Validation of earthworm toxicity tests by comparison with field studies: a review of benomyl, carbendazim, carbofuran, and carbaryl.

To investigate whether results of laboratory toxicity tests with earthworms are capable of being used to predict effects in the field, a literature study was carried out. Benomyl, its metabolite carbendazim, carbofuran, and carbaryl were chosen as model substances. From data on the behavior of these pesticides in soil, it can be concluded that shortly after application most of the dosage will be in the top 2.5-cm soil layer. Soil concentrations can be estimated from field dosages used. Estimated field soil concentrations that affected earthworm populations were in agreement with effect levels determined in laboratory studies. In the field, species living in the surface layers (e.g., juveniles of many species) or coming to the soil surface to feed (e.g., Lumbricus terrestris) are most affected, since they experience a high degree of exposure. Evidently, species having long generation times need a relatively long time to recover. Both the distribution of the pesticide and the behavior of earthworms in soil affect earthworm exposure. Insight into these aspects may provide tools to predict both short- and long-term effects of pesticides on earthworm populations in field soils.