What causes variability in the Folsomia candida reproduction test?

Large variability is often observed in results of the Folsomia candida reproduction test [ISO 11267, Soil quality-inhibition of reproduction of Collembola (Folsomia candida) by soil pollutants. Inter. Stand. Org. Ed. Geneve. (1998) 1-16] and can be detrimental to the test sensitivity. So, we investigated the effects of certain parameters (small differences of ambient temperature and age of the animals) on the variability of reproduction of F candida. We show that a 1 degreesC difference has no perceptible effect but that a 1 day difference in age has. Studying the reproduction of isolated individuals shows that a strong apparent interindividual variability exists. Lastly, we compared the variability of reproduction in two tests differing from one another in duration; variability was clearly decreased by lengthening the test. (C) 2002 Elsevier Science B.V. All rights reserved.