Validation of the Berlese-funnel technique for thrips extraction.

In order to get the accreditation EN ISO/IEC 17025 for Thrips palmi the Berlese-funnel technique, which is used for the isolation of quarantine insects out of plant material, was validated. Following parameters were investigated: cleaning of the funnel, temperature during isolation, detection limit and duration of the isolation period. Thrips fuscipennis was collected from heavily infected rosehip and used as target organism. Besides orchids, artificially contaminated maple leaves (Acer pseudoplatanus) were used for the validation. Results showed that thrips and other organisms can be present alive or dead in the funnel after removing the treated plants and can contaminate the next sample or isolate. Cleaning of the funnel with a vacuum cleaner and compressed-air apparatus is necessary before running a new extraction. Contamination of the recipient is also possible from the environment. This can be avoided by closing the opening between the funnel and the recipient. To reach an optimal temperature for isolation of the thrips a 60 Watt bulb is necessary. The results showed that the maximum temperature doesn't reach a temperature above 51 degrees C, the average temperatures were situated between 35, 74 degrees C and 39, 38 degrees C. A 40 Watt bulb doesn't create enough heat to guarantee an efficient isolation of the thrips; the average temperature was 34, 74 degrees C and the maximum temperature 36, 80 degrees C. Based on the results we can conclude that an isolation time of 20 hours is necessary to obtain accurate data. Dependent on the number of thrips in the artificially infected samples 87 to 95% is isolated after 20 hours. The detection limit is 1 thrips with a probability of 95% being isolated after 20 hours.

Acarological diagnostic research at the Diagnostic Centre for Plants during the period 2004-2006.

During the period 2004-2006, 1691 samples of different origin were examined at the Diagnostic Centre for Plants. We received 1046 samples of imported plant material for detection and identification of quarantine organisms. More than 200 samples were checked on mites and insects to get a phytosanitary certificate for export and 391 samples were investigated for diagnostic reason. The Berlese-funnel and dissecting microscopy technique were used to separate mites from the samples. For identification, the mites were slide mounted in Berlese-Hoyer's medium and examined by using phase-contrast microscopy. In 3% of the samples examined on the presence of quarantine organisms, phytophagous mites belonging to the superfamily Tetranychoidea were found, but none with the quarantine status in accordance with the EPPO A1/A2 list. Besides Tetranychus urticae detected on different crops, the cassava green mite Mononychellus progresivus was found on cassava (import Cameroon) in 2006. Tenuipalpus elegans (Tenuipalpidae) was found on cut foliage (import South Africa) in 2004. In 19.9% of the investigated samples for diagnostic reason mites were found. In 47.7% of the infested samples mites were definitely the reason for the damage; in 15.9% mites were secondary and in 36.4% the occurrence of mites was not relevant for the injury. An overview of the determined mites will be given. During this 3 years diagnostic research a few new pest mites belonging to families Tetranychidae and Eriophyidae can be reported. In 2006 Panonychus citri was found on Prunus laurocerasus and later on Eleaegnus sp. and Skimmia sp.. Aceria silvicola was determined on Rubus idaeus in 2006 and Aculus ulae and Aceria carpini on Carpinus betulus in 2005. Besides new pest mites, never seen problems with the broad mite Polyphagotarsonemus latus (Fam. Tarsonemidae) occurred in tree-nurseries in 2005 and 2006. Also 20 samples coming from private persons were investigated. The main problems indoor were caused by Dermanyssus gallinae and Bryobia praetiosa. In gardens especially spider mite problems occurred. Eurytetranychus buxi, Oligonychus ununguis, Eotetranychus carpini and Eotetranychus tiliarium caused considerable damage in topiary and formal fences.

Inventarisation of natural enemies in witloof chicory fields: preliminary results.

Due to residues on the witloof chicory heads the use of insecticides is forbidden during forcing. At this moment a suitable chemical control of the leafminer Napomyza cichorii is carried out in the field, based on the phenology and the population density and taking into account the economic threshold level. No chemical treatment is recognized against the root aphid Pemphigus bursarius. For monitoring these pests during the growing season water traps were placed on observation fields, scattered over the Belgian endive production area. The large numbers and the wide variety of other insects caught in the traps in recent years indicate that there is a potential of natural enemies. An inventarisation of the native enemies in witloof chicory fields was started recently using yellow-coloured water traps and pitfall traps; at the same time field observations were done. In all the observation fields we found besides Carabidae and Staphilinidae also Coccinellidae and Syrphidae in large numbers. The numbers and the diversity of Hymenoptera in the water traps were very large. Apart from the field observations witloof chicory heads were investigated during harvest. Parasitized pupae were collected and kept in a climate room. Dacnusa leptogaster (Braconidae), a specific parasite of the witloof chicory fly, hatched. This parasite was also found in the water traps during the growing season.

First report of Eotetranychus fagi in Belgium.

Eotetranychus fagi (Acari: Tetranychidae) was first recorded in Belgium on Fagus sylvatica in Kortrijk in October 2002. In the autumn of 2003 E. fagi was noticed again at several locations in Flanders. Because F. sylvatica is often used as hedge plants in private gardens, it is expected that further spread of this spider mite will occur in the next few years.