Can avoidance behavior of the mite Oppia nitens be used as a rapid toxicity test for soils contaminated with metals or organic chemicals?

Survival and reproduction soil toxicity tests for a new mite test species, Oppia nitens, have recently been developed for boreal ecosystems; however, the tests require 28 to 35 d. Avoidance tests have the potential to allow for rapid preliminary screening assessments of soils. The objective of this investigation was to determine the relevance of the avoidance test with the oribatid mite O. nitens as a short screening test in lower-tier environmental risk assessment. We assessed the effects of soil properties and chemicals on O. nitens avoidance behavior as well as the minimum time required to obtain a significant avoidance response from the mite. Specimens of this mite were exposed in Organisation for Economic Co-Operation and Development (OECD) artificial soils that had been adjusted to achieve varying soil properties as well as to a range of concentrations of the following contaminants: Cu, Zn, Cd, Pb, phenanthrene, benzo[a]pyrene, geraniol, and boric acid over 1, 2, or 5 d. The results were then compared with those of parallel life-cycle toxicity studies. The results showed that 24 h was adequate to obtain a significant response of the mites and that the soil properties tested (moisture, pH, organic matter, and clay content) had little influence on mite avoidance. The median effective concentration (EC50) for avoidance response was lower than or in the same range as the reproduction EC50 values for the organic compounds (phenanthrene and geraniol) and metals (Cu and Zn) or the median lethal concentration (LC50) values for Pb. The 24-h mite avoidance test is a suitable screening method across a range of soil properties and chemicals.