Reproduction test on the springtail Folsomia candida exposed via artificial test soils in a laboratory experiment

In a laboratory experiment, the soil invertebrate Folsomia candida (Collembola) was exposed to CuCl2 or copper oxide nanoparticles (CuO-NP) for 28 days. The animals were exposed via artificial test soil which varied in the size (19 or 30% of total mass) or the clay type of their clay fraction (kaolin or montmorillonite). The test substances were dissolved (CuCl2) or dispersed (CuO-NP) in pure miliQ water and stirred into the dry test soils to end up with test concentrations of 1, 3, 10 and 32 mg Cu/kg and a water content of 50% of the maximum water holding capacity of the respective soils. As a control, soil with miliQ water only was tested. At the beginning of the experiment, 5 animals at the age of 10-12 days were inserted into the test vessels containing the spiked test soil. After 28 days, the previously inserted adult animals and the juvenile animals produced within the last 28 days were extracted by floatation of the test soils with tap water. The water surface was photographed and the number of produced juveniles was counted manually with the computer programme ImageJ to assess the reproductive output of the animals and their survival rate. The adult animals were collected from the water surface and further analysed for dry mass and Cu body concentration. The endpoints survival, reproduction and dry mass per individual were referred to the average values of the negative control. All endpoints were statistically compared to the control by a linear model