Behavioral response and dynamics of Eisenia fetida hemocytes exposed to environmentally relevant concentration of sulfentrazone

Abstract

Although the toxicity of the pesticide sulfentrazone in some aquatic organisms is known, its effects on edaphic organisms such as earthworms remain completely unknown. Thus, we aimed at evaluating the behavior and immune response of Eisenia fetida exposed to sulfentrazone at environmentally relevant concentrations (EC). E. fetida representatives exposed to this contaminant (for 48 h) were divided in the following groups: environmental concentration (EC1x: 318 ng sulfentrazone/g of dry weight soil) and EC100x (concentration 100 times higher than in EC1x). Based on the avoidance test results, earthworms responded to this pesticide and proved the toxicity of sulfentrazone. The observed immune response induction was expressed by increased granulocytes presenting phagocytic vacuoles and agglomerations/encapsulations, mainly in animals belonging to groups EC1x and EC100x. However, the reduced frequency of plasmocytes in these animals' hemolymphs suggested that the phagocytic immune response was not efficient to assure 100% survival. Our study is the first to report sulfentrazone toxicity in an edaphic organism, at environmental concentration.