Activity levels of B-esterases in the tadpoles of 11 species of frogs in the middle Paraná River floodplain: Implication for ecological risk assessment of soybean crops.

LAJMANOVICH R. C.; PELTZER P. M.; JUNGES C. M.; ATTADEMO A. M.; SANCHEZ L. C. ; BASSÓ A.

ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2010 vol. 73 p. 1517 - 1524

0147-6513

Soybean fields provide habitats for many species of amphibians. However, the persistence and health ofamphibian populations may be at risk from the increasing use of pesticides and other agriculturalchemicals. We examined the activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE),and carboxylesterases (CbEs) in 11 syntopic species of larval anurans. In vitro effects of malaoxoncausing 50% BChE inhibition (IC50) were also studied. In addition, we calculated a relative risk index (RI)based on the geographic distributions of the anurans, the phenology of soybean cultivation,and basal enzymatic values related to potential pesticide detoxification. Among the 11 species, AChEactivity varied from 17.571.6 to 68.274.7 nmol min1 mg1 protein (PT). BChE activity alsovaried significantly, ranging from 3.370.4 to 7.570.4 nmol min1 mg1 PT. Both measures ofCbE activities varied widely (CbE a-NA: 2.170.5–12.471.1 nmol min1 mg1 PT; CbE-4NPV:21.871.8–102.677.9 nmol min1 mg1 PT). We also corroborate that lower BChE activity levels forthe tadpoles were associated at minor IC50 values. The results of this study demonstrate significantvariation in enzymatic levels among several tadpole species and intermediate to high RI values for 7species. Based on these results, it appears that a conversion of native ecosystems to soybean crops maylead to increased ecological risk for anuran amphibians.