Mortality and toxicity of a commercial formulation of cypermethrin in Physalaemus gracilis tadpoles

Abstract

This study evaluated the lethal, sublethal, and toxic of a commercial formulation of cypermethrin in the anuran species Physalaemus gracilis. In the acute test, concentrations of 100-800 μg L^-1 were tested over 96 h. In the chronic test, cypermethrin concentrations recorded in nature (1, 3, 6, and 20 μg L^-1) were tested for mortality and then used for the micronucleus test and erythrocyte nuclear abnormalities over a 7-days period. The LC₅₀ determined for P. gracilis for the commercial cypermethrin formulation was 273.41 μg L^-1. In the chronic test, a mortality of more than 50% was observed at the highest concentration (20 μg L^-1), as it caused half of the tadpoles studied to die. The micronucleus test showed significant results at concentrations of 6 and 20 μg L^-1 and recorded the presence of several nuclear abnormalities, indicating the genotoxic potential of the commercial cypermethrin formulation for P. gracilis. Cypermethrin presented a high risk to the species, indicating that it has the potential to cause several problems in the short and long term and to affect the dynamics of this ecosystem. Therefore, it can be concluded that the commercial formulation of cypermethrin had toxicological effects on P. gracilis.

Figure 1

Cumulative mortality (%) of P. gracilis tadpoles exposed to different concentrations of the commercial formulation of cypermethrin during the acute test.

Figure 2

Cumulative mortality (%) of P. gracilis tadpoles exposed to different concentrations of the commercial formulation of cypermethrin during the chronic test.

Figure 3

Micronucleus and erythrocyte nuclear abnormalities in P. gracilis tadpoles exposed to concentrations of the commercial formulation of cypermethrin. (A; control) cells with normal nuclei, (B) cell with micronucleus; (C) cells with apoptosis; (D) binucleated cell; (E) cell with bubble or bud; (F) cells with karyolysis; (G) notched cell; (H) lobed cells; (I) cells with microcytosis.