Toxicity of Organophosphate Insecticide Abate® to Larvaes of Poecilia reticulata

The pesticide Abate®, which contains 1% of organophosphate temephos as active ingredient, has been used to control the larva of the mosquito responsible for dengue. However, little information is available about the impact of this pesticide in the aquatic environment. This study evaluated the effect of the Abate® on the survival of larvaes of Poecilia reticulata, a larvivorous fish that serves as biological control of Aedes aegypti. In order to estimate the lethal time for 50% of exposed larvae (LT50), the organisms were exposed to five treatments (0.0; 0.375; 0.5; 0.625 and 0.750 mg.L-1 of Abate®) with nine replicates each. Concentrations equal or higher than 0.375 mg.L-1 of Abate® showed to be lethal to larvaes of P. reticulata. LT50 was estimated for the 2nd larvae was 239 ± 41 minutes for a concentration of 0.750 mg.L-1 and 401 ± 104 minutes for 0.375mg.L-1. In addition, larvaes that survived to the Abate® exposure presented mortality after transference to clean water, indicating a possible residual effect of the insecticide. Keywords: Organophosphorus pesticides, Poecilia reticulata, LT50