrates (CDNB and DCNB) and GSH concentrations were tested. Studies on the detoxification enzymes of generalist and specialist herbivores would be undertaken to determine accurately the effect of the host plant on the organisms eating them, particularly in terms of biochemical and ecological advantages. [less ▲]

Evaluation de la diversité des espèces de Syrphidae d’un site de la région liégeoise (ru de Targnon, Theux, Belgique)

in Notes Fauniques de Gembloux (2001)

Partial Purification Of The Soluble Glutathione S-Transferases Of Two Aphid Species, Alaucorthum Solani And Acyrthosiphon Pisum

in Chemico-Biological Interactions (2001), 133(1-3),

Effects of insecticide treatments on insect density and diversity in vegetable open fields

in Med. Fac. Landbouw. Univ. Gent (2001), 66(2a), 403-411