In many parts of Africa, pesticides are used indiscriminately. Yet, ecotoxicological data relevant for the protection of soil organisms have usually been obtained under temperate conditions. In order to assess the effects of three commonly used insecticides (deltamethrin, dimethoate, chlorpyrifos) on microarthropods in African soils, uncontaminated natural soils were collected from Nigeria and Tunisia. In addition, two common test soils (OECD artificial soil and LUFA 2.3 soil) were used in OECD standard reproduction tests. Two microarthropod species, the springtail Folsomia candida and the predatory mite Hypoaspis aculeifer, were exposed in these four soils spiked individually with the insecticides. The collembolan F. candida was more sensitive than the mite H. aculeifer for all three insecticides. The toxicity of each insecticide in the four soils varied, with few exceptions, by less than an order of magnitude. The lowest toxicity was often, but not always, found in OECD artificial soil. Soil- and insecticide-specific patterns of toxicity to F. candida and H. aculeifer might be related to the physicochemical properties of the soils and, thus, to the bioavailability of the insecticides. Following the rules laid down in the European Union for the registration of pesticides and using standard European exposure scenarios, neither an acute nor a chronic risk of dimethoate and chlorpyrifos can be excluded (with few exceptions) in all four soils. Lower risks were identified for deltamethrin. For pesticides used in Africa, an environmental risk assessment based on data gained in tests with at least one additional natural field soil, preferably of African origin, should be performed using the same risk assessment principles as in the European Union.
For additional information, see the publication in Integrated Environmental Assessment and Management:
Jaabiri Kamoun, I., Jegede, O.O., Owojori, O.J., Bouzid, J., Gargouri, R., Römbke, J. (2018). Effects of deltamethrin, dimethoate, and chlorpyrifos on survival and reproduction of the collembolan Folsomia candida and the predatory mite Hypoaspis aculeifer in two African and two European soils. Integrated Environmental Assessment and Management 14, 92-104.
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