Int. J. Environment and Health, Vol. 3, No. 4, 2009 379 Copyright © 2009 Inderscience Enterprises Ltd. Impact of endosulphan and cypermethrin mixture on amphibians under field use for biotech soya bean production María Gabriela Agostini, Guillermo Sebastián Natale and Alicia Estela Ronco* Centro de Investigaciones del Medio Ambiente (CIMA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina Email: gagostini@quimica.unlp.edu.ar Email: gnatale@quimica.unlp.edu.ar Email: cima@quimica.unlp.edu.ar *Corresponding author Abstract: This study presents results at a local scale of the impact of pesticide aerial applications containing a mixture of endosulphan and cypermethrin on anurans assessed by means of field evaluations. Additionally, effects were compared with laboratory toxicity tests in standardised conditions. Field assessment with native population allowed the detection of dead anuran larvae of the species present in the stream of water after fumigation, in coincidence with the decrease in the frequency of live larvae (p < 0.01) from sampling nets. Cage experiments showed significant differences (p < 0.01) in anuran larvae survival before and after fumigations. Laboratory acute toxicity tests with endosulphan formulation demonstrated sublethal symptoms in Hypsiboas pulchellus larvae 24 h after initial exposure time. The 96 h LC-50 was 0.13 µg endosulphan/litre, which is over 1000 times lower than the cypermethrin LC-50 value. Endosulphan seems to be the insecticide responsible for the drastic effects on anuran larvae detected in the field during studied events. Keywords: anuran; tadpoles; soya bean; endosulphan; cypermethrin; acute toxicity; Hypsiboas pulchellus; Rhinella fernandezae; Leptodactylus latinasus; field assessments; caged toxicity tests; laboratory toxicity tests. Reference to this paper should be made as follows: Agostini, M.G., Natale, G.S. and Ronco, A.E. (2009) ‘Impact of endosulphan and cypermethrin mixture on amphibians under field use for biotech soya bean production’, Int. J. Environment and Health, Vol. 3, No. 4, pp.379–389. Biographical notes: M. Gabriela Agostini is a graduate student of Biology at the National University of La Plata, Argentina, and at present a fellowship holder of the National Research Council. Her field of research is in amphibian ecotoxicology, with particular attention to the study of native populations of agroecosystems of the Pampas region. She is a Teaching Assistant in Statistics and Zoology of Vertebrates in the Faculty of Natural Sciences of the National University of La Plata.