Immuno-modulator effects of carbaryl and 2,4 D in the earthworm Eisenia fetida andrei

Carbaryl and 2,4 dichlorophenoxy acetic acid (2,4 D) exerted differential effects on the earthworm E. f. andrei functions related to immune defense. As determined by contact test assay, carbaryl activity is characterized by a low LC50 value of 3.4 mu g/cm(2), compared to 18 mu g/cm(2) for 2,4 D. Incubating earthworms with doses of carbaryl as low as 0.1 mu g/cm(2) resulted in the inhibition of the lysozyme activity detected in the cytosol (CL). A strong inhibition of phagocytosis was also obtained but with 1.5 mu g/cm(2). On the other hand, low doses of carbaryl significantly stimulated cytolysis (0.1 mu g/cm(2)), serine protease activity (0.1 mu g/cm(2)) in the coelomic fluid (CF) and serine protease activity in the CL (0.05 mu g/cm(2)) Concerning 2,4 D, both cytolysis in the CF and serine protease activity in the CL were stimulated by respectively 3.5 mu g/cm(2) and 18 mu g/cm(2) Phagocytosis was inhibited only with 18 mu g/cm(2). Lysozyme and serine protease inhibitor activities were not affected. The immune toxicological assays we developed in earthworms, allow to distinguish between chemicals with different immuno-modulatory properties. Moreover, earthworms appear to be a particularly well adapted sentinel organism for the evaluation of soil contamination.