Is acetylcholinesterase a biomarker of susceptibility in Daphnia magna (Crustacea, Cladocera) after deltamethrin exposure?. (February 2015) - Toumi, Héla
Highlights: LOECs of AChE activity differ by four-fold between the three strains of Daphnia magna . AChE is a biomarker of susceptibility after deltamethrin exposure in Daphnia magna . Ratios of AChE IC50 and the immobility EC50-48 h is a potential indication of genetic heterogeneity. Abstract: In the present study, we explored the possibility of using the acetylcholinesterase (AChE) as a biomarker after deltamethrin (pyrethroid insecticide) exposure with three strains of the cladoceran Daphnia magna . Four calculated time-weighted deltamethrin concentrations (20.1, 40.3, 80.6 and 161.3 ng L −1 ) were compared against control acetylcholinesterase activity. Our results showed that after 48 h of deltamethrin exposure, all treatments induced a significant decrease of AChE activities whatever the three considered strains. However, diverse responses were registered in terms of lowest observed effect concentrations (LOEC: 80.6 ng L −1 for strain 1 and 20.1 ng L −1 for strains 2 and 3) revealing differences in sensitivity among the three tested strains of D. magna . Our results suggest that after deltamethrin exposure, the AChE activity responses can be also used as a biomarker of susceptibility (i.e., variation of strain specific response). Moreover, our results show that strain 1 is the less sensitive in terms of IC50-48 h of AChE, whereas it became the most sensitive when considering the EC50-48 h estimated in the standard ecotoxicity test.