New Techniques for Counting and Isolating Free Living Nematodes From Small Soil Samples and From Oak Forest Litter

Publisher： Brill

ISSN： 1875-2926

Source： Nematologica, Vol.1, Iss.3, 1956-01, pp. : 216-226

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Abstract

Four different techniques are described by which it appeared possible to investigate the nematode population in samples of soil and litter quantitatively: I. a. A staining technique. This was the standard method by which it was possible to isolate practically all nematodes from a given sample. I. b. Centrifugal flotation: This method took about one eighth of the time required by the foregoing method, but was only slightly less reliable (table i). This technique is based on the fact that nematodes float in a strong magnesium sulphate solution whereas most soil and humus particles sink. The separation of the floating and the sinking fractions is accelerated by centrifuging. Isolation of the nematodes from the small amount of debris in the counting dish takes little time. 2. a. The isolation of nematodes from oak forest litter had to be done in quite another way. The Baermann technique gives an incomplete separation and little reliability. Highly reliable results were obtained by placing a sample in water on a piece of coppergauze in a beaker, and shaking for I minute followed by 4 minutes of rest, during 24 hours. The number of nematodes caught after 24 hours had to be multiplied by the factor 1.25 to obtain approximately the number of nematodes orginally present in the sample. 2. b. The number of nematodes still present in a litter sample after a shaking period of 24 hours was determined after bleaching this material with 6% hydrogenperoxyde to which some ammonia was added until the leaves were yellowish white. Then followed staining with a hot solution (60-70° C) of a dye dissolved in lactophenol. Acid fuchsin or cottonblue were more suitable for staining nematodes while trypanblue was found best for bacteria and fungi.