Richness and density of aquatic benthic macroinvertebrates after exposure to fungicides and insecticides in rice paddy elds

The objective of this study was to verify the richness and density of aquatic benthic macroinvertebrates after exposure to fungicides and insecticides of the rice paddy elds. In the crop seasons of 2012/13 and 2013/14, eld experiments were performed, which consisted of single-dose applications of the fungicides tri oxystrobin + tebuconazole and tricyclazole, and the insecticides lambda-cyhalothrin + thiamethoxam and di ubenzuron, in 10 m experimental plots, over rice plants in the R3 stage. Control plots with and without rice plants were maintained in order to simulate a natural environment. Soil samples were collected during rice cultivation for assessment of the macroinvertebrate fauna. Chemical-physical parameters assessed in the experiments included temperature, pH and oxygen dissolved in the water and pesticide persistence in the water and in the soil. The application of a single dose of the pesticides and fungicides in the recommended period does not cause signi cant negative e ects over the richness and density of the macroinvertebrates. Tebuconazole, tricyclazole and thiamethoxam showed high persistence in the irrigation water of rice paddy elds. Thus, the doses and number of applications of these products in crops should be carefully handled in order to avoid contamination of the environment.