Lethal and sublethal effects of the commercial formulation Zero® (5% lambda-cyhalothrin) on tadpoles of Ceratophrys ornata

BARRETO, E.; PANTUCCI, M.; RIMOLDI, F.; SALGADO COSTA C.; VENTURINO A.; NATALE G. S.

Capital Federal

Jornada; XX Jornadas Anuales Multidisciplinarias de la SAB ?Nanotecnología: pequeñas soluciones para grandes problemas; 2018

Sociedad Argentina de Biología

Lambda-cyhalothrin (LCT) is a synthetic pyrethroid insecticide commonly used in the pampean region (central eastern Argentina) to control agricultural pests, and it is classified as very toxic to aquatic organisms. The effects of this insecticide on non-target biota have been reported meanly in invertebrates and fishes. This study assessed lethal and sublethal effects of the commercial product Zero® (5% of LCT) on the tadpoles of the native horned frog Ceratophrys ornata. Spawning was induced by the Amphiplex method and eggs were maintained in plastic trays until individuals reached Gosner stage 31. The experimental design consisted of exposing organisms individually in 200 ml glass chambers during 96 h. Final nominal LCT concentrations ranged from 0.01 to 2.5 ug/L and all solutions were fully renewed every 24 h. Tests included 10 replicates per concentration and a negative control group (water without insecticide). Lethal and sublethal endpoints were recorded every 24 h, including mortality, swimming activity and the presence of morphologic abnormalities. Also, tadpoles were recorded at 96 h of exposure, while emitting sounds, in an acoustic room and with a calibrated system (directional microphone connected to an audio plate). For each recorded sound, three bioacoustic variables were determined: sound duration (s), number of pulses and dominant frequency (Hz). The LC-50/EC-50, LOEC and NOEC for each endpoint were obtained by PROBIT analysis. One-way ANOVA with Dunnett tests were performed to compare treatments with the control group. Results showed significant high sensitivity (p < 0.05) of C. ornata to this insecticide compared with other anuran species like Xenopus laevis and Boana pulchella (unpublished data). Bioacoustic effects were detected at lower concentrations than other endpoints. This study provides evidence in favor of using the species as a valid model in ecotoxicology. We suggest that tadpole vocalizations are a sensitive and useful non-lethal endpoint to evaluate the effects of very toxic insecticides.