Evironmental project, 986 – Background report on pre-validation of an OECD springtail test guideline

Background Report on Pre-validation of an OECD Springtail Test Guideline

4 Conclusion

Searching the literature a variety of collembolan species have been used in terrestrial ecology. For the draft OECD guideline two collembolan species, Folsomia fimetaria and Folsomia candida, were chosen as these two species have been much used in terrestrial ecotoxicology and standard tests are available. The two selected species represents two ecological and biological approaches. F. candida's habitat is primarily high organic soils, whereas F. fimetaria is present in most agricultural soils. F. candida is parthenogenetic (asexual) reproducing, whereas F. fimetaria is sexually reproducing as are most other species. It was attempted to include juvenile sex-determination as an additional endpoint for the test, but due to overlapping juvenile clutches (within one test) this was not possible. Given the differences between the two species these were reviewed with respect to differences in sensitivity to chemicals, with particular emphasis on possible alterations caused by differences in their size. Neither the literature study nor the laboratory studies resulted in conclusive differences in sensitivity between the species. A comparison in size-class related differences between the two species revealed that there was a slight difference in sensitivity for animals of the same size, but a pronounced stage related difference in toxicity. Hence, the life-stage at which the organisms are exposed determines the sensitivity of the test.

In connection with the test guideline (and a ring-test) it will be necessary to have a positive control to ensure the stability of the test-system. Three compounds were tested in order to identify future test ranges. The compounds were fipronil, 3,5-dichlorophenol and boric acid. The tests performed with these chemicals indicated that the test range for fipronil should be 0 to 10 mg fipronil kg^-1, for 3,5-Dichlorophenol 0 to 15 mg 3,5-dichlorophenol kg^-1 soil and for Boric acid 0 to 300 mg boric acid kg^-1.