Oribatid mites: prospects for their use in ecotoxicology

Oribatid mites are a group of arthropods that have had remarkable evolutionary success with regard to species richness, variety of habitats colonized, life-cycle variation and reporductive patterns. The aim of this paper is to review some of the important features of Oribatida in relation to the possible use of these animals in ecotoxicological experiments. Their often sedentary way of living, combined with a narrow dependence on microhabitats qualify oribatids as potential indicator organisms for air and soil quality. Some species have been shown to be extremely sensitive to air pollutants such as SO2 and NO2. A low metabolic rate may be the driving force for slow development, low fertility, iteroparity and long adult life. Given these life-cycle characteristics, oribatids may be particularly vulnerable to intoxication by persistent contaminants. Work done on heavy metals suggests that the capacity for accumulation differs greatly between species. The camisiid Platynothrus peltifer accumulates high amounts of trace metals, specifically Mn. The toxicity of Cd, Cu and Pb has been studied in P. peltifer, demonstrating the necessity to consider egg production as a sensitive criterion. It is concluded that oribatid mites hold a great potential for use in ecotoxicology, due to the structural and functional complexity of their communities, and several peculiarities not found in other arthropods. The possibilities offered by this diverse group have not yet been fully employed by ecotoxicologists.