The effect of temperature on the efficiency of extracting astigmatic mites from hay - a trial with a heat extractor

The effect of temperature on the extraction efficiency for Astigmata mites from hay was studied by comparing the results of heated and unheated extractors. In ali, 1 560 Astigmata mites (mainly Acarus siro) were picked alive and half of them were placed into containers with mite-free hay of the heated and cooled extractor and half into the unheated extractor. Thus 780 mites were placed in each extractor, 30 to each container with 3 g of mite-free hay. The extractor was a modification of the socalled Lussenhop-device. The temperature of the heated extractor was raised gradually as follows: Starting point 30° C, second day 45o C, 3rd-4th day 55° C, 5-6th day 70° C and 7-9th days 90° C. The heat extractor was a modification of the so-called Lussenhop deviee with four 250 W lamps warming the sample from above. The extraction efficiency (85 %) for Astigmata was significantly higher in the high gradient extractor than in the unheated and uncooled extractor at room temperature (73 %). Also the repeatability of the former method was slightly better than of the latter. The results support the presumption suggested by NEF that heating has also an independent effect on extraction efficiency, in addition to its drying effect.