Inhibition of cholinesterases and carboxylesterases of two invertebrate species, Biomphalaria glabrata and Lumbriculus variegatus, by the carbamate pesticide carbaryl

• Published in: Aquatic toxicology 2010-01, Vol.96 (2), p.115-123
• Main Authors: Kristoff, Gisela, Guerrero, Noemi R. Verrengia, Cochón, Adriana C.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; aquatic invertebrates; bioassays; Biological and medical sciences; Biomphalaria - drug effects; Biomphalaria - enzymology; Biomphalaria glabrata; Carbaryl; Carbaryl - toxicity; carboxylesterase; Carboxylesterases; Carboxylic Ester Hydrolases - metabolism; cholinesterase; Cholinesterases; Cholinesterases - metabolism; Ecotoxicology, biological effects of pollution; effective concentration 50; enzyme activity; enzyme inhibition; Enzyme Inhibitors - toxicity; Fundamental and applied biological sciences. Psychology; Gastropoda; General aspects; Inhibitory Concentration 50; Invertebrata; Lumbriculus variegatus; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; Oligochaeta; Oligochaeta - drug effects; Oligochaeta - enzymology; Pesticides - toxicity; Time Factors; toxicity testing; Vectors. Intermediate hosts; Water Pollutants, Chemical - toxicity; water pollution
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2009.10.001

In this study, the effects of sublethal concentrations of the carbamate carbaryl on the cholinesterase (ChE) and carboxylesterase (CES) activities present in the oligochaete Lumbriculus variegatus and in the pigmented Biomphalaria glabrata gastropod were investigated. The results showed that ChE activity from both species was inhibited by in vivo and in vitro exposure to carbaryl, with EC 50 and IC 50 values approximately 20 times lower for the oligochaete than for the gastropod. On the other hand, the recovery process in uncontaminated media was more efficient in oligochaetes than in snails. Thus, in only 2 h the oligochaetes showed no inhibition with respect to control values whereas the snails did not reach control values even after 48 h of being in pesticide-free water. CES activity was investigated in whole body soft tissue homogenates using three different substrates: p-nitrophenyl butyrate, 1-naphthyl acetate (NA) and 2-NA. In addition, the presence of multiple CES isozymes in L. variegatus and B. glabrata extracts, with activity towards 1- and 2-NA, was confirmed by native polyacrylamide electrophoresis. In both species, the activities measured using the naphthyl substrates were higher than the activity towards p-nitrophenyl butyrate. In addition, B. glabrata showed a higher CES activity than L. variegatus independently of the substrate used. In L. variegatus, in vivo CES activity towards the different substrates was less sensitive to carbaryl inhibition than ChE activity. In contrast, in B. glabrata, CES activity towards p-nitrophenyl butyrate was inhibited at lower insecticide concentrations than ChE. The results of this study contribute to the knowledge of the sensitivity of non-target freshwater invertebrate Type B-esterases towards pesticides.