Differential Sensitivities of Neurotoxic and Enzymatic Responses to Carbaryl and Acetamiprid in Chilina gibbosa

JULIO PAINEFILU; GISELA KRISTOFF; LUCILA THOMSETT HERBERT; CAROLINA MENGONI; PAULA FANNY COSSI; CARLOS MARCELO LUQUET

Ciudad Autónoma de Buenos Aires

Jornada; Jornadas Interdisciplinarias Química Biológica 2017; 2017

Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires

Chilina gibbosa is a freshwater snail endemic to southern Argentina and Chile, commonly found in rivers, lakes and reservoirs of the Río Negro and Neuquén provinces, where fruit production is one of the main economic activities and large amounts of pesticides of different chemical nature have been found in the surrounding water. Our aim was to characterize the acute effect of carbaryl (CAR, carbamate) and acetamiprid (ACP, neonicotinoid) on C. gibbosaneurotoxic response and enzymatic activities. We define neurotoxic response as the protrusion of the entire head-foot. Measured enzymes were cholinesterases (ChE), carboxylesterases (CE) using p-nitrophenyl acetate (p-NPA) and p-nitrophenyl butyrate (p-NPB) as substrates, and glutathione S-transferase (GST). We exposed snails for 48 h to a range of 0.05 to 500 μg L-1 CAR or 10 to 1000 μg L-1 ACP. In the case of CAR, we obtained similar sensitivities between the activities of ChE (NOEC 5 μg L-1; LOEC 13 μg L-1; IC50 37 μg L-1; 75% inhibition at 500 μg L-1) and CE measured using p-NPB (IC50 11 μg L-1;88 % inhibition at 500 μg L-1; no dose response relationship found ≤ 5 μg L-1). There were no effects on the activities of CE using p-NPA and GST. For ACP, we found an increase in CE activity using p-NPA and no effect on ChE, CE using p-NFB and GST. Neurotoxic response was not observed for either pesticide. Our laboratory has previously reported C. gibbosa neurotoxic response and ChE activity as very sensitive biomarkers for acute toxicity of azinphos-methyl (AZM, organophosphate). Contrastingly, ChE activity is less sensitive for CAR and is not altered by ACP. We provide further information on the adverse effects of two different pesticides on an endemic species of South America and aid towards a better ecological risk assessment of pesticides on non-standard organisms.