Applicablle extraction techniques applicable to the ecological study of house-dust mites. Qualitative and quantitative comparison of various types of dust
1975 - Volume: 17 Issue: 4 pages: 693-708
Techniques d’extraction applicables à l’étude écologique des acariens des poussières de maison. Comparaison qualitative et quantitative de divers types de poussières. - This paper deals with the mechanical extraction methods for house-dust mites. Indeed, a suitable extraction technique is of prime importance in studying the principal causes of changes in number of individuals. There is a need therefore to develop the most appropriate technique which would take into account the physical properties of dust-material (nature of the substrate, specific gravity, solubility of the organic and inorganic compounds ... ) First, we have reviewed and discussed the advantages and the inconvenients of some mechanical methods currently used in the isolation of Acaridida. Owing to their non-selectivity, their simple manipulations and the better adaptation to the physical and chemical properties of dust-matter, four techniques have been selected to test the extraction efficiency. These mechanical methods are the immersion, the washing and both of the Fain s method with and without detergent. By comparative studies of the extractive procedures, we have detected differential extractions in relation with the composition of contaminated dust and with the method used for those samples. Moreover, the washing procedure appears to be as efficient as the immersion one. Concerning the potentialities of the Fain s method, the efficacy depends on the quantity of wetting agent, the ’real’ density of the:floatation solution, the size and the density of the mites and yet other factors. In this case, there are suggestions of a classification of dust-material (from fibrous matter to fine de bris), using a different treatment for each category of dust. Finally about the occurence of mites in house dust, it is shown that the three specific biotopes of a house (the mattress, the carpet and the:floor under a bed) have respectively particular faunistic compositions with distinct densities. So, owing to the favourable ecological conditions, the most abundant species collected in mattress-dust are Dermatophagoides pteronyssinus (about 90 %) and also a nonnegligible proportion of Tarsonemidae (5 %). About the carpet and floor samples, a rich fauna is encountered in the dust composed of Pyroglyphidae, Acaridae, Glycyphagidae, Cheyletidae, Bdellidae because they assemble populations coming from different biotopes.
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