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.

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.

Progressive cone dystrophy and sensorineural hearing loss.

A 39-year old man presented 13 years ago with a history of progressive loss of vision and photophobia. A full ophthalmological and ENT work-up during several years of follow-up, including psychophysical as well as electrophysiological tests, revealed a progressive cone dystrophy in combination with sensorineural hearing loss. His younger sister presented with very similar features and underwent the same work-up. A novel syndrome of progressive cone dystrophy and sensorineural hearing loss is described in both siblings. Both also suffered from non-ocular disease possibly related to ciliary dysfunction. The condition is likely to be inherited as an autosomal recessive trait.

A model of the elastic take-off energy in the long jump.

A theoretical analysis of the long jump take-off is presented, with the conclusion that elastic effects are important. Measured data from the literature for groups of top athletes and average performers in the long jump confirm this conclusion and lead to an estimate of elastic energy conversion efficiency, which is very low (between 0.2 and 0.3), in contrast with much higher conversion efficiencies for the running stride.

The design and testing of a wire velocimeter.

The basic principles underlying the design of a velocimeter based on an unwinding wire, for use in athletics research, are discussed. It is shown by theoretical analysis that, in order to avoid runaway effects, the tension on the wire should be either high or low but not of intermediate strength. The low tension regime is shown to be theoretically the most favourable as it combines high accuracy of speed measurements in decelerated motion with insensitivity to resonance oscillations of the wire. Practical considerations concerning the ruggedness of the apparatus, however, favour the high tension regime. A modern apparatus incorporating microprocessors and working with thin nylon wire stretched by a force of the order of 1 N, i.e. in the high tension regime, has been constructed and tested. The test results show that the velocity of decelerated motions (up to decelerations of the order of 10 m s-2) can be faithfully recorded in the velocity range 0-15 m s-1. The relative error for the measurement of constant speed up to 15 m s-1 is about one in a thousand, which is very small and practically unattainable by other methods. An application to the study of the long jump is demonstrated and validated by the use of film analysis.