Acute toxicity of two carbamates to the Guppy (Poecilia reticulata) and the Zebrafish (Brachydanio rerio)

In this study the acute toxicity of two carbamate pesticides, Carbaryl and Aldicarb, to the Guppy and the Zebrafish has been separately assessed with 96-h toxicity tests, performed using a semistatic procedure according to EEC guidelines. There was no significant difference in the toxicity of Aldicarb and Carbaryl to the Zebrafish, but Aldicarb was ∼ 4 times more toxic than Carbaryl to the Guppy. Moreover, the toxicity of both carbamates was higher to the Guppy than to the Zebrafish. Values for the 96-h LC50 obtained with Aldicarb were 52.9 μmol/l for the Zebrafish and 3.5 μmol/l for the Guppy. LC50 values obtained with Carbaryl were 46.0 μmol/l for the Zebrafish and 12.5 μmol/l for the Guppy. Analysis of test substance concentrations in the test system demonstrated, for each substance, a loss during each 24-h exposure period. In spite of the variability observed, the losses of Carbaryl appeared independent of time, whereas the losses of Aldicarb were higher during the initial exposure days. In addition, there was an indication that the rate of loss observed with both substances was greater in the presence of the Guppy than in the presence of the Zebrafish.