Earthworm injury test for in-situ biomonitoring of pesticides in biobeds

Abstract

Biobeds are presented as an alternative for good pesticide wastewater managementon farms. This work proposes a new test for in-situ biomonitoring of pesticidedetoxification in biobeds. It is based on the assessment of visually appreciable injuriesto Eisenia fetida. The severity of the injury to each exposed individual is assessed fromthe morphological changes observed in comparison with the patterns established inseven categories and, an injury index is calculated. A linear relationship between theproposed injury index and the pesticide concentration was determined for eachpesticide sprayed individually in the biomixture. The five pesticides used were atrazine,prometryn, clethodim, haloxyfop-P-methyl and dicamba. In addition, a multiple linearregression model (i.e., a multivariate response surface) was fitted, which showed agood generalization capacity. The sensitivity range of the injury test was tested from0.01 to 630 mg kg-1 as the total pesticide concentration. This index is then used tomonitor the detoxification of these pesticides in a biomixture (composed of wheatstubble, river waste, and soil, 50:25:25% by volume) over 210 days. The results arecompared with standardized tests (Eisenia fetida avoidance test and Lactuca sativaseed germination test) carried out on the same biomixture. The results are alsocompared with data on the removal of pesticides. The injury test showed a bettercorrelation with the removal of pesticides than the avoidance test and seedgermination test. This simple and inexpensive test has proved to be useful fordecontamination in-situ monitoring in biobeds.